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git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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f932adcc86
Startup code that may execute from the early 1:1 mapping of memory will be confined into its own address space, and only be permitted to access ordinary kernel symbols if this is known to be safe. Introduce a macro helper SYM_PIC_ALIAS() that emits a __pi_ prefixed alias for a symbol, which allows startup code to access it. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: David Woodhouse <dwmw@amazon.co.uk> Cc: Dionna Amalie Glaze <dionnaglaze@google.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kees Cook <keescook@chromium.org> Cc: Kevin Loughlin <kevinloughlin@google.com> Cc: Len Brown <len.brown@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: linux-efi@vger.kernel.org Link: https://lore.kernel.org/r/20250504095230.2932860-38-ardb+git@google.com
155 lines
4.3 KiB
C
155 lines
4.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_LINKAGE_H
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#define _ASM_X86_LINKAGE_H
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#include <linux/stringify.h>
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#include <asm/ibt.h>
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#undef notrace
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#define notrace __attribute__((no_instrument_function))
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#ifdef CONFIG_64BIT
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/*
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* The generic version tends to create spurious ENDBR instructions under
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* certain conditions.
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*/
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#define _THIS_IP_ ({ unsigned long __here; asm ("lea 0(%%rip), %0" : "=r" (__here)); __here; })
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#endif
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#ifdef CONFIG_X86_32
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#define asmlinkage CPP_ASMLINKAGE __attribute__((regparm(0)))
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#endif /* CONFIG_X86_32 */
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#define __ALIGN .balign CONFIG_FUNCTION_ALIGNMENT, 0x90;
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#define __ALIGN_STR __stringify(__ALIGN)
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#if defined(CONFIG_CALL_PADDING) && !defined(__DISABLE_EXPORTS) && !defined(BUILD_VDSO)
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#define FUNCTION_PADDING .skip CONFIG_FUNCTION_ALIGNMENT, 0x90;
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#else
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#define FUNCTION_PADDING
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#endif
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#if (CONFIG_FUNCTION_ALIGNMENT > 8) && !defined(__DISABLE_EXPORTS) && !defined(BUILD_VDSO)
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# define __FUNC_ALIGN __ALIGN; FUNCTION_PADDING
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#else
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# define __FUNC_ALIGN __ALIGN
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#endif
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#define ASM_FUNC_ALIGN __stringify(__FUNC_ALIGN)
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#define SYM_F_ALIGN __FUNC_ALIGN
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#ifdef __ASSEMBLER__
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#if defined(CONFIG_MITIGATION_RETHUNK) && !defined(__DISABLE_EXPORTS) && !defined(BUILD_VDSO)
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#define RET jmp __x86_return_thunk
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#else /* CONFIG_MITIGATION_RETPOLINE */
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#ifdef CONFIG_MITIGATION_SLS
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#define RET ret; int3
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#else
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#define RET ret
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#endif
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#endif /* CONFIG_MITIGATION_RETPOLINE */
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#else /* __ASSEMBLER__ */
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#if defined(CONFIG_MITIGATION_RETHUNK) && !defined(__DISABLE_EXPORTS) && !defined(BUILD_VDSO)
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#define ASM_RET "jmp __x86_return_thunk\n\t"
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#else /* CONFIG_MITIGATION_RETPOLINE */
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#ifdef CONFIG_MITIGATION_SLS
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#define ASM_RET "ret; int3\n\t"
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#else
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#define ASM_RET "ret\n\t"
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#endif
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#endif /* CONFIG_MITIGATION_RETPOLINE */
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#endif /* __ASSEMBLER__ */
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/*
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* Depending on -fpatchable-function-entry=N,N usage (CONFIG_CALL_PADDING) the
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* CFI symbol layout changes.
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*
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* Without CALL_THUNKS:
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*
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* .align FUNCTION_ALIGNMENT
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* __cfi_##name:
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* .skip FUNCTION_PADDING, 0x90
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* .byte 0xb8
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* .long __kcfi_typeid_##name
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* name:
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*
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* With CALL_THUNKS:
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*
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* .align FUNCTION_ALIGNMENT
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* __cfi_##name:
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* .byte 0xb8
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* .long __kcfi_typeid_##name
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* .skip FUNCTION_PADDING, 0x90
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* name:
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*
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* In both cases the whole thing is FUNCTION_ALIGNMENT aligned and sized.
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*/
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#ifdef CONFIG_CALL_PADDING
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#define CFI_PRE_PADDING
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#define CFI_POST_PADDING .skip CONFIG_FUNCTION_PADDING_BYTES, 0x90;
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#else
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#define CFI_PRE_PADDING .skip CONFIG_FUNCTION_PADDING_BYTES, 0x90;
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#define CFI_POST_PADDING
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#endif
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#define __CFI_TYPE(name) \
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SYM_START(__cfi_##name, SYM_L_LOCAL, SYM_A_NONE) \
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CFI_PRE_PADDING \
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.byte 0xb8 ASM_NL \
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.long __kcfi_typeid_##name ASM_NL \
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CFI_POST_PADDING \
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SYM_FUNC_END(__cfi_##name)
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/* UML needs to be able to override memcpy() and friends for KASAN. */
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#ifdef CONFIG_UML
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# define SYM_FUNC_ALIAS_MEMFUNC SYM_FUNC_ALIAS_WEAK
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#else
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# define SYM_FUNC_ALIAS_MEMFUNC SYM_FUNC_ALIAS
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#endif
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/* SYM_TYPED_FUNC_START -- use for indirectly called globals, w/ CFI type */
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#define SYM_TYPED_FUNC_START(name) \
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SYM_TYPED_START(name, SYM_L_GLOBAL, SYM_F_ALIGN) \
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ENDBR
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/* SYM_FUNC_START -- use for global functions */
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#define SYM_FUNC_START(name) \
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SYM_START(name, SYM_L_GLOBAL, SYM_F_ALIGN)
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/* SYM_FUNC_START_NOALIGN -- use for global functions, w/o alignment */
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#define SYM_FUNC_START_NOALIGN(name) \
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SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE)
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/* SYM_FUNC_START_LOCAL -- use for local functions */
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#define SYM_FUNC_START_LOCAL(name) \
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SYM_START(name, SYM_L_LOCAL, SYM_F_ALIGN)
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/* SYM_FUNC_START_LOCAL_NOALIGN -- use for local functions, w/o alignment */
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#define SYM_FUNC_START_LOCAL_NOALIGN(name) \
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SYM_START(name, SYM_L_LOCAL, SYM_A_NONE)
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/* SYM_FUNC_START_WEAK -- use for weak functions */
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#define SYM_FUNC_START_WEAK(name) \
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SYM_START(name, SYM_L_WEAK, SYM_F_ALIGN)
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/* SYM_FUNC_START_WEAK_NOALIGN -- use for weak functions, w/o alignment */
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#define SYM_FUNC_START_WEAK_NOALIGN(name) \
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SYM_START(name, SYM_L_WEAK, SYM_A_NONE)
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/*
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* Expose 'sym' to the startup code in arch/x86/boot/startup/, by emitting an
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* alias prefixed with __pi_
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*/
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#ifdef __ASSEMBLER__
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#define SYM_PIC_ALIAS(sym) SYM_ALIAS(__pi_ ## sym, sym, SYM_L_GLOBAL)
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#else
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#define SYM_PIC_ALIAS(sym) extern typeof(sym) __PASTE(__pi_, sym) __alias(sym)
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#endif
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#endif /* _ASM_X86_LINKAGE_H */
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