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[/] [openrisc/] [trunk/] [gnu-src/] [gdb-7.1/] [gdb/] [frame.c] - Rev 553
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/* Cache and manage frames for GDB, the GNU debugger. Copyright (C) 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000, 2001, 2002, 2003, 2004, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. This file is part of GDB. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include "defs.h" #include "frame.h" #include "target.h" #include "value.h" #include "inferior.h" /* for inferior_ptid */ #include "regcache.h" #include "gdb_assert.h" #include "gdb_string.h" #include "user-regs.h" #include "gdb_obstack.h" #include "dummy-frame.h" #include "sentinel-frame.h" #include "gdbcore.h" #include "annotate.h" #include "language.h" #include "frame-unwind.h" #include "frame-base.h" #include "command.h" #include "gdbcmd.h" #include "observer.h" #include "objfiles.h" #include "exceptions.h" #include "gdbthread.h" #include "block.h" #include "inline-frame.h" static struct frame_info *get_prev_frame_1 (struct frame_info *this_frame); static struct frame_info *get_prev_frame_raw (struct frame_info *this_frame); /* We keep a cache of stack frames, each of which is a "struct frame_info". The innermost one gets allocated (in wait_for_inferior) each time the inferior stops; current_frame points to it. Additional frames get allocated (in get_prev_frame) as needed, and are chained through the next and prev fields. Any time that the frame cache becomes invalid (most notably when we execute something, but also if we change how we interpret the frames (e.g. "set heuristic-fence-post" in mips-tdep.c, or anything which reads new symbols)), we should call reinit_frame_cache. */ struct frame_info { /* Level of this frame. The inner-most (youngest) frame is at level 0. As you move towards the outer-most (oldest) frame, the level increases. This is a cached value. It could just as easily be computed by counting back from the selected frame to the inner most frame. */ /* NOTE: cagney/2002-04-05: Perhaps a level of ``-1'' should be reserved to indicate a bogus frame - one that has been created just to keep GDB happy (GDB always needs a frame). For the moment leave this as speculation. */ int level; /* The frame's program space. */ struct program_space *pspace; /* The frame's address space. */ struct address_space *aspace; /* The frame's low-level unwinder and corresponding cache. The low-level unwinder is responsible for unwinding register values for the previous frame. The low-level unwind methods are selected based on the presence, or otherwise, of register unwind information such as CFI. */ void *prologue_cache; const struct frame_unwind *unwind; /* Cached copy of the previous frame's architecture. */ struct { int p; struct gdbarch *arch; } prev_arch; /* Cached copy of the previous frame's resume address. */ struct { int p; CORE_ADDR value; } prev_pc; /* Cached copy of the previous frame's function address. */ struct { CORE_ADDR addr; int p; } prev_func; /* This frame's ID. */ struct { int p; struct frame_id value; } this_id; /* The frame's high-level base methods, and corresponding cache. The high level base methods are selected based on the frame's debug info. */ const struct frame_base *base; void *base_cache; /* Pointers to the next (down, inner, younger) and previous (up, outer, older) frame_info's in the frame cache. */ struct frame_info *next; /* down, inner, younger */ int prev_p; struct frame_info *prev; /* up, outer, older */ /* The reason why we could not set PREV, or UNWIND_NO_REASON if we could. Only valid when PREV_P is set. */ enum unwind_stop_reason stop_reason; }; /* A frame stash used to speed up frame lookups. */ /* We currently only stash one frame at a time, as this seems to be sufficient for now. */ static struct frame_info *frame_stash = NULL; /* Add the following FRAME to the frame stash. */ static void frame_stash_add (struct frame_info *frame) { frame_stash = frame; } /* Search the frame stash for an entry with the given frame ID. If found, return that frame. Otherwise return NULL. */ static struct frame_info * frame_stash_find (struct frame_id id) { if (frame_stash && frame_id_eq (frame_stash->this_id.value, id)) return frame_stash; return NULL; } /* Invalidate the frame stash by removing all entries in it. */ static void frame_stash_invalidate (void) { frame_stash = NULL; } /* Flag to control debugging. */ int frame_debug; static void show_frame_debug (struct ui_file *file, int from_tty, struct cmd_list_element *c, const char *value) { fprintf_filtered (file, _("Frame debugging is %s.\n"), value); } /* Flag to indicate whether backtraces should stop at main et.al. */ static int backtrace_past_main; static void show_backtrace_past_main (struct ui_file *file, int from_tty, struct cmd_list_element *c, const char *value) { fprintf_filtered (file, _("\ Whether backtraces should continue past \"main\" is %s.\n"), value); } static int backtrace_past_entry; static void show_backtrace_past_entry (struct ui_file *file, int from_tty, struct cmd_list_element *c, const char *value) { fprintf_filtered (file, _("\ Whether backtraces should continue past the entry point of a program is %s.\n"), value); } static int backtrace_limit = INT_MAX; static void show_backtrace_limit (struct ui_file *file, int from_tty, struct cmd_list_element *c, const char *value) { fprintf_filtered (file, _("\ An upper bound on the number of backtrace levels is %s.\n"), value); } static void fprint_field (struct ui_file *file, const char *name, int p, CORE_ADDR addr) { if (p) fprintf_unfiltered (file, "%s=%s", name, hex_string (addr)); else fprintf_unfiltered (file, "!%s", name); } void fprint_frame_id (struct ui_file *file, struct frame_id id) { fprintf_unfiltered (file, "{"); fprint_field (file, "stack", id.stack_addr_p, id.stack_addr); fprintf_unfiltered (file, ","); fprint_field (file, "code", id.code_addr_p, id.code_addr); fprintf_unfiltered (file, ","); fprint_field (file, "special", id.special_addr_p, id.special_addr); if (id.inline_depth) fprintf_unfiltered (file, ",inlined=%d", id.inline_depth); fprintf_unfiltered (file, "}"); } static void fprint_frame_type (struct ui_file *file, enum frame_type type) { switch (type) { case NORMAL_FRAME: fprintf_unfiltered (file, "NORMAL_FRAME"); return; case DUMMY_FRAME: fprintf_unfiltered (file, "DUMMY_FRAME"); return; case INLINE_FRAME: fprintf_unfiltered (file, "INLINE_FRAME"); return; case SENTINEL_FRAME: fprintf_unfiltered (file, "SENTINEL_FRAME"); return; case SIGTRAMP_FRAME: fprintf_unfiltered (file, "SIGTRAMP_FRAME"); return; case ARCH_FRAME: fprintf_unfiltered (file, "ARCH_FRAME"); return; default: fprintf_unfiltered (file, "<unknown type>"); return; }; } static void fprint_frame (struct ui_file *file, struct frame_info *fi) { if (fi == NULL) { fprintf_unfiltered (file, "<NULL frame>"); return; } fprintf_unfiltered (file, "{"); fprintf_unfiltered (file, "level=%d", fi->level); fprintf_unfiltered (file, ","); fprintf_unfiltered (file, "type="); if (fi->unwind != NULL) fprint_frame_type (file, fi->unwind->type); else fprintf_unfiltered (file, "<unknown>"); fprintf_unfiltered (file, ","); fprintf_unfiltered (file, "unwind="); if (fi->unwind != NULL) gdb_print_host_address (fi->unwind, file); else fprintf_unfiltered (file, "<unknown>"); fprintf_unfiltered (file, ","); fprintf_unfiltered (file, "pc="); if (fi->next != NULL && fi->next->prev_pc.p) fprintf_unfiltered (file, "%s", hex_string (fi->next->prev_pc.value)); else fprintf_unfiltered (file, "<unknown>"); fprintf_unfiltered (file, ","); fprintf_unfiltered (file, "id="); if (fi->this_id.p) fprint_frame_id (file, fi->this_id.value); else fprintf_unfiltered (file, "<unknown>"); fprintf_unfiltered (file, ","); fprintf_unfiltered (file, "func="); if (fi->next != NULL && fi->next->prev_func.p) fprintf_unfiltered (file, "%s", hex_string (fi->next->prev_func.addr)); else fprintf_unfiltered (file, "<unknown>"); fprintf_unfiltered (file, "}"); } /* Given FRAME, return the enclosing normal frame for inlined function frames. Otherwise return the original frame. */ static struct frame_info * skip_inlined_frames (struct frame_info *frame) { while (get_frame_type (frame) == INLINE_FRAME) frame = get_prev_frame (frame); return frame; } /* Return a frame uniq ID that can be used to, later, re-find the frame. */ struct frame_id get_frame_id (struct frame_info *fi) { if (fi == NULL) return null_frame_id; if (!fi->this_id.p) { if (frame_debug) fprintf_unfiltered (gdb_stdlog, "{ get_frame_id (fi=%d) ", fi->level); /* Find the unwinder. */ if (fi->unwind == NULL) fi->unwind = frame_unwind_find_by_frame (fi, &fi->prologue_cache); /* Find THIS frame's ID. */ /* Default to outermost if no ID is found. */ fi->this_id.value = outer_frame_id; fi->unwind->this_id (fi, &fi->prologue_cache, &fi->this_id.value); gdb_assert (frame_id_p (fi->this_id.value)); fi->this_id.p = 1; if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame_id (gdb_stdlog, fi->this_id.value); fprintf_unfiltered (gdb_stdlog, " }\n"); } } frame_stash_add (fi); return fi->this_id.value; } struct frame_id get_stack_frame_id (struct frame_info *next_frame) { return get_frame_id (skip_inlined_frames (next_frame)); } struct frame_id frame_unwind_caller_id (struct frame_info *next_frame) { struct frame_info *this_frame; /* Use get_prev_frame_1, and not get_prev_frame. The latter will truncate the frame chain, leading to this function unintentionally returning a null_frame_id (e.g., when a caller requests the frame ID of "main()"s caller. */ next_frame = skip_inlined_frames (next_frame); this_frame = get_prev_frame_1 (next_frame); if (this_frame) return get_frame_id (skip_inlined_frames (this_frame)); else return null_frame_id; } const struct frame_id null_frame_id; /* All zeros. */ const struct frame_id outer_frame_id = { 0, 0, 0, 0, 0, 1, 0 }; struct frame_id frame_id_build_special (CORE_ADDR stack_addr, CORE_ADDR code_addr, CORE_ADDR special_addr) { struct frame_id id = null_frame_id; id.stack_addr = stack_addr; id.stack_addr_p = 1; id.code_addr = code_addr; id.code_addr_p = 1; id.special_addr = special_addr; id.special_addr_p = 1; return id; } struct frame_id frame_id_build (CORE_ADDR stack_addr, CORE_ADDR code_addr) { struct frame_id id = null_frame_id; id.stack_addr = stack_addr; id.stack_addr_p = 1; id.code_addr = code_addr; id.code_addr_p = 1; return id; } struct frame_id frame_id_build_wild (CORE_ADDR stack_addr) { struct frame_id id = null_frame_id; id.stack_addr = stack_addr; id.stack_addr_p = 1; return id; } int frame_id_p (struct frame_id l) { int p; /* The frame is valid iff it has a valid stack address. */ p = l.stack_addr_p; /* outer_frame_id is also valid. */ if (!p && memcmp (&l, &outer_frame_id, sizeof (l)) == 0) p = 1; if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ frame_id_p (l="); fprint_frame_id (gdb_stdlog, l); fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", p); } return p; } int frame_id_inlined_p (struct frame_id l) { if (!frame_id_p (l)) return 0; return (l.inline_depth != 0); } int frame_id_eq (struct frame_id l, struct frame_id r) { int eq; if (!l.stack_addr_p && l.special_addr_p && !r.stack_addr_p && r.special_addr_p) /* The outermost frame marker is equal to itself. This is the dodgy thing about outer_frame_id, since between execution steps we might step into another function - from which we can't unwind either. More thought required to get rid of outer_frame_id. */ eq = 1; else if (!l.stack_addr_p || !r.stack_addr_p) /* Like a NaN, if either ID is invalid, the result is false. Note that a frame ID is invalid iff it is the null frame ID. */ eq = 0; else if (l.stack_addr != r.stack_addr) /* If .stack addresses are different, the frames are different. */ eq = 0; else if (l.code_addr_p && r.code_addr_p && l.code_addr != r.code_addr) /* An invalid code addr is a wild card. If .code addresses are different, the frames are different. */ eq = 0; else if (l.special_addr_p && r.special_addr_p && l.special_addr != r.special_addr) /* An invalid special addr is a wild card (or unused). Otherwise if special addresses are different, the frames are different. */ eq = 0; else if (l.inline_depth != r.inline_depth) /* If inline depths are different, the frames must be different. */ eq = 0; else /* Frames are equal. */ eq = 1; if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ frame_id_eq (l="); fprint_frame_id (gdb_stdlog, l); fprintf_unfiltered (gdb_stdlog, ",r="); fprint_frame_id (gdb_stdlog, r); fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", eq); } return eq; } /* Safety net to check whether frame ID L should be inner to frame ID R, according to their stack addresses. This method cannot be used to compare arbitrary frames, as the ranges of valid stack addresses may be discontiguous (e.g. due to sigaltstack). However, it can be used as safety net to discover invalid frame IDs in certain circumstances. Assuming that NEXT is the immediate inner frame to THIS and that NEXT and THIS are both NORMAL frames: * The stack address of NEXT must be inner-than-or-equal to the stack address of THIS. Therefore, if frame_id_inner (THIS, NEXT) holds, some unwind error has occurred. * If NEXT and THIS have different stack addresses, no other frame in the frame chain may have a stack address in between. Therefore, if frame_id_inner (TEST, THIS) holds, but frame_id_inner (TEST, NEXT) does not hold, TEST cannot refer to a valid frame in the frame chain. The sanity checks above cannot be performed when a SIGTRAMP frame is involved, because signal handlers might be executed on a different stack than the stack used by the routine that caused the signal to be raised. This can happen for instance when a thread exceeds its maximum stack size. In this case, certain compilers implement a stack overflow strategy that cause the handler to be run on a different stack. */ static int frame_id_inner (struct gdbarch *gdbarch, struct frame_id l, struct frame_id r) { int inner; if (!l.stack_addr_p || !r.stack_addr_p) /* Like NaN, any operation involving an invalid ID always fails. */ inner = 0; else if (l.inline_depth > r.inline_depth && l.stack_addr == r.stack_addr && l.code_addr_p == r.code_addr_p && l.special_addr_p == r.special_addr_p && l.special_addr == r.special_addr) { /* Same function, different inlined functions. */ struct block *lb, *rb; gdb_assert (l.code_addr_p && r.code_addr_p); lb = block_for_pc (l.code_addr); rb = block_for_pc (r.code_addr); if (lb == NULL || rb == NULL) /* Something's gone wrong. */ inner = 0; else /* This will return true if LB and RB are the same block, or if the block with the smaller depth lexically encloses the block with the greater depth. */ inner = contained_in (lb, rb); } else /* Only return non-zero when strictly inner than. Note that, per comment in "frame.h", there is some fuzz here. Frameless functions are not strictly inner than (same .stack but different .code and/or .special address). */ inner = gdbarch_inner_than (gdbarch, l.stack_addr, r.stack_addr); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ frame_id_inner (l="); fprint_frame_id (gdb_stdlog, l); fprintf_unfiltered (gdb_stdlog, ",r="); fprint_frame_id (gdb_stdlog, r); fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", inner); } return inner; } struct frame_info * frame_find_by_id (struct frame_id id) { struct frame_info *frame, *prev_frame; /* ZERO denotes the null frame, let the caller decide what to do about it. Should it instead return get_current_frame()? */ if (!frame_id_p (id)) return NULL; /* Try using the frame stash first. Finding it there removes the need to perform the search by looping over all frames, which can be very CPU-intensive if the number of frames is very high (the loop is O(n) and get_prev_frame performs a series of checks that are relatively expensive). This optimization is particularly useful when this function is called from another function (such as value_fetch_lazy, case VALUE_LVAL (val) == lval_register) which already loops over all frames, making the overall behavior O(n^2). */ frame = frame_stash_find (id); if (frame) return frame; for (frame = get_current_frame (); ; frame = prev_frame) { struct frame_id this = get_frame_id (frame); if (frame_id_eq (id, this)) /* An exact match. */ return frame; prev_frame = get_prev_frame (frame); if (!prev_frame) return NULL; /* As a safety net to avoid unnecessary backtracing while trying to find an invalid ID, we check for a common situation where we can detect from comparing stack addresses that no other frame in the current frame chain can have this ID. See the comment at frame_id_inner for details. */ if (get_frame_type (frame) == NORMAL_FRAME && !frame_id_inner (get_frame_arch (frame), id, this) && frame_id_inner (get_frame_arch (prev_frame), id, get_frame_id (prev_frame))) return NULL; } return NULL; } static CORE_ADDR frame_unwind_pc (struct frame_info *this_frame) { if (!this_frame->prev_pc.p) { CORE_ADDR pc; if (gdbarch_unwind_pc_p (frame_unwind_arch (this_frame))) { /* The right way. The `pure' way. The one true way. This method depends solely on the register-unwind code to determine the value of registers in THIS frame, and hence the value of this frame's PC (resume address). A typical implementation is no more than: frame_unwind_register (this_frame, ISA_PC_REGNUM, buf); return extract_unsigned_integer (buf, size of ISA_PC_REGNUM); Note: this method is very heavily dependent on a correct register-unwind implementation, it pays to fix that method first; this method is frame type agnostic, since it only deals with register values, it works with any frame. This is all in stark contrast to the old FRAME_SAVED_PC which would try to directly handle all the different ways that a PC could be unwound. */ pc = gdbarch_unwind_pc (frame_unwind_arch (this_frame), this_frame); } else internal_error (__FILE__, __LINE__, _("No unwind_pc method")); this_frame->prev_pc.value = pc; this_frame->prev_pc.p = 1; if (frame_debug) fprintf_unfiltered (gdb_stdlog, "{ frame_unwind_caller_pc (this_frame=%d) -> %s }\n", this_frame->level, hex_string (this_frame->prev_pc.value)); } return this_frame->prev_pc.value; } CORE_ADDR frame_unwind_caller_pc (struct frame_info *this_frame) { return frame_unwind_pc (skip_inlined_frames (this_frame)); } CORE_ADDR get_frame_func (struct frame_info *this_frame) { struct frame_info *next_frame = this_frame->next; if (!next_frame->prev_func.p) { /* Make certain that this, and not the adjacent, function is found. */ CORE_ADDR addr_in_block = get_frame_address_in_block (this_frame); next_frame->prev_func.p = 1; next_frame->prev_func.addr = get_pc_function_start (addr_in_block); if (frame_debug) fprintf_unfiltered (gdb_stdlog, "{ get_frame_func (this_frame=%d) -> %s }\n", this_frame->level, hex_string (next_frame->prev_func.addr)); } return next_frame->prev_func.addr; } static int do_frame_register_read (void *src, int regnum, gdb_byte *buf) { return frame_register_read (src, regnum, buf); } struct regcache * frame_save_as_regcache (struct frame_info *this_frame) { struct address_space *aspace = get_frame_address_space (this_frame); struct regcache *regcache = regcache_xmalloc (get_frame_arch (this_frame), aspace); struct cleanup *cleanups = make_cleanup_regcache_xfree (regcache); regcache_save (regcache, do_frame_register_read, this_frame); discard_cleanups (cleanups); return regcache; } void frame_pop (struct frame_info *this_frame) { struct frame_info *prev_frame; struct regcache *scratch; struct cleanup *cleanups; if (get_frame_type (this_frame) == DUMMY_FRAME) { /* Popping a dummy frame involves restoring more than just registers. dummy_frame_pop does all the work. */ dummy_frame_pop (get_frame_id (this_frame)); return; } /* Ensure that we have a frame to pop to. */ prev_frame = get_prev_frame_1 (this_frame); if (!prev_frame) error (_("Cannot pop the initial frame.")); /* Make a copy of all the register values unwound from this frame. Save them in a scratch buffer so that there isn't a race between trying to extract the old values from the current regcache while at the same time writing new values into that same cache. */ scratch = frame_save_as_regcache (prev_frame); cleanups = make_cleanup_regcache_xfree (scratch); /* FIXME: cagney/2003-03-16: It should be possible to tell the target's register cache that it is about to be hit with a burst register transfer and that the sequence of register writes should be batched. The pair target_prepare_to_store() and target_store_registers() kind of suggest this functionality. Unfortunately, they don't implement it. Their lack of a formal definition can lead to targets writing back bogus values (arguably a bug in the target code mind). */ /* Now copy those saved registers into the current regcache. Here, regcache_cpy() calls regcache_restore(). */ regcache_cpy (get_current_regcache (), scratch); do_cleanups (cleanups); /* We've made right mess of GDB's local state, just discard everything. */ reinit_frame_cache (); } void frame_register_unwind (struct frame_info *frame, int regnum, int *optimizedp, enum lval_type *lvalp, CORE_ADDR *addrp, int *realnump, gdb_byte *bufferp) { struct value *value; /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates that the value proper does not need to be fetched. */ gdb_assert (optimizedp != NULL); gdb_assert (lvalp != NULL); gdb_assert (addrp != NULL); gdb_assert (realnump != NULL); /* gdb_assert (bufferp != NULL); */ value = frame_unwind_register_value (frame, regnum); gdb_assert (value != NULL); *optimizedp = value_optimized_out (value); *lvalp = VALUE_LVAL (value); *addrp = value_address (value); *realnump = VALUE_REGNUM (value); if (bufferp) memcpy (bufferp, value_contents_all (value), TYPE_LENGTH (value_type (value))); /* Dispose of the new value. This prevents watchpoints from trying to watch the saved frame pointer. */ release_value (value); value_free (value); } void frame_register (struct frame_info *frame, int regnum, int *optimizedp, enum lval_type *lvalp, CORE_ADDR *addrp, int *realnump, gdb_byte *bufferp) { /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates that the value proper does not need to be fetched. */ gdb_assert (optimizedp != NULL); gdb_assert (lvalp != NULL); gdb_assert (addrp != NULL); gdb_assert (realnump != NULL); /* gdb_assert (bufferp != NULL); */ /* Obtain the register value by unwinding the register from the next (more inner frame). */ gdb_assert (frame != NULL && frame->next != NULL); frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp, realnump, bufferp); } void frame_unwind_register (struct frame_info *frame, int regnum, gdb_byte *buf) { int optimized; CORE_ADDR addr; int realnum; enum lval_type lval; frame_register_unwind (frame, regnum, &optimized, &lval, &addr, &realnum, buf); } void get_frame_register (struct frame_info *frame, int regnum, gdb_byte *buf) { frame_unwind_register (frame->next, regnum, buf); } struct value * frame_unwind_register_value (struct frame_info *frame, int regnum) { struct gdbarch *gdbarch; struct value *value; gdb_assert (frame != NULL); gdbarch = frame_unwind_arch (frame); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "\ { frame_unwind_register_value (frame=%d,regnum=%d(%s),...) ", frame->level, regnum, user_reg_map_regnum_to_name (gdbarch, regnum)); } /* Find the unwinder. */ if (frame->unwind == NULL) frame->unwind = frame_unwind_find_by_frame (frame, &frame->prologue_cache); /* Ask this frame to unwind its register. */ value = frame->unwind->prev_register (frame, &frame->prologue_cache, regnum); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "->"); if (value_optimized_out (value)) fprintf_unfiltered (gdb_stdlog, " optimized out"); else { if (VALUE_LVAL (value) == lval_register) fprintf_unfiltered (gdb_stdlog, " register=%d", VALUE_REGNUM (value)); else if (VALUE_LVAL (value) == lval_memory) fprintf_unfiltered (gdb_stdlog, " address=%s", paddress (gdbarch, value_address (value))); else fprintf_unfiltered (gdb_stdlog, " computed"); if (value_lazy (value)) fprintf_unfiltered (gdb_stdlog, " lazy"); else { int i; const gdb_byte *buf = value_contents (value); fprintf_unfiltered (gdb_stdlog, " bytes="); fprintf_unfiltered (gdb_stdlog, "["); for (i = 0; i < register_size (gdbarch, regnum); i++) fprintf_unfiltered (gdb_stdlog, "%02x", buf[i]); fprintf_unfiltered (gdb_stdlog, "]"); } } fprintf_unfiltered (gdb_stdlog, " }\n"); } return value; } struct value * get_frame_register_value (struct frame_info *frame, int regnum) { return frame_unwind_register_value (frame->next, regnum); } LONGEST frame_unwind_register_signed (struct frame_info *frame, int regnum) { struct gdbarch *gdbarch = frame_unwind_arch (frame); enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); int size = register_size (gdbarch, regnum); gdb_byte buf[MAX_REGISTER_SIZE]; frame_unwind_register (frame, regnum, buf); return extract_signed_integer (buf, size, byte_order); } LONGEST get_frame_register_signed (struct frame_info *frame, int regnum) { return frame_unwind_register_signed (frame->next, regnum); } ULONGEST frame_unwind_register_unsigned (struct frame_info *frame, int regnum) { struct gdbarch *gdbarch = frame_unwind_arch (frame); enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); int size = register_size (gdbarch, regnum); gdb_byte buf[MAX_REGISTER_SIZE]; frame_unwind_register (frame, regnum, buf); return extract_unsigned_integer (buf, size, byte_order); } ULONGEST get_frame_register_unsigned (struct frame_info *frame, int regnum) { return frame_unwind_register_unsigned (frame->next, regnum); } void put_frame_register (struct frame_info *frame, int regnum, const gdb_byte *buf) { struct gdbarch *gdbarch = get_frame_arch (frame); int realnum; int optim; enum lval_type lval; CORE_ADDR addr; frame_register (frame, regnum, &optim, &lval, &addr, &realnum, NULL); if (optim) error (_("Attempt to assign to a value that was optimized out.")); switch (lval) { case lval_memory: { /* FIXME: write_memory doesn't yet take constant buffers. Arrrg! */ gdb_byte tmp[MAX_REGISTER_SIZE]; memcpy (tmp, buf, register_size (gdbarch, regnum)); write_memory (addr, tmp, register_size (gdbarch, regnum)); break; } case lval_register: regcache_cooked_write (get_current_regcache (), realnum, buf); break; default: error (_("Attempt to assign to an unmodifiable value.")); } } /* frame_register_read () Find and return the value of REGNUM for the specified stack frame. The number of bytes copied is REGISTER_SIZE (REGNUM). Returns 0 if the register value could not be found. */ int frame_register_read (struct frame_info *frame, int regnum, gdb_byte *myaddr) { int optimized; enum lval_type lval; CORE_ADDR addr; int realnum; frame_register (frame, regnum, &optimized, &lval, &addr, &realnum, myaddr); return !optimized; } int get_frame_register_bytes (struct frame_info *frame, int regnum, CORE_ADDR offset, int len, gdb_byte *myaddr) { struct gdbarch *gdbarch = get_frame_arch (frame); int i; int maxsize; int numregs; /* Skip registers wholly inside of OFFSET. */ while (offset >= register_size (gdbarch, regnum)) { offset -= register_size (gdbarch, regnum); regnum++; } /* Ensure that we will not read beyond the end of the register file. This can only ever happen if the debug information is bad. */ maxsize = -offset; numregs = gdbarch_num_regs (gdbarch) + gdbarch_num_pseudo_regs (gdbarch); for (i = regnum; i < numregs; i++) { int thissize = register_size (gdbarch, i); if (thissize == 0) break; /* This register is not available on this architecture. */ maxsize += thissize; } if (len > maxsize) { warning (_("Bad debug information detected: " "Attempt to read %d bytes from registers."), len); return 0; } /* Copy the data. */ while (len > 0) { int curr_len = register_size (gdbarch, regnum) - offset; if (curr_len > len) curr_len = len; if (curr_len == register_size (gdbarch, regnum)) { if (!frame_register_read (frame, regnum, myaddr)) return 0; } else { gdb_byte buf[MAX_REGISTER_SIZE]; if (!frame_register_read (frame, regnum, buf)) return 0; memcpy (myaddr, buf + offset, curr_len); } myaddr += curr_len; len -= curr_len; offset = 0; regnum++; } return 1; } void put_frame_register_bytes (struct frame_info *frame, int regnum, CORE_ADDR offset, int len, const gdb_byte *myaddr) { struct gdbarch *gdbarch = get_frame_arch (frame); /* Skip registers wholly inside of OFFSET. */ while (offset >= register_size (gdbarch, regnum)) { offset -= register_size (gdbarch, regnum); regnum++; } /* Copy the data. */ while (len > 0) { int curr_len = register_size (gdbarch, regnum) - offset; if (curr_len > len) curr_len = len; if (curr_len == register_size (gdbarch, regnum)) { put_frame_register (frame, regnum, myaddr); } else { gdb_byte buf[MAX_REGISTER_SIZE]; frame_register_read (frame, regnum, buf); memcpy (buf + offset, myaddr, curr_len); put_frame_register (frame, regnum, buf); } myaddr += curr_len; len -= curr_len; offset = 0; regnum++; } } /* Create a sentinel frame. */ static struct frame_info * create_sentinel_frame (struct program_space *pspace, struct regcache *regcache) { struct frame_info *frame = FRAME_OBSTACK_ZALLOC (struct frame_info); frame->level = -1; frame->pspace = pspace; frame->aspace = get_regcache_aspace (regcache); /* Explicitly initialize the sentinel frame's cache. Provide it with the underlying regcache. In the future additional information, such as the frame's thread will be added. */ frame->prologue_cache = sentinel_frame_cache (regcache); /* For the moment there is only one sentinel frame implementation. */ frame->unwind = sentinel_frame_unwind; /* Link this frame back to itself. The frame is self referential (the unwound PC is the same as the pc), so make it so. */ frame->next = frame; /* Make the sentinel frame's ID valid, but invalid. That way all comparisons with it should fail. */ frame->this_id.p = 1; frame->this_id.value = null_frame_id; if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ create_sentinel_frame (...) -> "); fprint_frame (gdb_stdlog, frame); fprintf_unfiltered (gdb_stdlog, " }\n"); } return frame; } /* Info about the innermost stack frame (contents of FP register) */ static struct frame_info *current_frame; /* Cache for frame addresses already read by gdb. Valid only while inferior is stopped. Control variables for the frame cache should be local to this module. */ static struct obstack frame_cache_obstack; void * frame_obstack_zalloc (unsigned long size) { void *data = obstack_alloc (&frame_cache_obstack, size); memset (data, 0, size); return data; } /* Return the innermost (currently executing) stack frame. This is split into two functions. The function unwind_to_current_frame() is wrapped in catch exceptions so that, even when the unwind of the sentinel frame fails, the function still returns a stack frame. */ static int unwind_to_current_frame (struct ui_out *ui_out, void *args) { struct frame_info *frame = get_prev_frame (args); /* A sentinel frame can fail to unwind, e.g., because its PC value lands in somewhere like start. */ if (frame == NULL) return 1; current_frame = frame; return 0; } struct frame_info * get_current_frame (void) { /* First check, and report, the lack of registers. Having GDB report "No stack!" or "No memory" when the target doesn't even have registers is very confusing. Besides, "printcmd.exp" explicitly checks that ``print $pc'' with no registers prints "No registers". */ if (!target_has_registers) error (_("No registers.")); if (!target_has_stack) error (_("No stack.")); if (!target_has_memory) error (_("No memory.")); if (ptid_equal (inferior_ptid, null_ptid)) error (_("No selected thread.")); if (is_exited (inferior_ptid)) error (_("Invalid selected thread.")); if (is_executing (inferior_ptid)) error (_("Target is executing.")); if (current_frame == NULL) { struct frame_info *sentinel_frame = create_sentinel_frame (current_program_space, get_current_regcache ()); if (catch_exceptions (uiout, unwind_to_current_frame, sentinel_frame, RETURN_MASK_ERROR) != 0) { /* Oops! Fake a current frame? Is this useful? It has a PC of zero, for instance. */ current_frame = sentinel_frame; } } return current_frame; } /* The "selected" stack frame is used by default for local and arg access. May be zero, for no selected frame. */ static struct frame_info *selected_frame; int has_stack_frames (void) { if (!target_has_registers || !target_has_stack || !target_has_memory) return 0; /* No current inferior, no frame. */ if (ptid_equal (inferior_ptid, null_ptid)) return 0; /* Don't try to read from a dead thread. */ if (is_exited (inferior_ptid)) return 0; /* ... or from a spinning thread. */ if (is_executing (inferior_ptid)) return 0; return 1; } /* Return the selected frame. Always non-NULL (unless there isn't an inferior sufficient for creating a frame) in which case an error is thrown. */ struct frame_info * get_selected_frame (const char *message) { if (selected_frame == NULL) { if (message != NULL && !has_stack_frames ()) error (("%s"), message); /* Hey! Don't trust this. It should really be re-finding the last selected frame of the currently selected thread. This, though, is better than nothing. */ select_frame (get_current_frame ()); } /* There is always a frame. */ gdb_assert (selected_frame != NULL); return selected_frame; } /* This is a variant of get_selected_frame() which can be called when the inferior does not have a frame; in that case it will return NULL instead of calling error(). */ struct frame_info * deprecated_safe_get_selected_frame (void) { if (!has_stack_frames ()) return NULL; return get_selected_frame (NULL); } /* Select frame FI (or NULL - to invalidate the current frame). */ void select_frame (struct frame_info *fi) { struct symtab *s; selected_frame = fi; /* NOTE: cagney/2002-05-04: FI can be NULL. This occurs when the frame is being invalidated. */ if (deprecated_selected_frame_level_changed_hook) deprecated_selected_frame_level_changed_hook (frame_relative_level (fi)); /* FIXME: kseitz/2002-08-28: It would be nice to call selected_frame_level_changed_event() right here, but due to limitations in the current interfaces, we would end up flooding UIs with events because select_frame() is used extensively internally. Once we have frame-parameterized frame (and frame-related) commands, the event notification can be moved here, since this function will only be called when the user's selected frame is being changed. */ /* Ensure that symbols for this frame are read in. Also, determine the source language of this frame, and switch to it if desired. */ if (fi) { /* We retrieve the frame's symtab by using the frame PC. However we cannot use the frame PC as-is, because it usually points to the instruction following the "call", which is sometimes the first instruction of another function. So we rely on get_frame_address_in_block() which provides us with a PC which is guaranteed to be inside the frame's code block. */ s = find_pc_symtab (get_frame_address_in_block (fi)); if (s && s->language != current_language->la_language && s->language != language_unknown && language_mode == language_mode_auto) { set_language (s->language); } } } /* Create an arbitrary (i.e. address specified by user) or innermost frame. Always returns a non-NULL value. */ struct frame_info * create_new_frame (CORE_ADDR addr, CORE_ADDR pc) { struct frame_info *fi; if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ create_new_frame (addr=%s, pc=%s) ", hex_string (addr), hex_string (pc)); } fi = FRAME_OBSTACK_ZALLOC (struct frame_info); fi->next = create_sentinel_frame (current_program_space, get_current_regcache ()); /* Set/update this frame's cached PC value, found in the next frame. Do this before looking for this frame's unwinder. A sniffer is very likely to read this, and the corresponding unwinder is entitled to rely that the PC doesn't magically change. */ fi->next->prev_pc.value = pc; fi->next->prev_pc.p = 1; /* We currently assume that frame chain's can't cross spaces. */ fi->pspace = fi->next->pspace; fi->aspace = fi->next->aspace; /* Select/initialize both the unwind function and the frame's type based on the PC. */ fi->unwind = frame_unwind_find_by_frame (fi, &fi->prologue_cache); fi->this_id.p = 1; fi->this_id.value = frame_id_build (addr, pc); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, fi); fprintf_unfiltered (gdb_stdlog, " }\n"); } return fi; } /* Return the frame that THIS_FRAME calls (NULL if THIS_FRAME is the innermost frame). Be careful to not fall off the bottom of the frame chain and onto the sentinel frame. */ struct frame_info * get_next_frame (struct frame_info *this_frame) { if (this_frame->level > 0) return this_frame->next; else return NULL; } /* Observer for the target_changed event. */ static void frame_observer_target_changed (struct target_ops *target) { reinit_frame_cache (); } /* Flush the entire frame cache. */ void reinit_frame_cache (void) { struct frame_info *fi; /* Tear down all frame caches. */ for (fi = current_frame; fi != NULL; fi = fi->prev) { if (fi->prologue_cache && fi->unwind->dealloc_cache) fi->unwind->dealloc_cache (fi, fi->prologue_cache); if (fi->base_cache && fi->base->unwind->dealloc_cache) fi->base->unwind->dealloc_cache (fi, fi->base_cache); } /* Since we can't really be sure what the first object allocated was */ obstack_free (&frame_cache_obstack, 0); obstack_init (&frame_cache_obstack); if (current_frame != NULL) annotate_frames_invalid (); current_frame = NULL; /* Invalidate cache */ select_frame (NULL); frame_stash_invalidate (); if (frame_debug) fprintf_unfiltered (gdb_stdlog, "{ reinit_frame_cache () }\n"); } /* Find where a register is saved (in memory or another register). The result of frame_register_unwind is just where it is saved relative to this particular frame. */ static void frame_register_unwind_location (struct frame_info *this_frame, int regnum, int *optimizedp, enum lval_type *lvalp, CORE_ADDR *addrp, int *realnump) { gdb_assert (this_frame == NULL || this_frame->level >= 0); while (this_frame != NULL) { frame_register_unwind (this_frame, regnum, optimizedp, lvalp, addrp, realnump, NULL); if (*optimizedp) break; if (*lvalp != lval_register) break; regnum = *realnump; this_frame = get_next_frame (this_frame); } } /* Return a "struct frame_info" corresponding to the frame that called THIS_FRAME. Returns NULL if there is no such frame. Unlike get_prev_frame, this function always tries to unwind the frame. */ static struct frame_info * get_prev_frame_1 (struct frame_info *this_frame) { struct frame_id this_id; struct gdbarch *gdbarch; gdb_assert (this_frame != NULL); gdbarch = get_frame_arch (this_frame); if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame_1 (this_frame="); if (this_frame != NULL) fprintf_unfiltered (gdb_stdlog, "%d", this_frame->level); else fprintf_unfiltered (gdb_stdlog, "<NULL>"); fprintf_unfiltered (gdb_stdlog, ") "); } /* Only try to do the unwind once. */ if (this_frame->prev_p) { if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, this_frame->prev); fprintf_unfiltered (gdb_stdlog, " // cached \n"); } return this_frame->prev; } /* If the frame unwinder hasn't been selected yet, we must do so before setting prev_p; otherwise the check for misbehaved sniffers will think that this frame's sniffer tried to unwind further (see frame_cleanup_after_sniffer). */ if (this_frame->unwind == NULL) this_frame->unwind = frame_unwind_find_by_frame (this_frame, &this_frame->prologue_cache); this_frame->prev_p = 1; this_frame->stop_reason = UNWIND_NO_REASON; /* If we are unwinding from an inline frame, all of the below tests were already performed when we unwound from the next non-inline frame. We must skip them, since we can not get THIS_FRAME's ID until we have unwound all the way down to the previous non-inline frame. */ if (get_frame_type (this_frame) == INLINE_FRAME) return get_prev_frame_raw (this_frame); /* Check that this frame's ID was valid. If it wasn't, don't try to unwind to the prev frame. Be careful to not apply this test to the sentinel frame. */ this_id = get_frame_id (this_frame); if (this_frame->level >= 0 && frame_id_eq (this_id, outer_frame_id)) { if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, NULL); fprintf_unfiltered (gdb_stdlog, " // this ID is NULL }\n"); } this_frame->stop_reason = UNWIND_NULL_ID; return NULL; } /* Check that this frame's ID isn't inner to (younger, below, next) the next frame. This happens when a frame unwind goes backwards. This check is valid only if this frame and the next frame are NORMAL. See the comment at frame_id_inner for details. */ if (get_frame_type (this_frame) == NORMAL_FRAME && this_frame->next->unwind->type == NORMAL_FRAME && frame_id_inner (get_frame_arch (this_frame->next), this_id, get_frame_id (this_frame->next))) { if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, NULL); fprintf_unfiltered (gdb_stdlog, " // this frame ID is inner }\n"); } this_frame->stop_reason = UNWIND_INNER_ID; return NULL; } /* Check that this and the next frame are not identical. If they are, there is most likely a stack cycle. As with the inner-than test above, avoid comparing the inner-most and sentinel frames. */ if (this_frame->level > 0 && frame_id_eq (this_id, get_frame_id (this_frame->next))) { if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, NULL); fprintf_unfiltered (gdb_stdlog, " // this frame has same ID }\n"); } this_frame->stop_reason = UNWIND_SAME_ID; return NULL; } /* Check that this and the next frame do not unwind the PC register to the same memory location. If they do, then even though they have different frame IDs, the new frame will be bogus; two functions can't share a register save slot for the PC. This can happen when the prologue analyzer finds a stack adjustment, but no PC save. This check does assume that the "PC register" is roughly a traditional PC, even if the gdbarch_unwind_pc method adjusts it (we do not rely on the value, only on the unwound PC being dependent on this value). A potential improvement would be to have the frame prev_pc method and the gdbarch unwind_pc method set the same lval and location information as frame_register_unwind. */ if (this_frame->level > 0 && gdbarch_pc_regnum (gdbarch) >= 0 && get_frame_type (this_frame) == NORMAL_FRAME && (get_frame_type (this_frame->next) == NORMAL_FRAME || get_frame_type (this_frame->next) == INLINE_FRAME)) { int optimized, realnum, nrealnum; enum lval_type lval, nlval; CORE_ADDR addr, naddr; frame_register_unwind_location (this_frame, gdbarch_pc_regnum (gdbarch), &optimized, &lval, &addr, &realnum); frame_register_unwind_location (get_next_frame (this_frame), gdbarch_pc_regnum (gdbarch), &optimized, &nlval, &naddr, &nrealnum); if ((lval == lval_memory && lval == nlval && addr == naddr) || (lval == lval_register && lval == nlval && realnum == nrealnum)) { if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, NULL); fprintf_unfiltered (gdb_stdlog, " // no saved PC }\n"); } this_frame->stop_reason = UNWIND_NO_SAVED_PC; this_frame->prev = NULL; return NULL; } } return get_prev_frame_raw (this_frame); } /* Construct a new "struct frame_info" and link it previous to this_frame. */ static struct frame_info * get_prev_frame_raw (struct frame_info *this_frame) { struct frame_info *prev_frame; /* Allocate the new frame but do not wire it in to the frame chain. Some (bad) code in INIT_FRAME_EXTRA_INFO tries to look along frame->next to pull some fancy tricks (of course such code is, by definition, recursive). Try to prevent it. There is no reason to worry about memory leaks, should the remainder of the function fail. The allocated memory will be quickly reclaimed when the frame cache is flushed, and the `we've been here before' check above will stop repeated memory allocation calls. */ prev_frame = FRAME_OBSTACK_ZALLOC (struct frame_info); prev_frame->level = this_frame->level + 1; /* For now, assume we don't have frame chains crossing address spaces. */ prev_frame->pspace = this_frame->pspace; prev_frame->aspace = this_frame->aspace; /* Don't yet compute ->unwind (and hence ->type). It is computed on-demand in get_frame_type, frame_register_unwind, and get_frame_id. */ /* Don't yet compute the frame's ID. It is computed on-demand by get_frame_id(). */ /* The unwound frame ID is validate at the start of this function, as part of the logic to decide if that frame should be further unwound, and not here while the prev frame is being created. Doing this makes it possible for the user to examine a frame that has an invalid frame ID. Some very old VAX code noted: [...] For the sake of argument, suppose that the stack is somewhat trashed (which is one reason that "info frame" exists). So, return 0 (indicating we don't know the address of the arglist) if we don't know what frame this frame calls. */ /* Link it in. */ this_frame->prev = prev_frame; prev_frame->next = this_frame; if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "-> "); fprint_frame (gdb_stdlog, prev_frame); fprintf_unfiltered (gdb_stdlog, " }\n"); } return prev_frame; } /* Debug routine to print a NULL frame being returned. */ static void frame_debug_got_null_frame (struct frame_info *this_frame, const char *reason) { if (frame_debug) { fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame (this_frame="); if (this_frame != NULL) fprintf_unfiltered (gdb_stdlog, "%d", this_frame->level); else fprintf_unfiltered (gdb_stdlog, "<NULL>"); fprintf_unfiltered (gdb_stdlog, ") -> // %s}\n", reason); } } /* Is this (non-sentinel) frame in the "main"() function? */ static int inside_main_func (struct frame_info *this_frame) { struct minimal_symbol *msymbol; CORE_ADDR maddr; if (symfile_objfile == 0) return 0; msymbol = lookup_minimal_symbol (main_name (), NULL, symfile_objfile); if (msymbol == NULL) return 0; /* Make certain that the code, and not descriptor, address is returned. */ maddr = gdbarch_convert_from_func_ptr_addr (get_frame_arch (this_frame), SYMBOL_VALUE_ADDRESS (msymbol), ¤t_target); return maddr == get_frame_func (this_frame); } /* Test whether THIS_FRAME is inside the process entry point function. */ static int inside_entry_func (struct frame_info *this_frame) { CORE_ADDR entry_point; if (!entry_point_address_query (&entry_point)) return 0; return get_frame_func (this_frame) == entry_point; } /* Return a structure containing various interesting information about the frame that called THIS_FRAME. Returns NULL if there is entier no such frame or the frame fails any of a set of target-independent condition that should terminate the frame chain (e.g., as unwinding past main()). This function should not contain target-dependent tests, such as checking whether the program-counter is zero. */ struct frame_info * get_prev_frame (struct frame_info *this_frame) { struct frame_info *prev_frame; /* There is always a frame. If this assertion fails, suspect that something should be calling get_selected_frame() or get_current_frame(). */ gdb_assert (this_frame != NULL); /* tausq/2004-12-07: Dummy frames are skipped because it doesn't make much sense to stop unwinding at a dummy frame. One place where a dummy frame may have an address "inside_main_func" is on HPUX. On HPUX, the pcsqh register (space register for the instruction at the head of the instruction queue) cannot be written directly; the only way to set it is to branch to code that is in the target space. In order to implement frame dummies on HPUX, the called function is made to jump back to where the inferior was when the user function was called. If gdb was inside the main function when we created the dummy frame, the dummy frame will point inside the main function. */ if (this_frame->level >= 0 && get_frame_type (this_frame) == NORMAL_FRAME && !backtrace_past_main && inside_main_func (this_frame)) /* Don't unwind past main(). Note, this is done _before_ the frame has been marked as previously unwound. That way if the user later decides to enable unwinds past main(), that will automatically happen. */ { frame_debug_got_null_frame (this_frame, "inside main func"); return NULL; } /* If the user's backtrace limit has been exceeded, stop. We must add two to the current level; one of those accounts for backtrace_limit being 1-based and the level being 0-based, and the other accounts for the level of the new frame instead of the level of the current frame. */ if (this_frame->level + 2 > backtrace_limit) { frame_debug_got_null_frame (this_frame, "backtrace limit exceeded"); return NULL; } /* If we're already inside the entry function for the main objfile, then it isn't valid. Don't apply this test to a dummy frame - dummy frame PCs typically land in the entry func. Don't apply this test to the sentinel frame. Sentinel frames should always be allowed to unwind. */ /* NOTE: cagney/2003-07-07: Fixed a bug in inside_main_func() - wasn't checking for "main" in the minimal symbols. With that fixed asm-source tests now stop in "main" instead of halting the backtrace in weird and wonderful ways somewhere inside the entry file. Suspect that tests for inside the entry file/func were added to work around that (now fixed) case. */ /* NOTE: cagney/2003-07-15: danielj (if I'm reading it right) suggested having the inside_entry_func test use the inside_main_func() msymbol trick (along with entry_point_address() I guess) to determine the address range of the start function. That should provide a far better stopper than the current heuristics. */ /* NOTE: tausq/2004-10-09: this is needed if, for example, the compiler applied tail-call optimizations to main so that a function called from main returns directly to the caller of main. Since we don't stop at main, we should at least stop at the entry point of the application. */ if (this_frame->level >= 0 && get_frame_type (this_frame) == NORMAL_FRAME && !backtrace_past_entry && inside_entry_func (this_frame)) { frame_debug_got_null_frame (this_frame, "inside entry func"); return NULL; } /* Assume that the only way to get a zero PC is through something like a SIGSEGV or a dummy frame, and hence that NORMAL frames will never unwind a zero PC. */ if (this_frame->level > 0 && (get_frame_type (this_frame) == NORMAL_FRAME || get_frame_type (this_frame) == INLINE_FRAME) && get_frame_type (get_next_frame (this_frame)) == NORMAL_FRAME && get_frame_pc (this_frame) == 0) { frame_debug_got_null_frame (this_frame, "zero PC"); return NULL; } return get_prev_frame_1 (this_frame); } CORE_ADDR get_frame_pc (struct frame_info *frame) { gdb_assert (frame->next != NULL); return frame_unwind_pc (frame->next); } /* Return an address that falls within THIS_FRAME's code block. */ CORE_ADDR get_frame_address_in_block (struct frame_info *this_frame) { /* A draft address. */ CORE_ADDR pc = get_frame_pc (this_frame); struct frame_info *next_frame = this_frame->next; /* Calling get_frame_pc returns the resume address for THIS_FRAME. Normally the resume address is inside the body of the function associated with THIS_FRAME, but there is a special case: when calling a function which the compiler knows will never return (for instance abort), the call may be the very last instruction in the calling function. The resume address will point after the call and may be at the beginning of a different function entirely. If THIS_FRAME is a signal frame or dummy frame, then we should not adjust the unwound PC. For a dummy frame, GDB pushed the resume address manually onto the stack. For a signal frame, the OS may have pushed the resume address manually and invoked the handler (e.g. GNU/Linux), or invoked the trampoline which called the signal handler - but in either case the signal handler is expected to return to the trampoline. So in both of these cases we know that the resume address is executable and related. So we only need to adjust the PC if THIS_FRAME is a normal function. If the program has been interrupted while THIS_FRAME is current, then clearly the resume address is inside the associated function. There are three kinds of interruption: debugger stop (next frame will be SENTINEL_FRAME), operating system signal or exception (next frame will be SIGTRAMP_FRAME), or debugger-induced function call (next frame will be DUMMY_FRAME). So we only need to adjust the PC if NEXT_FRAME is a normal function. We check the type of NEXT_FRAME first, since it is already known; frame type is determined by the unwinder, and since we have THIS_FRAME we've already selected an unwinder for NEXT_FRAME. If the next frame is inlined, we need to keep going until we find the real function - for instance, if a signal handler is invoked while in an inlined function, then the code address of the "calling" normal function should not be adjusted either. */ while (get_frame_type (next_frame) == INLINE_FRAME) next_frame = next_frame->next; if (get_frame_type (next_frame) == NORMAL_FRAME && (get_frame_type (this_frame) == NORMAL_FRAME || get_frame_type (this_frame) == INLINE_FRAME)) return pc - 1; return pc; } void find_frame_sal (struct frame_info *frame, struct symtab_and_line *sal) { struct frame_info *next_frame; int notcurrent; /* If the next frame represents an inlined function call, this frame's sal is the "call site" of that inlined function, which can not be inferred from get_frame_pc. */ next_frame = get_next_frame (frame); if (frame_inlined_callees (frame) > 0) { struct symbol *sym; if (next_frame) sym = get_frame_function (next_frame); else sym = inline_skipped_symbol (inferior_ptid); init_sal (sal); if (SYMBOL_LINE (sym) != 0) { sal->symtab = SYMBOL_SYMTAB (sym); sal->line = SYMBOL_LINE (sym); } else /* If the symbol does not have a location, we don't know where the call site is. Do not pretend to. This is jarring, but we can't do much better. */ sal->pc = get_frame_pc (frame); return; } /* If FRAME is not the innermost frame, that normally means that FRAME->pc points at the return instruction (which is *after* the call instruction), and we want to get the line containing the call (because the call is where the user thinks the program is). However, if the next frame is either a SIGTRAMP_FRAME or a DUMMY_FRAME, then the next frame will contain a saved interrupt PC and such a PC indicates the current (rather than next) instruction/line, consequently, for such cases, want to get the line containing fi->pc. */ notcurrent = (get_frame_pc (frame) != get_frame_address_in_block (frame)); (*sal) = find_pc_line (get_frame_pc (frame), notcurrent); } /* Per "frame.h", return the ``address'' of the frame. Code should really be using get_frame_id(). */ CORE_ADDR get_frame_base (struct frame_info *fi) { return get_frame_id (fi).stack_addr; } /* High-level offsets into the frame. Used by the debug info. */ CORE_ADDR get_frame_base_address (struct frame_info *fi) { if (get_frame_type (fi) != NORMAL_FRAME) return 0; if (fi->base == NULL) fi->base = frame_base_find_by_frame (fi); /* Sneaky: If the low-level unwind and high-level base code share a common unwinder, let them share the prologue cache. */ if (fi->base->unwind == fi->unwind) return fi->base->this_base (fi, &fi->prologue_cache); return fi->base->this_base (fi, &fi->base_cache); } CORE_ADDR get_frame_locals_address (struct frame_info *fi) { void **cache; if (get_frame_type (fi) != NORMAL_FRAME) return 0; /* If there isn't a frame address method, find it. */ if (fi->base == NULL) fi->base = frame_base_find_by_frame (fi); /* Sneaky: If the low-level unwind and high-level base code share a common unwinder, let them share the prologue cache. */ if (fi->base->unwind == fi->unwind) return fi->base->this_locals (fi, &fi->prologue_cache); return fi->base->this_locals (fi, &fi->base_cache); } CORE_ADDR get_frame_args_address (struct frame_info *fi) { void **cache; if (get_frame_type (fi) != NORMAL_FRAME) return 0; /* If there isn't a frame address method, find it. */ if (fi->base == NULL) fi->base = frame_base_find_by_frame (fi); /* Sneaky: If the low-level unwind and high-level base code share a common unwinder, let them share the prologue cache. */ if (fi->base->unwind == fi->unwind) return fi->base->this_args (fi, &fi->prologue_cache); return fi->base->this_args (fi, &fi->base_cache); } /* Return true if the frame unwinder for frame FI is UNWINDER; false otherwise. */ int frame_unwinder_is (struct frame_info *fi, const struct frame_unwind *unwinder) { if (fi->unwind == NULL) fi->unwind = frame_unwind_find_by_frame (fi, &fi->prologue_cache); return fi->unwind == unwinder; } /* Level of the selected frame: 0 for innermost, 1 for its caller, ... or -1 for a NULL frame. */ int frame_relative_level (struct frame_info *fi) { if (fi == NULL) return -1; else return fi->level; } enum frame_type get_frame_type (struct frame_info *frame) { if (frame->unwind == NULL) /* Initialize the frame's unwinder because that's what provides the frame's type. */ frame->unwind = frame_unwind_find_by_frame (frame, &frame->prologue_cache); return frame->unwind->type; } struct program_space * get_frame_program_space (struct frame_info *frame) { return frame->pspace; } struct program_space * frame_unwind_program_space (struct frame_info *this_frame) { gdb_assert (this_frame); /* This is really a placeholder to keep the API consistent --- we assume for now that we don't have frame chains crossing spaces. */ return this_frame->pspace; } struct address_space * get_frame_address_space (struct frame_info *frame) { return frame->aspace; } /* Memory access methods. */ void get_frame_memory (struct frame_info *this_frame, CORE_ADDR addr, gdb_byte *buf, int len) { read_memory (addr, buf, len); } LONGEST get_frame_memory_signed (struct frame_info *this_frame, CORE_ADDR addr, int len) { struct gdbarch *gdbarch = get_frame_arch (this_frame); enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); return read_memory_integer (addr, len, byte_order); } ULONGEST get_frame_memory_unsigned (struct frame_info *this_frame, CORE_ADDR addr, int len) { struct gdbarch *gdbarch = get_frame_arch (this_frame); enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); return read_memory_unsigned_integer (addr, len, byte_order); } int safe_frame_unwind_memory (struct frame_info *this_frame, CORE_ADDR addr, gdb_byte *buf, int len) { /* NOTE: target_read_memory returns zero on success! */ return !target_read_memory (addr, buf, len); } /* Architecture methods. */ struct gdbarch * get_frame_arch (struct frame_info *this_frame) { return frame_unwind_arch (this_frame->next); } struct gdbarch * frame_unwind_arch (struct frame_info *next_frame) { if (!next_frame->prev_arch.p) { struct gdbarch *arch; if (next_frame->unwind == NULL) next_frame->unwind = frame_unwind_find_by_frame (next_frame, &next_frame->prologue_cache); if (next_frame->unwind->prev_arch != NULL) arch = next_frame->unwind->prev_arch (next_frame, &next_frame->prologue_cache); else arch = get_frame_arch (next_frame); next_frame->prev_arch.arch = arch; next_frame->prev_arch.p = 1; if (frame_debug) fprintf_unfiltered (gdb_stdlog, "{ frame_unwind_arch (next_frame=%d) -> %s }\n", next_frame->level, gdbarch_bfd_arch_info (arch)->printable_name); } return next_frame->prev_arch.arch; } struct gdbarch * frame_unwind_caller_arch (struct frame_info *next_frame) { return frame_unwind_arch (skip_inlined_frames (next_frame)); } /* Stack pointer methods. */ CORE_ADDR get_frame_sp (struct frame_info *this_frame) { struct gdbarch *gdbarch = get_frame_arch (this_frame); /* Normality - an architecture that provides a way of obtaining any frame inner-most address. */ if (gdbarch_unwind_sp_p (gdbarch)) /* NOTE drow/2008-06-28: gdbarch_unwind_sp could be converted to operate on THIS_FRAME now. */ return gdbarch_unwind_sp (gdbarch, this_frame->next); /* Now things are really are grim. Hope that the value returned by the gdbarch_sp_regnum register is meaningful. */ if (gdbarch_sp_regnum (gdbarch) >= 0) return get_frame_register_unsigned (this_frame, gdbarch_sp_regnum (gdbarch)); internal_error (__FILE__, __LINE__, _("Missing unwind SP method")); } /* Return the reason why we can't unwind past FRAME. */ enum unwind_stop_reason get_frame_unwind_stop_reason (struct frame_info *frame) { /* If we haven't tried to unwind past this point yet, then assume that unwinding would succeed. */ if (frame->prev_p == 0) return UNWIND_NO_REASON; /* Otherwise, we set a reason when we succeeded (or failed) to unwind. */ return frame->stop_reason; } /* Return a string explaining REASON. */ const char * frame_stop_reason_string (enum unwind_stop_reason reason) { switch (reason) { case UNWIND_NULL_ID: return _("unwinder did not report frame ID"); case UNWIND_INNER_ID: return _("previous frame inner to this frame (corrupt stack?)"); case UNWIND_SAME_ID: return _("previous frame identical to this frame (corrupt stack?)"); case UNWIND_NO_SAVED_PC: return _("frame did not save the PC"); case UNWIND_NO_REASON: case UNWIND_FIRST_ERROR: default: internal_error (__FILE__, __LINE__, "Invalid frame stop reason"); } } /* Clean up after a failed (wrong unwinder) attempt to unwind past FRAME. */ static void frame_cleanup_after_sniffer (void *arg) { struct frame_info *frame = arg; /* The sniffer should not allocate a prologue cache if it did not match this frame. */ gdb_assert (frame->prologue_cache == NULL); /* No sniffer should extend the frame chain; sniff based on what is already certain. */ gdb_assert (!frame->prev_p); /* The sniffer should not check the frame's ID; that's circular. */ gdb_assert (!frame->this_id.p); /* Clear cached fields dependent on the unwinder. The previous PC is independent of the unwinder, but the previous function is not (see get_frame_address_in_block). */ frame->prev_func.p = 0; frame->prev_func.addr = 0; /* Discard the unwinder last, so that we can easily find it if an assertion in this function triggers. */ frame->unwind = NULL; } /* Set FRAME's unwinder temporarily, so that we can call a sniffer. Return a cleanup which should be called if unwinding fails, and discarded if it succeeds. */ struct cleanup * frame_prepare_for_sniffer (struct frame_info *frame, const struct frame_unwind *unwind) { gdb_assert (frame->unwind == NULL); frame->unwind = unwind; return make_cleanup (frame_cleanup_after_sniffer, frame); } extern initialize_file_ftype _initialize_frame; /* -Wmissing-prototypes */ static struct cmd_list_element *set_backtrace_cmdlist; static struct cmd_list_element *show_backtrace_cmdlist; static void set_backtrace_cmd (char *args, int from_tty) { help_list (set_backtrace_cmdlist, "set backtrace ", -1, gdb_stdout); } static void show_backtrace_cmd (char *args, int from_tty) { cmd_show_list (show_backtrace_cmdlist, from_tty, ""); } void _initialize_frame (void) { obstack_init (&frame_cache_obstack); observer_attach_target_changed (frame_observer_target_changed); add_prefix_cmd ("backtrace", class_maintenance, set_backtrace_cmd, _("\ Set backtrace specific variables.\n\ Configure backtrace variables such as the backtrace limit"), &set_backtrace_cmdlist, "set backtrace ", 0/*allow-unknown*/, &setlist); add_prefix_cmd ("backtrace", class_maintenance, show_backtrace_cmd, _("\ Show backtrace specific variables\n\ Show backtrace variables such as the backtrace limit"), &show_backtrace_cmdlist, "show backtrace ", 0/*allow-unknown*/, &showlist); add_setshow_boolean_cmd ("past-main", class_obscure, &backtrace_past_main, _("\ Set whether backtraces should continue past \"main\"."), _("\ Show whether backtraces should continue past \"main\"."), _("\ Normally the caller of \"main\" is not of interest, so GDB will terminate\n\ the backtrace at \"main\". Set this variable if you need to see the rest\n\ of the stack trace."), NULL, show_backtrace_past_main, &set_backtrace_cmdlist, &show_backtrace_cmdlist); add_setshow_boolean_cmd ("past-entry", class_obscure, &backtrace_past_entry, _("\ Set whether backtraces should continue past the entry point of a program."), _("\ Show whether backtraces should continue past the entry point of a program."), _("\ Normally there are no callers beyond the entry point of a program, so GDB\n\ will terminate the backtrace there. Set this variable if you need to see \n\ the rest of the stack trace."), NULL, show_backtrace_past_entry, &set_backtrace_cmdlist, &show_backtrace_cmdlist); add_setshow_integer_cmd ("limit", class_obscure, &backtrace_limit, _("\ Set an upper bound on the number of backtrace levels."), _("\ Show the upper bound on the number of backtrace levels."), _("\ No more than the specified number of frames can be displayed or examined.\n\ Zero is unlimited."), NULL, show_backtrace_limit, &set_backtrace_cmdlist, &show_backtrace_cmdlist); /* Debug this files internals. */ add_setshow_zinteger_cmd ("frame", class_maintenance, &frame_debug, _("\ Set frame debugging."), _("\ Show frame debugging."), _("\ When non-zero, frame specific internal debugging is enabled."), NULL, show_frame_debug, &setdebuglist, &showdebuglist); }
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