Re: [BUGFIX PATCH bpf-next] error-injection: Fix to prohibit jump optimization
On 03/12/2018 03:06 PM, Masami Hiramatsu wrote: > On Mon, 12 Mar 2018 11:44:21 +0100 > Daniel Borkmann wrote: >> On 03/12/2018 11:27 AM, Masami Hiramatsu wrote: >>> On Mon, 12 Mar 2018 19:00:49 +0900 >>> Masami Hiramatsu wrote: >>> Since the kprobe which was optimized by jump can not change the execution path, the kprobe for error-injection must not be optimized. To prohibit it, set a dummy post-handler as officially stated in Documentation/kprobes.txt. >>> >>> Note that trace-probe based BPF is not affected, because it >>> ensures the trace-probe is based on ftrace, which is not >>> jump optimized. >> >> Thanks for the fix! I presume this should go via bpf instead of bpf-next >> tree since 4b1a29a7f542 ("error-injection: Support fault injection >> framework") >> is in Linus' tree as well. Unless there are objection I would rather route >> it that way so it would be for 4.16. > > Ah, right! It should go into 4.16. It should be applicable cleanly either tree > since there is only the above commit on kernel/fail_function.c :) Applied to bpf tree, thanks Masami! -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [BUGFIX PATCH bpf-next] error-injection: Fix to prohibit jump optimization
On Mon, 12 Mar 2018 11:44:21 +0100 Daniel Borkmann wrote: > Hi Masami, > > On 03/12/2018 11:27 AM, Masami Hiramatsu wrote: > > On Mon, 12 Mar 2018 19:00:49 +0900 > > Masami Hiramatsu wrote: > > > >> Since the kprobe which was optimized by jump can not change > >> the execution path, the kprobe for error-injection must not > >> be optimized. To prohibit it, set a dummy post-handler as > >> officially stated in Documentation/kprobes.txt. > > > > Note that trace-probe based BPF is not affected, because it > > ensures the trace-probe is based on ftrace, which is not > > jump optimized. > > Thanks for the fix! I presume this should go via bpf instead of bpf-next > tree since 4b1a29a7f542 ("error-injection: Support fault injection framework") > is in Linus' tree as well. Unless there are objection I would rather route > it that way so it would be for 4.16. Ah, right! It should go into 4.16. It should be applicable cleanly either tree since there is only the above commit on kernel/fail_function.c :) Thanks, > > Thanks, > Daniel > > > Thanks, > > > >> > >> Fixes: 4b1a29a7f542 ("error-injection: Support fault injection framework") > >> Signed-off-by: Masami Hiramatsu > >> --- > >> kernel/fail_function.c | 10 ++ > >> 1 file changed, 10 insertions(+) > >> > >> diff --git a/kernel/fail_function.c b/kernel/fail_function.c > >> index 21b0122cb39c..1d5632d8bbcc 100644 > >> --- a/kernel/fail_function.c > >> +++ b/kernel/fail_function.c > >> @@ -14,6 +14,15 @@ > >> > >> static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs); > >> > >> +static void fei_post_handler(struct kprobe *kp, struct pt_regs *regs, > >> + unsigned long flags) > >> +{ > >> + /* > >> + * A dummy post handler is required to prohibit optimizing, because > >> + * jump optimization does not support execution path overriding. > >> + */ > >> +} > >> + > >> struct fei_attr { > >>struct list_head list; > >>struct kprobe kp; > >> @@ -56,6 +65,7 @@ static struct fei_attr *fei_attr_new(const char *sym, > >> unsigned long addr) > >>return NULL; > >>} > >>attr->kp.pre_handler = fei_kprobe_handler; > >> + attr->kp.post_handler = fei_post_handler; > >>attr->retval = adjust_error_retval(addr, 0); > >>INIT_LIST_HEAD(&attr->list); > >>} > >> > > > > > -- Masami Hiramatsu -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [BUGFIX PATCH bpf-next] error-injection: Fix to prohibit jump optimization
Hi Masami, On 03/12/2018 11:27 AM, Masami Hiramatsu wrote: > On Mon, 12 Mar 2018 19:00:49 +0900 > Masami Hiramatsu wrote: > >> Since the kprobe which was optimized by jump can not change >> the execution path, the kprobe for error-injection must not >> be optimized. To prohibit it, set a dummy post-handler as >> officially stated in Documentation/kprobes.txt. > > Note that trace-probe based BPF is not affected, because it > ensures the trace-probe is based on ftrace, which is not > jump optimized. Thanks for the fix! I presume this should go via bpf instead of bpf-next tree since 4b1a29a7f542 ("error-injection: Support fault injection framework") is in Linus' tree as well. Unless there are objection I would rather route it that way so it would be for 4.16. Thanks, Daniel > Thanks, > >> >> Fixes: 4b1a29a7f542 ("error-injection: Support fault injection framework") >> Signed-off-by: Masami Hiramatsu >> --- >> kernel/fail_function.c | 10 ++ >> 1 file changed, 10 insertions(+) >> >> diff --git a/kernel/fail_function.c b/kernel/fail_function.c >> index 21b0122cb39c..1d5632d8bbcc 100644 >> --- a/kernel/fail_function.c >> +++ b/kernel/fail_function.c >> @@ -14,6 +14,15 @@ >> >> static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs); >> >> +static void fei_post_handler(struct kprobe *kp, struct pt_regs *regs, >> + unsigned long flags) >> +{ >> +/* >> + * A dummy post handler is required to prohibit optimizing, because >> + * jump optimization does not support execution path overriding. >> + */ >> +} >> + >> struct fei_attr { >> struct list_head list; >> struct kprobe kp; >> @@ -56,6 +65,7 @@ static struct fei_attr *fei_attr_new(const char *sym, >> unsigned long addr) >> return NULL; >> } >> attr->kp.pre_handler = fei_kprobe_handler; >> +attr->kp.post_handler = fei_post_handler; >> attr->retval = adjust_error_retval(addr, 0); >> INIT_LIST_HEAD(&attr->list); >> } >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [BUGFIX PATCH bpf-next] error-injection: Fix to prohibit jump optimization
On Mon, 12 Mar 2018 19:00:49 +0900 Masami Hiramatsu wrote: > Since the kprobe which was optimized by jump can not change > the execution path, the kprobe for error-injection must not > be optimized. To prohibit it, set a dummy post-handler as > officially stated in Documentation/kprobes.txt. Note that trace-probe based BPF is not affected, because it ensures the trace-probe is based on ftrace, which is not jump optimized. Thanks, > > Fixes: 4b1a29a7f542 ("error-injection: Support fault injection framework") > Signed-off-by: Masami Hiramatsu > --- > kernel/fail_function.c | 10 ++ > 1 file changed, 10 insertions(+) > > diff --git a/kernel/fail_function.c b/kernel/fail_function.c > index 21b0122cb39c..1d5632d8bbcc 100644 > --- a/kernel/fail_function.c > +++ b/kernel/fail_function.c > @@ -14,6 +14,15 @@ > > static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs); > > +static void fei_post_handler(struct kprobe *kp, struct pt_regs *regs, > + unsigned long flags) > +{ > + /* > + * A dummy post handler is required to prohibit optimizing, because > + * jump optimization does not support execution path overriding. > + */ > +} > + > struct fei_attr { > struct list_head list; > struct kprobe kp; > @@ -56,6 +65,7 @@ static struct fei_attr *fei_attr_new(const char *sym, > unsigned long addr) > return NULL; > } > attr->kp.pre_handler = fei_kprobe_handler; > + attr->kp.post_handler = fei_post_handler; > attr->retval = adjust_error_retval(addr, 0); > INIT_LIST_HEAD(&attr->list); > } > -- Masami Hiramatsu -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[BUGFIX PATCH bpf-next] error-injection: Fix to prohibit jump optimization
Since the kprobe which was optimized by jump can not change the execution path, the kprobe for error-injection must not be optimized. To prohibit it, set a dummy post-handler as officially stated in Documentation/kprobes.txt. Fixes: 4b1a29a7f542 ("error-injection: Support fault injection framework") Signed-off-by: Masami Hiramatsu --- kernel/fail_function.c | 10 ++ 1 file changed, 10 insertions(+) diff --git a/kernel/fail_function.c b/kernel/fail_function.c index 21b0122cb39c..1d5632d8bbcc 100644 --- a/kernel/fail_function.c +++ b/kernel/fail_function.c @@ -14,6 +14,15 @@ static int fei_kprobe_handler(struct kprobe *kp, struct pt_regs *regs); +static void fei_post_handler(struct kprobe *kp, struct pt_regs *regs, +unsigned long flags) +{ + /* +* A dummy post handler is required to prohibit optimizing, because +* jump optimization does not support execution path overriding. +*/ +} + struct fei_attr { struct list_head list; struct kprobe kp; @@ -56,6 +65,7 @@ static struct fei_attr *fei_attr_new(const char *sym, unsigned long addr) return NULL; } attr->kp.pre_handler = fei_kprobe_handler; + attr->kp.post_handler = fei_post_handler; attr->retval = adjust_error_retval(addr, 0); INIT_LIST_HEAD(&attr->list); } -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html