1 /* Copyright (C) 2001-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
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.
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.
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/>. */
19 #include <pointer_guard.h>
20 #include <jmpbuf-offsets.h>
21 #include <jmp_buf-ssp.h>
22 #include <asm-syntax.h>
23 #include <stap-probe.h>
25 /* Don't restore shadow stack register if shadow stack isn't enabled. */
27 # undef SHADOW_STACK_POINTER_OFFSET
30 .section .rodata.str1.1,"aMS",@progbits,1
31 .type longjmp_msg,@object
33 .string "longjmp causes uninitialized stack frame"
34 .size longjmp_msg, .-longjmp_msg
38 # define CALL_FAIL movl %ebx, %ecx; \
39 cfi_register(%ebx,%ecx); \
41 leal longjmp_msg@GOTOFF(%ebx), %eax; \
43 call HIDDEN_JUMPTARGET(__fortify_fail)
45 # define CALL_FAIL movl $longjmp_msg, %eax; \
47 call HIDDEN_JUMPTARGET(__fortify_fail)
52 ENTRY (____longjmp_chk)
53 movl 4(%esp), %ecx /* User's jmp_buf in %ecx. */
55 #ifdef SHADOW_STACK_POINTER_OFFSET
56 # if IS_IN (libc) && defined SHARED && defined FEATURE_1_OFFSET
57 /* Check if Shadow Stack is enabled. */
58 testl $X86_FEATURE_1_SHSTK, %gs:FEATURE_1_OFFSET
63 /* Check and adjust the Shadow-Stack-Pointer. */
65 /* And compare it with the saved ssp value. */
66 subl SHADOW_STACK_POINTER_OFFSET(%ecx), %edx
68 /* Count the number of frames to adjust and adjust it
69 with incssp instruction. The instruction can adjust
70 the ssp by [0..255] value only thus use a loop if
71 the number of frames is bigger than 255. */
74 /* NB: We saved Shadow-Stack-Pointer of setjmp. Since we are
75 restoring Shadow-Stack-Pointer of setjmp's caller, we
76 need to unwind shadow stack by one more frame. */
87 /* Save the return address now. */
88 movl (JB_PC*4)(%ecx), %edx
89 /* Get the stack pointer. */
90 movl (JB_SP*4)(%ecx), %edi
99 cfi_adjust_cfa_offset(12)
102 movl $__NR_sigaltstack, %eax
104 /* Without working sigaltstack we cannot perform the test. */
118 .Lok2: addl $12, %esp
119 cfi_adjust_cfa_offset(-12)
123 LIBC_PROBE (longjmp, 3, 4@%ecx, -4@8(%esp), 4@%edx)
124 /* We add unwind information for the target here. */
126 cfi_register(%eip, %edx)
127 cfi_register(%esp, %edi)
128 cfi_offset(%ebx, JB_BX*4)
129 cfi_offset(%esi, JB_SI*4)
130 cfi_offset(%edi, JB_DI*4)
131 cfi_offset(%ebp, JB_BP*4)
133 movl 8(%esp), %eax /* Second argument is return value. */
136 /* Restore registers. */
137 movl (JB_BX*4)(%ecx), %ebx
138 movl (JB_SI*4)(%ecx), %esi
139 movl (JB_DI*4)(%ecx), %edi
140 movl (JB_BP*4)(%ecx), %ebp
146 /* Jump to saved PC. */
147 LIBC_PROBE (longjmp_target, 3, 4@%ecx, -4@%eax, 4@%edx)
149 END (____longjmp_chk)