From: Naveen N Rao Date: Wed, 30 Oct 2024 07:08:35 +0000 (+0530) Subject: powerpc/kprobes: Use ftrace to determine if a probe is at function entry X-Git-Tag: microblaze-v6.16~562^2~56 X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=be87d713eaddf0421ccd61cc060c4c29bc36fc9b;p=linux-2.6-microblaze.git powerpc/kprobes: Use ftrace to determine if a probe is at function entry 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) Signed-off-by: Naveen N Rao Signed-off-by: Michael Ellerman Link: https://patch.msgid.link/20241030070850.1361304-3-hbathini@linux.ibm.com --- diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index f8aa91bc3b17..bf382c459e1f 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; 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); }