On Fri, 8 Dec 2023 22:00:44 +0530
Naveen N Rao <nav...@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) <mhira...@kernel.org>
Thanks,
> Signed-off-by: Naveen N Rao <nav...@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) <mhira...@kernel.org>
