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/* Copyright (C) 2001-2021 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 <jmpbuf-offsets.h>
#include <asm-syntax.h>
#include <stap-probe.h>
#include <sigaltstack-offsets.h>
#include <jmp_buf-ssp.h>
/* 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 __longjmp ____longjmp_chk
#ifdef PIC
# 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
#else
# define CALL_FAIL sub $8, %RSP_LP; \
cfi_remember_state; \
cfi_def_cfa_offset(16); \
mov $longjmp_msg, %RDI_LP; \
call HIDDEN_JUMPTARGET(__fortify_fail); \
nop; \
cfi_restore_state
#endif
/* 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)
# ifdef __ILP32__
/* We ignored the high bits of the %rbp value because only the low
bits are mangled. But we cannot presume that %rbp is being used
as a pointer and truncate it, so recover the high bits. */
movl (JB_RBP*8 + 4)(%rdi), %eax
shlq $32, %rax
orq %rax, %r9
# endif
#endif
cmp %R8_LP, %RSP_LP
jbe .Lok
/* Save function parameters. */
movq %rdi, %r10
cfi_register (%rdi, %r10)
movl %esi, %ebx
cfi_register (%rsi, %rbx)
xorl %edi, %edi
lea -sizeSS(%rsp), %RSI_LP
movl $__NR_sigaltstack, %eax
syscall
/* Without working sigaltstack we cannot perform the test. */
testl %eax, %eax
jne .Lok2
testl $1, (-sizeSS + oSS_FLAGS)(%rsp)
jz .Lfail
mov (-sizeSS + oSS_SP)(%rsp), %RAX_LP
add (-sizeSS + oSS_SIZE)(%rsp), %RAX_LP
sub %R8_LP, %RAX_LP
cmp (-sizeSS + oSS_SIZE)(%rsp), %RAX_LP
jae .Lok2
.Lfail: CALL_FAIL
.Lok2: movq %r10, %rdi
cfi_restore (%rdi)
movl %ebx, %esi
cfi_restore (%rsi)
.Lok:
#ifdef SHADOW_STACK_POINTER_OFFSET
# if IS_IN (libc) && defined SHARED && defined FEATURE_1_OFFSET
/* Check if Shadow Stack is enabled. */
testl $X86_FEATURE_1_SHSTK, %fs:FEATURE_1_OFFSET
jz L(skip_ssp)
# else
xorl %eax, %eax
# endif
/* Check and adjust the Shadow-Stack-Pointer. */
rdsspq %rax
/* And compare it with the saved ssp value. */
subq SHADOW_STACK_POINTER_OFFSET(%rdi), %rax
je L(skip_ssp)
/* Count the number of frames to adjust and adjust it
with incssp instruction. The instruction can adjust
the ssp by [0..255] value only thus use a loop if
the number of frames is bigger than 255. */
negq %rax
shrq $3, %rax
/* NB: We saved Shadow-Stack-Pointer of setjmp. Since we are
restoring Shadow-Stack-Pointer of setjmp's caller, we
need to unwind shadow stack by one more frame. */
addq $1, %rax
movl $255, %ebx
L(loop):
cmpq %rbx, %rax
cmovb %rax, %rbx
incsspq %rbx
subq %rbx, %rax
ja L(loop)
L(skip_ssp):
#endif
LIBC_PROBE (longjmp, 3, LP_SIZE@%RDI_LP, -4@%esi, LP_SIZE@%RDX_LP)
/* 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
LIBC_PROBE (longjmp_target, 3,
LP_SIZE@%RDI_LP, -4@%eax, LP_SIZE@%RDX_LP)
jmpq *%rdx
END (____longjmp_chk)
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