Hi Nick, Thanks for the reviews! On Mon, Jul 01, 2024 at 06:40:50PM GMT, Nicholas Piggin wrote: > On Fri Jun 21, 2024 at 4:54 AM AEST, Naveen N Rao wrote: > > Rather than hard-coding the offset into a function to be used to > > determine if a kprobe is at function entry, use ftrace_location() to > > determine the ftrace location within the function and categorize all > > instructions till that offset to be function entry. > > > > For functions that cannot be traced, we fall back to using a fixed > > offset of 8 (two instructions) to categorize a probe as being at > > function entry for 64-bit elfv2, unless we are using pcrel. > > > > Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> > > Signed-off-by: Naveen N Rao <naveen@xxxxxxxxxx> > > --- > > arch/powerpc/kernel/kprobes.c | 18 ++++++++---------- > > 1 file changed, 8 insertions(+), 10 deletions(-) > > > > diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c > > index 14c5ddec3056..ca204f4f21c1 100644 > > --- a/arch/powerpc/kernel/kprobes.c > > +++ b/arch/powerpc/kernel/kprobes.c > > @@ -105,24 +105,22 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset) > > return addr; > > } > > > > -static bool arch_kprobe_on_func_entry(unsigned long offset) > > +static bool arch_kprobe_on_func_entry(unsigned long addr, unsigned long offset) > > { > > -#ifdef CONFIG_PPC64_ELF_ABI_V2 > > -#ifdef CONFIG_KPROBES_ON_FTRACE > > - return offset <= 16; > > -#else > > - return offset <= 8; > > -#endif > > -#else > > + unsigned long ip = ftrace_location(addr); > > + > > + if (ip) > > + return offset <= (ip - addr); > > + if (IS_ENABLED(CONFIG_PPC64_ELF_ABI_V2) && !IS_ENABLED(CONFIG_PPC_KERNEL_PCREL)) > > + return offset <= 8; > > If it is PCREL, why not offset == 0 as well? That's handled by the fallback code that is after the above line: return !offset; That addresses both pcrel, as well as 32-bit powerpc. Thanks, Naveen