libgcc/config/i386/sol2-unwind.h

/* DWARF2 EH unwinding support for AMD x86-64 and x86.
   Copyright (C) 2009-2023 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.  */

#include <ucontext.h>
#include <sys/frame.h>

#ifdef __x86_64__

#define MD_FALLBACK_FRAME_STATE_FOR x86_64_fallback_frame_state

static _Unwind_Reason_Code
x86_64_fallback_frame_state (struct _Unwind_Context *context,
			     _Unwind_FrameState *fs)
{
  unsigned char *pc = context->ra;
  mcontext_t *mctx;
  long new_cfa;

  if (/* Solaris 10+
	------------
	<__sighndlr+0>:      push   %rbp
	<__sighndlr+1>:      mov    %rsp,%rbp
	<__sighndlr+4>:      callq  *%rcx
	<__sighndlr+6>:      leaveq           <--- PC
	<__sighndlr+7>:      retq  */
      *(unsigned long *)(pc - 6) == 0xc3c9d1ffe5894855)

    /* We need to move up three frames:

		<signal handler>	<-- context->cfa
		__sighndlr
		call_user_handler
		sigacthandler
		<kernel>

       context->cfa points into the frame after the saved frame pointer and
       saved pc (struct frame).

       The ucontext_t structure is in the kernel frame after the signal
       number and a siginfo_t *.  Since the frame sizes vary even within
       Solaris 10 updates, we need to walk the stack to get there.  */
    {
      struct frame *fp = (struct frame *) context->cfa - 1;
      struct handler_args {
	int signo;
	siginfo_t *sip;
	ucontext_t ucontext;
      } *handler_args;
      ucontext_t *ucp;

      /* Next frame: __sighndlr frame pointer.  */
      fp = (struct frame *) fp->fr_savfp;
      /* call_user_handler frame pointer.  */
      fp = (struct frame *) fp->fr_savfp;
      /* sigacthandler frame pointer.  */
      fp = (struct frame *) fp->fr_savfp;

      /* The argument area precedes the struct frame.  */
      handler_args = (struct handler_args *) (fp + 1);
      ucp = &handler_args->ucontext;
      mctx = &ucp->uc_mcontext;
    }
  else
    return _URC_END_OF_STACK;

  new_cfa = mctx->gregs[REG_RSP];

  fs->regs.cfa_how = CFA_REG_OFFSET;
  fs->regs.cfa_reg = 7;
  fs->regs.cfa_offset = new_cfa - (long) context->cfa;

  /* The SVR4 register numbering macros aren't usable in libgcc.  */
  fs->regs.how[0] = REG_SAVED_OFFSET;
  fs->regs.reg[0].loc.offset = (long)&mctx->gregs[REG_RAX] - new_cfa;
  fs->regs.how[1] = REG_SAVED_OFFSET;
  fs->regs.reg[1].loc.offset = (long)&mctx->gregs[REG_RDX] - new_cfa;
  fs->regs.how[2] = REG_SAVED_OFFSET;
  fs->regs.reg[2].loc.offset = (long)&mctx->gregs[REG_RCX] - new_cfa;
  fs->regs.how[3] = REG_SAVED_OFFSET;
  fs->regs.reg[3].loc.offset = (long)&mctx->gregs[REG_RBX] - new_cfa;
  fs->regs.how[4] = REG_SAVED_OFFSET;
  fs->regs.reg[4].loc.offset = (long)&mctx->gregs[REG_RSI] - new_cfa;
  fs->regs.how[5] = REG_SAVED_OFFSET;
  fs->regs.reg[5].loc.offset = (long)&mctx->gregs[REG_RDI] - new_cfa;
  fs->regs.how[6] = REG_SAVED_OFFSET;
  fs->regs.reg[6].loc.offset = (long)&mctx->gregs[REG_RBP] - new_cfa;
  fs->regs.how[8] = REG_SAVED_OFFSET;
  fs->regs.reg[8].loc.offset = (long)&mctx->gregs[REG_R8] - new_cfa;
  fs->regs.how[9] = REG_SAVED_OFFSET;
  fs->regs.reg[9].loc.offset = (long)&mctx->gregs[REG_R9] - new_cfa;
  fs->regs.how[10] = REG_SAVED_OFFSET;
  fs->regs.reg[10].loc.offset = (long)&mctx->gregs[REG_R10] - new_cfa;
  fs->regs.how[11] = REG_SAVED_OFFSET;
  fs->regs.reg[11].loc.offset = (long)&mctx->gregs[REG_R11] - new_cfa;
  fs->regs.how[12] = REG_SAVED_OFFSET;
  fs->regs.reg[12].loc.offset = (long)&mctx->gregs[REG_R12] - new_cfa;
  fs->regs.how[13] = REG_SAVED_OFFSET;
  fs->regs.reg[13].loc.offset = (long)&mctx->gregs[REG_R13] - new_cfa;
  fs->regs.how[14] = REG_SAVED_OFFSET;
  fs->regs.reg[14].loc.offset = (long)&mctx->gregs[REG_R14] - new_cfa;
  fs->regs.how[15] = REG_SAVED_OFFSET;
  fs->regs.reg[15].loc.offset = (long)&mctx->gregs[REG_R15] - new_cfa;
  fs->regs.how[16] = REG_SAVED_OFFSET;
  fs->regs.reg[16].loc.offset = (long)&mctx->gregs[REG_RIP] - new_cfa;
  fs->retaddr_column = 16;
  fs->signal_frame = 1;

  return _URC_NO_REASON;
}

#else

#define MD_FALLBACK_FRAME_STATE_FOR x86_fallback_frame_state

static _Unwind_Reason_Code
x86_fallback_frame_state (struct _Unwind_Context *context,
			  _Unwind_FrameState *fs)
{
  unsigned char *pc = context->ra;
  mcontext_t *mctx;
  long new_cfa;

  if (/* Solaris 11 since snv_125
	   -------------------------
	  <__sighndlr+0>       	push   %ebp
	  <__sighndlr+1>       	mov    %esp,%ebp
	  <__sighndlr+3>       	and    $0xfffffff0,%esp
	  <__sighndlr+6>       	sub    $0x4,%esp
	  <__sighndlr+9>      	pushl  0x10(%ebp)
	  <__sighndlr+12>      	pushl  0xc(%ebp)
	  <__sighndlr+15>      	pushl  0x8(%ebp)
	  <__sighndlr+18>      	call   *0x14(%ebp)
	  <__sighndlr+21>      	leave                <--- PC
	  <__sighndlr+22>      	ret  */
	 (*(unsigned long *)(pc - 21) == 0x83ec8b55
	  && *(unsigned long *)(pc - 17) == 0xec83f0e4
	  && *(unsigned long *)(pc - 13)  == 0x1075ff04
	  && *(unsigned long *)(pc - 9)  == 0xff0c75ff
	  && *(unsigned long *)(pc - 5)  == 0x55ff0875
	  && (*(unsigned long *)(pc - 1) & 0x00ffffff) == 0x00c3c914))
    {
      struct handler_args {
	int signo;
	siginfo_t *sip;
	ucontext_t *ucontext;
      } *handler_args = context->cfa;
      mctx = &handler_args->ucontext->uc_mcontext;
    }
  else
    return _URC_END_OF_STACK;

  new_cfa = mctx->gregs[UESP];

  fs->regs.cfa_how = CFA_REG_OFFSET;
  fs->regs.cfa_reg = 4;
  fs->regs.cfa_offset = new_cfa - (long) context->cfa;

  /* The SVR4 register numbering macros aren't usable in libgcc.  */
  fs->regs.how[0] = REG_SAVED_OFFSET;
  fs->regs.reg[0].loc.offset = (long)&mctx->gregs[EAX] - new_cfa;
  fs->regs.how[3] = REG_SAVED_OFFSET;
  fs->regs.reg[3].loc.offset = (long)&mctx->gregs[EBX] - new_cfa;
  fs->regs.how[1] = REG_SAVED_OFFSET;
  fs->regs.reg[1].loc.offset = (long)&mctx->gregs[ECX] - new_cfa;
  fs->regs.how[2] = REG_SAVED_OFFSET;
  fs->regs.reg[2].loc.offset = (long)&mctx->gregs[EDX] - new_cfa;
  fs->regs.how[6] = REG_SAVED_OFFSET;
  fs->regs.reg[6].loc.offset = (long)&mctx->gregs[ESI] - new_cfa;
  fs->regs.how[7] = REG_SAVED_OFFSET;
  fs->regs.reg[7].loc.offset = (long)&mctx->gregs[EDI] - new_cfa;
  fs->regs.how[5] = REG_SAVED_OFFSET;
  fs->regs.reg[5].loc.offset = (long)&mctx->gregs[EBP] - new_cfa;
  fs->regs.how[8] = REG_SAVED_OFFSET;
  fs->regs.reg[8].loc.offset = (long)&mctx->gregs[EIP] - new_cfa;
  fs->retaddr_column = 8;

  /* SIGFPE for IEEE-754 exceptions is delivered after the faulting insn
     rather than before it, so don't set fs->signal_frame in that case.
     We test whether the ES field of the Status Register is zero.  */
  if ((mctx->fpregs.fp_reg_set.fpchip_state.status & 0x80) == 0)
    fs->signal_frame = 1;

  return _URC_NO_REASON;
}

#endif