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Message-ID: <172951436219.167263.18330240454389154327.stgit@devnote2>
Date: Mon, 21 Oct 2024 21:39:22 +0900
From: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
x86@...nel.org,
"H . Peter Anvin" <hpa@...or.com>,
linux-kernel@...r.kernel.org,
linux-trace-kernel@...r.kernel.org
Subject: [PATCH] x86/kprobes: Cleanup kprobes on ftrace code
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
Cleanup kprobes on ftrace code for x86.
- Set instruction pointer (ip + MCOUNT_INSN_SIZE) after pre_handler only
when p->post_handler exists.
- Use INT3_INSN_SIZE instead of 1.
- Use instruction_pointer/instruction_pointer_set() functions instead of
accessing regs->ip directly.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
---
arch/x86/kernel/kprobes/ftrace.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/kprobes/ftrace.c b/arch/x86/kernel/kprobes/ftrace.c
index 15af7e98e161..2be55ec3f392 100644
--- a/arch/x86/kernel/kprobes/ftrace.c
+++ b/arch/x86/kernel/kprobes/ftrace.c
@@ -9,6 +9,7 @@
#include <linux/hardirq.h>
#include <linux/preempt.h>
#include <linux/ftrace.h>
+#include <asm/text-patching.h>
#include "common.h"
@@ -36,23 +37,25 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
if (kprobe_running()) {
kprobes_inc_nmissed_count(p);
} else {
- unsigned long orig_ip = regs->ip;
+ unsigned long orig_ip = instruction_pointer(regs);
+
/* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */
- regs->ip = ip + sizeof(kprobe_opcode_t);
+ instruction_pointer_set(regs, ip + INT3_INSN_SIZE);
__this_cpu_write(current_kprobe, p);
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
if (!p->pre_handler || !p->pre_handler(p, regs)) {
- /*
- * Emulate singlestep (and also recover regs->ip)
- * as if there is a 5byte nop
- */
- regs->ip = (unsigned long)p->addr + MCOUNT_INSN_SIZE;
if (unlikely(p->post_handler)) {
+ /*
+ * Emulate singlestep (and also recover regs->ip)
+ * as if there is a 5byte nop
+ */
+ instruction_pointer_set(regs, ip + MCOUNT_INSN_SIZE);
kcb->kprobe_status = KPROBE_HIT_SSDONE;
p->post_handler(p, regs, 0);
}
- regs->ip = orig_ip;
+ /* Recover IP address */
+ instruction_pointer_set(regs, orig_ip);
}
/*
* If pre_handler returns !0, it changes regs->ip. We have to
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