kernel/linux.git/tools/include/nolibc/stackprotector.h, branch v7.2-rc1

tools/nolibc: stackprotector: Avoid stalling program startup if crng is not init yet

2026-05-24T21:52:58+00:00

We are using the getrandom syscall to get a random seed for the stack protector canary but we are calling it with no flags which means it'll block until there is some real randomness to return. This means that if the crng is not ready yet program startup will block and if you are unlucky that could be for a long time and look like the program has crashed. Even if the call to getrandom does not yield any random data, we will still initialize the canary. Fixes: 7188d4637e95 ("tools/nolibc: add support for stack protector") Signed-off-by: Daniel Palmer Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260522090726.726985-1-daniel@thingy.jp Signed-off-by: Thomas Weißschuh

tools/nolibc: Rename __no_stack_protector to __nolibc_no_stack_protector

2026-04-27T16:14:47+00:00

To avoid polluting the namespace rename __no_stack_protector to __nolibc_no_stack_protector so its now within the nolibc umbrella. Suggested-by: Willy Tarreau Signed-off-by: Daniel Palmer Link: https://patch.msgid.link/20260425111315.3191461-2-daniel@thingy.jp Signed-off-by: Thomas Weißschuh

tools/nolibc: rename my_syscallX() to __nolibc_syscallX()

2026-02-25T07:21:17+00:00

The naming convention of the my_syscallX() macros is a bit unfortunate. They may conflict with application code and the name is very generic. Switch to __nolibc_syscallX(). The leading underscores place the symbols in the implementation-defined namespace, avoiding conflicting names. It is also clearer that these are non-standard extensions from nolibc. Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau Link: https://patch.msgid.link/20260223-nolibc-namespacing-v1-1-52574ffebb2c@weissschuh.net

tools/nolibc: add option to disable runtime

2025-10-29T15:29:16+00:00

In principle, it is possible to use nolibc for only some object files in a program. In that case, the startup code in _start and _start_c is not going to be used. Add the NOLIBC_NO_RUNTIME compile time option to disable it entirely and also remove anything that depends on it. Doing this avoids warnings from modpost for UML as the _start_c code references the main function from the .init.text section while it is not inside .init itself. Signed-off-by: Benjamin Berg Signed-off-by: Thomas Weißschuh

tools/nolibc: add prototypes for non-static functions

2025-02-03T19:57:37+00:00

With -Wmissing-prototypes the compiler will warn about non-static functions which don't have a prototype defined. This warning doesn't make much sense for nolibc itself but for user code it is still useful. To pacify the compiler add prototypes next to the function definitions, similar to how it is handled elsewhere in the kernel. Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20250123-nolibc-prototype-v1-1-e1afc5c1999a@weissschuh.net Signed-off-by: Thomas Weißschuh

tools/nolibc: stackprotector: mark implicitly used symbols as used

2024-08-16T15:23:13+00:00

During LTO the references from the compiler-generated prologue and epilogues to the stack protector symbols are not visible and the symbols are removed. This will then lead to errors during linking. As those symbols are already #ifdeffed-out if unused mark them as "used" to prevent their removal. Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20240812-nolibc-lto-v2-2-736af7bbefa8@weissschuh.net Signed-off-by: Thomas Weißschuh

tools/nolibc: stackprotector.h: make __stack_chk_init static

2023-08-23T03:17:07+00:00

This allows to generate smaller text/data/dec size. As the _start_c() function added by crt.h, __stack_chk_init() is called from _start_c() instead of the assembly _start. So, it is able to mark it with static now. Reviewed-by: Thomas Weißschuh Signed-off-by: Zhangjin Wu Signed-off-by: Willy Tarreau

tools/nolibc: stackprotector.h: add empty __stack_chk_init for !_NOLIBC_STACKPROTECTOR

2023-08-23T02:40:22+00:00

Let's define an empty __stack_chk_init for the !_NOLIBC_STACKPROTECTOR branch. This allows to remove #ifdef around every call of __stack_chk_init(). Signed-off-by: Zhangjin Wu Signed-off-by: Willy Tarreau

tools/nolibc: fix segfaults on compilers without attribute no_stack_protector

2023-06-09T18:46:08+00:00

Not all compilers, notably GCC < 10, have support for __attribute__((no_stack_protector)). Fall back to a mechanism that also works there. Tested with GCC 9.5.0 from kernel.org crosstools. Signed-off-by: Thomas Weißschuh Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney

tools/nolibc: add autodetection for stackprotector support

2023-06-09T18:46:08+00:00

The stackprotector support in nolibc should be enabled iff it is also enabled in the compiler. Use the preprocessor defines added by gcc and clang if stackprotector support is enable to automatically do so in nolibc. This completely removes the need for any user-visible API. To avoid inlining the lengthy preprocessor check into every user introduce a new header compiler.h that abstracts the logic away. As the define NOLIBC_STACKPROTECTOR is now not user-relevant anymore prefix it with an underscore. Suggested-by: Willy Tarreau Link: https://lore.kernel.org/lkml/20230520133237.GA27501@1wt.eu/ Signed-off-by: Thomas Weißschuh Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney