Ftrace on ppc32 expects a three instruction sequence at the beginning of
each function when specifying -pg:
mflr r0
stw r0,4(r1)
bl _mcount
This is the case with all supported versions of gcc. Clang however emits
a branch to _mcount after the function prologue, similar to the pre
-mprofile-kernel ABI on ppc64. This is not supported.
Disable ftrace on ppc32 if using clang for now. This can be re-enabled
later if clang picks up support for -fpatchable-function-entry on ppc32.
Signed-off-by: Naveen N Rao <nav...@kernel.org>
---
arch/powerpc/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index bff5820b7cda14..d85e3cf4016d90 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -236,7 +236,7 @@ config PPC
select HAVE_FUNCTION_DESCRIPTORS if PPC64_ELF_ABI_V1
select HAVE_FUNCTION_ERROR_INJECTION
select HAVE_FUNCTION_GRAPH_TRACER
- select HAVE_FUNCTION_TRACER
+ select HAVE_FUNCTION_TRACER if PPC64 || (PPC32 && CC_IS_GCC)
select HAVE_GCC_PLUGINS if GCC_VERSION >= 50200 #
plugin support on gcc <= 5.1 is buggy on PPC
select HAVE_GENERIC_VDSO
select HAVE_HARDLOCKUP_DETECTOR_ARCH if PPC_BOOK3S_64 && SMP
base-commit: bd517a8442b6c6646a136421cd4c1b95bf4ce32b
--
2.40.1
