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30891f35fa
We stopped adding "Contributed by" or similar lines in sources in 2012 in favour of git logs and keeping the Contributors section of the glibc manual up to date. Removing these lines makes the license header a bit more consistent across files and also removes the possibility of error in attribution when license blocks or files are copied across since the contributed-by lines don't actually reflect reality in those cases. Move all "Contributed by" and similar lines (Written by, Test by, etc.) into a new file CONTRIBUTED-BY to retain record of these contributions. These contributors are also mentioned in manual/contrib.texi, so we just maintain this additional record as a courtesy to the earlier developers. The following scripts were used to filter a list of files to edit in place and to clean up the CONTRIBUTED-BY file respectively. These were not added to the glibc sources because they're not expected to be of any use in future given that this is a one time task: https://gist.github.com/siddhesh/b5ecac94eabfd72ed2916d6d8157e7dc https://gist.github.com/siddhesh/15ea1f5e435ace9774f485030695ee02 Reviewed-by: Carlos O'Donell <carlos@redhat.com>
124 lines
3.8 KiB
ArmAsm
124 lines
3.8 KiB
ArmAsm
/* Copyright (C) 2002-2021 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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#if SHSTK_ENABLED
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# include <asm/prctl.h>
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# include "ucontext_i.h"
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/* Use CALL to push __start_context onto the new stack as well as the new
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shadow stack. RDI points to ucontext:
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Incoming:
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__ssp[0]: The original caller's shadow stack pointer.
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__ssp[1]: The size of the new shadow stack.
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__ssp[2]: The size of the new shadow stack.
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Outgoing:
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__ssp[0]: The new shadow stack pointer.
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__ssp[1]: The base address of the new shadow stack.
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__ssp[2]: The size of the new shadow stack.
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*/
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ENTRY(__push___start_context)
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/* Save the pointer to ucontext. */
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movq %rdi, %r9
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/* Get the original shadow stack pointer. */
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rdsspq %r8
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/* Save the original stack pointer. */
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movq %rsp, %rdx
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/* Load the top of the new stack into RSI. */
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movq oRSP(%rdi), %rsi
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/* Add 8 bytes to RSI since CALL will push the 8-byte return
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address onto stack. */
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leaq 8(%rsi), %rsp
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/* Allocate the new shadow stack. The size of the new shadow
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stack is passed in __ssp[1]. */
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lea (oSSP + 8)(%rdi), %RSI_LP
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movl $ARCH_CET_ALLOC_SHSTK, %edi
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movl $__NR_arch_prctl, %eax
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/* The new shadow stack base is returned in __ssp[1]. */
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syscall
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testq %rax, %rax
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jne L(hlt) /* This should never happen. */
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/* Get the size of the new shadow stack. */
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movq 8(%rsi), %rdi
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/* Get the base address of the new shadow stack. */
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movq (%rsi), %rsi
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/* Use the restore stoken to restore the new shadow stack. */
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rstorssp -8(%rsi, %rdi)
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/* Save the restore token on the original shadow stack. */
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saveprevssp
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/* Push the address of "jmp __start_context" onto the new stack
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as well as the new shadow stack. */
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call 1f
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jmp __start_context
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1:
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/* Get the new shadow stack pointer. */
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rdsspq %rdi
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/* Use the restore stoken to restore the original shadow stack. */
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rstorssp -8(%r8)
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/* Save the restore token on the new shadow stack. */
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saveprevssp
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/* Store the new shadow stack pointer in __ssp[0]. */
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movq %rdi, oSSP(%r9)
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/* Restore the original stack. */
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mov %rdx, %rsp
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ret
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END(__push___start_context)
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#endif
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/* This is the helper code which gets called if a function which is
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registered with 'makecontext' returns. In this case we have to
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install the context listed in the uc_link element of the context
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'makecontext' manipulated at the time of the 'makecontext' call.
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If the pointer is NULL the process must terminate. */
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ENTRY(__start_context)
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/* This removes the parameters passed to the function given to
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'makecontext' from the stack. RBX contains the address
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on the stack pointer for the next context. */
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movq %rbx, %rsp
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/* Don't use pop here so that stack is aligned to 16 bytes. */
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movq (%rsp), %rdi /* This is the next context. */
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testq %rdi, %rdi
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je 2f /* If it is zero exit. */
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call __setcontext
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/* If this returns (which can happen if the syscall fails) we'll
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exit the program with the return error value (-1). */
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movq %rax,%rdi
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2:
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call HIDDEN_JUMPTARGET(exit)
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/* The 'exit' call should never return. In case it does cause
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the process to terminate. */
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L(hlt):
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hlt
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END(__start_context)
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