diff mbox series

[v7,1/3] kprobes/ftrace: Use ftrace_location() when [dis]arming probes

Message ID 20191225172752.70be1dc1@xhacker.debian (mailing list archive)
State New, archived
Headers show
Series arm64: implement KPROBES_ON_FTRACE | expand

Commit Message

Jisheng Zhang Dec. 25, 2019, 9:42 a.m. UTC 
Ftrace location could include more than a single instruction in case
of some architectures (powerpc64, for now). In this case, kprobe is
permitted on any of those instructions, and uses ftrace infrastructure
for functioning.

However, [dis]arm_kprobe_ftrace() uses the kprobe address when setting
up ftrace filter IP. This won't work if the address points to any
instruction apart from the one that has a branch to _mcount(). To
resolve this, have [dis]arm_kprobe_ftrace() use ftrace_function() to
identify the filter IP.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
---
 kernel/kprobes.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

Comments

Jisheng Zhang Dec. 25, 2019, 9:46 a.m. UTC | #1 
On Wed, 25 Dec 2019 09:42:07 +0000 Jisheng Zhang wrote:
> 

oops, I missed "From: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>"

I will take care this point when posting new version.


> Ftrace location could include more than a single instruction in case
> of some architectures (powerpc64, for now). In this case, kprobe is
> permitted on any of those instructions, and uses ftrace infrastructure
> for functioning.
> 
> However, [dis]arm_kprobe_ftrace() uses the kprobe address when setting
> up ftrace filter IP. This won't work if the address points to any
> instruction apart from the one that has a branch to _mcount(). To
> resolve this, have [dis]arm_kprobe_ftrace() use ftrace_function() to
> identify the filter IP.
> 
> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
> Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
> ---
>  kernel/kprobes.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> index 53534aa258a6..5c630b424e3a 100644
> --- a/kernel/kprobes.c
> +++ b/kernel/kprobes.c
> @@ -986,9 +986,10 @@ static int prepare_kprobe(struct kprobe *p)
>  static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
>                                int *cnt)
>  {
> +       unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr);
>         int ret = 0;
> 
> -       ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0);
> +       ret = ftrace_set_filter_ip(ops, ftrace_ip, 0, 0);
>         if (ret) {
>                 pr_debug("Failed to arm kprobe-ftrace at %pS (%d)\n",
>                          p->addr, ret);
> @@ -1011,7 +1012,7 @@ static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
>          * At this point, sinec ops is not registered, we should be sefe from
>          * registering empty filter.
>          */
> -       ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
> +       ftrace_set_filter_ip(ops, ftrace_ip, 1, 0);
>         return ret;
>  }
> 
> @@ -1028,6 +1029,7 @@ static int arm_kprobe_ftrace(struct kprobe *p)
>  static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
>                                   int *cnt)
>  {
> +       unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr);
>         int ret = 0;
> 
>         if (*cnt == 1) {
> @@ -1038,7 +1040,7 @@ static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
> 
>         (*cnt)--;
> 
> -       ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
> +       ret = ftrace_set_filter_ip(ops, ftrace_ip, 1, 0);
>         WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (%d)\n",
>                   p->addr, ret);
>         return ret;
> --
> 2.24.1
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> https://urldefense.proofpoint.com/v2/url?u=http-3A__lists.infradead.org_mailman_listinfo_linux-2Darm-2Dkernel&d=DwICAg&c=7dfBJ8cXbWjhc0BhImu8wQ&r=wlaKTGoVCDxOzHc2QUzpzGEf9oY3eidXlAe3OF1omvo&m=BG5GowWc97yveg-i3gFbh3N7PDT3S3FwcxnpOSRpvIs&s=plWeJUToTNi5CWx998a_VbVx3eFc-MNhUNv4fLpmyiU&e=
diff mbox series

Patch

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 53534aa258a6..5c630b424e3a 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -986,9 +986,10 @@  static int prepare_kprobe(struct kprobe *p)
 static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
 			       int *cnt)
 {
+	unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr);
 	int ret = 0;
 
-	ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0);
+	ret = ftrace_set_filter_ip(ops, ftrace_ip, 0, 0);
 	if (ret) {
 		pr_debug("Failed to arm kprobe-ftrace at %pS (%d)\n",
 			 p->addr, ret);
@@ -1011,7 +1012,7 @@  static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
 	 * At this point, sinec ops is not registered, we should be sefe from
 	 * registering empty filter.
 	 */
-	ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
+	ftrace_set_filter_ip(ops, ftrace_ip, 1, 0);
 	return ret;
 }
 
@@ -1028,6 +1029,7 @@  static int arm_kprobe_ftrace(struct kprobe *p)
 static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
 				  int *cnt)
 {
+	unsigned long ftrace_ip = ftrace_location((unsigned long)p->addr);
 	int ret = 0;
 
 	if (*cnt == 1) {
@@ -1038,7 +1040,7 @@  static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
 
 	(*cnt)--;
 
-	ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
+	ret = ftrace_set_filter_ip(ops, ftrace_ip, 1, 0);
 	WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (%d)\n",
 		  p->addr, ret);
 	return ret;