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setcontext and swapcontext put a restore token on the old shadow stack which is used to restore the target shadow stack when switching user contexts. When longjmp from a user context, the target shadow stack can be different from the current shadow stack and INCSSP can't be used to restore the shadow stack pointer to the target shadow stack. Update longjmp to search for a restore token. If found, use the token to restore the shadow stack pointer before using INCSSP to pop the shadow stack. Stop the token search and use INCSSP if the shadow stack entry value is the same as the current shadow stack pointer. It is a user error if there is a shadow stack switch without leaving a restore token on the old shadow stack. The only difference between __longjmp.S and __longjmp_chk.S is that __longjmp_chk.S has a check for invalid longjmp usages. Merge __longjmp.S and __longjmp_chk.S by adding the CHECK_INVALID_LONGJMP macro. Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
24 lines
979 B
ArmAsm
24 lines
979 B
ArmAsm
/* __longjmp_cancel for x86.
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Copyright (C) 2018-2024 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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/* Don't restore shadow stack register for __longjmp_cancel. */
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#define DO_NOT_RESTORE_SHADOW_STACK
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#define __longjmp __longjmp_cancel
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#include <__longjmp.S>
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