foo

Author: akpm00

patches/kasan-clean-up-comments-in-internal-kasanh.patch

@@ -0,0 +1,197 @@
+From: Andrey Konovalov <[email protected]>
+Subject: kasan: clean up comments in internal kasan.h
+
+Clean up comments in mm/kasan/kasan.h: clarify, unify styles, fix
+punctuation, etc.
+
+Link: https://lkml.kernel.org/r/a0680ff30035b56cb7bdd5f59fd400e71712ceb5.1652111464.git.andreyknvl@google.com
+Signed-off-by: Andrey Konovalov <[email protected]>
+Reviewed-by: Alexander Potapenko <[email protected]>
+Cc: Marco Elver <[email protected]>
+Cc: Alexander Potapenko <[email protected]>
+Cc: Dmitry Vyukov <[email protected]>
+Cc: Andrey Ryabinin <[email protected]>
+Signed-off-by: Andrew Morton <[email protected]>
+---
+
+ mm/kasan/kasan.h |   74 ++++++++++++++++++++-------------------------
+ 1 file changed, 33 insertions(+), 41 deletions(-)
+
+--- a/mm/kasan/kasan.h~kasan-clean-up-comments-in-internal-kasanh
++++ a/mm/kasan/kasan.h
+@@ -42,6 +42,7 @@ static inline bool kasan_sync_fault_poss
+ {
+ 	return kasan_mode == KASAN_MODE_SYNC || kasan_mode == KASAN_MODE_ASYMM;
+ }
++
+ #else
+ 
+ static inline bool kasan_stack_collection_enabled(void)
+@@ -73,47 +74,41 @@ static inline bool kasan_sync_fault_poss
+ #define KASAN_MEMORY_PER_SHADOW_PAGE	(KASAN_GRANULE_SIZE << PAGE_SHIFT)
+ 
+ #ifdef CONFIG_KASAN_GENERIC
+-#define KASAN_FREE_PAGE         0xFF  /* page was freed */
+-#define KASAN_PAGE_REDZONE      0xFE  /* redzone for kmalloc_large allocations */
+-#define KASAN_KMALLOC_REDZONE   0xFC  /* redzone inside slub object */
+-#define KASAN_KMALLOC_FREE      0xFB  /* object was freed (kmem_cache_free/kfree) */
+-#define KASAN_VMALLOC_INVALID   0xF8  /* unallocated space in vmapped page */
++#define KASAN_FREE_PAGE         0xFF  /* freed page */
++#define KASAN_PAGE_REDZONE      0xFE  /* redzone for kmalloc_large allocation */
++#define KASAN_KMALLOC_REDZONE   0xFC  /* redzone for slab object */
++#define KASAN_KMALLOC_FREE      0xFB  /* freed slab object */
++#define KASAN_VMALLOC_INVALID   0xF8  /* inaccessible space in vmap area */
+ #else
+ #define KASAN_FREE_PAGE         KASAN_TAG_INVALID
+ #define KASAN_PAGE_REDZONE      KASAN_TAG_INVALID
+ #define KASAN_KMALLOC_REDZONE   KASAN_TAG_INVALID
+ #define KASAN_KMALLOC_FREE      KASAN_TAG_INVALID
+-#define KASAN_VMALLOC_INVALID   KASAN_TAG_INVALID /* only for SW_TAGS */
++#define KASAN_VMALLOC_INVALID   KASAN_TAG_INVALID /* only used for SW_TAGS */
+ #endif
+ 
+ #ifdef CONFIG_KASAN_GENERIC
+ 
+-#define KASAN_KMALLOC_FREETRACK 0xFA  /* object was freed and has free track set */
++#define KASAN_KMALLOC_FREETRACK 0xFA  /* freed slab object with free track */
+ #define KASAN_GLOBAL_REDZONE    0xF9  /* redzone for global variable */
+ 
+-/*
+- * Stack redzone shadow values
+- * (Those are compiler's ABI, don't change them)
+- */
++/* Stack redzone shadow values. Compiler ABI, do not change. */
+ #define KASAN_STACK_LEFT        0xF1
+ #define KASAN_STACK_MID         0xF2
+ #define KASAN_STACK_RIGHT       0xF3
+ #define KASAN_STACK_PARTIAL     0xF4
+ 
+-/*
+- * alloca redzone shadow values
+- */
++/* alloca redzone shadow values. */
+ #define KASAN_ALLOCA_LEFT	0xCA
+ #define KASAN_ALLOCA_RIGHT	0xCB
+ 
++/* alloca redzone size. Compiler ABI, do not change. */
+ #define KASAN_ALLOCA_REDZONE_SIZE	32
+ 
+-/*
+- * Stack frame marker (compiler ABI).
+- */
++/* Stack frame marker. Compiler ABI, do not change. */
+ #define KASAN_CURRENT_STACK_FRAME_MAGIC 0x41B58AB3
+ 
+-/* Don't break randconfig/all*config builds */
++/* Dummy value to avoid breaking randconfig/all*config builds. */
+ #ifndef KASAN_ABI_VERSION
+ #define KASAN_ABI_VERSION 1
+ #endif
+@@ -141,21 +136,21 @@ struct kasan_report_info {
+ 	unsigned long ip;
+ };
+ 
+-/* The layout of struct dictated by compiler */
++/* Do not change the struct layout: compiler ABI. */
+ struct kasan_source_location {
+ 	const char *filename;
+ 	int line_no;
+ 	int column_no;
+ };
+ 
+-/* The layout of struct dictated by compiler */
++/* Do not change the struct layout: compiler ABI. */
+ struct kasan_global {
+ 	const void *beg;		/* Address of the beginning of the global variable. */
+ 	size_t size;			/* Size of the global variable. */
+-	size_t size_with_redzone;	/* Size of the variable + size of the red zone. 32 bytes aligned */
++	size_t size_with_redzone;	/* Size of the variable + size of the redzone. 32 bytes aligned. */
+ 	const void *name;
+ 	const void *module_name;	/* Name of the module where the global variable is declared. */
+-	unsigned long has_dynamic_init;	/* This needed for C++ */
++	unsigned long has_dynamic_init;	/* This is needed for C++. */
+ #if KASAN_ABI_VERSION >= 4
+ 	struct kasan_source_location *location;
+ #endif
+@@ -164,9 +159,7 @@ struct kasan_global {
+ #endif
+ };
+ 
+-/**
+- * Structures to keep alloc and free tracks *
+- */
++/* Structures for keeping alloc and free tracks. */
+ 
+ #define KASAN_STACK_DEPTH 64
+ 
+@@ -183,11 +176,8 @@ struct kasan_track {
+ 
+ struct kasan_alloc_meta {
+ 	struct kasan_track alloc_track;
++	/* Generic mode stores free track in kasan_free_meta. */
+ #ifdef CONFIG_KASAN_GENERIC
+-	/*
+-	 * The auxiliary stack is stored into struct kasan_alloc_meta.
+-	 * The free stack is stored into struct kasan_free_meta.
+-	 */
+ 	depot_stack_handle_t aux_stack[2];
+ #else
+ 	struct kasan_track free_track[KASAN_NR_FREE_STACKS];
+@@ -203,18 +193,18 @@ struct qlist_node {
+ };
+ 
+ /*
+- * Generic mode either stores free meta in the object itself or in the redzone
+- * after the object. In the former case free meta offset is 0, in the latter
+- * case it has some sane value smaller than INT_MAX. Use INT_MAX as free meta
+- * offset when free meta isn't present.
++ * Free meta is stored either in the object itself or in the redzone after the
++ * object. In the former case, free meta offset is 0. In the latter case, the
++ * offset is between 0 and INT_MAX. INT_MAX marks that free meta is not present.
+  */
+ #define KASAN_NO_FREE_META INT_MAX
+ 
++/*
++ * Free meta is only used by Generic mode while the object is in quarantine.
++ * After that, slab allocator stores the freelist pointer in the object.
++ */
+ struct kasan_free_meta {
+ #ifdef CONFIG_KASAN_GENERIC
+-	/* This field is used while the object is in the quarantine.
+-	 * Otherwise it might be used for the allocator freelist.
+-	 */
+ 	struct qlist_node quarantine_link;
+ 	struct kasan_track free_track;
+ #endif
+@@ -417,9 +407,10 @@ static inline void kasan_unpoison(const
+ 		return;
+ 	/*
+ 	 * Explicitly initialize the memory with the precise object size to
+-	 * avoid overwriting the SLAB redzone. This disables initialization in
+-	 * the arch code and may thus lead to performance penalty. The penalty
+-	 * is accepted since SLAB redzones aren't enabled in production builds.
++	 * avoid overwriting the slab redzone. This disables initialization in
++	 * the arch code and may thus lead to performance penalty. This penalty
++	 * does not affect production builds, as slab redzones are not enabled
++	 * there.
+ 	 */
+ 	if (__slub_debug_enabled() &&
+ 	    init && ((unsigned long)size & KASAN_GRANULE_MASK)) {
+@@ -503,8 +494,9 @@ void kasan_restore_multi_shot(bool enabl
+ 
+ /*
+  * Exported functions for interfaces called from assembly or from generated
+- * code. Declarations here to avoid warning about missing declarations.
++ * code. Declared here to avoid warnings about missing declarations.
+  */
++
+ asmlinkage void kasan_unpoison_task_stack_below(const void *watermark);
+ void __asan_register_globals(struct kasan_global *globals, size_t size);
+ void __asan_unregister_globals(struct kasan_global *globals, size_t size);
+@@ -573,4 +565,4 @@ void __hwasan_storeN_noabort(unsigned lo
+ 
+ void __hwasan_tag_memory(unsigned long addr, u8 tag, unsigned long size);
+ 
+-#endif
++#endif /* __MM_KASAN_KASAN_H */
+_