From: Michael Ellerman <mpe@ellerman.id.au> stable inclusion from stable-v5.10.137 commit 4234c5f34e71ca389f146de06f52b641fb2f7697 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I60PLB Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit be640317a1d0b9cf42fedb2debc2887a7cfa38de ] With GCC 12 allmodconfig prom_init fails to build: Error: External symbol 'memset' referenced from prom_init.c make[2]: *** [arch/powerpc/kernel/Makefile:204: arch/powerpc/kernel/prom_init_check] Error 1 The allmodconfig build enables KASAN, so all calls to memset in prom_init should be converted to __memset by the #ifdefs in asm/string.h, because prom_init must use the non-KASAN instrumented versions. The build failure happens because there's a call to memset that hasn't been caught by the pre-processor and converted to __memset. Typically that's because it's a memset generated by the compiler itself, and that is the case here. With GCC 12, allmodconfig enables CONFIG_INIT_STACK_ALL_PATTERN, which causes the compiler to emit memset calls to initialise on-stack variables with a pattern. Because prom_init is non-user-facing boot-time only code, as a workaround just disable stack variable initialisation to unbreak the build. Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220718134418.354114-1-mpe@ellerman.id.au Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> Reviewed-by: Wei Li <liwei391@huawei.com> --- arch/powerpc/kernel/Makefile | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index 32c617ba6901..8a8642350ec7 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -20,6 +20,7 @@ CFLAGS_prom.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) CFLAGS_prom_init.o += -fno-stack-protector CFLAGS_prom_init.o += -DDISABLE_BRANCH_PROFILING CFLAGS_prom_init.o += -ffreestanding +CFLAGS_prom_init.o += $(call cc-option, -ftrivial-auto-var-init=uninitialized) ifdef CONFIG_FUNCTION_TRACER # Do not trace early boot code -- 2.20.1