[PATCH RFC 07/10] kfence, kmemleak: make KFENCE compatible with KMEMLEAK

[Marco Elver]

From: Alexander Potapenko <glider@xxxxxxxxxx>

Add compatibility with KMEMLEAK, by making KMEMLEAK aware of the KFENCE
memory pool. This allows building debug kernels with both enabled, which
also helped in debugging KFENCE.

Co-developed-by: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
---
 mm/kmemleak.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 5e252d91eb14..2809c25c0a88 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -97,6 +97,7 @@
 #include <linux/atomic.h>
 
 #include <linux/kasan.h>
+#include <linux/kfence.h>
 #include <linux/kmemleak.h>
 #include <linux/memory_hotplug.h>
 
@@ -1946,8 +1947,18 @@ void __init kmemleak_init(void)
 	/* register the data/bss sections */
 	create_object((unsigned long)_sdata, _edata - _sdata,
 		      KMEMLEAK_GREY, GFP_ATOMIC);
+#if defined(CONFIG_KFENCE) && defined(CONFIG_HAVE_ARCH_KFENCE_STATIC_POOL)
+	/* KFENCE objects are located in .bss, which may confuse kmemleak. Skip them. */
+	create_object((unsigned long)__bss_start, __kfence_pool - __bss_start,
+		      KMEMLEAK_GREY, GFP_ATOMIC);
+	create_object((unsigned long)__kfence_pool + KFENCE_POOL_SIZE,
+		      __bss_stop - (__kfence_pool + KFENCE_POOL_SIZE),
+		      KMEMLEAK_GREY, GFP_ATOMIC);
+#else
 	create_object((unsigned long)__bss_start, __bss_stop - __bss_start,
 		      KMEMLEAK_GREY, GFP_ATOMIC);
+#endif
+
 	/* only register .data..ro_after_init if not within .data */
 	if (&__start_ro_after_init < &_sdata || &__end_ro_after_init > &_edata)
 		create_object((unsigned long)__start_ro_after_init,
-- 
2.28.0.526.ge36021eeef-goog