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From: glider@google.com
To: Vegard Nossum <vegard.nossum@oracle.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	linux-mm@kvack.org
Cc: viro@zeniv.linux.org.uk, akpm@linux-foundation.org,
	 aryabinin@virtuozzo.com, luto@kernel.org,
	ard.biesheuvel@linaro.org,  arnd@arndb.de, hch@lst.de,
	dmitry.torokhov@gmail.com, edumazet@google.com,
	 ericvh@gmail.com, gregkh@linuxfoundation.org,
	harry.wentland@amd.com,  herbert@gondor.apana.org.au,
	mingo@elte.hu, axboe@kernel.dk,  martin.petersen@oracle.com,
	schwidefsky@de.ibm.com, mst@redhat.com,  monstr@monstr.eu,
	pmladek@suse.com, sergey.senozhatsky@gmail.com,
	 rostedt@goodmis.org, tiwai@suse.com, tytso@mit.edu,
	tglx@linutronix.de,  wsa@the-dreams.de, gor@linux.ibm.com,
	iii@linux.ibm.com, mark.rutland@arm.com,  willy@infradead.org,
	rdunlap@infradead.org, andreyknvl@google.com,  elver@google.com,
	Alexander Potapenko <glider@google.com>
Subject: [PATCH RFC v2 04/25] stackdepot: reserve 5 extra bits in depot_stack_handle_t
Date: Wed, 30 Oct 2019 15:22:16 +0100	[thread overview]
Message-ID: <20191030142237.249532-5-glider@google.com> (raw)
In-Reply-To: <20191030142237.249532-1-glider@google.com>

Some users (currently only KMSAN) may want to use spare bits in
depot_stack_handle_t. Let them do so and provide get_dsh_extra_bits()
and set_dsh_extra_bits() to access those bits.

Signed-off-by: Alexander Potapenko <glider@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: linux-mm@kvack.org
---

Change-Id: I23580dbde85908eeda0bdd8f83a8c3882ab3e012
---
 include/linux/stackdepot.h |  8 ++++++++
 lib/stackdepot.c           | 24 +++++++++++++++++++++++-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/include/linux/stackdepot.h b/include/linux/stackdepot.h
index 24d49c732341..ac1b5a78d7f6 100644
--- a/include/linux/stackdepot.h
+++ b/include/linux/stackdepot.h
@@ -12,6 +12,11 @@
 #define _LINUX_STACKDEPOT_H
 
 typedef u32 depot_stack_handle_t;
+/*
+ * Number of bits in the handle that stack depot doesn't use. Users may store
+ * information in them.
+ */
+#define STACK_DEPOT_EXTRA_BITS 5
 
 depot_stack_handle_t stack_depot_save(unsigned long *entries,
 				      unsigned int nr_entries, gfp_t gfp_flags);
@@ -20,5 +25,8 @@ unsigned int stack_depot_fetch(depot_stack_handle_t handle,
 			       unsigned long **entries);
 
 unsigned int filter_irq_stacks(unsigned long *entries, unsigned int nr_entries);
+depot_stack_handle_t set_dsh_extra_bits(depot_stack_handle_t handle,
+					unsigned int bits);
+unsigned int get_dsh_extra_bits(depot_stack_handle_t handle);
 
 #endif
diff --git a/lib/stackdepot.c b/lib/stackdepot.c
index decb1e073b58..460efd3ef742 100644
--- a/lib/stackdepot.c
+++ b/lib/stackdepot.c
@@ -40,8 +40,10 @@
 #define STACK_ALLOC_ALIGN 4
 #define STACK_ALLOC_OFFSET_BITS (STACK_ALLOC_ORDER + PAGE_SHIFT - \
 					STACK_ALLOC_ALIGN)
+
 #define STACK_ALLOC_INDEX_BITS (DEPOT_STACK_BITS - \
-		STACK_ALLOC_NULL_PROTECTION_BITS - STACK_ALLOC_OFFSET_BITS)
+		STACK_ALLOC_NULL_PROTECTION_BITS - \
+		STACK_ALLOC_OFFSET_BITS - STACK_DEPOT_EXTRA_BITS)
 #define STACK_ALLOC_SLABS_CAP 8192
 #define STACK_ALLOC_MAX_SLABS \
 	(((1LL << (STACK_ALLOC_INDEX_BITS)) < STACK_ALLOC_SLABS_CAP) ? \
@@ -54,6 +56,7 @@ union handle_parts {
 		u32 slabindex : STACK_ALLOC_INDEX_BITS;
 		u32 offset : STACK_ALLOC_OFFSET_BITS;
 		u32 valid : STACK_ALLOC_NULL_PROTECTION_BITS;
+		u32 extra : STACK_DEPOT_EXTRA_BITS;
 	};
 };
 
@@ -72,6 +75,24 @@ static int next_slab_inited;
 static size_t depot_offset;
 static DEFINE_SPINLOCK(depot_lock);
 
+depot_stack_handle_t set_dsh_extra_bits(depot_stack_handle_t handle,
+					u32 bits)
+{
+	union handle_parts parts = { .handle = handle };
+
+	parts.extra = bits & ((1U << STACK_DEPOT_EXTRA_BITS) - 1);
+	return parts.handle;
+}
+EXPORT_SYMBOL_GPL(set_dsh_extra_bits);
+
+u32 get_dsh_extra_bits(depot_stack_handle_t handle)
+{
+	union handle_parts parts = { .handle = handle };
+
+	return parts.extra;
+}
+EXPORT_SYMBOL_GPL(get_dsh_extra_bits);
+
 static bool init_stack_slab(void **prealloc)
 {
 	if (!*prealloc)
@@ -132,6 +153,7 @@ static struct stack_record *depot_alloc_stack(unsigned long *entries, int size,
 	stack->handle.slabindex = depot_index;
 	stack->handle.offset = depot_offset >> STACK_ALLOC_ALIGN;
 	stack->handle.valid = 1;
+	stack->handle.extra = 0;
 	memcpy(stack->entries, entries, size * sizeof(unsigned long));
 	depot_offset += required_size;
 
-- 
2.24.0.rc0.303.g954a862665-goog



  parent reply	other threads:[~2019-10-30 14:22 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-30 14:22 [PATCH RFC v2 00/25] Add KernelMemorySanitizer infrastructure glider
2019-10-30 14:22 ` [PATCH RFC v2 01/25] stackdepot: check depot_index before accessing the stack slab glider
2019-10-30 14:22 ` [PATCH RFC v2 02/25] stackdepot: prevent Clang from optimizing away stackdepot_memcmp() glider
2019-11-01  5:50   ` Sergey Senozhatsky
2019-11-06 11:43     ` Alexander Potapenko
2019-11-07  6:08       ` Sergey Senozhatsky
2019-11-07  9:04         ` Arnd Bergmann
2019-11-07  9:22           ` Alexander Potapenko
2019-11-07  9:28             ` Arnd Bergmann
2019-11-07  9:43               ` Alexander Potapenko
     [not found]             ` <47fdac13-fa2c-2acd-2480-5e6d4db208f8@virtuozzo.com>
2019-11-07 10:00               ` Arnd Bergmann
     [not found]                 ` <6875c6e6-2f1f-f8e6-e5d7-d451c48397ff@virtuozzo.com>
2019-11-07 10:30                   ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 03/25] kasan: stackdepot: move filter_irq_stacks() to stackdepot.c glider
2019-10-30 14:22 ` glider [this message]
2019-10-30 14:22 ` [PATCH RFC v2 05/25] kmsan: add ReST documentation glider
2019-10-30 14:22 ` [PATCH RFC v2 06/25] kmsan: gfp: introduce __GFP_NO_KMSAN_SHADOW glider
2019-10-30 14:22 ` [PATCH RFC v2 07/25] kmsan: introduce __no_sanitize_memory and __SANITIZE_MEMORY__ glider
2019-10-30 15:50   ` Andrey Konovalov
2019-11-01 12:52     ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 08/25] kmsan: reduce vmalloc space glider
2019-10-30 14:22 ` [PATCH RFC v2 09/25] kmsan: add KMSAN runtime glider
2019-11-08 12:08   ` Dmitry Vyukov
2019-11-08 12:17     ` Dmitry Vyukov
2019-11-21 12:06       ` Alexander Potapenko
2019-11-13  8:13   ` Wolfram Sang
2019-11-21 12:01     ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 10/25] kmsan: define READ_ONCE_NOCHECK() glider
2019-11-05 14:21   ` Mark Rutland
2019-11-21 12:08     ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 11/25] kmsan: x86: sync metadata pages on page fault glider
2019-10-30 14:22 ` [PATCH RFC v2 12/25] kmsan: add tests for KMSAN glider
2019-10-30 14:22 ` [PATCH RFC v2 13/25] kmsan: make READ_ONCE_TASK_STACK() return initialized values glider
2019-10-30 14:22 ` [PATCH RFC v2 14/25] kmsan: Kconfig changes to disable options incompatible with KMSAN glider
2019-10-30 14:34   ` Qian Cai
2019-10-30 14:34   ` Christoph Hellwig
2019-10-30 14:22 ` [PATCH RFC v2 15/25] kmsan: Changing existing files to enable KMSAN builds glider
2019-10-30 14:36   ` Christoph Hellwig
2019-10-30 14:22 ` [PATCH RFC v2 16/25] kmsan: disable KMSAN instrumentation for certain kernel parts glider
2019-10-30 14:22 ` [PATCH RFC v2 17/25] kmsan: mm: call KMSAN hooks from SLUB code glider
2019-10-30 16:07   ` Andrey Konovalov
2019-10-30 14:22 ` [PATCH RFC v2 18/25] kmsan: call KMSAN hooks where needed glider
2019-10-31 11:49   ` Petr Mladek
2019-11-01  8:26     ` Sergey Senozhatsky
2019-11-05 14:12       ` Alexander Potapenko
2019-11-06  9:04         ` Petr Mladek
2019-11-06  9:07         ` Sergey Senozhatsky
2019-10-30 14:22 ` [PATCH RFC v2 19/25] kmsan: disable instrumentation of certain functions glider
2019-10-30 14:22 ` [PATCH RFC v2 20/25] kmsan: unpoison |tlb| in arch_tlb_gather_mmu() glider
2019-10-30 14:22 ` [PATCH RFC v2 21/25] kmsan: use __msan_memcpy() where possible glider
2019-10-30 14:22 ` [PATCH RFC v2 22/25] kmsan: unpoisoning buffers from devices etc glider
2019-10-30 14:38   ` Christoph Hellwig
2019-11-05 15:02     ` Alexander Potapenko
2019-11-07 13:00       ` Alexander Potapenko
2019-11-13 11:07         ` Alexander Potapenko
2019-10-30 14:22 ` [PATCH RFC v2 23/25] kmsan: hooks for copy_to_user() and friends glider
2019-10-30 14:22 ` [PATCH RFC v2 24/25] kmsan: disable strscpy() optimization under KMSAN glider
2019-10-30 14:22 ` [PATCH RFC v2 25/25] net: kasan: kmsan: support CONFIG_GENERIC_CSUM on x86, enable it for KASAN/KMSAN glider

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