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authorKees Cook <keescook@chromium.org>2022-02-09 01:53:44 +0300
committerKees Cook <keescook@chromium.org>2022-02-14 03:50:06 +0300
commitf0202b8ca48cef152d4cdf775f39be6d3b372e1e (patch)
tree1d332148ff239d1761954c05dca2795a6abf7ec1 /include/linux/compiler_attributes.h
parentf361143141362485b39eb40bb4910e3f4219180f (diff)
downloadlinux-f0202b8ca48cef152d4cdf775f39be6d3b372e1e.tar.xz
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.h14
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__))