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138 lines
3.7 KiB
ArmAsm
138 lines
3.7 KiB
ArmAsm
/* Save current context.
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Copyright (C) 2002-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Andreas Jaeger <aj@suse.de>, 2002.
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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 <asm/prctl.h>
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#include "ucontext_i.h"
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/* int __getcontext (ucontext_t *ucp)
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Saves the machine context in UCP such that when it is activated,
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it appears as if __getcontext() returned again.
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This implementation is intended to be used for *synchronous* context
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switches only. Therefore, it does not have to save anything
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other than the PRESERVED state. */
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ENTRY(__getcontext)
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/* Save the preserved registers, the registers used for passing
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args, and the return address. */
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movq %rbx, oRBX(%rdi)
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movq %rbp, oRBP(%rdi)
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movq %r12, oR12(%rdi)
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movq %r13, oR13(%rdi)
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movq %r14, oR14(%rdi)
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movq %r15, oR15(%rdi)
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movq %rdi, oRDI(%rdi)
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movq %rsi, oRSI(%rdi)
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movq %rdx, oRDX(%rdi)
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movq %rcx, oRCX(%rdi)
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movq %r8, oR8(%rdi)
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movq %r9, oR9(%rdi)
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movq (%rsp), %rcx
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movq %rcx, oRIP(%rdi)
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leaq 8(%rsp), %rcx /* Exclude the return address. */
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movq %rcx, oRSP(%rdi)
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#if SHSTK_ENABLED
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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(no_shstk)
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/* Save RDI in RDX which won't be clobbered by syscall. */
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movq %rdi, %rdx
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xorl %eax, %eax
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cmpq %fs:SSP_BASE_OFFSET, %rax
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jnz L(shadow_stack_bound_recorded)
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/* Get the base address and size of the default shadow stack
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which must be the current shadow stack since nothing has
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been recorded yet. */
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sub $24, %RSP_LP
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mov %RSP_LP, %RSI_LP
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movl $ARCH_CET_STATUS, %edi
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movl $__NR_arch_prctl, %eax
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syscall
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testq %rax, %rax
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jz L(continue_no_err)
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/* This should never happen. */
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hlt
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L(continue_no_err):
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/* Record the base of the current shadow stack. */
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movq 8(%rsp), %rax
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movq %rax, %fs:SSP_BASE_OFFSET
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add $24, %RSP_LP
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/* Restore RDI. */
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movq %rdx, %rdi
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L(shadow_stack_bound_recorded):
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/* Get the current shadow stack pointer. */
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rdsspq %rax
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/* NB: Save the caller's shadow stack so that we can jump back
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to the caller directly. */
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addq $8, %rax
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movq %rax, oSSP(%rdx)
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/* Save the current shadow stack base in ucontext. */
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movq %fs:SSP_BASE_OFFSET, %rax
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movq %rax, (oSSP + 8)(%rdi)
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L(no_shstk):
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#endif
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/* We have separate floating-point register content memory on the
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stack. We use the __fpregs_mem block in the context. Set the
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links up correctly. */
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leaq oFPREGSMEM(%rdi), %rcx
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movq %rcx, oFPREGS(%rdi)
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/* Save the floating-point environment. */
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fnstenv (%rcx)
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fldenv (%rcx)
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stmxcsr oMXCSR(%rdi)
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/* Save the current signal mask with
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rt_sigprocmask (SIG_BLOCK, NULL, set,_NSIG/8). */
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leaq oSIGMASK(%rdi), %rdx
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xorl %esi,%esi
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#if SIG_BLOCK == 0
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xorl %edi, %edi
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#else
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movl $SIG_BLOCK, %edi
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#endif
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movl $_NSIG8,%r10d
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movl $__NR_rt_sigprocmask, %eax
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syscall
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cmpq $-4095, %rax /* Check %rax for error. */
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jae SYSCALL_ERROR_LABEL /* Jump to error handler if error. */
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/* All done, return 0 for success. */
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xorl %eax, %eax
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ret
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PSEUDO_END(__getcontext)
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weak_alias (__getcontext, getcontext)
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