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cfi: Drop __CFI_ADDRESSABLE

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The __CFI_ADDRESSABLE macro is used for init_module and cleanup_module
to ensure we have the address of the CFI jump table, and with
CONFIG_X86_KERNEL_IBT to ensure LTO won't optimize away the symbols.
As __CFI_ADDRESSABLE is no longer necessary with -fsanitize=kcfi, add
a more flexible version of the __ADDRESSABLE macro and always ensure
these symbols won't be dropped.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220908215504.3686827-5-samitolvanen@google.com
This commit is contained in:
Sami Tolvanen
2022-09-08 14:54:46 -07:00
committed by Kees Cook
parent 9fca711582
commit 92efda8eb1
3 changed files with 6 additions and 24 deletions
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20
include/linux/cfi.h
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@@ -13,26 +13,6 @@ typedef void (*cfi_check_fn)(uint64_t id, void *ptr, void *diag);
/* Compiler-generated function in each module, and the kernel */
extern void __cfi_check(uint64_t id, void *ptr, void *diag);
/*
* Force the compiler to generate a CFI jump table entry for a function
* and store the jump table address to __cfi_jt_<function>.
*/
#define __CFI_ADDRESSABLE(fn, __attr) \
const void *__cfi_jt_ ## fn __visible __attr = (void *)&fn
#else /* !CONFIG_CFI_CLANG */
#ifdef CONFIG_X86_KERNEL_IBT
#define __CFI_ADDRESSABLE(fn, __attr) \
const void *__cfi_jt_ ## fn __visible __attr = (void *)&fn
#endif /* CONFIG_X86_KERNEL_IBT */
#endif /* CONFIG_CFI_CLANG */
#ifndef __CFI_ADDRESSABLE
#define __CFI_ADDRESSABLE(fn, __attr)
#endif
#endif /* _LINUX_CFI_H */