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786 |
skrzyp |
/*=============================================================================
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//
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// context.S
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//
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// SPARC context switch code
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//
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//=============================================================================
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// ####ECOSGPLCOPYRIGHTBEGIN####
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// -------------------------------------------
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// This file is part of eCos, the Embedded Configurable Operating System.
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// Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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//
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// eCos 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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//
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// eCos is distributed in the hope that it will be useful, but WITHOUT
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// ANY 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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//
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// You should have received a copy of the GNU General Public License
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// along with eCos; if not, write to the Free Software Foundation, Inc.,
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// 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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//
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// As a special exception, if other files instantiate templates or use
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// macros or inline functions from this file, or you compile this file
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// and link it with other works to produce a work based on this file,
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// this file does not by itself cause the resulting work to be covered by
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// the GNU General Public License. However the source code for this file
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// must still be made available in accordance with section (3) of the GNU
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// General Public License v2.
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//
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// This exception does not invalidate any other reasons why a work based
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// on this file might be covered by the GNU General Public License.
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// -------------------------------------------
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// ####ECOSGPLCOPYRIGHTEND####
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//=============================================================================
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//#####DESCRIPTIONBEGIN####
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//
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// Author(s): nickg, gthomas, hmt
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// Contributors: nickg, gthomas, hmt
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// Date: 1998-12-15
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// Purpose: SPARC context switch code
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// Description: This file contains implementations of the thread context
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// switch routines. It also contains the longjmp() and setjmp()
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// routines.
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//
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//####DESCRIPTIONEND####
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//
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//===========================================================================*/
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#include
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#include
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#define DELAYS_AFTER_WRPSR_SAME_WINDOW
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#define DELAYS_AFTER_WRWIM
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.text
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! ------------------------------------------------------------------------------
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! hal_thread_switch_context
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! Switch thread contexts
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! %o0 = address of sp of next thread to execute
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! %o1 = address of sp save location of current thread
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.global hal_thread_switch_context
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hal_thread_switch_context:
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! First take the stack down to make room for the saved register
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! state, including a window save area at the base. Leave the
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! current window save area undisturbed. It is unused within the
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! save but will become current again when we continue in this
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! context. This lets us do this whole piece of work without
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! diabling interrupts for too long, since, for example, we can
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! lower the stack atomically with one instruction:
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sub %sp, SAVE_REGS_SIZE, %sp
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st %sp, [ %o1 ] ! return SP for this thread
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std %l0, [%sp + 0 * 4] ! save L & I registers
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std %l2, [%sp + 2 * 4]
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std %l4, [%sp + 4 * 4]
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std %l6, [%sp + 6 * 4]
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std %i0, [%sp + 8 * 4]
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std %i2, [%sp + 10 * 4]
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std %i4, [%sp + 12 * 4]
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std %i6, [%sp + 14 * 4]
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#ifdef CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
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st %o7, [%sp + 31 * 4] ! save only the return address
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! and no need to preserve %o0 even though it is restored
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#else // save a maximal context
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st %g1, [%sp + 17 * 4] ! save G & O registers
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std %g2, [%sp + 18 * 4]
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std %g4, [%sp + 20 * 4]
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std %g6, [%sp + 22 * 4]
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std %o0, [%sp + 24 * 4]
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std %o2, [%sp + 26 * 4]
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std %o4, [%sp + 28 * 4]
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std %o6, [%sp + 30 * 4]
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#endif // !CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
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! and save the CWP in %g0 save place
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rd %psr, %g7
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st %g7, [%sp + 16 * 4]
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! Now load the destination thread by dropping through
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! to hal_thread_load_context
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! ------------------------------------------------------------------------------
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! hal_thread_load_context
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! Load thread context
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! %o0 = address of sp of next thread to execute
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! Note that this function is also the second half of hal_thread_switch_context
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! and is simply dropped into from it.
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.global hal_thread_load_context
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hal_thread_load_context:
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! Here, we are a leaf routine but with slightly odd properties.
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! The stack is still the callers at this point but the register
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! set is up for grabs. So we can use globals:
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ld [ %o0 ], %g7 ! Get the next saved SP
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! DISABLE INTERRUPTS *ONLY* NOT TRAPS
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rd %psr, %g6
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or %g6, 0xfe0, %g5 ! PIL up to 15 leave traps enabled
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wr %g5, %psr
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nop; nop; nop
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! force out all our callers register sets onto the stack
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! if necessary: the system will handily take care of this for
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! us as follows:
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save %sp, -16 * 4, %sp ! need all these to preserve
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save %sp, -16 * 4, %sp ! the linked list property...
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save %sp, -16 * 4, %sp
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save %sp, -16 * 4, %sp
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#if 6 < __WINSIZE
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save %sp, -16 * 4, %sp
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#if 7 < __WINSIZE
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save %sp, -16 * 4, %sp
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#endif
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#endif
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! Fewer saves if fewer register windows. For 8 register windows,
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! six of these is correct; a seventh would force out the current
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! set that was already saved manually above. Note that minimal
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! space is allowed on stack for locals and ins in case this
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! sequence itself gets interrupted and recurses too deep.
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! now select the new window with traps disabled...
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! get the new PSR and CWP that we will ultimately restore
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! from the %g0 save place...
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ld [%g7 + 16 * 4], %g6 ! %g7 holds the new stack pointer
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andn %g6, 0x20, %g5 ! clear ET into %g5
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and %g6, __WINBITS, %g4 ! CWP bits only in %g4
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! calculate a new WIM...
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add %g4, 1, %g3 ! required invalid window number
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#if 8 == __WINSIZE
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and %g3, __WINBITS, %g3 ! modulo 8
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#else // expect 5 or 6 or 7 windows
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cmp %g3, __WINSIZE
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bge,a 567f ! taken: do delay slot, handle overflow
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mov 0, %g3 ! only if .ge. above
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567:
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#endif
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mov 1, %g2
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sll %g2, %g3, %g2 ! converted to a mask for the WIM
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! DISABLE INTERRUPTS (TRAPS)
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wr %g5, %psr ! set CWP to new window, disable traps
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wr %g2, %wim ! and WIM to new value
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nop
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nop
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nop
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! Must do this atomically so that the registers match the stack.
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! After locals and ins are loaded, we are conformant to the PCS
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! so can re-enable interrupts.
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mov %g7, %sp ! target sp in situ (%sp = %o6)
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ldd [%sp + 0 * 4], %l0 ! restore L & I registers
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ldd [%sp + 2 * 4], %l2
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ldd [%sp + 4 * 4], %l4
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ldd [%sp + 6 * 4], %l6
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ldd [%sp + 8 * 4], %i0
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ldd [%sp + 10 * 4], %i2
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ldd [%sp + 12 * 4], %i4
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ldd [%sp + 14 * 4], %i6
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! RESTORE INTERRUPTS to saved state
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wr %g6, %psr ! set new CWP and old ET and PIL
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nop
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nop
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nop
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! now load the rest of the context; we can be interrupted here
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! (if the saved context was a voluntary yield or threadstart)
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! but that is OK, other state will be preserved in that case...
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#ifdef CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
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ld [%sp + 24 * 4], %o0 ! must load the initial argument
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#else // restore a maximal context
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ld [%sp + 17 * 4], %g1
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ldd [%sp + 18 * 4], %g2
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ldd [%sp + 20 * 4], %g4
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ldd [%sp + 22 * 4], %g6
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ldd [%sp + 24 * 4], %o0
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ldd [%sp + 26 * 4], %o2
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ldd [%sp + 28 * 4], %o4
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#endif // !CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
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! %o6 = %sp, already set up
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ld [%sp + 31 * 4], %o7 ! "return" address
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retl
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add %sp, SAVE_REGS_SIZE, %sp ! and set the stack back
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! to its entrant value
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! ------------------------------------------------------------------------------
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! HAL longjmp, setjmp implementations
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!FUNC_START(hal_setjmp)
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.global hal_setjmp
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hal_setjmp:
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! Treat this as a leaf routine, may as well.
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! %o0 is the address of the buffer.
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std %l0, [%o0 + 0 * 4] ! save L & I registers
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std %l2, [%o0 + 2 * 4]
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std %l4, [%o0 + 4 * 4]
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std %l6, [%o0 + 6 * 4]
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std %i0, [%o0 + 8 * 4]
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std %i2, [%o0 + 10 * 4]
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std %i4, [%o0 + 12 * 4]
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std %i6, [%o0 + 14 * 4]
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#ifdef CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
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std %o6, [%o0 + 30 * 4] ! just save %sp and return address
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#else // save a maximal context
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st %g1, [%o0 + 17 * 4] ! save G & O registers
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| 249 |
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std %g2, [%o0 + 18 * 4]
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std %g4, [%o0 + 20 * 4]
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std %g6, [%o0 + 22 * 4]
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std %o0, [%o0 + 24 * 4]
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std %o2, [%o0 + 26 * 4]
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std %o4, [%o0 + 28 * 4]
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std %o6, [%o0 + 30 * 4]
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#endif // !CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
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! and save the CWP in %g0 save place
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rd %psr, %g7
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st %g7, [%o0 + 16 * 4]
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| 262 |
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| 263 |
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! DISABLE INTERRUPTS *ONLY* NOT TRAPS
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| 264 |
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or %g7, 0xfe0, %g6 ! PIL up to 15 leave traps enabled
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| 265 |
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wr %g6, %psr
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nop; nop; nop
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| 267 |
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| 268 |
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! force out all our callers register sets onto the stack
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| 269 |
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! if necessary: the system will handily take care of this for
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| 270 |
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! us as follows:
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| 271 |
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save %sp, -16 * 4, %sp ! need all these to preserve
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| 272 |
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save %sp, -16 * 4, %sp ! the linked list property...
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| 273 |
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save %sp, -16 * 4, %sp
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| 274 |
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save %sp, -16 * 4, %sp
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| 275 |
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#if 6 < __WINSIZE
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| 276 |
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save %sp, -16 * 4, %sp
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| 277 |
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#if 7 < __WINSIZE
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| 278 |
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save %sp, -16 * 4, %sp
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| 279 |
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#endif
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| 280 |
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#endif
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| 281 |
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! Fewer saves if fewer register windows. For 8 register windows,
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| 282 |
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! six of these is correct; a seventh would force out the current
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| 283 |
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! set that was already saved manually above. Note that minimal
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| 284 |
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! space is allowed on stack for locals and ins in case this
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| 285 |
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! sequence itself gets interrupted and recurses too deep.
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| 286 |
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| 287 |
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! (after all, we are about to call deeper not shallower, otherwise
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| 288 |
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! using setjmp is inappropriate)
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| 289 |
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| 290 |
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! ENABLE INTERRUPTS
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| 291 |
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wr %g7, %psr ! set CWP back to as-was
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| 292 |
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nop
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| 293 |
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nop
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| 294 |
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nop
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| 295 |
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| 296 |
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#ifndef CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
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| 297 |
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ldd [%o0 + 22 * 4], %g6 ! preserve %g7 and %g6
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| 298 |
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#endif
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| 299 |
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| 300 |
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retl ! ret and return zero to indicate
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| 301 |
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mov 0, %o0 ! not longjumped-to
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| 302 |
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| 303 |
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! hal_longjmp loads state from arg0 and returns arg1
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| 304 |
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!FUNC_START(hal_longjmp)
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| 305 |
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.global hal_longjmp
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| 306 |
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hal_longjmp:
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| 307 |
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! This is kind of a leaf routine, it returns elsewhere
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| 308 |
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! %o0 is the address of the buffer.
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| 309 |
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! %o1 is the value to return in %o0 (since we are a leaf)
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| 310 |
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| 311 |
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mov %o0, %g7 ! keep the pointer handy
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| 312 |
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mov %o1, %g1 ! and the return value
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| 313 |
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! now select the new window with traps disabled...
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| 314 |
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rd %psr, %g6
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| 315 |
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! preserve ET, clear CWP
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| 316 |
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andn %g6, __WINBITS_MAXIMAL, %g6
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| 317 |
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andn %g6, 0x20, %g5 ! clear ET also into %g5
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| 318 |
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| 319 |
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! get new CWP from %g0 save place...
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| 320 |
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ld [%g7 + 16 * 4], %g4 ! %g7 holds the new stack pointer
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| 321 |
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and %g4, __WINBITS, %g4 ! preserve CWP bits
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| 322 |
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| 323 |
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! calculate a new WIM...
|
| 324 |
|
|
add %g4, 1, %g3 ! required invalid window number
|
| 325 |
|
|
#if 8 == __WINSIZE
|
| 326 |
|
|
and %g3, __WINBITS, %g3 ! modulo 8
|
| 327 |
|
|
#else // expect 5 or 6 or 7 windows
|
| 328 |
|
|
cmp %g3, __WINSIZE
|
| 329 |
|
|
bge,a 567f ! taken: do delay slot, handle overflow
|
| 330 |
|
|
mov 0, %g3 ! only if .ge. above
|
| 331 |
|
|
567:
|
| 332 |
|
|
#endif
|
| 333 |
|
|
mov 1, %g2
|
| 334 |
|
|
sll %g2, %g3, %g2 ! converted to a mask for the WIM
|
| 335 |
|
|
|
| 336 |
|
|
! DISABLE INTERRUPTS
|
| 337 |
|
|
wr %g5, %g4, %psr ! set CWP to new window, disable traps
|
| 338 |
|
|
wr %g2, %wim ! and WIM to new value
|
| 339 |
|
|
nop
|
| 340 |
|
|
nop
|
| 341 |
|
|
nop
|
| 342 |
|
|
|
| 343 |
|
|
! Must do this atomically so that the registers match the stack.
|
| 344 |
|
|
! After locals and ins are loaded, we are conformant to the PCS
|
| 345 |
|
|
! so can re-enable interrupts.
|
| 346 |
|
|
|
| 347 |
|
|
ldd [%g7 + 0 * 4], %l0 ! restore L & I registers
|
| 348 |
|
|
ldd [%g7 + 2 * 4], %l2
|
| 349 |
|
|
ldd [%g7 + 4 * 4], %l4
|
| 350 |
|
|
ldd [%g7 + 6 * 4], %l6
|
| 351 |
|
|
|
| 352 |
|
|
ldd [%g7 + 8 * 4], %i0
|
| 353 |
|
|
ldd [%g7 + 10 * 4], %i2
|
| 354 |
|
|
ldd [%g7 + 12 * 4], %i4
|
| 355 |
|
|
ldd [%g7 + 14 * 4], %i6
|
| 356 |
|
|
|
| 357 |
|
|
ld [%g7 + 30 * 4], %sp ! %o6 = %sp, set up now so as to conform
|
| 358 |
|
|
! to PCS and so be interruptible
|
| 359 |
|
|
! ENABLE INTERRUPTS
|
| 360 |
|
|
wr %g6, %g4, %psr ! set new CWP and old ET
|
| 361 |
|
|
nop
|
| 362 |
|
|
nop
|
| 363 |
|
|
nop
|
| 364 |
|
|
|
| 365 |
|
|
! now load the rest of the context; we can be interrupted here, but
|
| 366 |
|
|
! that is OK, other state will be preserved in that case...
|
| 367 |
|
|
#ifdef CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
|
| 368 |
|
|
! we are not preserving globals...
|
| 369 |
|
|
! %o6 = %sp, already set up
|
| 370 |
|
|
ld [%g7 + 31 * 4], %o7 ! "return" address
|
| 371 |
|
|
retl ! %g1 still holds the return value
|
| 372 |
|
|
mov %g1, %o0
|
| 373 |
|
|
|
| 374 |
|
|
#else // load a maximal context
|
| 375 |
|
|
mov %g7, %o0 ! original pointer was in %o0 anyway
|
| 376 |
|
|
|
| 377 |
|
|
ldd [%o0 + 18 * 4], %g2
|
| 378 |
|
|
ldd [%o0 + 20 * 4], %g4
|
| 379 |
|
|
ldd [%o0 + 22 * 4], %g6
|
| 380 |
|
|
|
| 381 |
|
|
ld [%o0 + 25 * 4], %o1 ! %o0 = original pointer
|
| 382 |
|
|
ldd [%o0 + 26 * 4], %o2
|
| 383 |
|
|
ldd [%o0 + 28 * 4], %o4
|
| 384 |
|
|
! %o6 = %sp, already set up
|
| 385 |
|
|
ld [%o0 + 31 * 4], %o7 ! "return" address
|
| 386 |
|
|
|
| 387 |
|
|
! %g1 still holds the return value; want to get this into %o0
|
| 388 |
|
|
! and restore %g1 from the saved state; %o0 is the state pointer:
|
| 389 |
|
|
! g1 = R, o0 = P
|
| 390 |
|
|
xor %o0, %g1, %g1 ! g1 = R^P, o0 = P
|
| 391 |
|
|
xor %o0, %g1, %o0 ! g1 = R^P, o0 = R
|
| 392 |
|
|
xor %o0, %g1, %g1 ! g1 = P, o0 = R all done
|
| 393 |
|
|
|
| 394 |
|
|
retl
|
| 395 |
|
|
ld [%g1 + 17 * 4], %g1 ! and finally restore %g1
|
| 396 |
|
|
#endif // !CYGDBG_HAL_COMMON_CONTEXT_SAVE_MINIMUM
|
| 397 |
|
|
|
| 398 |
|
|
! ------------------------------------------------------------------------------
|
| 399 |
|
|
! end of context.S
|
| 400 |
|
|
|
| 401 |
|
|
|
| 402 |
|
|
|
