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jlechner |
/* DWARF2 EH unwinding support for S/390 Linux.
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Copyright (C) 2004, 2005 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 2, or (at your option) any later
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version.
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In addition to the permissions in the GNU General Public License, the
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Free Software Foundation gives you unlimited permission to link the
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compiled version of this file with other programs, and to distribute
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those programs without any restriction coming from the use of this
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file. (The General Public License restrictions do apply in other
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respects; for example, they cover modification of the file, and
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distribution when not linked into another program.)
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to the Free
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Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301, USA. */
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/* Do code reading to identify a signal frame, and set the frame
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state data appropriately. See unwind-dw2.c for the structs. */
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#define MD_FALLBACK_FRAME_STATE_FOR s390_fallback_frame_state
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static _Unwind_Reason_Code
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s390_fallback_frame_state (struct _Unwind_Context *context,
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_Unwind_FrameState *fs)
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{
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unsigned char *pc = context->ra;
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long new_cfa;
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int i;
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typedef struct
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{
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unsigned long psw_mask;
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unsigned long psw_addr;
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unsigned long gprs[16];
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unsigned int acrs[16];
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unsigned int fpc;
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unsigned int __pad;
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double fprs[16];
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} __attribute__ ((__aligned__ (8))) sigregs_;
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sigregs_ *regs;
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int *signo = NULL;
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/* svc $__NR_sigreturn or svc $__NR_rt_sigreturn */
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if (pc[0] != 0x0a || (pc[1] != 119 && pc[1] != 173))
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return _URC_END_OF_STACK;
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/* New-style RT frame:
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retcode + alignment (8 bytes)
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siginfo (128 bytes)
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ucontext (contains sigregs) */
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if (context->ra == context->cfa)
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{
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struct ucontext_
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{
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unsigned long uc_flags;
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struct ucontext_ *uc_link;
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unsigned long uc_stack[3];
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sigregs_ uc_mcontext;
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} *uc = context->cfa + 8 + 128;
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regs = &uc->uc_mcontext;
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signo = context->cfa + sizeof(long);
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}
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/* Old-style RT frame and all non-RT frames:
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old signal mask (8 bytes)
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pointer to sigregs */
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else
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{
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regs = *(sigregs_ **)(context->cfa + 8);
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/* Recent kernels store the signal number immediately after
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the sigregs; old kernels have the return trampoline at
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this location. */
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if ((void *)(regs + 1) != context->ra)
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signo = (int *)(regs + 1);
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}
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new_cfa = regs->gprs[15] + 16*sizeof(long) + 32;
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fs->cfa_how = CFA_REG_OFFSET;
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fs->cfa_reg = 15;
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fs->cfa_offset =
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new_cfa - (long) context->cfa + 16*sizeof(long) + 32;
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for (i = 0; i < 16; i++)
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{
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fs->regs.reg[i].how = REG_SAVED_OFFSET;
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fs->regs.reg[i].loc.offset =
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(long)®s->gprs[i] - new_cfa;
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}
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for (i = 0; i < 16; i++)
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{
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fs->regs.reg[16+i].how = REG_SAVED_OFFSET;
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fs->regs.reg[16+i].loc.offset =
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(long)®s->fprs[i] - new_cfa;
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}
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/* Load return addr from PSW into dummy register 32. */
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fs->regs.reg[32].how = REG_SAVED_OFFSET;
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fs->regs.reg[32].loc.offset = (long)®s->psw_addr - new_cfa;
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fs->retaddr_column = 32;
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/* If we got a SIGSEGV or a SIGBUS, the PSW address points *to*
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the faulting instruction, not after it. This causes the logic
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in unwind-dw2.c that decrements the RA to determine the correct
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CFI region to get confused. To fix that, we *increment* the RA
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here in that case. Note that we cannot modify the RA in place,
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and the frame state wants a *pointer*, not a value; thus we put
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the modified RA value into the unused register 33 slot of FS and
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have the register 32 save address point to that slot.
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Unfortunately, for regular signals on old kernels, we don't know
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the signal number. We default to not fiddling with the RA;
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that can fail in rare cases. Upgrade your kernel. */
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if (signo && (*signo == 11 || *signo == 7))
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{
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fs->regs.reg[33].loc.exp =
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(unsigned char *)regs->psw_addr + 1;
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fs->regs.reg[32].loc.offset =
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(long)&fs->regs.reg[33].loc.exp - new_cfa;
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}
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return _URC_NO_REASON;
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}
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