linux-kernel - [tip:perf/probes] tracing/kprobes: Fix profiling alignment for perf

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Date:	Sat, 17 Oct 2009 10:01:41 GMT
From:	tip-bot for Masami Hiramatsu <mhiramat@...hat.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	mingo@...hat.com, peterz@...radead.org, fweisbec@...il.com,
	rostedt@...dmis.org, ak@...ux.intel.com, jbaron@...hat.com,
	tglx@...utronix.de, laijs@...fujitsu.com, mhiramat@...hat.com,
	linux-kernel@...r.kernel.org, hpa@...or.com, fche@...hat.com,
	jkenisto@...ibm.com, tzanussi@...il.com, lizf@...fujitsu.com,
	hch@...radead.org, ananth@...ibm.com, srikar@...ux.vnet.ibm.com,
	mingo@...e.hu, prasad@...ux.vnet.ibm.com
Subject: [tip:perf/probes] tracing/kprobes: Fix profiling alignment for perf_counter buffer

Commit-ID:  74ebb63e7cd25f6fb02a45fc2ea7735bce1217c9
Gitweb:     http://git.kernel.org/tip/74ebb63e7cd25f6fb02a45fc2ea7735bce1217c9
Author:     Masami Hiramatsu <mhiramat@...hat.com>
AuthorDate: Mon, 14 Sep 2009 16:49:28 -0400
Committer:  Frederic Weisbecker <fweisbec@...il.com>
CommitDate: Thu, 17 Sep 2009 04:03:57 +0200

tracing/kprobes: Fix profiling alignment for perf_counter buffer

Fix *probe_profile_func() to align buffer size, since perf_counter
requires its buffer entries to be 8 bytes aligned.

Signed-off-by: Masami Hiramatsu <mhiramat@...hat.com>
Acked-by: Steven Rostedt <rostedt@...dmis.org>
Cc: Jim Keniston <jkenisto@...ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
Cc: Andi Kleen <ak@...ux.intel.com>
Cc: Christoph Hellwig <hch@...radead.org>
Cc: Frank Ch. Eigler <fche@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Jason Baron <jbaron@...hat.com>
Cc: K.Prasad <prasad@...ux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@...fujitsu.com>
Cc: Li Zefan <lizf@...fujitsu.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc: Tom Zanussi <tzanussi@...il.com>
LKML-Reference: <20090914204928.18779.60029.stgit@...p-100-2-132.bos.redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@...il.com>
---
 kernel/trace/trace_kprobe.c |   17 ++++++++++++-----
 1 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 70b632c..d8db935 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -1149,18 +1149,23 @@ static __kprobes int kprobe_profile_func(struct kprobe *kp,
 	struct trace_probe *tp = container_of(kp, struct trace_probe, rp.kp);
 	struct ftrace_event_call *call = &tp->call;
 	struct kprobe_trace_entry *entry;
-	int size, i, pc;
+	int size, __size, i, pc;
 	unsigned long irq_flags;
 
 	local_save_flags(irq_flags);
 	pc = preempt_count();
 
-	size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);
+	__size = SIZEOF_KPROBE_TRACE_ENTRY(tp->nr_args);
+	size = ALIGN(__size + sizeof(u32), sizeof(u64));
+	size -= sizeof(u32);
 
 	do {
 		char raw_data[size];
 		struct trace_entry *ent;
-
+		/*
+		 * Zero dead bytes from alignment to avoid stack leak
+		 * to userspace
+		 */
 		*(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL;
 		entry = (struct kprobe_trace_entry *)raw_data;
 		ent = &entry->ent;
@@ -1183,13 +1188,15 @@ static __kprobes int kretprobe_profile_func(struct kretprobe_instance *ri,
 	struct trace_probe *tp = container_of(ri->rp, struct trace_probe, rp);
 	struct ftrace_event_call *call = &tp->call;
 	struct kretprobe_trace_entry *entry;
-	int size, i, pc;
+	int size, __size, i, pc;
 	unsigned long irq_flags;
 
 	local_save_flags(irq_flags);
 	pc = preempt_count();
 
-	size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);
+	__size = SIZEOF_KRETPROBE_TRACE_ENTRY(tp->nr_args);
+	size = ALIGN(__size + sizeof(u32), sizeof(u64));
+	size -= sizeof(u32);
 
 	do {
 		char raw_data[size];
--
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