Re: [PATCH v2 2/5] powerpc: kprobes: fix handling of function offsets on ABIv2
From: Masami Hiramatsu <mhiramat@kernel.org>
Date: 2017-04-13 04:28:16
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On Wed, 12 Apr 2017 16:28:25 +0530 "Naveen N. Rao" [off-list ref] wrote:
quoted hunk ↗ jump to hunk
commit 239aeba76409 ("perf powerpc: Fix kprobe and kretprobe handling with kallsyms on ppc64le") changed how we use the offset field in struct kprobe on ABIv2. perf now offsets from the GEP (Global entry point) if an offset is specified and otherwise chooses the LEP (Local entry point). Fix the same in kernel for kprobe API users. We do this by extending kprobe_lookup_name() to accept an additional parameter to indicate the offset specified with the kprobe registration. If offset is 0, we return the local function entry and return the global entry point otherwise. With: # cd /sys/kernel/debug/tracing/ # echo "p _do_fork" >> kprobe_events # echo "p _do_fork+0x10" >> kprobe_events before this patch: # cat ../kprobes/list c0000000000d0748 k _do_fork+0x8 [DISABLED] c0000000000d0758 k _do_fork+0x18 [DISABLED] c0000000000412b0 k kretprobe_trampoline+0x0 [OPTIMIZED] and after: # cat ../kprobes/list c0000000000d04c8 k _do_fork+0x8 [DISABLED] c0000000000d04d0 k _do_fork+0x10 [DISABLED] c0000000000412b0 k kretprobe_trampoline+0x0 [OPTIMIZED] Acked-by: Ananth N Mavinakayanahalli <redacted> Signed-off-by: Naveen N. Rao <redacted> --- arch/powerpc/kernel/kprobes.c | 4 ++-- arch/powerpc/kernel/optprobes.c | 4 ++-- include/linux/kprobes.h | 2 +- kernel/kprobes.c | 7 ++++--- 4 files changed, 9 insertions(+), 8 deletions(-)diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index a7aa7394954d..0732a0291ace 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c@@ -42,14 +42,14 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); struct kretprobe_blackpoint kretprobe_blacklist[] = {{NULL, NULL}}; -kprobe_opcode_t *kprobe_lookup_name(const char *name) +kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
Hmm, if we do this change, it is natural that kprobe_lookup_name() returns the address + offset. Thank you, -- Masami Hiramatsu [off-list ref]