From 60c71369ee356d11ad845ddeb28ceb70ec6cd70e Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Wed, 11 Mar 2026 17:39:56 -0700 Subject: [PATCH] powerpc/vdso: Drop -DCC_USING_PATCHABLE_FUNCTION_ENTRY from 32-bit flags with clang After commit 73cdf24e81e4 ("powerpc64: make clang cross-build friendly"), building 64-bit little endian + CONFIG_COMPAT=y with clang results in many warnings along the lines of: $ cat arch/powerpc/configs/compat.config CONFIG_COMPAT=y $ make -skj"$(nproc)" ARCH=powerpc LLVM=1 ppc64le_defconfig compat.config arch/powerpc/kernel/vdso/ ... In file included from :4: In file included from lib/vdso/gettimeofday.c:6: In file included from include/vdso/datapage.h:15: In file included from include/vdso/cache.h:5: arch/powerpc/include/asm/cache.h:77:8: warning: unknown attribute 'patchable_function_entry' ignored [-Wunknown-attributes] 77 | static inline u32 l1_icache_bytes(void) | ^~~~~~ include/linux/compiler_types.h:235:58: note: expanded from macro 'inline' 235 | #define inline inline __gnu_inline __inline_maybe_unused notrace | ^~~~~~~ include/linux/compiler_types.h:215:34: note: expanded from macro 'notrace' 215 | #define notrace __attribute__((patchable_function_entry(0, 0))) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ... arch/powerpc/Makefile adds -DCC_USING_PATCHABLE_FUNCTION_ENTRY to KBUILD_CPPFLAGS, which is inherited by the 32-bit vDSO. However, the 32-bit little endian target does not support '-fpatchable-function-entry', resulting in the warnings above. Remove -DCC_USING_PATCHABLE_FUNCTION_ENTRY from the 32-bit vDSO flags when building with clang to avoid the warnings. Fixes: 73cdf24e81e4 ("powerpc64: make clang cross-build friendly") Signed-off-by: Nathan Chancellor Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260311-ppc-vdso-drop-cc-using-pfe-define-clang-v1-1-66c790e22650@kernel.org --- arch/powerpc/kernel/vdso/Makefile | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile index 8834dfe9d727..368759f81708 100644 --- a/arch/powerpc/kernel/vdso/Makefile +++ b/arch/powerpc/kernel/vdso/Makefile @@ -62,6 +62,12 @@ CC32FLAGSREMOVE += -fno-stack-clash-protection # 32-bit one. clang validates the values passed to these arguments during # parsing, even when -fno-stack-protector is passed afterwards. CC32FLAGSREMOVE += -mstack-protector-guard% +# ftrace is disabled for the vdso but arch/powerpc/Makefile adds this define to +# KBUILD_CPPFLAGS, which enables use of the 'patchable_function_entry' +# attribute in the 'inline' define via 'notrace'. This attribute is not +# supported for the powerpcle target, resulting in many instances of +# -Wunknown-attributes. +CC32FLAGSREMOVE += -DCC_USING_PATCHABLE_FUNCTION_ENTRY endif LD32FLAGS := -Wl,-soname=linux-vdso32.so.1 AS32FLAGS := -D__VDSO32__