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authorAndrey Konovalov <andreyknvl@google.com>2023-02-10 22:16:03 +0100
committerAndrew Morton <akpm@linux-foundation.org>2023-02-16 20:43:51 -0800
commit36aa1e6779c3c6f8e0d4552544214f5cffe3c287 (patch)
tree1639d4bb581f0baab0ebed256c8e2af3a0fa6c5e /lib
parentd11a5621f3252120dfc7cef7600a90bd8e605caf (diff)
lib/stacktrace, kasan, kmsan: rework extra_bits interface
The current implementation of the extra_bits interface is confusing: passing extra_bits to __stack_depot_save makes it seem that the extra bits are somehow stored in stack depot. In reality, they are only embedded into a stack depot handle and are not used within stack depot. Drop the extra_bits argument from __stack_depot_save and instead provide a new stack_depot_set_extra_bits function (similar to the exsiting stack_depot_get_extra_bits) that saves extra bits into a stack depot handle. Update the callers of __stack_depot_save to use the new interace. This change also fixes a minor issue in the old code: __stack_depot_save does not return NULL if saving stack trace fails and extra_bits is used. Link: https://lkml.kernel.org/r/317123b5c05e2f82854fc55d8b285e0869d3cb77.1676063693.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Alexander Potapenko <glider@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib')
-rw-r--r--lib/stackdepot.c42
1 files changed, 33 insertions, 9 deletions
diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index 4df162a84bfe..8c6e4e9cb535 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -357,7 +357,6 @@ static inline struct stack_record *find_stack(struct stack_record *bucket,
*
* @entries: Pointer to storage array
* @nr_entries: Size of the storage array
- * @extra_bits: Flags to store in unused bits of depot_stack_handle_t
* @alloc_flags: Allocation gfp flags
* @can_alloc: Allocate stack pools (increased chance of failure if false)
*
@@ -369,10 +368,6 @@ static inline struct stack_record *find_stack(struct stack_record *bucket,
* If the stack trace in @entries is from an interrupt, only the portion up to
* interrupt entry is saved.
*
- * Additional opaque flags can be passed in @extra_bits, stored in the unused
- * bits of the stack handle, and retrieved using stack_depot_get_extra_bits()
- * without calling stack_depot_fetch().
- *
* Context: Any context, but setting @can_alloc to %false is required if
* alloc_pages() cannot be used from the current context. Currently
* this is the case from contexts where neither %GFP_ATOMIC nor
@@ -382,7 +377,6 @@ static inline struct stack_record *find_stack(struct stack_record *bucket,
*/
depot_stack_handle_t __stack_depot_save(unsigned long *entries,
unsigned int nr_entries,
- unsigned int extra_bits,
gfp_t alloc_flags, bool can_alloc)
{
struct stack_record *found = NULL, **bucket;
@@ -471,8 +465,6 @@ exit:
if (found)
retval.handle = found->handle.handle;
fast_exit:
- retval.extra = extra_bits;
-
return retval.handle;
}
EXPORT_SYMBOL_GPL(__stack_depot_save);
@@ -493,7 +485,7 @@ depot_stack_handle_t stack_depot_save(unsigned long *entries,
unsigned int nr_entries,
gfp_t alloc_flags)
{
- return __stack_depot_save(entries, nr_entries, 0, alloc_flags, true);
+ return __stack_depot_save(entries, nr_entries, alloc_flags, true);
}
EXPORT_SYMBOL_GPL(stack_depot_save);
@@ -576,6 +568,38 @@ int stack_depot_snprint(depot_stack_handle_t handle, char *buf, size_t size,
}
EXPORT_SYMBOL_GPL(stack_depot_snprint);
+/**
+ * stack_depot_set_extra_bits - Set extra bits in a stack depot handle
+ *
+ * @handle: Stack depot handle returned from stack_depot_save()
+ * @extra_bits: Value to set the extra bits
+ *
+ * Return: Stack depot handle with extra bits set
+ *
+ * Stack depot handles have a few unused bits, which can be used for storing
+ * user-specific information. These bits are transparent to the stack depot.
+ */
+depot_stack_handle_t __must_check stack_depot_set_extra_bits(
+ depot_stack_handle_t handle, unsigned int extra_bits)
+{
+ union handle_parts parts = { .handle = handle };
+
+ /* Don't set extra bits on empty handles. */
+ if (!handle)
+ return 0;
+
+ parts.extra = extra_bits;
+ return parts.handle;
+}
+EXPORT_SYMBOL(stack_depot_set_extra_bits);
+
+/**
+ * stack_depot_get_extra_bits - Retrieve extra bits from a stack depot handle
+ *
+ * @handle: Stack depot handle with extra bits saved
+ *
+ * Return: Extra bits retrieved from the stack depot handle
+ */
unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle)
{
union handle_parts parts = { .handle = handle };