| From ec0e39ee06deea0dba53054e577ecfad661406f7 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Mon, 18 Jul 2022 23:44:18 +1000 |
| Subject: powerpc/64s: Disable stack variable initialisation for prom_init |
| |
| From: Michael Ellerman <mpe@ellerman.id.au> |
| |
| [ 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> |
| --- |
| arch/powerpc/kernel/Makefile | 1 + |
| 1 file changed, 1 insertion(+) |
| |
| diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile |
| index 4ddd161aef32..63c384c3e6d4 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 |
| -- |
| 2.35.1 |
| |
