146 lines
4.4 KiB
ArmAsm
146 lines
4.4 KiB
ArmAsm
/* longjmp for i386.
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Copyright (C) 1995-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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#include <jmpbuf-offsets.h>
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#include <jmp_buf-ssp.h>
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#include <asm-syntax.h>
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#include <stap-probe.h>
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/* Don't restore shadow stack register if
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1. Shadow stack isn't enabled. Or
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2. __longjmp is defined for __longjmp_cancel.
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*/
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#if !SHSTK_ENABLED || defined __longjmp
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# undef SHADOW_STACK_POINTER_OFFSET
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#endif
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.text
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ENTRY (__longjmp)
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#ifdef PTR_DEMANGLE
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movl 4(%esp), %eax /* User's jmp_buf in %eax. */
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# ifdef SHADOW_STACK_POINTER_OFFSET
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# if IS_IN (libc) && defined SHARED && defined FEATURE_1_OFFSET
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/* Check if Shadow Stack is enabled. */
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testl $X86_FEATURE_1_SHSTK, %gs:FEATURE_1_OFFSET
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jz L(skip_ssp)
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# else
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xorl %edx, %edx
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# endif
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/* Check and adjust the Shadow-Stack-Pointer. */
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rdsspd %edx
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/* And compare it with the saved ssp value. */
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subl SHADOW_STACK_POINTER_OFFSET(%eax), %edx
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je L(skip_ssp)
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/* Count the number of frames to adjust and adjust it
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with incssp instruction. The instruction can adjust
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the ssp by [0..255] value only thus use a loop if
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the number of frames is bigger than 255. */
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negl %edx
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shrl $2, %edx
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/* NB: We saved Shadow-Stack-Pointer of setjmp. Since we are
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restoring Shadow-Stack-Pointer of setjmp's caller, we
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need to unwind shadow stack by one more frame. */
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addl $1, %edx
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movl $255, %ebx
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L(loop):
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cmpl %ebx, %edx
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cmovb %edx, %ebx
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incsspd %ebx
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subl %ebx, %edx
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ja L(loop)
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L(skip_ssp):
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# endif
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/* Save the return address now. */
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movl (JB_PC*4)(%eax), %edx
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/* Get the stack pointer. */
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movl (JB_SP*4)(%eax), %ecx
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PTR_DEMANGLE (%edx)
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PTR_DEMANGLE (%ecx)
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LIBC_PROBE (longjmp, 3, 4@%eax, -4@8(%esp), 4@%edx)
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cfi_def_cfa(%eax, 0)
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cfi_register(%eip, %edx)
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cfi_register(%esp, %ecx)
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cfi_offset(%ebx, JB_BX*4)
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cfi_offset(%esi, JB_SI*4)
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cfi_offset(%edi, JB_DI*4)
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cfi_offset(%ebp, JB_BP*4)
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/* Restore registers. */
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movl (JB_BX*4)(%eax), %ebx
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movl (JB_SI*4)(%eax), %esi
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movl (JB_DI*4)(%eax), %edi
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movl (JB_BP*4)(%eax), %ebp
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cfi_restore(%ebx)
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cfi_restore(%esi)
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cfi_restore(%edi)
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cfi_restore(%ebp)
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LIBC_PROBE (longjmp_target, 3, 4@%eax, -4@8(%esp), 4@%edx)
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movl 8(%esp), %eax /* Second argument is return value. */
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movl %ecx, %esp
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#else
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movl 4(%esp), %ecx /* User's jmp_buf in %ecx. */
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movl 8(%esp), %eax /* Second argument is return value. */
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# ifdef SHADOW_STACK_POINTER_OFFSET
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# if IS_IN (libc) && defined SHARED
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/* Check if Shadow Stack is enabled. */
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testl $X86_FEATURE_1_SHSTK, %gs:FEATURE_1_OFFSET
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jz L(skip_ssp)
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# endif
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/* Check and adjust the Shadow-Stack-Pointer. */
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xorl %edx, %edx
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/* Get the current ssp. */
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rdsspd %edx
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/* And compare it with the saved ssp value. */
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subl SHADOW_STACK_POINTER_OFFSET(%ecx), %edx
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je L(skip_ssp)
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/* Count the number of frames to adjust and adjust it
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with incssp instruction. The instruction can adjust
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the ssp by [0..255] value only thus use a loop if
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the number of frames is bigger than 255. */
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negl %edx
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shrl $2, %edx
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/* NB: We saved Shadow-Stack-Pointer of setjmp. Since we are
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restoring Shadow-Stack-Pointer of setjmp's caller, we
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need to unwind shadow stack by one more frame. */
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addl $1, %edx
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movl $255, %ebx
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L(loop):
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cmpl %ebx, %edx
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cmovb %edx, %ebx
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incsspd %ebx
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subl %ebx, %edx
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ja L(loop)
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L(skip_ssp):
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# endif
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/* Save the return address now. */
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movl (JB_PC*4)(%ecx), %edx
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LIBC_PROBE (longjmp, 3, 4@%ecx, -4@%eax, 4@%edx)
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/* Restore registers. */
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movl (JB_BX*4)(%ecx), %ebx
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movl (JB_SI*4)(%ecx), %esi
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movl (JB_DI*4)(%ecx), %edi
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movl (JB_BP*4)(%ecx), %ebp
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movl (JB_SP*4)(%ecx), %esp
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LIBC_PROBE (longjmp_target, 3, 4@%ecx, -4@%ecx, 4@%edx)
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#endif
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/* Jump to saved PC. */
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jmp *%edx
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END (__longjmp)
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