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/* DWARF2 EH unwinding support for FreeBSD: AMD x86-64 and x86.
Copyright (C) 2015-2022 Free Software Foundation, Inc.
Contributed by John Marino <gnugcc@marino.st>
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 <sys/types.h>
#include <signal.h>
#include <unistd.h>
#include <sys/sysctl.h>
#include <sys/ucontext.h>
#include <sys/user.h>
#include <machine/sigframe.h>
#define REG_NAME(reg) sf_uc.uc_mcontext.mc_## reg
#ifdef __x86_64__
#define MD_FALLBACK_FRAME_STATE_FOR x86_64_freebsd_fallback_frame_state
#ifdef KERN_PROC_SIGTRAMP
/* FreeBSD past 9.3 provides a kern.proc.sigtramp.<pid> sysctl that
returns the location of the signal trampoline. Use this to find
out whether we're in a trampoline.
*/
static int
x86_64_outside_sigtramp_range (unsigned char *pc)
{
static int sigtramp_range_determined = 0;
static unsigned char *sigtramp_start, *sigtramp_end;
if (sigtramp_range_determined == 0)
{
struct kinfo_sigtramp kst = {0};
size_t len = sizeof (kst);
int mib[4] = { CTL_KERN, KERN_PROC, KERN_PROC_SIGTRAMP, getpid() };
sigtramp_range_determined = 1;
if (sysctl (mib, 4, &kst, &len, NULL, 0) == 0)
{
sigtramp_range_determined = 2;
sigtramp_start = kst.ksigtramp_start;
sigtramp_end = kst.ksigtramp_end;
}
}
if (sigtramp_range_determined < 2) /* sysctl failed if < 2 */
return 1;
return (pc < sigtramp_start || pc >= sigtramp_end);
}
#endif
static _Unwind_Reason_Code
x86_64_freebsd_fallback_frame_state
(struct _Unwind_Context *context, _Unwind_FrameState *fs)
{
struct sigframe *sf;
long new_cfa;
#ifndef KERN_PROC_SIGTRAMP
/* Prior to FreeBSD 9, the signal trampoline was located immediately
before the ps_strings. To support non-executable stacks on AMD64,
the sigtramp was moved to a shared page for FreeBSD 9. Unfortunately
this means looking frame patterns again (sys/amd64/amd64/sigtramp.S)
rather than using the robust and convenient KERN_PS_STRINGS trick.
<pc + 00>: lea 0x10(%rsp),%rdi
<pc + 05>: pushq $0x0
<pc + 17>: mov $0x1a1,%rax
<pc + 14>: syscall
If we can't find this pattern, we're at the end of the stack.
*/
if (!( *(unsigned int *)(context->ra) == 0x247c8d48
&& *(unsigned int *)(context->ra + 4) == 0x48006a10
&& *(unsigned int *)(context->ra + 8) == 0x01a1c0c7
&& *(unsigned int *)(context->ra + 12) == 0x050f0000 ))
return _URC_END_OF_STACK;
#else
if (x86_64_outside_sigtramp_range(context->ra))
return _URC_END_OF_STACK;
#endif
sf = (struct sigframe *) context->cfa;
new_cfa = sf->REG_NAME(rsp);
fs->regs.cfa_how = CFA_REG_OFFSET;
fs->regs.cfa_reg = __LIBGCC_STACK_POINTER_REGNUM__;
fs->regs.cfa_offset = new_cfa - (long) context->cfa;
/* The SVR4 register numbering macros aren't usable in libgcc. */
fs->regs.reg[0].how = REG_SAVED_OFFSET;
fs->regs.reg[0].loc.offset = (long)&sf->REG_NAME(rax) - new_cfa;
fs->regs.reg[1].how = REG_SAVED_OFFSET;
fs->regs.reg[1].loc.offset = (long)&sf->REG_NAME(rdx) - new_cfa;
fs->regs.reg[2].how = REG_SAVED_OFFSET;
fs->regs.reg[2].loc.offset = (long)&sf->REG_NAME(rcx) - new_cfa;
fs->regs.reg[3].how = REG_SAVED_OFFSET;
fs->regs.reg[3].loc.offset = (long)&sf->REG_NAME(rbx) - new_cfa;
fs->regs.reg[4].how = REG_SAVED_OFFSET;
fs->regs.reg[4].loc.offset = (long)&sf->REG_NAME(rsi) - new_cfa;
fs->regs.reg[5].how = REG_SAVED_OFFSET;
fs->regs.reg[5].loc.offset = (long)&sf->REG_NAME(rdi) - new_cfa;
fs->regs.reg[6].how = REG_SAVED_OFFSET;
fs->regs.reg[6].loc.offset = (long)&sf->REG_NAME(rbp) - new_cfa;
fs->regs.reg[8].how = REG_SAVED_OFFSET;
fs->regs.reg[8].loc.offset = (long)&sf->REG_NAME(r8) - new_cfa;
fs->regs.reg[9].how = REG_SAVED_OFFSET;
fs->regs.reg[9].loc.offset = (long)&sf->REG_NAME(r9) - new_cfa;
fs->regs.reg[10].how = REG_SAVED_OFFSET;
fs->regs.reg[10].loc.offset = (long)&sf->REG_NAME(r10) - new_cfa;
fs->regs.reg[11].how = REG_SAVED_OFFSET;
fs->regs.reg[11].loc.offset = (long)&sf->REG_NAME(r11) - new_cfa;
fs->regs.reg[12].how = REG_SAVED_OFFSET;
fs->regs.reg[12].loc.offset = (long)&sf->REG_NAME(r12) - new_cfa;
fs->regs.reg[13].how = REG_SAVED_OFFSET;
fs->regs.reg[13].loc.offset = (long)&sf->REG_NAME(r13) - new_cfa;
fs->regs.reg[14].how = REG_SAVED_OFFSET;
fs->regs.reg[14].loc.offset = (long)&sf->REG_NAME(r14) - new_cfa;
fs->regs.reg[15].how = REG_SAVED_OFFSET;
fs->regs.reg[15].loc.offset = (long)&sf->REG_NAME(r15) - new_cfa;
fs->regs.reg[16].how = REG_SAVED_OFFSET;
fs->regs.reg[16].loc.offset = (long)&sf->REG_NAME(rip) - new_cfa;
fs->retaddr_column = 16;
fs->signal_frame = 1;
return _URC_NO_REASON;
}
#else /* Next section is for i386 */
#define MD_FALLBACK_FRAME_STATE_FOR x86_freebsd_fallback_frame_state
/*
* We can't use KERN_PS_STRINGS anymore if we want to support FreeBSD32
* compat on AMD64. The sigtramp is in a shared page in that case so the
* x86_sigtramp_range only works on a true i386 system. We have to
* search for the sigtramp frame if we want it working everywhere.
*/
static _Unwind_Reason_Code
x86_freebsd_fallback_frame_state
(struct _Unwind_Context *context, _Unwind_FrameState *fs)
{
struct sigframe *sf;
long new_cfa;
/*
* i386 sigtramp frame we are looking for follows.
* Apparently PSL_VM is variable, so we can't look past context->ra + 4
* <sigcode>:
* 0: ff 54 24 10 call *0x10(%esp) *SIGF_HANDLER
* 4: 8d 44 24 20 lea 0x20(%esp),%eax SIGF_UC
* 8: 50 push %eax
* 9: f7 40 54 00 00 02 00 testl $0x20000,0x54(%eax) $PSL_VM
* 10: 75 03 jne 15 <sigcode+0x15>
* 12: 8e 68 14 mov 0x14(%eax),%gs UC_GS
* 15: b8 a1 01 00 00 mov 0x1a1,%eax $SYS_sigreturn
*/
if (!( *(unsigned int *)(context->ra - 4) == 0x102454ff
&& *(unsigned int *)(context->ra) == 0x2024448d ))
return _URC_END_OF_STACK;
sf = (struct sigframe *) context->cfa;
new_cfa = sf->REG_NAME(esp);
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.reg[0].how = REG_SAVED_OFFSET;
fs->regs.reg[0].loc.offset = (long)&sf->REG_NAME(eax) - new_cfa;
fs->regs.reg[3].how = REG_SAVED_OFFSET;
fs->regs.reg[3].loc.offset = (long)&sf->REG_NAME(ebx) - new_cfa;
fs->regs.reg[1].how = REG_SAVED_OFFSET;
fs->regs.reg[1].loc.offset = (long)&sf->REG_NAME(ecx) - new_cfa;
fs->regs.reg[2].how = REG_SAVED_OFFSET;
fs->regs.reg[2].loc.offset = (long)&sf->REG_NAME(edx) - new_cfa;
fs->regs.reg[6].how = REG_SAVED_OFFSET;
fs->regs.reg[6].loc.offset = (long)&sf->REG_NAME(esi) - new_cfa;
fs->regs.reg[7].how = REG_SAVED_OFFSET;
fs->regs.reg[7].loc.offset = (long)&sf->REG_NAME(edi) - new_cfa;
fs->regs.reg[5].how = REG_SAVED_OFFSET;
fs->regs.reg[5].loc.offset = (long)&sf->REG_NAME(ebp) - new_cfa;
fs->regs.reg[8].how = REG_SAVED_OFFSET;
fs->regs.reg[8].loc.offset = (long)&sf->REG_NAME(eip) - new_cfa;
fs->retaddr_column = 8;
fs->signal_frame = 1;
return _URC_NO_REASON;
}
#endif /* ifdef __x86_64__ */