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lib/stackdepot: add depot_fetch_stack helper

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Add a helper depot_fetch_stack function that fetches the pointer to a
stack record.

With this change, all static depot_* functions now operate on stack pools
and the exported stack_depot_* functions operate on the hash table.

Link: https://lkml.kernel.org/r/170d8c202f29dc8e3d5491ee074d1e9e029a46db.1700502145.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Andrey Konovalov 2023-11-20 18:47:03 +01:00 committed by Andrew Morton
parent 5f9ce55e02
commit 83130ab2d8
1 changed files with 28 additions and 17 deletions
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45
lib/stackdepot.c
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@ -310,6 +310,7 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc)
stack->handle.extra = 0;
memcpy(stack->entries, entries, flex_array_size(stack, entries, size));
pool_offset += required_size;
/*
* Let KMSAN know the stored stack record is initialized. This shall
* prevent false positive reports if instrumented code accesses it.
@ -319,6 +320,32 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc)
return stack;
}
static struct stack_record *depot_fetch_stack(depot_stack_handle_t handle)
{
union handle_parts parts = { .handle = handle };
/*
* READ_ONCE pairs with potential concurrent write in
* depot_alloc_stack().
*/
int pool_index_cached = READ_ONCE(pool_index);
void *pool;
size_t offset = parts.offset << DEPOT_STACK_ALIGN;
struct stack_record *stack;
if (parts.pool_index > pool_index_cached) {
WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n",
parts.pool_index, pool_index_cached, handle);
return NULL;
}
pool = stack_pools[parts.pool_index];
if (!pool)
return NULL;
stack = pool + offset;
return stack;
}
/* Calculates the hash for a stack. */
static inline u32 hash_stack(unsigned long *entries, unsigned int size)
{
@ -462,14 +489,6 @@ EXPORT_SYMBOL_GPL(stack_depot_save);
unsigned int stack_depot_fetch(depot_stack_handle_t handle,
unsigned long **entries)
{
union handle_parts parts = { .handle = handle };
/*
* READ_ONCE pairs with potential concurrent write in
* depot_alloc_stack.
*/
int pool_index_cached = READ_ONCE(pool_index);
void *pool;
size_t offset = parts.offset << DEPOT_STACK_ALIGN;
struct stack_record *stack;
*entries = NULL;
@ -482,15 +501,7 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
if (!handle || stack_depot_disabled)
return 0;
if (parts.pool_index > pool_index_cached) {
WARN(1, "pool index %d out of bounds (%d) for stack id %08x\n",
parts.pool_index, pool_index_cached, handle);
return 0;
}
pool = stack_pools[parts.pool_index];
if (!pool)
return 0;
stack = pool + offset;
stack = depot_fetch_stack(handle);
*entries = stack->entries;
return stack->size;