diff options
| author | Kees Cook <keescook@chromium.org> | 2022-02-08 14:53:44 -0800 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2022-02-13 16:50:06 -0800 |
| commit | f0202b8ca48cef152d4cdf775f39be6d3b372e1e (patch) | |
| tree | 1d332148ff239d1761954c05dca2795a6abf7ec1 /include/linux/compiler_attributes.h | |
| parent | f361143141362485b39eb40bb4910e3f4219180f (diff) | |
Compiler Attributes: Add __pass_object_size for Clang
In order to gain greater visibility to type information when using
__builtin_object_size(), Clang has a function attribute "pass_object_size"
that will make size information available for marked arguments in
a function by way of implicit additional function arguments that are
then wired up the __builtin_object_size().
This is needed to implement FORTIFY_SOURCE in Clang, as a workaround
to Clang's __builtin_object_size() having limited visibility[1] into types
across function calls (even inlines).
This attribute has an additional benefit that it can be used even on
non-inline functions to gain argument size information.
[1] https://github.com/llvm/llvm-project/issues/53516
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: llvm@lists.linux.dev
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20220208225350.1331628-3-keescook@chromium.org
Diffstat (limited to 'include/linux/compiler_attributes.h')
| -rw-r--r-- | include/linux/compiler_attributes.h | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index 37e260020221..d0c503772061 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -264,6 +264,20 @@ #define __packed __attribute__((__packed__)) /* + * Note: the "type" argument should match any __builtin_object_size(p, type) usage. + * + * Optional: not supported by gcc. + * Optional: not supported by icc. + * + * clang: https://clang.llvm.org/docs/AttributeReference.html#pass-object-size-pass-dynamic-object-size + */ +#if __has_attribute(__pass_object_size__) +# define __pass_object_size(type) __attribute__((__pass_object_size__(type))) +#else +# define __pass_object_size(type) +#endif + +/* * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute */ #define __pure __attribute__((__pure__)) |