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113 lines
3.4 KiB
ArmAsm
113 lines
3.4 KiB
ArmAsm
/* Copyright (C) 2001-2020 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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/* Jump to the position specified by ENV, causing the
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setjmp call there to return VAL, or 1 if VAL is 0.
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void __longjmp (__jmp_buf env, int val). */
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.text
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ENTRY(__longjmp)
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/* Restore registers. */
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mov (JB_RSP*8)(%rdi),%R8_LP
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mov (JB_RBP*8)(%rdi),%R9_LP
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mov (JB_PC*8)(%rdi),%RDX_LP
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#ifdef PTR_DEMANGLE
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PTR_DEMANGLE (%R8_LP)
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PTR_DEMANGLE (%R9_LP)
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PTR_DEMANGLE (%RDX_LP)
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# ifdef __ILP32__
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/* We ignored the high bits of the %rbp value because only the low
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bits are mangled. But we cannot presume that %rbp is being used
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as a pointer and truncate it, so recover the high bits. */
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movl (JB_RBP*8 + 4)(%rdi), %eax
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shlq $32, %rax
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orq %rax, %r9
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# endif
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#endif
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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, %fs:FEATURE_1_OFFSET
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jz L(skip_ssp)
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# else
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xorl %eax, %eax
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# endif
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/* Check and adjust the Shadow-Stack-Pointer. */
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/* Get the current ssp. */
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rdsspq %rax
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/* And compare it with the saved ssp value. */
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subq SHADOW_STACK_POINTER_OFFSET(%rdi), %rax
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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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negq %rax
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shrq $3, %rax
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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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addq $1, %rax
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movl $255, %ebx
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L(loop):
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cmpq %rbx, %rax
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cmovb %rax, %rbx
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incsspq %rbx
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subq %rbx, %rax
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ja L(loop)
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L(skip_ssp):
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#endif
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LIBC_PROBE (longjmp, 3, LP_SIZE@%RDI_LP, -4@%esi, LP_SIZE@%RDX_LP)
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/* We add unwind information for the target here. */
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cfi_def_cfa(%rdi, 0)
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cfi_register(%rsp,%r8)
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cfi_register(%rbp,%r9)
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cfi_register(%rip,%rdx)
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cfi_offset(%rbx,JB_RBX*8)
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cfi_offset(%r12,JB_R12*8)
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cfi_offset(%r13,JB_R13*8)
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cfi_offset(%r14,JB_R14*8)
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cfi_offset(%r15,JB_R15*8)
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movq (JB_RBX*8)(%rdi),%rbx
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movq (JB_R12*8)(%rdi),%r12
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movq (JB_R13*8)(%rdi),%r13
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movq (JB_R14*8)(%rdi),%r14
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movq (JB_R15*8)(%rdi),%r15
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/* Set return value for setjmp. */
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mov %esi, %eax
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mov %R8_LP,%RSP_LP
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movq %r9,%rbp
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LIBC_PROBE (longjmp_target, 3,
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LP_SIZE@%RDI_LP, -4@%eax, LP_SIZE@%RDX_LP)
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jmpq *%rdx
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END (__longjmp)
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