A-Team_Digital_Solutions/android_kernel_motorola_sm6375
Watch
2
0
Fork
You've already forked android_kernel_motorola_sm6375
 0
mirror of https://github.com/BobTheBlinker/android_kernel_motorola_sm6375.git synced 2026-10-28 02:32:09 -04:00
Code Issues Projects Releases Packages Wiki Activity

FROMGIT: kfence: add option to use KFENCE without static keys

Browse source 
For certain usecases, specifically where the sample interval is always
set to a very low value such as 1ms, it can make sense to use a dynamic
branch instead of static branches due to the overhead of toggling a
static branch.

Therefore, add a new Kconfig option to remove the static branches and
instead check kfence_allocation_gate if a KFENCE allocation should be
set up.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Marco Elver <[email protected]>
Suggested-by: Jörn Engel <[email protected]>
Reviewed-by: Jörn Engel <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Jann Horn <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Bug: 177201466
(cherry picked from commit c01761611b325c1e4ec7d3e236cc9db003cb82fd
    https://github.com/hnaz/linux-mm v5.11-rc4-mmots-2021-01-21-20-10)
Test: CONFIG_KFENCE_KUNIT_TEST=y passes on Cuttlefish
Signed-off-by: Alexander Potapenko <[email protected]>
Change-Id: I68a112a8ff68fa24742b198e036f130a9757c27f
This commit is contained in:
Marco Elver 2021-01-22 09:18:33 +00:00 • committed by Michael Bestas
commit 9339667c95
No known key found for this signature in database
GPG key ID: CC95044519BE6669
3 changed files with 39 additions and 16 deletions
Download patch file Download diff file Expand all files Collapse all files

30
mm/kfence/core.c
View file

@ -95,11 +95,13 @@ struct kfence_metadata kfence_metadata[CONFIG_KFENCE_NUM_OBJECTS];
static struct list_head kfence_freelist = LIST_HEAD_INIT(kfence_freelist);
static DEFINE_RAW_SPINLOCK(kfence_freelist_lock); /* Lock protecting freelist. */
#ifdef CONFIG_KFENCE_STATIC_KEYS
/* The static key to set up a KFENCE allocation. */
DEFINE_STATIC_KEY_FALSE(kfence_allocation_key);
#endif
/* Gates the allocation, ensuring only one succeeds in a given period. */
static atomic_t allocation_gate = ATOMIC_INIT(1);
atomic_t kfence_allocation_gate = ATOMIC_INIT(1);
/* Statistics counters for debugfs. */
enum kfence_counter_id {
@ -579,29 +581,31 @@ late_initcall(kfence_debugfs_init);
static struct delayed_work kfence_timer;
static void toggle_allocation_gate(struct work_struct *work)
{
unsigned long end_wait;
if (!READ_ONCE(kfence_enabled))
return;
/* Enable static key, and await allocation to happen. */
atomic_set(&allocation_gate, 0);
atomic_set(&kfence_allocation_gate, 0);
#ifdef CONFIG_KFENCE_STATIC_KEYS
static_branch_enable(&kfence_allocation_key);
/*
* Await an allocation. Timeout after 1 second, in case the kernel stops
* doing allocations, to avoid stalling this worker task for too long.
*/
end_wait = jiffies + HZ;
do {
set_current_state(TASK_UNINTERRUPTIBLE);
if (atomic_read(&allocation_gate) != 0)
break;
schedule_timeout(1);
} while (time_before(jiffies, end_wait));
__set_current_state(TASK_RUNNING);
{
unsigned long end_wait = jiffies + HZ;
do {
set_current_state(TASK_UNINTERRUPTIBLE);
if (atomic_read(&kfence_allocation_gate) != 0)
break;
schedule_timeout(1);
} while (time_before(jiffies, end_wait));
__set_current_state(TASK_RUNNING);
}
/* Disable static key and reset timer. */
static_branch_disable(&kfence_allocation_key);
#endif
schedule_delayed_work(&kfence_timer, msecs_to_jiffies(kfence_sample_interval));
}
static DECLARE_DELAYED_WORK(kfence_timer, toggle_allocation_gate);
@ -707,7 +711,7 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags)
* sense to continue writing to it and pay the associated contention
* cost, in case we have a large number of concurrent allocations.
*/
if (atomic_read(&allocation_gate) || atomic_inc_return(&allocation_gate) > 1)
if (atomic_read(&kfence_allocation_gate) || atomic_inc_return(&kfence_allocation_gate) > 1)
return NULL;
if (!READ_ONCE(kfence_enabled))