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CFI: Move function_nocfi() into compiler.h

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Currently the common definition of function_nocfi() is provided by
<linux/mm.h>, and architectures are expected to provide a definition in
<asm/memory.h>. Due to header dependencies, this can make it hard to use
function_nocfi() in low-level headers.

As function_nocfi() has no dependency on any mm code, nor on any memory
definitions, it doesn't need to live in <linux/mm.h> or <asm/memory.h>.
Generally, it would make more sense for it to live in
<linux/compiler.h>, where an architecture can override it in
<asm/compiler.h>.

Move the definitions accordingly.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210602153701.35957-1-mark.rutland@arm.com
This commit is contained in:
Mark Rutland 2021-06-02 16:37:01 +01:00 committed by Kees Cook
parent 3f1639f8f9
commit 590e8a082a
4 changed files with 26 additions and 26 deletions
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16
arch/arm64/include/asm/compiler.h
View file

@ -23,4 +23,20 @@
#define __builtin_return_address(val) \
(void *)(ptrauth_clear_pac((unsigned long)__builtin_return_address(val)))
#ifdef CONFIG_CFI_CLANG
/*
* With CONFIG_CFI_CLANG, the compiler replaces function address
* references with the address of the function's CFI jump table
* entry. The function_nocfi macro always returns the address of the
* actual function instead.
*/
#define function_nocfi(x) ({ \
void *addr; \
asm("adrp %0, " __stringify(x) "\n\t" \
"add %0, %0, :lo12:" __stringify(x) \
: "=r" (addr)); \
addr; \
})
#endif
#endif /* __ASM_COMPILER_H */

16
arch/arm64/include/asm/memory.h
View file

@ -323,22 +323,6 @@ static inline void *phys_to_virt(phys_addr_t x)
#define virt_to_pfn(x) __phys_to_pfn(__virt_to_phys((unsigned long)(x)))
#define sym_to_pfn(x) __phys_to_pfn(__pa_symbol(x))
#ifdef CONFIG_CFI_CLANG
/*
* With CONFIG_CFI_CLANG, the compiler replaces function address
* references with the address of the function's CFI jump table
* entry. The function_nocfi macro always returns the address of the
* actual function instead.
*/
#define function_nocfi(x) ({ \
void *addr; \
asm("adrp %0, " __stringify(x) "\n\t" \
"add %0, %0, :lo12:" __stringify(x) \
: "=r" (addr)); \
addr; \
})
#endif
/*
* virt_to_page(x) convert a _valid_ virtual address to struct page *
* virt_addr_valid(x) indicates whether a virtual address is valid

10
include/linux/compiler.h
View file

@ -213,6 +213,16 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
__v; \
})
/*
* With CONFIG_CFI_CLANG, the compiler replaces function addresses in
* instrumented C code with jump table addresses. Architectures that
* support CFI can define this macro to return the actual function address
* when needed.
*/
#ifndef function_nocfi
#define function_nocfi(x) (x)
#endif
#endif /* __KERNEL__ */
/*

10
include/linux/mm.h
View file

@ -124,16 +124,6 @@ extern int mmap_rnd_compat_bits __read_mostly;
#define lm_alias(x) __va(__pa_symbol(x))
#endif
/*
* With CONFIG_CFI_CLANG, the compiler replaces function addresses in
* instrumented C code with jump table addresses. Architectures that
* support CFI can define this macro to return the actual function address
* when needed.
*/
#ifndef function_nocfi
#define function_nocfi(x) (x)
#endif
/*
* To prevent common memory management code establishing
* a zero page mapping on a read fault.