From: Masami Hiramatsu <mhiramat@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>, Ingo Molnar <mingo@kernel.org>
Cc: Joe Lawrence <joe.lawrence@redhat.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
live-patching@vger.kernel.org, linux-kernel@vger.kernel.org,
"Naveen N . Rao" <naveen.n.rao@linux.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
"David S . Miller" <davem@davemloft.net>
Subject: [PATCH] kprobes: Allow kprobes coexist with livepatch
Date: Thu, 25 Jul 2019 15:24:37 +0900 [thread overview]
Message-ID: <156403587671.30117.5233558741694155985.stgit@devnote2> (raw)
Allow kprobes which do not modify regs->ip, coexist with livepatch
by dropping FTRACE_OPS_FL_IPMODIFY from ftrace_ops.
User who wants to modify regs->ip (e.g. function fault injection)
must set a dummy post_handler to its kprobes when registering.
However, if such regs->ip modifying kprobes is set on a function,
that function can not be livepatched.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
kernel/kprobes.c | 56 +++++++++++++++++++++++++++++++++++++++---------------
1 file changed, 40 insertions(+), 16 deletions(-)
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 9873fc627d61..29065380dad0 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -961,9 +961,16 @@ static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
#ifdef CONFIG_KPROBES_ON_FTRACE
static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
+ .func = kprobe_ftrace_handler,
+ .flags = FTRACE_OPS_FL_SAVE_REGS,
+};
+
+static struct ftrace_ops kprobe_ipmodify_ops __read_mostly = {
.func = kprobe_ftrace_handler,
.flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY,
};
+
+static int kprobe_ipmodify_enabled;
static int kprobe_ftrace_enabled;
/* Must ensure p->addr is really on ftrace */
@@ -976,58 +983,75 @@ static int prepare_kprobe(struct kprobe *p)
}
/* Caller must lock kprobe_mutex */
-static int arm_kprobe_ftrace(struct kprobe *p)
+static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
+ int *cnt)
{
int ret = 0;
- ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
- (unsigned long)p->addr, 0, 0);
+ ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0);
if (ret) {
pr_debug("Failed to arm kprobe-ftrace at %pS (%d)\n",
p->addr, ret);
return ret;
}
- if (kprobe_ftrace_enabled == 0) {
- ret = register_ftrace_function(&kprobe_ftrace_ops);
+ if (*cnt == 0) {
+ ret = register_ftrace_function(ops);
if (ret) {
pr_debug("Failed to init kprobe-ftrace (%d)\n", ret);
goto err_ftrace;
}
}
- kprobe_ftrace_enabled++;
+ (*cnt)++;
return ret;
err_ftrace:
/*
- * Note: Since kprobe_ftrace_ops has IPMODIFY set, and ftrace requires a
- * non-empty filter_hash for IPMODIFY ops, we're safe from an accidental
- * empty filter_hash which would undesirably trace all functions.
+ * At this point, sinec ops is not registered, we should be sefe from
+ * registering empty filter.
*/
- ftrace_set_filter_ip(&kprobe_ftrace_ops, (unsigned long)p->addr, 1, 0);
+ ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
return ret;
}
+static int arm_kprobe_ftrace(struct kprobe *p)
+{
+ bool ipmodify = (p->post_handler != NULL);
+
+ return __arm_kprobe_ftrace(p,
+ ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops,
+ ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
+}
+
/* Caller must lock kprobe_mutex */
-static int disarm_kprobe_ftrace(struct kprobe *p)
+static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
+ int *cnt)
{
int ret = 0;
- if (kprobe_ftrace_enabled == 1) {
- ret = unregister_ftrace_function(&kprobe_ftrace_ops);
+ if (*cnt == 1) {
+ ret = unregister_ftrace_function(ops);
if (WARN(ret < 0, "Failed to unregister kprobe-ftrace (%d)\n", ret))
return ret;
}
- kprobe_ftrace_enabled--;
+ (*cnt)--;
- ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
- (unsigned long)p->addr, 1, 0);
+ ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (%d)\n",
p->addr, ret);
return ret;
}
+
+static int disarm_kprobe_ftrace(struct kprobe *p)
+{
+ bool ipmodify = (p->post_handler != NULL);
+
+ return __disarm_kprobe_ftrace(p,
+ ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops,
+ ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
+}
#else /* !CONFIG_KPROBES_ON_FTRACE */
#define prepare_kprobe(p) arch_prepare_kprobe(p)
#define arm_kprobe_ftrace(p) (-ENODEV)
next reply other threads:[~2019-07-25 6:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 6:24 Masami Hiramatsu [this message]
2019-07-25 13:33 ` [PATCH] kprobes: Allow kprobes coexist with livepatch Steven Rostedt
2019-07-26 2:07 ` Joe Lawrence
2019-07-26 16:14 ` Steven Rostedt
2019-07-26 17:38 ` Joe Lawrence
2019-07-26 18:06 ` Steven Rostedt
2019-07-27 9:41 ` Masami Hiramatsu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=156403587671.30117.5233558741694155985.stgit@devnote2 \
--to=mhiramat@kernel.org \
--cc=anil.s.keshavamurthy@intel.com \
--cc=davem@davemloft.net \
--cc=joe.lawrence@redhat.com \
--cc=jpoimboe@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=live-patching@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=naveen.n.rao@linux.ibm.com \
--cc=rostedt@goodmis.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).