Messages in this thread Patch in this message | | | Date | Fri, 10 Jun 2022 16:34:57 -0700 | Subject | [RFC PATCH v3 04/20] cfi: Drop __CFI_ADDRESSABLE | From | Sami Tolvanen <> |
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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> --- include/linux/cfi.h | 20 -------------------- include/linux/compiler.h | 6 ++++-- include/linux/module.h | 4 ++-- 3 files changed, 6 insertions(+), 24 deletions(-)
diff --git a/include/linux/cfi.h b/include/linux/cfi.h index 4ab51c067007..2cdbc0fbd0ab 100644 --- a/include/linux/cfi.h +++ b/include/linux/cfi.h @@ -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 */ diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 01ce94b58b42..63be1c23d676 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -221,9 +221,11 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, * otherwise, or eliminated entirely due to lack of references that are * visible to the compiler. */ -#define __ADDRESSABLE(sym) \ - static void * __section(".discard.addressable") __used \ +#define ___ADDRESSABLE(sym, __attrs) \ + static void * __used __attrs \ __UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)&sym; +#define __ADDRESSABLE(sym) \ + ___ADDRESSABLE(sym, __section(".discard.addressable")) /** * offset_to_ptr - convert a relative memory offset to an absolute pointer diff --git a/include/linux/module.h b/include/linux/module.h index abd9fa916b7d..efecd65a976d 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -132,7 +132,7 @@ extern void cleanup_module(void); { return initfn; } \ int init_module(void) __copy(initfn) \ __attribute__((alias(#initfn))); \ - __CFI_ADDRESSABLE(init_module, __initdata); + ___ADDRESSABLE(init_module, __initdata); /* This is only required if you want to be unloadable. */ #define module_exit(exitfn) \ @@ -140,7 +140,7 @@ extern void cleanup_module(void); { return exitfn; } \ void cleanup_module(void) __copy(exitfn) \ __attribute__((alias(#exitfn))); \ - __CFI_ADDRESSABLE(cleanup_module, __exitdata); + ___ADDRESSABLE(cleanup_module, __exitdata); #endif -- 2.36.1.476.g0c4daa206d-goog
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