Re: [PATCH] powerpc/ftrace: Ignore weak functions
flat view
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2022-08-16 14:23:22
On Tue, 9 Aug 2022 16:24:25 +0530 "Naveen N. Rao" [off-list ref] wrote:
Extend commit b39181f7c6907d ("ftrace: Add FTRACE_MCOUNT_MAX_OFFSET to
avoid adding weak function") to ppc32 and ppc64 -mprofile-kernel by
defining FTRACE_MCOUNT_MAX_OFFSET.
For ppc64 -mprofile-kernel ABI, we can have two instructions at function
entry for TOC setup followed by 'mflr r0' and 'bl _mcount'. So, the
mcount location is at most the 4th instruction in a function. For ppc32,
mcount location is always the 3rd instruction in a function, preceded by
'mflr r0' and 'stw r0,4(r1)'.
With this patch, and with ppc64le_guest_defconfig and some ftrace/bpf
config items enabled:
# grep __ftrace_invalid_address available_filter_functions | wc -l
79I wonder if this patch answers the question to my last email. ;-) Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> -- Steve
quoted hunk ↗ jump to hunk
Signed-off-by: Naveen N. Rao <redacted> --- arch/powerpc/include/asm/ftrace.h | 7 +++++++ 1 file changed, 7 insertions(+)diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index 3cee7115441b41..ade406dc6504e3 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h@@ -10,6 +10,13 @@ #define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR +/* Ignore unused weak functions which will have larger offsets */ +#ifdef CONFIG_MPROFILE_KERNEL +#define FTRACE_MCOUNT_MAX_OFFSET 12 +#elif defined(CONFIG_PPC32) +#define FTRACE_MCOUNT_MAX_OFFSET 8 +#endif + #ifndef __ASSEMBLY__ extern void _mcount(void);base-commit: ff1ed171e05c971652a0ede3d716997de8ee41c9