| Message ID | 20190820114224.0c8963c4@xhacker.debian (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: KPROBES_ON_FTRACE | expand |
Jisheng Zhang wrote: > For KPROBES_ON_FTRACE case, we need to adjust the kprobe's addr > correspondingly. > > Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com> > --- > kernel/kprobes.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 9873fc627d61..3fd2f68644da 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -1484,15 +1484,19 @@ static inline int check_kprobe_rereg(struct kprobe *p) > > int __weak arch_check_ftrace_location(struct kprobe *p) > { > - unsigned long ftrace_addr; > + unsigned long ftrace_addr, addr = (unsigned long)p->addr; > > - ftrace_addr = ftrace_location((unsigned long)p->addr); > +#ifdef CONFIG_KPROBES_ON_FTRACE > + addr = ftrace_call_adjust(addr); > +#endif Looking at the commit message for patch 3/3, it looks like you want the probe to be placed on ftrace entry by default, and this patch seems to be aimed at that. If so, this is not the right approach. As I mentioned previously, you would want to over-ride kprobe_lookup_name(). This ensures that the address is changed only if the user provided a symbol, and not if the user wanted to probe at a very specific address. See commit 24bd909e94776 ("powerpc/kprobes: Prefer ftrace when probing function entry"). If this patch is for some other purpose, then it isn't clear from the commit log. Please provide a better explanation. - Naveen
On Tue, 20 Aug 2019 15:45:24 +0530 "Naveen N. Rao" wrote: > > > Jisheng Zhang wrote: > > For KPROBES_ON_FTRACE case, we need to adjust the kprobe's addr > > correspondingly. > > > > Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com> > > --- > > kernel/kprobes.c | 10 +++++++--- > > 1 file changed, 7 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > > index 9873fc627d61..3fd2f68644da 100644 > > --- a/kernel/kprobes.c > > +++ b/kernel/kprobes.c > > @@ -1484,15 +1484,19 @@ static inline int check_kprobe_rereg(struct kprobe *p) > > > > int __weak arch_check_ftrace_location(struct kprobe *p) > > { > > - unsigned long ftrace_addr; > > + unsigned long ftrace_addr, addr = (unsigned long)p->addr; > > > > - ftrace_addr = ftrace_location((unsigned long)p->addr); > > +#ifdef CONFIG_KPROBES_ON_FTRACE > > + addr = ftrace_call_adjust(addr); > > +#endif > > Looking at the commit message for patch 3/3, it looks like you want the > probe to be placed on ftrace entry by default, and this patch seems to > be aimed at that. Yeah. > > If so, this is not the right approach. As I mentioned previously, you > would want to over-ride kprobe_lookup_name(). This ensures that the > address is changed only if the user provided a symbol, and not if the > user wanted to probe at a very specific address. See commit Great! Now I understand the reason. > 24bd909e94776 ("powerpc/kprobes: Prefer ftrace when probing function > entry"). Now, I got your meaning. You are right. I will update the patch in newer version. Thanks a lot! > > If this patch is for some other purpose, then it isn't clear from the > commit log. Please provide a better explanation. > > > - Naveen >
Hi Jisheng, On Tue, 20 Aug 2019 03:53:31 +0000 Jisheng Zhang <Jisheng.Zhang@synaptics.com> wrote: > For KPROBES_ON_FTRACE case, we need to adjust the kprobe's addr > correspondingly. Either KPROBES_ON_FTRACE=y or not, ftrace_location() check must be done correctly. If it failed, kprobes can modify the instruction which can be modified by ftrace. > > Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com> > --- > kernel/kprobes.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > index 9873fc627d61..3fd2f68644da 100644 > --- a/kernel/kprobes.c > +++ b/kernel/kprobes.c > @@ -1484,15 +1484,19 @@ static inline int check_kprobe_rereg(struct kprobe *p) > > int __weak arch_check_ftrace_location(struct kprobe *p) > { > - unsigned long ftrace_addr; > + unsigned long ftrace_addr, addr = (unsigned long)p->addr; > > - ftrace_addr = ftrace_location((unsigned long)p->addr); > +#ifdef CONFIG_KPROBES_ON_FTRACE > + addr = ftrace_call_adjust(addr); > +#endif > + ftrace_addr = ftrace_location(addr); No, this is not right way to do. If we always need to adjust address before calling ftrace_location(), something wrong with ftrace_location() interface. ftrace_location(addr) must check the address is within the range which can be changed by ftrace. (dyn->ip <= addr <= dyn->ip+MCOUNT_INSN_SIZE) > if (ftrace_addr) { > #ifdef CONFIG_KPROBES_ON_FTRACE > /* Given address is not on the instruction boundary */ > - if ((unsigned long)p->addr != ftrace_addr) > + if (addr != ftrace_addr) > return -EILSEQ; > p->flags |= KPROBE_FLAG_FTRACE; > + p->addr = (kprobe_opcode_t *)addr; And again, please don't change the p->addr silently. Thank you, > #else /* !CONFIG_KPROBES_ON_FTRACE */ > return -EINVAL; > #endif > -- > 2.23.0.rc1 >
Hi, On Wed, 21 Aug 2019 11:07:39 +0900 Masami Hiramatsu wrote: > > > Hi Jisheng, > > On Tue, 20 Aug 2019 03:53:31 +0000 > Jisheng Zhang <Jisheng.Zhang@synaptics.com> wrote: > > > For KPROBES_ON_FTRACE case, we need to adjust the kprobe's addr > > correspondingly. > > Either KPROBES_ON_FTRACE=y or not, ftrace_location() check must be > done correctly. If it failed, kprobes can modify the instruction > which can be modified by ftrace. > > > > > Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com> > > --- > > kernel/kprobes.c | 10 +++++++--- > > 1 file changed, 7 insertions(+), 3 deletions(-) > > > > diff --git a/kernel/kprobes.c b/kernel/kprobes.c > > index 9873fc627d61..3fd2f68644da 100644 > > --- a/kernel/kprobes.c > > +++ b/kernel/kprobes.c > > @@ -1484,15 +1484,19 @@ static inline int check_kprobe_rereg(struct kprobe *p) > > > > int __weak arch_check_ftrace_location(struct kprobe *p) > > { > > - unsigned long ftrace_addr; > > + unsigned long ftrace_addr, addr = (unsigned long)p->addr; > > > > - ftrace_addr = ftrace_location((unsigned long)p->addr); > > +#ifdef CONFIG_KPROBES_ON_FTRACE > > + addr = ftrace_call_adjust(addr); > > +#endif > > + ftrace_addr = ftrace_location(addr); > > No, this is not right way to do. If we always need to adjust address > before calling ftrace_location(), something wrong with ftrace_location() > interface. > ftrace_location(addr) must check the address is within the range which > can be changed by ftrace. (dyn->ip <= addr <= dyn->ip+MCOUNT_INSN_SIZE) yeah! I will try Naveen's suggestion, I.E patch kprobe_lookup_name() instead. Thanks > > > > if (ftrace_addr) { > > #ifdef CONFIG_KPROBES_ON_FTRACE > > /* Given address is not on the instruction boundary */ > > - if ((unsigned long)p->addr != ftrace_addr) > > + if (addr != ftrace_addr) > > return -EILSEQ; > > p->flags |= KPROBE_FLAG_FTRACE; > > + p->addr = (kprobe_opcode_t *)addr; > > And again, please don't change the p->addr silently. > > Thank you, > > > #else /* !CONFIG_KPROBES_ON_FTRACE */ > > return -EINVAL; > > #endif > > -- > > 2.23.0.rc1 > > > > > -- > Masami Hiramatsu <mhiramat@kernel.org>
diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 9873fc627d61..3fd2f68644da 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1484,15 +1484,19 @@ static inline int check_kprobe_rereg(struct kprobe *p) int __weak arch_check_ftrace_location(struct kprobe *p) { - unsigned long ftrace_addr; + unsigned long ftrace_addr, addr = (unsigned long)p->addr; - ftrace_addr = ftrace_location((unsigned long)p->addr); +#ifdef CONFIG_KPROBES_ON_FTRACE + addr = ftrace_call_adjust(addr); +#endif + ftrace_addr = ftrace_location(addr); if (ftrace_addr) { #ifdef CONFIG_KPROBES_ON_FTRACE /* Given address is not on the instruction boundary */ - if ((unsigned long)p->addr != ftrace_addr) + if (addr != ftrace_addr) return -EILSEQ; p->flags |= KPROBE_FLAG_FTRACE; + p->addr = (kprobe_opcode_t *)addr; #else /* !CONFIG_KPROBES_ON_FTRACE */ return -EINVAL; #endif
For KPROBES_ON_FTRACE case, we need to adjust the kprobe's addr correspondingly. Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com> --- kernel/kprobes.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)