mirror of
https://github.com/zephyrproject-rtos/zephyr
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d3c89fea4f
Retpolines were never completely implemented, even on x86. Move this particular Kconfig to only concern itself with the assembly code, and don't default it on ever since we prefer SSBD instead. We can restore the common kernel-wide CONFIG_RETPOLINE once we have an end-to-end implementation. Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
90 lines
2.2 KiB
C
90 lines
2.2 KiB
C
/* asm.h - x86 tool dependent headers */
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/*
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* Copyright (c) 2007-2014 Wind River Systems, Inc.
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#ifndef ZEPHYR_INCLUDE_ARCH_X86_ASM_H_
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#define ZEPHYR_INCLUDE_ARCH_X86_ASM_H_
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#include <toolchain.h>
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#include <linker/sections.h>
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/* offsets from stack pointer to function arguments */
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#define SP_ARG0 0
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#define SP_ARG1 4
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#define SP_ARG2 8
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#define SP_ARG3 12
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#define SP_ARG4 16
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#define SP_ARG5 20
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#define SP_ARG6 24
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#define SP_ARG7 28
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#define SP_ARG8 32
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#if defined(_ASMLANGUAGE)
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#if defined(CONFIG_X86_RETPOLINE)
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/*
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* For a description of how retpolines are constructed for both indirect
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* jumps and indirect calls, please refer to this documentation:
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* https://support.google.com/faqs/answer/7625886
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*
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* Since these macros are used in a few places in arch/x86/core assembly
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* routines, with different reg parameters, it's not possible to use
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* the "out of line" construction technique to share a trampoline.
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*/
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#define INDIRECT_JMP_IMPL(reg, id) \
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call .set_up_target ## id; \
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.speculative_trap ## id: \
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pause; \
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jmp .speculative_trap ## id; \
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.set_up_target ## id: \
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mov reg, (%esp); \
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ret
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#define INDIRECT_CALL_IMPL(reg, id) \
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call .set_up_return ## id; \
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.inner_indirect_branch ## id: \
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call .set_up_target ## id; \
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.speculative_trap ## id: \
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pause; \
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jmp .speculative_trap ## id; \
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.set_up_target ## id: \
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mov reg, (%esp); \
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ret; \
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.set_up_return ## id: \
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call .inner_indirect_branch ## id
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#define INDIRECT_CALL_IMPL1(reg, id) INDIRECT_CALL_IMPL(reg, id)
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#define INDIRECT_JMP_IMPL1(reg, id) INDIRECT_JMP_IMPL(reg, id)
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#define INDIRECT_CALL(reg) INDIRECT_CALL_IMPL1(reg, __COUNTER__)
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#define INDIRECT_JMP(reg) INDIRECT_JMP_IMPL1(reg, __COUNTER__)
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#else
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#define INDIRECT_CALL(reg) call *reg
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#define INDIRECT_JMP(reg) jmp *reg
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#endif /* CONFIG_X86_RETPOLINE */
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#ifdef CONFIG_X86_KPTI
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GTEXT(z_x86_trampoline_to_user)
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GTEXT(z_x86_trampoline_to_kernel)
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#define KPTI_IRET jmp z_x86_trampoline_to_user
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#define KPTI_IRET_USER jmp z_x86_trampoline_to_user_always
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#else
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#define KPTI_IRET iret
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#define KPTI_IRET_USER iret
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#endif /* CONFIG_X86_KPTI */
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#endif /* _ASMLANGUAGE */
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#endif /* ZEPHYR_INCLUDE_ARCH_X86_ASM_H_ */
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