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authorTianchen Ding <dtcccc@linux.alibaba.com>2022-03-23 00:48:10 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-23 01:57:11 +0300
commit698361bca2d59fd29d46c757163854454df477f1 (patch)
treec1e26247a7a199ae6730c8edd22bd72931e23ab4 /mm
parent56eb8e9416e85ca7db4550b58e93ac88d7993c13 (diff)
downloadlinux-698361bca2d59fd29d46c757163854454df477f1.tar.xz
kfence: allow re-enabling KFENCE after system startup
Patch series "provide the flexibility to enable KFENCE", v3. If CONFIG_CONTIG_ALLOC is not supported, we fallback to try alloc_pages_exact(). Allocating pages in this way has limits about MAX_ORDER (default 11). So we will not support allocating kfence pool after system startup with a large KFENCE_NUM_OBJECTS. When handling failures in kfence_init_pool_late(), we pair free_pages_exact() to alloc_pages_exact() for compatibility consideration, though it actually does the same as free_contig_range(). This patch (of 2): If once KFENCE is disabled by: echo 0 > /sys/module/kfence/parameters/sample_interval KFENCE could never be re-enabled until next rebooting. Allow re-enabling it by writing a positive num to sample_interval. Link: https://lkml.kernel.org/r/20220307074516.6920-1-dtcccc@linux.alibaba.com Link: https://lkml.kernel.org/r/20220307074516.6920-2-dtcccc@linux.alibaba.com Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/kfence/core.c21
1 files changed, 18 insertions, 3 deletions
diff --git a/mm/kfence/core.c b/mm/kfence/core.c
index 13128fa13062..caa4e84c8b79 100644
--- a/mm/kfence/core.c
+++ b/mm/kfence/core.c
@@ -38,14 +38,17 @@
#define KFENCE_WARN_ON(cond) \
({ \
const bool __cond = WARN_ON(cond); \
- if (unlikely(__cond)) \
+ if (unlikely(__cond)) { \
WRITE_ONCE(kfence_enabled, false); \
+ disabled_by_warn = true; \
+ } \
__cond; \
})
/* === Data ================================================================= */
static bool kfence_enabled __read_mostly;
+static bool disabled_by_warn __read_mostly;
unsigned long kfence_sample_interval __read_mostly = CONFIG_KFENCE_SAMPLE_INTERVAL;
EXPORT_SYMBOL_GPL(kfence_sample_interval); /* Export for test modules. */
@@ -55,6 +58,7 @@ EXPORT_SYMBOL_GPL(kfence_sample_interval); /* Export for test modules. */
#endif
#define MODULE_PARAM_PREFIX "kfence."
+static int kfence_enable_late(void);
static int param_set_sample_interval(const char *val, const struct kernel_param *kp)
{
unsigned long num;
@@ -65,10 +69,11 @@ static int param_set_sample_interval(const char *val, const struct kernel_param
if (!num) /* Using 0 to indicate KFENCE is disabled. */
WRITE_ONCE(kfence_enabled, false);
- else if (!READ_ONCE(kfence_enabled) && system_state != SYSTEM_BOOTING)
- return -EINVAL; /* Cannot (re-)enable KFENCE on-the-fly. */
*((unsigned long *)kp->arg) = num;
+
+ if (num && !READ_ONCE(kfence_enabled) && system_state != SYSTEM_BOOTING)
+ return disabled_by_warn ? -EINVAL : kfence_enable_late();
return 0;
}
@@ -787,6 +792,16 @@ void __init kfence_init(void)
(void *)(__kfence_pool + KFENCE_POOL_SIZE));
}
+static int kfence_enable_late(void)
+{
+ if (!__kfence_pool)
+ return -EINVAL;
+
+ WRITE_ONCE(kfence_enabled, true);
+ queue_delayed_work(system_unbound_wq, &kfence_timer, 0);
+ return 0;
+}
+
void kfence_shutdown_cache(struct kmem_cache *s)
{
unsigned long flags;