linux-kernel - [PATCH 22/24] tracing/kprobes: Fix profiling alignment for perf

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Message-Id: <1253648302-5771-23-git-send-email-fweisbec@gmail.com>
Date:	Tue, 22 Sep 2009 21:38:20 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Masami Hiramatsu <mhiramat@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Li Zefan <lizf@...fujitsu.com>,
	Jim Keniston <jkenisto@...ibm.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Andi Kleen <ak@...ux.intel.com>,
	Christoph Hellwig <hch@...radead.org>,
	"Frank Ch. Eigler" <fche@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Jason Baron <jbaron@...hat.com>,
	"K.Prasad" <prasad@...ux.vnet.ibm.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Tom Zanussi <tzanussi@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: [PATCH 22/24] tracing/kprobes: Fix profiling alignment for perf_counter buffer

From: Masami Hiramatsu <mhiramat@...hat.com>

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];
-- 
1.6.2.3

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