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[3.8] tracing: Minor fixes for 3.8

GIT PULL Superseded Steven Rostedt 3 participants 8 messages Jan 3, 2013 – Jan 24, 2013

Subsystems (2)
Tracing ftrace

v1 of 2 Superseded Latest is v2 →

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Steven Rostedt

author maintainer
#0 lore raw

Ingo,

As it's still an early -rc, it would be good to get these fixes into mainline before the next release.

Thanks,

-- Steve

Please pull the latest tip/perf/urgent tree, which can be found at:

git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
tip/perf/urgent

Head SHA1: f9dd9809c1426ccc7e997201b9b839c96ac810ec

Jovi Zhang (1):
tracing: Verify target file before registering a uprobe event

Steven Rostedt (2):
ftrace: Be first to run code modification on modules
tracing: Fix sparse warning with is_signed_type() macro

----

 include/linux/ftrace_event.h |    2 +-
 kernel/trace/ftrace.c        |    2 +-
 kernel/trace/trace_uprobe.c  |    6 +++++-
 3 files changed, 7 insertions(+), 3 deletions(-)
author maintainer
#1 lore raw

PATCH 1/3 ftrace: Be first to run code modification on modules

From: Steven Rostedt <[email protected]>

If some other kernel subsystem has a module notifier, and adds a kprobe to a ftrace mcount point (now that kprobes work on ftrace points), when the ftrace notifier runs it will fail and disable ftrace, as well as kprobes that are attached to ftrace points.

Here's the error:

 WARNING: at kernel/trace/ftrace.c:1618 ftrace_bug+0x239/0x280()
 Hardware name: Bochs
 Modules linked in: fat(+) stap_56d28a51b3fe546293ca0700b10bcb29__8059(F) nfsv4 auth_rpcgss nfs dns_resolver fscache xt_nat iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack lockd sunrpc ppdev parport_pc parport microcode virtio_net i2c_piix4 drm_kms_helper ttm drm i2c_core [last unloaded: bid_shared]
 Pid: 8068, comm: modprobe Tainted: GF            3.7.0-0.rc8.git0.1.fc19.x86_64 #1
 Call Trace:
  [<ffffffff8105e70f>] warn_slowpath_common+0x7f/0xc0
  [<ffffffff81134106>] ? __probe_kernel_read+0x46/0x70
  [<ffffffffa0180000>] ? 0xffffffffa017ffff
  [<ffffffffa0180000>] ? 0xffffffffa017ffff
  [<ffffffff8105e76a>] warn_slowpath_null+0x1a/0x20
  [<ffffffff810fd189>] ftrace_bug+0x239/0x280
  [<ffffffff810fd626>] ftrace_process_locs+0x376/0x520
  [<ffffffff810fefb7>] ftrace_module_notify+0x47/0x50
  [<ffffffff8163912d>] notifier_call_chain+0x4d/0x70
  [<ffffffff810882f8>] __blocking_notifier_call_chain+0x58/0x80
  [<ffffffff81088336>] blocking_notifier_call_chain+0x16/0x20
  [<ffffffff810c2a23>] sys_init_module+0x73/0x220
  [<ffffffff8163d719>] system_call_fastpath+0x16/0x1b
 ---[ end trace 9ef46351e53bbf80 ]---
 ftrace failed to modify [<ffffffffa0180000>] init_once+0x0/0x20 [fat]
  actual: cc:bb:d2:4b:e1

A kprobe was added to the init_once() function in the fat module on load. But this happened before ftrace could have touched the code. As ftrace didn't run yet, the kprobe system had no idea it was a ftrace point and simply added a breakpoint to the code (0xcc in the cc:bb:d2:4b:e1).

Then when ftrace went to modify the location from a call to mcount/fentry into a nop, it didn't see a call op, but instead it saw the breakpoint op and not knowing what to do with it, ftrace shut itself down.

The solution is to simply give the ftrace module notifier the max priority. This should have been done regardless, as the core code ftrace modification also happens very early on in boot up. This makes the module modification closer to core modification.

Cc Masami Hiramatsu <[email protected]>
Reported-by Frank Ch. Eigler <[email protected]>
Signed-off-by Steven Rostedt <[email protected]>
---
 kernel/trace/ftrace.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
kernel/trace/ftrace.c +1 -1
index 51b7159..356bc2f 100644
@@ -3998,7 +3998,7 @@ static int ftrace_module_notify(struct notifier_block *self,
 
 struct notifier_block ftrace_module_nb = {
 	.notifier_call = ftrace_module_notify,
-	.priority = 0,
+	.priority = INT_MAX,	/* Run before anything that can use kprobes */
 };
 
 extern unsigned long __start_mcount_loc[];
Signature · 1 line
1.7.10.4
author maintainer
#2 lore raw

PATCH 2/3 tracing: Fix sparse warning with is_signed_type() macro

In reply to Steven Rostedt

From: Steven Rostedt <[email protected]>

Sparse complains when is_signed_type() is used on a pointer. This macro is needed for the format output used for ftrace and perf, to know if a binary field is a signed type or not. The is_signed_type() macro is used against all fields that are recorded by events to automate the operation.

The problem sparse has is with the current way is_signed_type() works:

((type)-1 < 0)

If "type" is a poiner, than sparse does not like it being compared to an integer (zero). The simple fix is to just give zero the same type. The runtime result stays the same.

Reported-by Robert Jarzmik <[email protected]>
Signed-off-by Steven Rostedt <[email protected]>
---
 include/linux/ftrace_event.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
include/linux/ftrace_event.h +1 -1
index 642928c..cc87955 100644
@@ -266,7 +266,7 @@ extern int trace_define_field(struct ftrace_event_call *call, const char *type,
 extern int trace_add_event_call(struct ftrace_event_call *call);
 extern void trace_remove_event_call(struct ftrace_event_call *call);
 
-#define is_signed_type(type)	(((type)(-1)) < 0)
+#define is_signed_type(type)	(((type)(-1)) < (type)0)
 
 int trace_set_clr_event(const char *system, const char *event, int set);
Signature · 1 line
1.7.10.4
author maintainer
#3 lore raw

PATCH 3/3 tracing: Verify target file before registering a uprobe event

In reply to Steven Rostedt

From: Jovi Zhang <[email protected]>

Without this patch, we can register a uprobe event for a directory. Enabling such a uprobe event would fail anyway .

Example:

$ echo 'p /bin:0x4245c0' > /sys/kernel/debug/tracing/uprobe_events

However dirctories cannot be valid targets for uprobe. Hence verify if the target is a regular file during the probe registration.

Signed-off-by Jovi Zhang <[email protected]>
Acked-by Srikar Dronamraju <[email protected]>
Signed-off-by Steven Rostedt <[email protected]>
---
 kernel/trace/trace_uprobe.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
kernel/trace/trace_uprobe.c +5 -1
index 03003cd..0815f25 100644
@@ -257,6 +257,10 @@ static int create_trace_uprobe(int argc, char **argv)
 		goto fail_address_parse;
 
 	inode = igrab(path.dentry->d_inode);
+	 if (!S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)) {
+		ret = -EINVAL;
+		goto fail_address_parse;
+	}
 
 	argc -= 2;
 	argv += 2;

@@ -356,7 +360,7 @@ fail_address_parse:
 	if (inode)
 		iput(inode);
 
-	pr_info("Failed to parse address.\n");
+	pr_info("Failed to parse address or file.\n");
 
 	return ret;
 }
Signature · 1 line
1.7.10.4
#4 lore raw

Re: [PATCH 3/3] tracing: Verify target file before registering a uprobe event

Hi, Steve.

Quoted 24 lines · Steven Rostedt

From: Jovi Zhang <[email protected]>

Without this patch, we can register a uprobe event for a directory. Enabling such a uprobe event would fail anyway .

Example:

$ echo 'p /bin:0x4245c0' > /sys/kernel/debug/tracing/uprobe_events

However dirctories cannot be valid targets for uprobe. Hence verify if the target is a regular file during the probe registration.

Signed-off-by Jovi Zhang <[email protected]>
Acked-by Srikar Dronamraju <[email protected]>
Signed-off-by Steven Rostedt <[email protected]>
---
 kernel/trace/trace_uprobe.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
kernel/trace/trace_uprobe.c +0 -0
index 03003cd..0815f25 100644

kernel/trace/trace_uprobe.c static int create_trace_uprobe(int argc, char **argv) · line 260

Quoted 4 lines
kernel/trace/trace_uprobe.c +1 -0
@@ -257,6 +257,10 @@ static int create_trace_uprobe(int argc, char **argv)
 		goto fail_address_parse;
 
 	inode = igrab(path.dentry->d_inode);
+	 if (!S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)) {

Doesn't !S_ISREG() include S_ISDIR() case too?

Anyway I can see an additional whitespace in front of the "if".

Thanks,
Namhyung

Quoted 15 lines
kernel/trace/trace_uprobe.c +4 -1
+		ret = -EINVAL;
+		goto fail_address_parse;
+	}
 
 	argc -= 2;
 	argv += 2;

@@ -356,7 +360,7 @@ fail_address_parse:
 	if (inode)
 		iput(inode);
 
-	pr_info("Failed to parse address.\n");
+	pr_info("Failed to parse address or file.\n");
 
 	return ret;
 }
author maintainer
#5 lore raw

Re: [PATCH 3/3] tracing: Verify target file before registering a uprobe event

Quoted 29 lines · Namhyung Kim

Hi, Steve.

Quoted 26 lines · Steven Rostedt

From: Jovi Zhang <[email protected]>

Without this patch, we can register a uprobe event for a directory. Enabling such a uprobe event would fail anyway .

Example:

$ echo 'p /bin:0x4245c0' > /sys/kernel/debug/tracing/uprobe_events

However dirctories cannot be valid targets for uprobe. Hence verify if the target is a regular file during the probe registration.

Signed-off-by Jovi Zhang <[email protected]>
Acked-by Srikar Dronamraju <[email protected]>
Signed-off-by Steven Rostedt <[email protected]>
---
 kernel/trace/trace_uprobe.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
kernel/trace/trace_uprobe.c +0 -0
index 03003cd..0815f25 100644
@@ -257,6 +257,10 @@ static int create_trace_uprobe(int argc, char **argv)
 		goto fail_address_parse;
Quoted 4 lines

kernel/trace/trace_uprobe.c static int create_trace_uprobe(int argc, char **argv) · line 260

Quoted 2 lines
kernel/trace/trace_uprobe.c +1 -0
 	inode = igrab(path.dentry->d_inode);
+	 if (!S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)) {

Doesn't !S_ISREG() include S_ISDIR() case too?

You're correct. Although I'm sure gcc should be smart enough to optimize that out.

Quoted 2 lines

Anyway I can see an additional whitespace in front of the "if".

Yep, I forgot to run checkpatch on this. OK, this bug isn't that big of a deal, so I'll take this patch out and put it into the 3.9 queue.

Thanks,

-- Steve

Quoted 20 lines

Thanks,
Namhyung

Quoted 15 lines
kernel/trace/trace_uprobe.c +4 -1
+		ret = -EINVAL;
+		goto fail_address_parse;
+	}
 
 	argc -= 2;
 	argv += 2;

@@ -356,7 +360,7 @@ fail_address_parse:
 	if (inode)
 		iput(inode);
 
-	pr_info("Failed to parse address.\n");
+	pr_info("Failed to parse address or file.\n");
 
 	return ret;
 }
author maintainer
#6 lore raw

Re: [PATCH 3/3] tracing: Verify target file before registering a uprobe event

In reply to Steven Rostedt

Jovi,

As Namhyung pointed out. Can you fix the below and resend.

Quoted 24 lines · Steven Rostedt

From: Jovi Zhang <[email protected]>

Without this patch, we can register a uprobe event for a directory. Enabling such a uprobe event would fail anyway .

Example:

$ echo 'p /bin:0x4245c0' > /sys/kernel/debug/tracing/uprobe_events

However dirctories cannot be valid targets for uprobe. Hence verify if the target is a regular file during the probe registration.

Signed-off-by Jovi Zhang <[email protected]>
Acked-by Srikar Dronamraju <[email protected]>
Signed-off-by Steven Rostedt <[email protected]>
---
 kernel/trace/trace_uprobe.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
kernel/trace/trace_uprobe.c +0 -0
index 03003cd..0815f25 100644

kernel/trace/trace_uprobe.c static int create_trace_uprobe(int argc, char **argv) · line 260

Quoted 4 lines
kernel/trace/trace_uprobe.c +1 -0
@@ -257,6 +257,10 @@ static int create_trace_uprobe(int argc, char **argv)
 		goto fail_address_parse;
 
 	inode = igrab(path.dentry->d_inode);
+	 if (!S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode)) {

Bad whitespace before 'if'.

Also, S_ISDIR() implies S_ISREG(), you can remove the "S_ISDIR()" check.

Thanks,

-- Steve

Quoted 15 lines
kernel/trace/trace_uprobe.c +4 -1
+		ret = -EINVAL;
+		goto fail_address_parse;
+	}
 
 	argc -= 2;
 	argv += 2;

@@ -356,7 +360,7 @@ fail_address_parse:
 	if (inode)
 		iput(inode);
 
-	pr_info("Failed to parse address.\n");
+	pr_info("Failed to parse address or file.\n");
 
 	return ret;
 }
#7 lore raw

[tip:perf/core] tracing: Verify target file before registering a uprobe event

In reply to Steven Rostedt
Commit-ID:  d24d7dbf3cc49b00a152e55e24f0eeb173c7a971
Gitweb:     http://git.kernel.org/tip/d24d7dbf3cc49b00a152e55e24f0eeb173c7a971
Author:     Jovi Zhang <[email protected]>
AuthorDate: Wed, 18 Jul 2012 18:16:44 +0800
Committer:  Steven Rostedt <[email protected]>
CommitDate: Mon, 21 Jan 2013 13:22:31 -0500

tracing: Verify target file before registering a uprobe event

Without this patch, we can register a uprobe event for a directory. Enabling such a uprobe event would anyway fail.

Example:

$ echo 'p /bin:0x4245c0' > /sys/kernel/debug/tracing/uprobe_events

However dirctories cannot be valid targets for uprobe. Hence verify if the target is a regular file during the probe registration.

Link http://lkml.kernel.org/r/[email protected] open here
Cc Namhyung Kim <[email protected]>
Signed-off-by Jovi Zhang <[email protected]>
Acked-by Srikar Dronamraju <[email protected]>
[ cleaned up whitespace and removed redundant IS_DIR() check ]
Signed-off-by Steven Rostedt <[email protected]>
---
 kernel/trace/trace_uprobe.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
kernel/trace/trace_uprobe.c +5 -1
index c86e6d4..87b6db4 100644
@@ -258,6 +258,10 @@ static int create_trace_uprobe(int argc, char **argv)
 		goto fail_address_parse;
 
 	inode = igrab(path.dentry->d_inode);
+	if (!S_ISREG(inode->i_mode)) {
+		ret = -EINVAL;
+		goto fail_address_parse;
+	}
 
 	argc -= 2;
 	argv += 2;

@@ -356,7 +360,7 @@ fail_address_parse:
 	if (inode)
 		iput(inode);
 
-	pr_info("Failed to parse address.\n");
+	pr_info("Failed to parse address or file.\n");
 
 	return ret;
 }