From: andrey.konovalov@linux.dev
To: Marco Elver <elver@google.com>,
Alexander Potapenko <glider@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>,
Dmitry Vyukov <dvyukov@google.com>,
Andrey Ryabinin <ryabinin.a.a@gmail.com>,
kasan-dev@googlegroups.com, linux-mm@kvack.org,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-arm-kernel@lists.infradead.org,
Peter Collingbourne <pcc@google.com>,
Evgenii Stepanov <eugenis@google.com>,
linux-kernel@vger.kernel.org,
Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH mm v3 27/38] kasan, page_alloc: allow skipping unpoisoning for HW_TAGS
Date: Mon, 13 Dec 2021 22:54:23 +0100 [thread overview]
Message-ID: <e9696ef1484c7057d1c048dda15819ac19dd4bea.1639432170.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1639432170.git.andreyknvl@google.com>
From: Andrey Konovalov <andreyknvl@google.com>
Add a new GFP flag __GFP_SKIP_KASAN_UNPOISON that allows skipping KASAN
poisoning for page_alloc allocations. The flag is only effective with
HW_TAGS KASAN.
This flag will be used by vmalloc code for page_alloc allocations
backing vmalloc() mappings in a following patch. The reason to skip
KASAN poisoning for these pages in page_alloc is because vmalloc code
will be poisoning them instead.
Also reword the comment for __GFP_SKIP_KASAN_POISON.
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
Changes v2->v3:
- Update patch description.
---
include/linux/gfp.h | 18 +++++++++++-------
mm/page_alloc.c | 24 +++++++++++++++++-------
2 files changed, 28 insertions(+), 14 deletions(-)
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 42b845cdc131..6781f84345d1 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -54,9 +54,10 @@ struct vm_area_struct;
#define ___GFP_THISNODE 0x200000u
#define ___GFP_ACCOUNT 0x400000u
#define ___GFP_ZEROTAGS 0x800000u
-#define ___GFP_SKIP_KASAN_POISON 0x1000000u
+#define ___GFP_SKIP_KASAN_UNPOISON 0x1000000u
+#define ___GFP_SKIP_KASAN_POISON 0x2000000u
#ifdef CONFIG_LOCKDEP
-#define ___GFP_NOLOCKDEP 0x2000000u
+#define ___GFP_NOLOCKDEP 0x4000000u
#else
#define ___GFP_NOLOCKDEP 0
#endif
@@ -231,21 +232,24 @@ struct vm_area_struct;
* %__GFP_ZEROTAGS zeroes memory tags at allocation time if the memory itself
* is being zeroed (either via __GFP_ZERO or via init_on_alloc).
*
- * %__GFP_SKIP_KASAN_POISON returns a page which does not need to be poisoned
- * on deallocation. Typically used for userspace pages. Currently only has an
- * effect in HW tags mode.
+ * %__GFP_SKIP_KASAN_UNPOISON makes KASAN skip unpoisoning on page allocation.
+ * Only effective in HW_TAGS mode.
+ *
+ * %__GFP_SKIP_KASAN_POISON makes KASAN skip poisoning on page deallocation.
+ * Typically, used for userspace pages. Only effective in HW_TAGS mode.
*/
#define __GFP_NOWARN ((__force gfp_t)___GFP_NOWARN)
#define __GFP_COMP ((__force gfp_t)___GFP_COMP)
#define __GFP_ZERO ((__force gfp_t)___GFP_ZERO)
#define __GFP_ZEROTAGS ((__force gfp_t)___GFP_ZEROTAGS)
-#define __GFP_SKIP_KASAN_POISON ((__force gfp_t)___GFP_SKIP_KASAN_POISON)
+#define __GFP_SKIP_KASAN_UNPOISON ((__force gfp_t)___GFP_SKIP_KASAN_UNPOISON)
+#define __GFP_SKIP_KASAN_POISON ((__force gfp_t)___GFP_SKIP_KASAN_POISON)
/* Disable lockdep for GFP context tracking */
#define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP)
/* Room for N __GFP_FOO bits */
-#define __GFP_BITS_SHIFT (25 + IS_ENABLED(CONFIG_LOCKDEP))
+#define __GFP_BITS_SHIFT (26 + IS_ENABLED(CONFIG_LOCKDEP))
#define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
/**
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 497db24ed169..f1d5b80591c4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2394,6 +2394,21 @@ static bool check_new_pages(struct page *page, unsigned int order)
return false;
}
+static inline bool should_skip_kasan_unpoison(gfp_t flags, bool init_tags)
+{
+ /* Don't skip if a software KASAN mode is enabled. */
+ if (!IS_ENABLED(CONFIG_KASAN_HW_TAGS))
+ return false;
+
+ /*
+ * For hardware tag-based KASAN, skip if either:
+ *
+ * 1. Memory tags have already been cleared via tag_clear_highpage().
+ * 2. Skipping has been requested via __GFP_SKIP_KASAN_UNPOISON.
+ */
+ return init_tags || (flags & __GFP_SKIP_KASAN_UNPOISON);
+}
+
inline void post_alloc_hook(struct page *page, unsigned int order,
gfp_t gfp_flags)
{
@@ -2433,13 +2448,8 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
/* Note that memory is already initialized by the loop above. */
init = false;
}
- /*
- * If either a software KASAN mode is enabled, or,
- * in the case of hardware tag-based KASAN,
- * if memory tags have not been cleared via tag_clear_highpage().
- */
- if (!IS_ENABLED(CONFIG_KASAN_HW_TAGS) || !init_tags) {
- /* Mark shadow memory or set memory tags. */
+ if (!should_skip_kasan_unpoison(gfp_flags, init_tags)) {
+ /* Unpoison shadow memory or set memory tags. */
kasan_unpoison_pages(page, order, init);
/* Note that memory is already initialized by KASAN. */
--
2.25.1
next prev parent reply other threads:[~2021-12-13 21:54 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-13 21:51 [PATCH mm v3 00/38] kasan, vmalloc, arm64: add vmalloc tagging support for SW/HW_TAGS andrey.konovalov
2021-12-13 21:51 ` [PATCH mm v3 01/38] kasan, page_alloc: deduplicate should_skip_kasan_poison andrey.konovalov
2021-12-13 21:51 ` [PATCH mm v3 02/38] kasan, page_alloc: move tag_clear_highpage out of kernel_init_free_pages andrey.konovalov
2021-12-13 21:51 ` [PATCH mm v3 03/38] kasan, page_alloc: merge kasan_free_pages into free_pages_prepare andrey.konovalov
2021-12-13 21:51 ` [PATCH mm v3 04/38] kasan, page_alloc: simplify kasan_poison_pages call site andrey.konovalov
2021-12-16 12:54 ` Alexander Potapenko
2021-12-13 21:51 ` [PATCH mm v3 05/38] kasan, page_alloc: init memory of skipped pages on free andrey.konovalov
2021-12-13 21:51 ` [PATCH mm v3 06/38] kasan: drop skip_kasan_poison variable in free_pages_prepare andrey.konovalov
2021-12-13 21:51 ` [PATCH mm v3 07/38] mm: clarify __GFP_ZEROTAGS comment andrey.konovalov
2021-12-13 21:51 ` [PATCH mm v3 08/38] kasan: only apply __GFP_ZEROTAGS when memory is zeroed andrey.konovalov
2021-12-13 21:51 ` [PATCH mm v3 09/38] kasan, page_alloc: refactor init checks in post_alloc_hook andrey.konovalov
2021-12-16 13:32 ` Alexander Potapenko
2021-12-13 21:51 ` [PATCH mm v3 10/38] kasan, page_alloc: merge kasan_alloc_pages into post_alloc_hook andrey.konovalov
2021-12-13 21:53 ` [PATCH mm v3 11/38] kasan, page_alloc: combine tag_clear_highpage calls in post_alloc_hook andrey.konovalov
2021-12-16 13:04 ` Alexander Potapenko
2021-12-13 21:53 ` [PATCH mm v3 12/38] kasan, page_alloc: move SetPageSkipKASanPoison " andrey.konovalov
2021-12-13 21:53 ` [PATCH mm v3 13/38] kasan, page_alloc: move kernel_init_free_pages " andrey.konovalov
2021-12-16 11:00 ` Alexander Potapenko
2021-12-13 21:53 ` [PATCH mm v3 14/38] kasan, page_alloc: simplify kasan_unpoison_pages call site andrey.konovalov
2021-12-13 21:53 ` [PATCH mm v3 15/38] kasan: clean up metadata byte definitions andrey.konovalov
2021-12-16 10:52 ` Alexander Potapenko
2021-12-13 21:53 ` [PATCH mm v3 16/38] kasan: define KASAN_VMALLOC_INVALID for SW_TAGS andrey.konovalov
2021-12-13 21:53 ` [PATCH mm v3 17/38] kasan, x86, arm64, s390: rename functions for modules shadow andrey.konovalov
2021-12-13 21:53 ` [PATCH mm v3 18/38] kasan, vmalloc: drop outdated VM_KASAN comment andrey.konovalov
2021-12-16 10:53 ` Alexander Potapenko
2021-12-13 21:53 ` [PATCH mm v3 19/38] kasan: reorder vmalloc hooks andrey.konovalov
2021-12-16 10:55 ` Alexander Potapenko
2021-12-13 21:53 ` [PATCH mm v3 20/38] kasan: add wrappers for " andrey.konovalov
2021-12-13 21:53 ` [PATCH mm v3 21/38] kasan, vmalloc: reset tags in vmalloc functions andrey.konovalov
2021-12-13 21:54 ` [PATCH mm v3 22/38] kasan, fork: reset pointer tags of vmapped stacks andrey.konovalov
2021-12-13 21:54 ` [PATCH mm v3 23/38] kasan, arm64: " andrey.konovalov
2021-12-13 21:59 ` Andrey Konovalov
2021-12-14 13:25 ` Catalin Marinas
2021-12-13 21:54 ` [PATCH mm v3 24/38] kasan, vmalloc: add vmalloc tagging for SW_TAGS andrey.konovalov
2021-12-13 21:54 ` [PATCH mm v3 25/38] kasan, vmalloc, arm64: mark vmalloc mappings as pgprot_tagged andrey.konovalov
2021-12-14 17:11 ` Catalin Marinas
2021-12-14 18:27 ` Andrey Konovalov
2021-12-14 19:27 ` Catalin Marinas
2021-12-20 21:38 ` Andrey Konovalov
2021-12-13 21:54 ` [PATCH mm v3 26/38] kasan, vmalloc: don't unpoison VM_ALLOC pages before mapping andrey.konovalov
2021-12-16 19:07 ` Alexander Potapenko
2021-12-20 21:35 ` Andrey Konovalov
2021-12-13 21:54 ` andrey.konovalov [this message]
2021-12-13 21:54 ` [PATCH mm v3 28/38] kasan, page_alloc: allow skipping memory init for HW_TAGS andrey.konovalov
2021-12-14 18:00 ` Marco Elver
2021-12-14 18:28 ` Andrey Konovalov
2021-12-17 1:50 ` Kuan-Ying Lee
2021-12-20 21:35 ` Andrey Konovalov
2021-12-13 21:54 ` [PATCH mm v3 29/38] kasan, vmalloc: add vmalloc tagging " andrey.konovalov
2021-12-14 19:55 ` Marco Elver
2021-12-14 22:08 ` Andrey Konovalov
2021-12-14 21:03 ` Marco Elver
2021-12-13 21:54 ` [PATCH mm v3 30/38] kasan, vmalloc: don't tag executable vmalloc allocations andrey.konovalov
2021-12-14 19:42 ` Andrey Konovalov
2021-12-13 21:54 ` [PATCH mm v3 31/38] kasan, arm64: " andrey.konovalov
2021-12-13 21:59 ` Andrey Konovalov
2021-12-17 13:45 ` Catalin Marinas
2021-12-13 21:54 ` [PATCH mm v3 32/38] kasan: mark kasan_arg_stacktrace as __initdata andrey.konovalov
2021-12-13 21:55 ` [PATCH mm v3 33/38] kasan: simplify kasan_init_hw_tags andrey.konovalov
2021-12-13 21:55 ` [PATCH mm v3 34/38] kasan: add kasan.vmalloc command line flag andrey.konovalov
2021-12-13 21:55 ` [PATCH mm v3 35/38] kasan: allow enabling KASAN_VMALLOC and SW/HW_TAGS andrey.konovalov
2021-12-13 21:55 ` [PATCH mm v3 36/38] arm64: select KASAN_VMALLOC for SW/HW_TAGS modes andrey.konovalov
2021-12-13 21:55 ` [PATCH mm v3 37/38] kasan: documentation updates andrey.konovalov
2021-12-13 21:55 ` [PATCH mm v3 38/38] kasan: improve vmalloc tests andrey.konovalov
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