kernel/linux.git/tools/include/nolibc/compiler.h, branch linux-7.0.y

tools/nolibc: avoid -Wundef warning for __STDC_VERSION__

2026-05-23T11:08:32+00:00

[ Upstream commit 3eb97c4cbd4d874e7e327ec512f6169934e12b8a ] With -std=c89 the macro __STDC_VERSION__ is not defined. While undefined identifiers in '#if' directives are assumed to be '0', with -Wundef a warning is emitted. Avoid the warning by explicitly falling back to '0' if __STDC_VERSION__ is not provided by the preprocessor. Fixes: 37219aa5b123 ("tools/nolibc: add __nolibc_static_assert()") Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260318-nolibc-wundef-v1-1-fcb7f9ac7298@weissschuh.net Signed-off-by: Sasha Levin

tools/nolibc: add __nolibc_static_assert()

2026-01-06T11:08:08+00:00

Add a wrapper for _Static_assert() to use within nolibc. While _Static_assert() itself was only standardized in C11, in GCC and clang dialects it is also available in older standards. Link: https://lore.kernel.org/lkml/20251203192330.GA12995@1wt.eu/ Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau Reviewed-by: Arnd Bergmann Link: https://patch.msgid.link/20251220-nolibc-uapi-types-v3-13-c662992f75d7@weissschuh.net

tools/nolibc: add compiler version detection macros

2026-01-06T11:08:07+00:00

Some upcoming logic needs to depend on the version of GCC or clang. Add some helper macros to keep the conditionals readable. Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau Reviewed-by: Arnd Bergmann Link: https://patch.msgid.link/20251220-nolibc-uapi-types-v3-12-c662992f75d7@weissschuh.net

tools/nolibc: use fallthrough rather than fallthrough

2025-10-29T15:29:15+00:00

Use the version of the attribute with underscores to avoid issues if fallthrough has been defined by another header file already. Signed-off-by: Benjamin Berg Signed-off-by: Thomas Weißschuh

tools/nolibc: add __nolibc_aligned() and __nolibc_aligned_as()

2025-04-19T12:17:52+00:00

Provide a convenience macro around __attribute__((aligned)). Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20250419-nolibc-ubsan-v2-2-060b8a016917@weissschuh.net

tools/nolibc: add __nolibc_has_feature()

2025-04-19T12:17:46+00:00

Certain compiler features are signaled via the __has_feature() preprocessor builtin. Add a nolibc wrapper for it, similar to __nolibc_has_attribute(). Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20250419-nolibc-ubsan-v2-1-060b8a016917@weissschuh.net

tools/nolibc: compiler: add macro __nolibc_fallthrough

2024-10-07T19:56:18+00:00

Recent version of GCC and clang gained -Wimplicit-fallthrough, warning about implicit fall-through between switch labels. As nolibc does not control the compilation flags, this can trigger warnings for when built by the user. Make use of the "fallthrough" attribute to explicitly annotate the expected fall-throughs and silence the warning. Link: https://lore.kernel.org/r/20240930-nolibc-fallthrough-v2-1-2e8d10fe3430@weissschuh.net Signed-off-by: Thomas Weißschuh

tools/nolibc: compiler: use attribute((naked)) if available

2024-08-12T20:22:03+00:00

The current entrypoint attributes optimize("Os", "omit-frame-pointer") are intended to avoid all compiler generated code, like function porologue and epilogue. This is the exact usecase implemented by the attribute "naked". Unfortunately this is not implemented by GCC for all targets, so only use it where available. This also provides compatibility with clang, which recognizes the "naked" attribute but not the previously used attribute "optimized". Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20240807-nolibc-llvm-v2-6-c20f2f5fc7c2@weissschuh.net Signed-off-by: Thomas Weißschuh

tools/nolibc: move entrypoint specifics to compiler.h

2024-08-12T20:21:00+00:00

The specific attributes for the _start entrypoint are duplicated for each architecture. Deduplicate it into a dedicated #define into compiler.h. For clang compatibility, the epilogue will also need to be adapted, so move that one, too. Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20240807-nolibc-llvm-v2-5-c20f2f5fc7c2@weissschuh.net Signed-off-by: Thomas Weißschuh

tools/nolibc: compiler: introduce __nolibc_has_attribute()

2024-08-10T15:08:19+00:00

Recent compilers support __has_attribute() to check if a certain compiler attribute is supported. Unfortunately we have to first check if __has_attribute is supported in the first place and then if a specific attribute is present. These two checks can't be folded into a single condition as that would lead to errors. Nesting the two conditions like below works, but becomes ugly as soon as #else blocks are used as those need to be duplicated for both levels of #if. #if defined __has_attribute # if __has_attribute (nonnull) # define ATTR_NONNULL __attribute__ ((nonnull)) # endif #endif Introduce a new helper which makes the usage of __has_attribute() nicer and migrate the current user to it. Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20240807-nolibc-llvm-v2-4-c20f2f5fc7c2@weissschuh.net Signed-off-by: Thomas Weißschuh