| Message ID | 1425306312-3437-28-git-send-email-wangnan0@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2015/3/2 22:25, Wang Nan wrote: > Newly introduced function kprobe_on_ftrace_get_old_insn() will be > called by ftrace when ftrace generating call instruction. It is for > retriving probed instructions which original nops are replaced by > kprobe. FTRACE_FL_EARLY_KPROBES bit in rec->flags is cleared, so after > calling kprobe_on_ftrace_get_old_insn() an ftrace record will not be > treated as early kprobed. > > Signed-off-by: Wang Nan <wangnan0@huawei.com> > --- > include/linux/kprobes.h | 9 +++++++++ > kernel/kprobes.c | 34 ++++++++++++++++++++++++++++++++++ > 2 files changed, 43 insertions(+) > > diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h > index 5a5290f..2d78bbb 100644 > --- a/include/linux/kprobes.h > +++ b/include/linux/kprobes.h > @@ -289,6 +289,8 @@ extern const unsigned char *arch_kprobe_on_ftrace_get_old_insn(struct kprobe *kp > > extern void init_kprobes_on_ftrace(void); > extern bool kprobe_fix_ftrace_make_nop(struct dyn_ftrace *rec); > +extern const unsigned char *kprobe_on_ftrace_get_old_insn(struct dyn_ftrace *rec, > + const unsigned char *ftrace_nop, unsigned char *dest, size_t insn_size); > #else > static inline void init_kprobes_on_ftrace(void) > { > @@ -299,6 +301,13 @@ static inline bool kprobe_fix_ftrace_make_nop(struct dyn_ftrace *_unused) > > return false; > } > + > +static inline const unsigned char * > +kprobe_on_ftrace_get_old_insn(struct dyn_ftrace *_unused, > + const unsigned char *ftrace_nop, unsigned char *_unused2, size_t _unused3) > +{ > + return ftrace_nop; > +} > #endif // CONFIG_EARLY_KPROBES && CONFIG_KPROBES_ON_FTRACE > > #ifdef CONFIG_EARLY_KPROBES > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 20b6ab8..c504c1c 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -2623,6 +2623,40 @@ bool kprobe_fix_ftrace_make_nop(struct dyn_ftrace *rec) > return true; > } > > +/* NOTE: caller must ensure holding kprobe_mutex */ > +const unsigned char * > +kprobe_on_ftrace_get_old_insn(struct dyn_ftrace *rec, > + const unsigned char *ftrace_nop, > + unsigned char *dest, size_t insn_size) > +{ > + const unsigned char *ret; > + struct kprobe *kp; > + void *addr; > + > + if (!(rec->flags & FTRACE_FL_EARLY_KPROBES)) > + return ftrace_nop; > + > + addr = (void *)rec->ip; > + > + /* > + * Note that get_kprobe always get the kprobe on table, for it > + * KPROBE_FLAG_OPTIMIZED is reliable. > + */ > + kp = get_kprobe(addr); > + > + if (!kp || !(kp->flags & KPROBE_FLAG_FTRACE_EARLY)) { > + mutex_unlock(&kprobe_mutex); This mutex_unlock() is buggy. I'll fix it in next version. > + return ftrace_nop; > + } > + > + ret = arch_kprobe_on_ftrace_get_old_insn(kp, ftrace_nop, > + dest, insn_size); > + > + /* Only give one chance for kprobe to retrive old insn. */ > + rec->flags &= ~FTRACE_FL_EARLY_KPROBES; > + return ret; > +} > + > void init_kprobes_on_ftrace(void) > { > kprobes_on_ftrace_initialized = true; >
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h index 5a5290f..2d78bbb 100644 --- a/include/linux/kprobes.h +++ b/include/linux/kprobes.h @@ -289,6 +289,8 @@ extern const unsigned char *arch_kprobe_on_ftrace_get_old_insn(struct kprobe *kp extern void init_kprobes_on_ftrace(void); extern bool kprobe_fix_ftrace_make_nop(struct dyn_ftrace *rec); +extern const unsigned char *kprobe_on_ftrace_get_old_insn(struct dyn_ftrace *rec, + const unsigned char *ftrace_nop, unsigned char *dest, size_t insn_size); #else static inline void init_kprobes_on_ftrace(void) { @@ -299,6 +301,13 @@ static inline bool kprobe_fix_ftrace_make_nop(struct dyn_ftrace *_unused) return false; } + +static inline const unsigned char * +kprobe_on_ftrace_get_old_insn(struct dyn_ftrace *_unused, + const unsigned char *ftrace_nop, unsigned char *_unused2, size_t _unused3) +{ + return ftrace_nop; +} #endif // CONFIG_EARLY_KPROBES && CONFIG_KPROBES_ON_FTRACE #ifdef CONFIG_EARLY_KPROBES diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 20b6ab8..c504c1c 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -2623,6 +2623,40 @@ bool kprobe_fix_ftrace_make_nop(struct dyn_ftrace *rec) return true; } +/* NOTE: caller must ensure holding kprobe_mutex */ +const unsigned char * +kprobe_on_ftrace_get_old_insn(struct dyn_ftrace *rec, + const unsigned char *ftrace_nop, + unsigned char *dest, size_t insn_size) +{ + const unsigned char *ret; + struct kprobe *kp; + void *addr; + + if (!(rec->flags & FTRACE_FL_EARLY_KPROBES)) + return ftrace_nop; + + addr = (void *)rec->ip; + + /* + * Note that get_kprobe always get the kprobe on table, for it + * KPROBE_FLAG_OPTIMIZED is reliable. + */ + kp = get_kprobe(addr); + + if (!kp || !(kp->flags & KPROBE_FLAG_FTRACE_EARLY)) { + mutex_unlock(&kprobe_mutex); + return ftrace_nop; + } + + ret = arch_kprobe_on_ftrace_get_old_insn(kp, ftrace_nop, + dest, insn_size); + + /* Only give one chance for kprobe to retrive old insn. */ + rec->flags &= ~FTRACE_FL_EARLY_KPROBES; + return ret; +} + void init_kprobes_on_ftrace(void) { kprobes_on_ftrace_initialized = true;
Newly introduced function kprobe_on_ftrace_get_old_insn() will be called by ftrace when ftrace generating call instruction. It is for retriving probed instructions which original nops are replaced by kprobe. FTRACE_FL_EARLY_KPROBES bit in rec->flags is cleared, so after calling kprobe_on_ftrace_get_old_insn() an ftrace record will not be treated as early kprobed. Signed-off-by: Wang Nan <wangnan0@huawei.com> --- include/linux/kprobes.h | 9 +++++++++ kernel/kprobes.c | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 43 insertions(+)