The patch titled
Subject: kasan, mm: allow cache merging with no metadata
has been added to the -mm tree. Its filename is
kasan-mm-allow-cache-merging-with-no-metadata.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/kasan-mm-allow-cache-merging-with-no-metadata.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/kasan-mm-allow-cache-merging-with-no-metadata.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Subject: kasan, mm: allow cache merging with no metadata
The reason cache merging is disabled with KASAN is because KASAN puts its
metadata right after the allocated object. When the merged caches have
slightly different sizes, the metadata ends up in different places, which
KASAN doesn't support.
It might be possible to adjust the metadata allocation algorithm and make
it friendly to the cache merging code. Instead this change takes a simpler
approach and allows merging caches when no metadata is present. Which is
the case for hardware tag-based KASAN with kasan.mode=prod.
Link: https://lkml.kernel.org/r/37497e940bfd4b32c0a93a702a9ae4cf061d5392.1606162397.git.andreyknvl@xxxxxxxxxx
Link: https://linux-review.googlesource.com/id/Ia114847dfb2244f297d2cb82d592bf6a07455dba
Co-developed-by: Vincenzo Frascino <Vincenzo.Frascino@xxxxxxx>
Signed-off-by: Vincenzo Frascino <Vincenzo.Frascino@xxxxxxx>
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Reviewed-by: Marco Elver <elver@xxxxxxxxxx>
Tested-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Branislav Rankov <Branislav.Rankov@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Evgenii Stepanov <eugenis@xxxxxxxxxx>
Cc: Kevin Brodsky <kevin.brodsky@xxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kasan.h | 21 +++++++++++++++++++--
mm/kasan/common.c | 11 +++++++++++
mm/slab_common.c | 3 ++-
3 files changed, 32 insertions(+), 3 deletions(-)
--- a/include/linux/kasan.h~kasan-mm-allow-cache-merging-with-no-metadata
+++ a/include/linux/kasan.h
@@ -81,17 +81,30 @@ struct kasan_cache {
};
#ifdef CONFIG_KASAN_HW_TAGS
+
DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
+
static __always_inline bool kasan_enabled(void)
{
return static_branch_likely(&kasan_flag_enabled);
}
-#else
+
+#else /* CONFIG_KASAN_HW_TAGS */
+
static inline bool kasan_enabled(void)
{
return true;
}
-#endif
+
+#endif /* CONFIG_KASAN_HW_TAGS */
+
+slab_flags_t __kasan_never_merge(void);
+static __always_inline slab_flags_t kasan_never_merge(void)
+{
+ if (kasan_enabled())
+ return __kasan_never_merge();
+ return 0;
+}
void __kasan_unpoison_range(const void *addr, size_t size);
static __always_inline void kasan_unpoison_range(const void *addr, size_t size)
@@ -238,6 +251,10 @@ static inline bool kasan_enabled(void)
{
return false;
}
+static inline slab_flags_t kasan_never_merge(void)
+{
+ return 0;
+}
static inline void kasan_unpoison_range(const void *address, size_t size) {}
static inline void kasan_alloc_pages(struct page *page, unsigned int order) {}
static inline void kasan_free_pages(struct page *page, unsigned int order) {}
--- a/mm/kasan/common.c~kasan-mm-allow-cache-merging-with-no-metadata
+++ a/mm/kasan/common.c
@@ -87,6 +87,17 @@ asmlinkage void kasan_unpoison_task_stac
}
#endif /* CONFIG_KASAN_STACK */
+/*
+ * Only allow cache merging when stack collection is disabled and no metadata
+ * is present.
+ */
+slab_flags_t __kasan_never_merge(void)
+{
+ if (kasan_stack_collection_enabled())
+ return SLAB_KASAN;
+ return 0;
+}
+
void __kasan_alloc_pages(struct page *page, unsigned int order)
{
u8 tag;
--- a/mm/slab_common.c~kasan-mm-allow-cache-merging-with-no-metadata
+++ a/mm/slab_common.c
@@ -19,6 +19,7 @@
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <linux/debugfs.h>
+#include <linux/kasan.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/page.h>
@@ -54,7 +55,7 @@ static DECLARE_WORK(slab_caches_to_rcu_d
*/
#define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
- SLAB_FAILSLAB | SLAB_KASAN)
+ SLAB_FAILSLAB | kasan_never_merge())
#define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
SLAB_CACHE_DMA32 | SLAB_ACCOUNT)
_
Patches currently in -mm which might be from andreyknvl@xxxxxxxxxx are
kasan-drop-unnecessary-gpl-text-from-comment-headers.patch
kasan-kasan_vmalloc-depends-on-kasan_generic.patch
kasan-group-vmalloc-code.patch
kasan-shadow-declarations-only-for-software-modes.patch
kasan-rename-unpoison_shadow-to-unpoison_range.patch
kasan-rename-kasan_shadow_-to-kasan_granule_.patch
kasan-only-build-initc-for-software-modes.patch
kasan-split-out-shadowc-from-commonc.patch
kasan-define-kasan_memory_per_shadow_page.patch
kasan-rename-report-and-tags-files.patch
kasan-dont-duplicate-config-dependencies.patch
kasan-hide-invalid-free-check-implementation.patch
kasan-decode-stack-frame-only-with-kasan_stack_enable.patch
kasan-arm64-only-init-shadow-for-software-modes.patch
kasan-arm64-only-use-kasan_depth-for-software-modes.patch
kasan-arm64-move-initialization-message.patch
kasan-arm64-rename-kasan_init_tags-and-mark-as-__init.patch
kasan-rename-addr_has_shadow-to-addr_has_metadata.patch
kasan-rename-print_shadow_for_address-to-print_memory_metadata.patch
kasan-rename-shadow-layout-macros-to-meta.patch
kasan-separate-metadata_fetch_row-for-each-mode.patch
kasan-arm64-dont-allow-sw_tags-with-arm64_mte.patch
kasan-introduce-config_kasan_hw_tags.patch
arm64-kasan-align-allocations-for-hw_tags.patch
arm64-kasan-add-arch-layer-for-memory-tagging-helpers.patch
kasan-define-kasan_granule_size-for-hw_tags.patch
kasan-x86-s390-update-undef-config_kasan.patch
kasan-arm64-expand-config_kasan-checks.patch
kasan-arm64-implement-hw_tags-runtime.patch
kasan-arm64-print-report-from-tag-fault-handler.patch
kasan-mm-reset-tags-when-accessing-metadata.patch
kasan-arm64-enable-config_kasan_hw_tags.patch
kasan-add-documentation-for-hardware-tag-based-mode.patch
kasan-simplify-quarantine_put-call-site.patch
kasan-rename-get_alloc-free_info.patch
kasan-introduce-set_alloc_info.patch
kasan-arm64-unpoison-stack-only-with-config_kasan_stack.patch
kasan-allow-vmap_stack-for-hw_tags-mode.patch
kasan-remove-__kasan_unpoison_stack.patch
kasan-inline-kasan_reset_tag-for-tag-based-modes.patch
kasan-inline-random_tag-for-hw_tags.patch
kasan-open-code-kasan_unpoison_slab.patch
kasan-inline-unpoison_range-and-check_invalid_free.patch
kasan-add-and-integrate-kasan-boot-parameters.patch
kasan-mm-check-kasan_enabled-in-annotations.patch
kasan-mm-rename-kasan_poison_kfree.patch
kasan-dont-round_up-too-much.patch
kasan-simplify-assign_tag-and-set_tag-calls.patch
kasan-clarify-comment-in-__kasan_kfree_large.patch
kasan-sanitize-objects-when-metadata-doesnt-fit.patch
kasan-mm-allow-cache-merging-with-no-metadata.patch
kasan-update-documentation.patch
