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/* Checked longjmp support. x86_64 Hurd version.
Copyright (C) 2001-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
#include <pointer_guard.h>
#include <jmpbuf-offsets.h>
#include <asm-syntax.h>
#include <tcb-offsets.h>
#include <jmp_buf-ssp.h>
#include <signal-defines.h>
#define SS_ONSTACK 1
/* Don't restore shadow stack register if shadow stack isn't enabled. */
#if !SHSTK_ENABLED
# undef SHADOW_STACK_POINTER_OFFSET
#endif
.section .rodata.str1.1,"aMS",@progbits,1
.type longjmp_msg,@object
longjmp_msg:
.string "longjmp causes uninitialized stack frame"
.size longjmp_msg, .-longjmp_msg
# define CALL_FAIL sub $8, %RSP_LP; \
cfi_remember_state; \
cfi_def_cfa_offset(16); \
lea longjmp_msg(%rip), %RDI_LP; \
call HIDDEN_JUMPTARGET(__fortify_fail); \
nop; \
cfi_restore_state
/* Jump to the position specified by ENV, causing the
setjmp call there to return VAL, or 1 if VAL is 0.
void __longjmp (__jmp_buf env, int val). */
.text
ENTRY(____longjmp_chk)
/* Restore registers. */
mov (JB_RSP*8)(%rdi), %R8_LP
mov (JB_RBP*8)(%rdi),%R9_LP
mov (JB_PC*8)(%rdi), %RDX_LP
#ifdef PTR_DEMANGLE
PTR_DEMANGLE (%R8_LP)
PTR_DEMANGLE (%R9_LP)
PTR_DEMANGLE (%RDX_LP)
#endif
#if !defined (SHARED) || IS_IN (rtld)
cmpb $0, __libc_tls_initialized(%rip)
jz .Lok /* TLS not initialized yet */
#endif
movq %fs:SIGSTATE_OFFSET, %R10_LP
testq %R10_LP, %R10_LP
jz .Lok /* sigstate not initialized yet */
testl $SS_ONSTACK, (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_FLAGS__OFFSET)(%R10_LP)
jnz .Lonstack
/* We were on the main stack. Jumping to a higher-address
frame is always allowed, otherwise it's not allowed. */
cmp %R8_LP, %RSP_LP
jbe .Lok
.Lfail: CALL_FAIL
.Lonstack:
/* We were on the alternate stack, can't really easily check anything
since longjmp may get us out of the alternate stack. */
cmpq (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SP__OFFSET)(%R10_LP), %R8_LP
jb .Loks /* Jumping below the altstack, switch */
movq (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SP__OFFSET)(%R10_LP), %R11_LP
addq (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SIZE__OFFSET)(%R10_LP), %R11_LP
cmpq %R11_LP, %R8_LP
jb .Lok /* Jumping inside the altstack, do not switch */
/* Jumping above the altstack, switch */
.Loks: /* We jump out of the alternate stack, clear SS_ONSTACK flag. */
andl $~(SS_ONSTACK), (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_FLAGS__OFFSET)(%R10_LP)
.Lok:
/* We add unwind information for the target here. */
cfi_def_cfa(%rdi, 0)
cfi_register(%rsp,%r8)
cfi_register(%rbp,%r9)
cfi_register(%rip,%rdx)
cfi_offset(%rbx,JB_RBX*8)
cfi_offset(%r12,JB_R12*8)
cfi_offset(%r13,JB_R13*8)
cfi_offset(%r14,JB_R14*8)
cfi_offset(%r15,JB_R15*8)
movq (JB_RBX*8)(%rdi), %rbx
movq (JB_R12*8)(%rdi), %r12
movq (JB_R13*8)(%rdi), %r13
movq (JB_R14*8)(%rdi), %r14
movq (JB_R15*8)(%rdi), %r15
/* Set return value for setjmp. */
movl %esi, %eax
mov %R8_LP, %RSP_LP
movq %r9,%rbp
jmpq *%rdx
END (____longjmp_chk)
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