kernel/tools/include/nolibc/arch-mips.h, branch linux-rolling-stable

tools/nolibc: add option to disable runtime

2025-10-29T15:29:16Z

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: MIPS: add support for N64 and N32 ABIs

2025-06-28T20:23:33Z

Add support for the MIPS 64bit N64 and ILP32 N32 ABIs. In addition to different byte orders and ABIs there are also different releases of the MIPS architecture. To avoid blowing up the test matrix, only add a subset of all possible test combinations. Signed-off-by: Thomas Weißschuh Tested-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20250623-nolibc-mips-n32-v3-4-6ae2d89f4259@weissschuh.net

tools/nolibc: MIPS: drop noreorder option

2025-06-28T20:23:25Z

There are no more statements in the assembly code which would require the usage of ".set noreorder". Remove the option. This also allows removal of the manual "nop" instruction in the delay slot. Suggested-by: Maciej W. Rozycki Link: https://lore.kernel.org/lkml/alpine.DEB.2.21.2502172208570.65342@angie.orcam.me.uk/ Signed-off-by: Thomas Weißschuh Tested-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20250623-nolibc-mips-n32-v3-3-6ae2d89f4259@weissschuh.net

tools/nolibc: MIPS: drop manual stack pointer alignment

2025-06-28T20:23:20Z

The stack pointer is already aligned by the kernel to a multiple of 16. All modifications of the register have been removed from the entrypoint, so the manual realignment is unnecessary. Drop the manual alignment. Suggested-by: Maciej W. Rozycki Link: https://lore.kernel.org/lkml/alpine.DEB.2.21.2502161523290.65342@angie.orcam.me.uk/ Signed-off-by: Thomas Weißschuh Tested-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20250623-nolibc-mips-n32-v3-2-6ae2d89f4259@weissschuh.net

tools/nolibc: MIPS: drop $gp setup

2025-06-28T20:23:02Z

The setup of the global pointer "$gp" register was necessary when the C entrypoint was called through "jal ". However since commit 0daf8c86a451 ("tools/nolibc: mips: load current function to $t9") "jalr" is used instead which does not require "$gp". Remove the unnecessary $gp setup, simplifying the code and opening the road for some other cleanups. Suggested-by: Maciej W. Rozycki Link: https://lore.kernel.org/lkml/alpine.DEB.2.21.2502172208570.65342@angie.orcam.me.uk/ Signed-off-by: Thomas Weißschuh Tested-by: Sebastian Andrzej Siewior Link: https://lore.kernel.org/r/20250623-nolibc-mips-n32-v3-1-6ae2d89f4259@weissschuh.net

tools/nolibc: add prototypes for non-static functions

2025-02-03T19:57:37Z

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: move entrypoint specifics to compiler.h

2024-08-12T20:21:00Z

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: mips: load current function to $t9

2024-08-10T15:08:10Z

The MIPS calling convention requires the address of the current function to be available in $t9. This was not done so far. For GCC this seems to have worked, but when compiled with clang the executable segfault instantly. Properly load the address of _start_c() into $t9 before calling it. Acked-by: Willy Tarreau Link: https://lore.kernel.org/r/20240807-nolibc-llvm-v2-2-c20f2f5fc7c2@weissschuh.net Signed-off-by: Thomas Weißschuh

tools/nolibc: mips: add support for PIC

2023-12-11T21:38:30Z

MIPS requires some extra instructions to set up the $gp register for the with a pointer to the global data area. This isn't needed for non-PIC builds, but this patch enables the code unconditionally to prevent bitrot. Also enable PIC in one of the test configurations for ongoing validation. Link: https://lore.kernel.org/r/20231108-nolibc-pic-v2-1-4fb0d6284757@weissschuh.net Signed-off-by: Thomas Weißschuh

tools/nolibc: move MIPS ABI validation into arch-mips.h

2023-12-11T21:38:21Z

When installing nolibc to a sysroot arch.h is not used so its ABI check is bypassed. This makes is possible to compile nolibc with a non O32 ABI which may build but can not run. Move the check into arch-mips.h so it will always be evaluated. Signed-off-by: Thomas Weißschuh Acked-by: Willy Tarreau