linux-kernel - [PATCH v2 1/5] stacktrace: move filter_irq

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Message-Id: <20210921101014.1938382-1-elver@google.com>
Date:   Tue, 21 Sep 2021 12:10:10 +0200
From:   Marco Elver <elver@...gle.com>
To:     elver@...gle.com, Andrew Morton <akpm@...ux-foundation.org>
Cc:     Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Jann Horn <jannh@...gle.com>,
        Aleksandr Nogikh <nogikh@...gle.com>,
        Taras Madan <tarasmadan@...gle.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        kasan-dev@...glegroups.com
Subject: [PATCH v2 1/5] stacktrace: move filter_irq_stacks() to kernel/stacktrace.c

filter_irq_stacks() has little to do with the stackdepot implementation,
except that it is usually used by users (such as KASAN) of stackdepot to
reduce the stack trace.

However, filter_irq_stacks() itself is not useful without a stack trace
as obtained by stack_trace_save() and friends.

Therefore, move filter_irq_stacks() to kernel/stacktrace.c, so that new
users of filter_irq_stacks() do not have to start depending on
STACKDEPOT only for filter_irq_stacks().

Signed-off-by: Marco Elver <elver@...gle.com>
---
v2:
* New patch.
---
 include/linux/stackdepot.h |  2 --
 include/linux/stacktrace.h |  1 +
 kernel/stacktrace.c        | 30 ++++++++++++++++++++++++++++++
 lib/stackdepot.c           | 24 ------------------------
 4 files changed, 31 insertions(+), 26 deletions(-)

diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h
index 6bb4bc1a5f54..22919a94ca19 100644
--- a/include/linux/stackdepot.h
+++ b/include/linux/stackdepot.h
@@ -19,8 +19,6 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries,
 unsigned int stack_depot_fetch(depot_stack_handle_t handle,
 			       unsigned long **entries);
 
-unsigned int filter_irq_stacks(unsigned long *entries, unsigned int nr_entries);
-
 #ifdef CONFIG_STACKDEPOT
 int stack_depot_init(void);
 #else
diff --git a/include/linux/stacktrace.h b/include/linux/stacktrace.h
index 9edecb494e9e..bef158815e83 100644
--- a/include/linux/stacktrace.h
+++ b/include/linux/stacktrace.h
@@ -21,6 +21,7 @@ unsigned int stack_trace_save_tsk(struct task_struct *task,
 unsigned int stack_trace_save_regs(struct pt_regs *regs, unsigned long *store,
 				   unsigned int size, unsigned int skipnr);
 unsigned int stack_trace_save_user(unsigned long *store, unsigned int size);
+unsigned int filter_irq_stacks(unsigned long *entries, unsigned int nr_entries);
 
 /* Internal interfaces. Do not use in generic code */
 #ifdef CONFIG_ARCH_STACKWALK
diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
index 9f8117c7cfdd..9c625257023d 100644
--- a/kernel/stacktrace.c
+++ b/kernel/stacktrace.c
@@ -13,6 +13,7 @@
 #include <linux/export.h>
 #include <linux/kallsyms.h>
 #include <linux/stacktrace.h>
+#include <linux/interrupt.h>
 
 /**
  * stack_trace_print - Print the entries in the stack trace
@@ -373,3 +374,32 @@ unsigned int stack_trace_save_user(unsigned long *store, unsigned int size)
 #endif /* CONFIG_USER_STACKTRACE_SUPPORT */
 
 #endif /* !CONFIG_ARCH_STACKWALK */
+
+static inline bool in_irqentry_text(unsigned long ptr)
+{
+	return (ptr >= (unsigned long)&__irqentry_text_start &&
+		ptr < (unsigned long)&__irqentry_text_end) ||
+		(ptr >= (unsigned long)&__softirqentry_text_start &&
+		 ptr < (unsigned long)&__softirqentry_text_end);
+}
+
+/**
+ * filter_irq_stacks - Find first IRQ stack entry in trace
+ * @entries:	Pointer to stack trace array
+ * @nr_entries:	Number of entries in the storage array
+ *
+ * Return: Number of trace entries until IRQ stack starts.
+ */
+unsigned int filter_irq_stacks(unsigned long *entries, unsigned int nr_entries)
+{
+	unsigned int i;
+
+	for (i = 0; i < nr_entries; i++) {
+		if (in_irqentry_text(entries[i])) {
+			/* Include the irqentry function into the stack. */
+			return i + 1;
+		}
+	}
+	return nr_entries;
+}
+EXPORT_SYMBOL_GPL(filter_irq_stacks);
diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 0a2e417f83cb..e90f0f19e77f 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -20,7 +20,6 @@
  */
 
 #include <linux/gfp.h>
-#include <linux/interrupt.h>
 #include <linux/jhash.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
@@ -341,26 +340,3 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries,
 	return retval;
 }
 EXPORT_SYMBOL_GPL(stack_depot_save);
-
-static inline int in_irqentry_text(unsigned long ptr)
-{
-	return (ptr >= (unsigned long)&__irqentry_text_start &&
-		ptr < (unsigned long)&__irqentry_text_end) ||
-		(ptr >= (unsigned long)&__softirqentry_text_start &&
-		 ptr < (unsigned long)&__softirqentry_text_end);
-}
-
-unsigned int filter_irq_stacks(unsigned long *entries,
-					     unsigned int nr_entries)
-{
-	unsigned int i;
-
-	for (i = 0; i < nr_entries; i++) {
-		if (in_irqentry_text(entries[i])) {
-			/* Include the irqentry function into the stack. */
-			return i + 1;
-		}
-	}
-	return nr_entries;
-}
-EXPORT_SYMBOL_GPL(filter_irq_stacks);
-- 
2.33.0.464.g1972c5931b-goog