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/* DWARF2 EH unwinding support for MIPS IRIX 6.
Copyright (C) 2011 Free Software Foundation, Inc.
This file is part of GCC.
GCC 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, or (at your option)
any later version.
GCC 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.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
/* Do code reading to identify a signal frame, and set the frame
state data appropriately. See unwind-dw2.c for the structs. */
/* This code was developed-for and only tested-in limited ABI
configurations. Characterize that. */
#if defined (_ABIN32) || defined (_ABI64)
#define SUPPORTED_ABI 1
#else
#define SUPPORTED_ABI 0
#endif
#include <signal.h>
#define MD_FALLBACK_FRAME_STATE_FOR mips_fallback_frame_state
/* Look at the code around RA to see if it matches a sighandler caller with a
sigcontext_t * argument (SA_SIGINFO cleared). Return that pointer argument
if it does match, or 0 otherwise. */
static sigcontext_t *
sigcontext_for (unsigned int *ra, void *cfa)
{
/* IRIX 6.5, mono-threaded application. We're lucky enough to be able
to expect a short very sighandler specific sequence around.
<_sigtramp+124>: li v0,1088 (SYS_sigreturn)
<_sigtramp+128>: syscall */
if ( ra[6] == 0x24020440
&& ra[7] == 0x0000000c)
return (sigcontext_t *)(cfa + 0x30);
/* IRIX 6.5 variants, multi-threaded application, pthreads. Nothing really
sighandler specific handy, so match a fairly long constant sequence. */
#if _MIPS_SIM == _ABIN32
/*
<sig_fixup_mask+40>: sd s0,0(sp)
<sig_fixup_mask+44>: sll ra,a0,0x2
<sig_fixup_mask+48>: addiu t9,t9,-28584/-28456/-28448
<sig_fixup_mask+52>: lw s0,3804(at)
<sig_fixup_mask+56>: addu t9,t9,ra
<sig_fixup_mask+60>: lw t9,0(t9)
<sig_fixup_mask+64>: ld at,3696(at)
<sig_fixup_mask+68>: ld s2,88(s0)
<sig_fixup_mask+72>: jalr t9
<sig_fixup_mask+76>: sd at,88(s0) */
if ( ra[-10] == 0xffb00000
&& ra[ -9] == 0x0004f880
&& (ra[-8] == 0x27399058
|| ra[-8] == 0x273990d8
|| ra[-8] == 0x273990e0)
&& ra[ -7] == 0x8c300edc
&& ra[ -6] == 0x033fc821
&& ra[ -5] == 0x8f390000
&& ra[ -4] == 0xdc210e70
&& ra[ -3] == 0xde120058
&& ra[ -2] == 0x0320f809
&& ra[ -1] == 0xfe010058)
#elif _MIPS_SIM == _ABI64
/*
<sig_fixup_mask+44>: sd s0,0(sp)
<sig_fixup_mask+48>: daddu t9,t9,ra
<sig_fixup_mask+52>: dsll ra,a0,0x3
<sig_fixup_mask+56>: ld s0,3880(at)
<sig_fixup_mask+60>: daddu t9,t9,ra
<sig_fixup_mask+64>: ld t9,0(t9)
<sig_fixup_mask+68>: ld at,3696(at)
<sig_fixup_mask+72>: ld s2,152(s0)
<sig_fixup_mask+76>: jalr t9
<sig_fixup_mask+80>: sd at,152(s0) */
if ( ra[-10] == 0xffb00000
&& ra[ -9] == 0x033fc82d
&& ra[ -8] == 0x0004f8f8
&& ra[ -7] == 0xdc300f28
&& ra[ -6] == 0x033fc82d
&& ra[ -5] == 0xdf390000
&& ra[ -4] == 0xdc210e70
&& ra[ -3] == 0xde120098
&& ra[ -2] == 0x0320f809
&& ra[ -1] == 0xfe010098)
#endif
return (sigcontext_t *)(cfa + 0x60);
return 0;
}
#define SIGCTX_GREG_ADDR(REGNO,SIGCTX) \
((void *) &(SIGCTX)->sc_regs[REGNO])
#define SIGCTX_FPREG_ADDR(REGNO,SIGCTX) \
((void *) &(SIGCTX)->sc_fpregs[REGNO])
static _Unwind_Reason_Code
mips_fallback_frame_state (struct _Unwind_Context *context,
_Unwind_FrameState *fs)
{
/* Return address and CFA of the frame we're attempting to unwind through,
possibly a signal handler. */
void *ctx_ra = (void *)context->ra;
void *ctx_cfa = (void *)context->cfa;
/* CFA of the intermediate abstract kernel frame between the interrupted
code and the signal handler, if we're indeed unwinding through a signal
handler. */
void *k_cfa;
/* Pointer to the sigcontext_t structure pushed by the kernel when we're
unwinding through a signal handler setup with SA_SIGINFO cleared. */
sigcontext_t *sigctx;
int i;
if (! SUPPORTED_ABI)
return _URC_END_OF_STACK;
sigctx = sigcontext_for (ctx_ra, ctx_cfa);
if (sigctx == 0)
return _URC_END_OF_STACK;
/* The abstract kernel frame's CFA is extactly the stack pointer
value at the interruption point. */
k_cfa = *(void **)SIGCTX_GREG_ADDR (CTX_SP, sigctx);
/* State the rules to compute the CFA we have the value of: use the
previous CFA and offset by the difference between the two. See
uw_update_context_1 for the supporting details. */
fs->regs.cfa_how = CFA_REG_OFFSET;
fs->regs.cfa_reg = __builtin_dwarf_sp_column ();
fs->regs.cfa_offset = k_cfa - ctx_cfa;
/* Fill the internal frame_state structure with information stating where
each register of interest can be found from the CFA. */
for (i = 0; i <= 31; i ++)
{
fs->regs.reg[i].how = REG_SAVED_OFFSET;
fs->regs.reg[i].loc.offset = SIGCTX_GREG_ADDR (i, sigctx) - k_cfa;
}
for (i = 0; i <= 31; i ++)
{
fs->regs.reg[32+i].how = REG_SAVED_OFFSET;
fs->regs.reg[32+i].loc.offset = SIGCTX_FPREG_ADDR (i, sigctx) - k_cfa;
}
/* State the rules to find the kernel's code "return address", which is the
address of the active instruction when the signal was caught. */
fs->retaddr_column = DWARF_FRAME_RETURN_COLUMN;
fs->regs.reg[fs->retaddr_column].how = REG_SAVED_OFFSET;
fs->regs.reg[fs->retaddr_column].loc.offset = (void *)&sigctx->sc_pc - k_cfa;
fs->signal_frame = 1;
return _URC_NO_REASON;
}
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