linux-kernel - [RFC patch 25/41] mm/kasan: Simplify stacktrace handling

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Message-Id: <20190410103645.862294081@linutronix.de>
Date:   Wed, 10 Apr 2019 12:28:19 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>, x86@...nel.org,
        Andy Lutomirski <luto@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, kasan-dev@...glegroups.com,
        linux-mm@...ck.org
Subject: [RFC patch 25/41] mm/kasan: Simplify stacktrace handling

Replace the indirection through struct stack_trace by using the storage
array based interfaces.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc: Alexander Potapenko <glider@...gle.com>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: kasan-dev@...glegroups.com
Cc: linux-mm@...ck.org
---
 mm/kasan/common.c |   30 ++++++++++++------------------
 mm/kasan/report.c |    7 ++++---
 2 files changed, 16 insertions(+), 21 deletions(-)

--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -48,34 +48,28 @@ static inline int in_irqentry_text(unsig
 		 ptr < (unsigned long)&__softirqentry_text_end);
 }
 
-static inline void filter_irq_stacks(struct stack_trace *trace)
+static inline unsigned int filter_irq_stacks(unsigned long *entries,
+					     unsigned int nr_entries)
 {
-	int i;
+	unsigned int i;
 
-	if (!trace->nr_entries)
-		return;
-	for (i = 0; i < trace->nr_entries; i++)
-		if (in_irqentry_text(trace->entries[i])) {
+	for (i = 0; i < nr_entries; i++) {
+		if (in_irqentry_text(entries[i])) {
 			/* Include the irqentry function into the stack. */
-			trace->nr_entries = i + 1;
-			break;
+			return i + 1;
 		}
+	}
+	return nr_entries;
 }
 
 static inline depot_stack_handle_t save_stack(gfp_t flags)
 {
 	unsigned long entries[KASAN_STACK_DEPTH];
-	struct stack_trace trace = {
-		.nr_entries = 0,
-		.entries = entries,
-		.max_entries = KASAN_STACK_DEPTH,
-		.skip = 0
-	};
+	unsigned int nent;
 
-	save_stack_trace(&trace);
-	filter_irq_stacks(&trace);
-
-	return depot_save_stack(&trace, flags);
+	nent = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
+	nent = filter_irq_stacks(entries, nent);
+	return stack_depot_save(entries, nent, flags);
 }
 
 static inline void set_track(struct kasan_track *track, gfp_t flags)
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -100,10 +100,11 @@ static void print_track(struct kasan_tra
 {
 	pr_err("%s by task %u:\n", prefix, track->pid);
 	if (track->stack) {
-		struct stack_trace trace;
+		unsigned long *entries;
+		unsigned int nent;
 
-		depot_fetch_stack(track->stack, &trace);
-		print_stack_trace(&trace, 0);
+		nent = stack_depot_fetch(track->stack, &entries);
+		stack_trace_print(entries, nent, 0);
 	} else {
 		pr_err("(stack is not available)\n");
 	}