kernel/git/stable/linux.git/arch/powerpc/tools/gcc-check-fpatchable-function-entry.sh, branch master

powerpc64: make clang cross-build friendly

2026-03-07T10:32:25+00:00

ARCH_USING_PATCHABLE_FUNCTION_ENTRY depends on toolchain support for -fpatchable-function-entry option. The current script that checks for this support only handles GCC. Rename the script and extend it to detect support for -fpatchable-function-entry with Clang as well, allowing clean cross-compilation with Clang toolchains. Signed-off-by: Hari Bathini Tested-by: Venkat Rao Bagalkote Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260127084926.34497-2-hbathini@linux.ibm.com

powerpc/tools: drop `-o pipefail` in gcc check scripts

2025-12-22T12:26:34+00:00

Fixes: 0f71dcfb4aef ("powerpc/ftrace: Add support for -fpatchable-function-entry") Fixes: b71c9ffb1405 ("powerpc: Add arch/powerpc/tools directory") Reported-by: Joe Lawrence Acked-by: Joe Lawrence Signed-off-by: Jan Stancek Fixes: 8c50b72a3b4f ("powerpc/ftrace: Add Kconfig & Make glue for mprofile-kernel") Fixes: abba759796f9 ("powerpc/kbuild: move -mprofile-kernel check to Kconfig") Tested-by: Justin M. Forbes Reviewed-by: Naveen N Rao (AMD) Reviewed-by: Josh Poimboeuf Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/cc6cdd116c3ad9d990df21f13c6d8e8a83815bbd.1758641374.git.jstancek@redhat.com

powerpc/ftrace: Add support for -fpatchable-function-entry

2023-08-21T14:09:06+00:00

GCC v13.1 updated support for -fpatchable-function-entry on ppc64le to emit nops after the local entry point, rather than before it. This allows us to use this in the kernel for ftrace purposes. A new script is added under arch/powerpc/tools/ to help detect if nops are emitted after the function local entry point, or before the global entry point. With -fpatchable-function-entry, we no longer have the profiling instructions generated at function entry, so we only need to validate the presence of two nops at the ftrace location in ftrace_init_nop(). We patch the preceding instruction with 'mflr r0' to match the -mprofile-kernel ABI for subsequent ftrace use. This changes the profiling instructions used on ppc32. The default -pg option emits an additional 'stw' instruction after 'mflr r0' and before the branch to _mcount 'bl _mcount'. This is very similar to the original -mprofile-kernel implementation on ppc64le, where an additional 'std' instruction was used to save LR to its save location in the caller's stackframe. Subsequently, this additional store was removed in later compiler versions for performance reasons. The same reasons apply for ppc32 so we only patch in a 'mflr r0'. Signed-off-by: Naveen N Rao Reviewed-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://msgid.link/68586d22981a2c3bb45f27a2b621173d10a7d092.1687166935.git.naveen@kernel.org