Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 11 Dec 2023 14:39:50 +0900 | From | Masami Hiramatsu (Google) <> | Subject | Re: [RFC PATCH 5/9] powerpc/kprobes: Use ftrace to determine if a probe is at function entry |
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On Fri, 8 Dec 2023 22:00:44 +0530 Naveen N Rao <naveen@kernel.org> 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. >
OK, so this can cover both KPROBES_ON_FTRACE=y/n cases and the function is traced by ftrace or not.
Looks good to me.
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Thanks,
> Signed-off-by: Naveen N Rao <naveen@kernel.org> > --- > 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 b20ee72e873a..42665dfab59e 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)) > + return offset <= 8; > return !offset; > -#endif > } > > /* XXX try and fold the magic of kprobe_lookup_name() in this */ > kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, > bool *on_func_entry) > { > - *on_func_entry = arch_kprobe_on_func_entry(offset); > + *on_func_entry = arch_kprobe_on_func_entry(addr, offset); > return (kprobe_opcode_t *)(addr + offset); > } > > -- > 2.43.0 >
-- Masami Hiramatsu (Google) <mhiramat@kernel.org>
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