1/* Copyright (C) 2001-2024 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <sysdep.h>
19#include <pointer_guard.h>
20#include <jmpbuf-offsets.h>
21#include <asm-syntax.h>
22#include <stap-probe.h>
23
24
25 .section .rodata.str1.1,"aMS",@progbits,1
26 .type longjmp_msg,@object
27longjmp_msg:
28 .string "longjmp causes uninitialized stack frame"
29 .size longjmp_msg, .-longjmp_msg
30
31
32#ifdef PIC
33# define CALL_FAIL movl %ebx, %ecx; \
34 cfi_register(%ebx,%ecx); \
35 LOAD_PIC_REG (bx); \
36 leal longjmp_msg@GOTOFF(%ebx), %eax; \
37 movl %eax, (%esp); \
38 call HIDDEN_JUMPTARGET(__fortify_fail)
39#else
40# define CALL_FAIL movl $longjmp_msg, %eax; \
41 movl %eax, (%esp); \
42 call HIDDEN_JUMPTARGET(__fortify_fail)
43#endif
44
45
46 .text
47ENTRY (____longjmp_chk)
48 movl 4(%esp), %ecx /* User's jmp_buf in %ecx. */
49
50 /* Save the return address now. */
51 movl (JB_PC*4)(%ecx), %edx
52 /* Get the stack pointer. */
53 movl (JB_SP*4)(%ecx), %edi
54 cfi_undefined(%edi)
55 PTR_DEMANGLE (%edx)
56 PTR_DEMANGLE (%edi)
57
58 cmpl %edi, %esp
59 jbe .Lok
60
61 subl $12, %esp
62 cfi_adjust_cfa_offset(12)
63 xorl %ebx, %ebx
64 movl %esp, %ecx
65 movl $__NR_sigaltstack, %eax
66 ENTER_KERNEL
67 /* Without working sigaltstack we cannot perform the test. */
68 test %eax, %eax
69 jne .Lok2
70 testl $1, 4(%esp)
71 jz .Lfail
72
73 movl (%esp), %eax
74 addl 8(%esp), %eax
75 subl %edi, %eax
76 cmpl 8(%esp), %eax
77 jae .Lok2
78
79.Lfail: CALL_FAIL
80
81.Lok2: addl $12, %esp
82 cfi_adjust_cfa_offset(-12)
83 movl 4(%esp), %ecx
84
85.Lok:
86 LIBC_PROBE (longjmp, 3, 4@%ecx, -4@8(%esp), 4@%edx)
87 /* We add unwind information for the target here. */
88 cfi_def_cfa(%ecx, 0)
89 cfi_register(%eip, %edx)
90 cfi_register(%esp, %edi)
91 cfi_offset(%ebx, JB_BX*4)
92 cfi_offset(%esi, JB_SI*4)
93 cfi_offset(%edi, JB_DI*4)
94 cfi_offset(%ebp, JB_BP*4)
95
96 movl 8(%esp), %eax /* Second argument is return value. */
97 movl %edi, %esp
98
99 /* Restore registers. */
100 movl (JB_BX*4)(%ecx), %ebx
101 movl (JB_SI*4)(%ecx), %esi
102 movl (JB_DI*4)(%ecx), %edi
103 movl (JB_BP*4)(%ecx), %ebp
104 cfi_restore(%ebx)
105 cfi_restore(%esi)
106 cfi_restore(%edi)
107 cfi_restore(%ebp)
108
109 /* Jump to saved PC. */
110 LIBC_PROBE (longjmp_target, 3, 4@%ecx, -4@%eax, 4@%edx)
111 jmp *%edx
112END (____longjmp_chk)
113

source code of glibc/sysdeps/unix/sysv/linux/i386/____longjmp_chk.S