From: Masami Hiramatsu (Google) <[email protected]> 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) <[email protected]> --- 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
