diff options
| -rw-r--r-- | arch/x86/Kconfig | 2 | ||||
| -rw-r--r-- | include/linux/compiler-clang.h | 2 | ||||
| -rw-r--r-- | include/linux/compiler.h | 2 | ||||
| -rw-r--r-- | include/linux/kcsan-checks.h | 22 | ||||
| -rw-r--r-- | include/linux/kcsan.h | 23 | ||||
| -rw-r--r-- | include/linux/seqlock.h | 8 | ||||
| -rw-r--r-- | kernel/kcsan/atomic.h | 2 | ||||
| -rw-r--r-- | kernel/kcsan/core.c | 59 | ||||
| -rw-r--r-- | kernel/kcsan/debugfs.c | 62 | ||||
| -rw-r--r-- | kernel/kcsan/encoding.h | 25 | ||||
| -rw-r--r-- | kernel/kcsan/kcsan.h | 11 | ||||
| -rw-r--r-- | kernel/kcsan/report.c | 42 | ||||
| -rw-r--r-- | kernel/kcsan/test.c | 6 | ||||
| -rw-r--r-- | kernel/sched/Makefile | 2 | ||||
| -rw-r--r-- | lib/Kconfig.kcsan | 16 |
15 files changed, 131 insertions, 153 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 9933ca8ffe16..9cfa4a5c6f42 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -226,7 +226,7 @@ config X86 select VIRT_TO_BUS select X86_FEATURE_NAMES if PROC_FS select PROC_PID_ARCH_STATUS if PROC_FS - select HAVE_ARCH_KCSAN if X86_64 + select HAVE_ARCH_KCSAN if X86_64 config INSTRUCTION_DECODER def_bool y diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h index a213eb55e725..2cb42d8bdedc 100644 --- a/include/linux/compiler-clang.h +++ b/include/linux/compiler-clang.h @@ -16,7 +16,7 @@ #define KASAN_ABI_VERSION 5 #if __has_feature(address_sanitizer) || __has_feature(hwaddress_sanitizer) -/* emulate gcc's __SANITIZE_ADDRESS__ flag */ +/* Emulate GCC's __SANITIZE_ADDRESS__ flag */ #define __SANITIZE_ADDRESS__ #define __no_sanitize_address \ __attribute__((no_sanitize("address", "hwaddress"))) diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 7d3e77781578..ad8c76144a3c 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -313,7 +313,7 @@ unsigned long read_word_at_a_time(const void *addr) #include <linux/kcsan.h> /* - * data_race: macro to document that accesses in an expression may conflict with + * data_race(): macro to document that accesses in an expression may conflict with * other concurrent accesses resulting in data races, but the resulting * behaviour is deemed safe regardless. * diff --git a/include/linux/kcsan-checks.h b/include/linux/kcsan-checks.h index e78220661086..ef3ee233a3fa 100644 --- a/include/linux/kcsan-checks.h +++ b/include/linux/kcsan-checks.h @@ -8,17 +8,17 @@ /* * Access type modifiers. */ -#define KCSAN_ACCESS_WRITE 0x1 +#define KCSAN_ACCESS_WRITE 0x1 #define KCSAN_ACCESS_ATOMIC 0x2 /* - * __kcsan_*: Always calls into runtime when KCSAN is enabled. This may be used + * __kcsan_*: Always calls into the runtime when KCSAN is enabled. This may be used * even in compilation units that selectively disable KCSAN, but must use KCSAN - * to validate access to an address. Never use these in header files! + * to validate access to an address. Never use these in header files! */ #ifdef CONFIG_KCSAN /** - * __kcsan_check_access - check generic access for data race + * __kcsan_check_access - check generic access for data races * * @ptr address of access * @size size of access @@ -32,7 +32,7 @@ static inline void __kcsan_check_access(const volatile void *ptr, size_t size, #endif /* - * kcsan_*: Only calls into runtime when the particular compilation unit has + * kcsan_*: Only calls into the runtime when the particular compilation unit has * KCSAN instrumentation enabled. May be used in header files. */ #ifdef __SANITIZE_THREAD__ @@ -77,16 +77,12 @@ static inline void kcsan_check_access(const volatile void *ptr, size_t size, kcsan_check_access(ptr, size, KCSAN_ACCESS_WRITE) /* - * Check for atomic accesses: if atomic access are not ignored, this simply - * aliases to kcsan_check_access, otherwise becomes a no-op. + * Check for atomic accesses: if atomic accesses are not ignored, this simply + * aliases to kcsan_check_access(), otherwise becomes a no-op. */ #ifdef CONFIG_KCSAN_IGNORE_ATOMICS -#define kcsan_check_atomic_read(...) \ - do { \ - } while (0) -#define kcsan_check_atomic_write(...) \ - do { \ - } while (0) +#define kcsan_check_atomic_read(...) do { } while (0) +#define kcsan_check_atomic_write(...) do { } while (0) #else #define kcsan_check_atomic_read(ptr, size) \ kcsan_check_access(ptr, size, KCSAN_ACCESS_ATOMIC) diff --git a/include/linux/kcsan.h b/include/linux/kcsan.h index 9047048fee84..1019e3a2c689 100644 --- a/include/linux/kcsan.h +++ b/include/linux/kcsan.h @@ -94,21 +94,14 @@ void kcsan_atomic_next(int n); #else /* CONFIG_KCSAN */ -static inline void kcsan_init(void) { } - -static inline void kcsan_disable_current(void) { } - -static inline void kcsan_enable_current(void) { } - -static inline void kcsan_nestable_atomic_begin(void) { } - -static inline void kcsan_nestable_atomic_end(void) { } - -static inline void kcsan_flat_atomic_begin(void) { } - -static inline void kcsan_flat_atomic_end(void) { } - -static inline void kcsan_atomic_next(int n) { } +static inline void kcsan_init(void) { } +static inline void kcsan_disable_current(void) { } +static inline void kcsan_enable_current(void) { } +static inline void kcsan_nestable_atomic_begin(void) { } +static inline void kcsan_nestable_atomic_end(void) { } +static inline void kcsan_flat_atomic_begin(void) { } +static inline void kcsan_flat_atomic_end(void) { } +static inline void kcsan_atomic_next(int n) { } #endif /* CONFIG_KCSAN */ diff --git a/include/linux/seqlock.h b/include/linux/seqlock.h index f52c91be8939..f80d50cac199 100644 --- a/include/linux/seqlock.h +++ b/include/linux/seqlock.h @@ -48,7 +48,7 @@ * * As a consequence, we take the following best-effort approach for raw usage * via seqcount_t under KCSAN: upon beginning a seq-reader critical section, - * pessimistically mark then next KCSAN_SEQLOCK_REGION_MAX memory accesses as + * pessimistically mark the next KCSAN_SEQLOCK_REGION_MAX memory accesses as * atomics; if there is a matching read_seqcount_retry() call, no following * memory operations are considered atomic. Usage of seqlocks via seqlock_t * interface is not affected. @@ -265,7 +265,7 @@ static inline void raw_write_seqcount_end(seqcount_t *s) * usual consistency guarantee. It is one wmb cheaper, because we can * collapse the two back-to-back wmb()s. * - * Note that, writes surrounding the barrier should be declared atomic (e.g. + * Note that writes surrounding the barrier should be declared atomic (e.g. * via WRITE_ONCE): a) to ensure the writes become visible to other threads * atomically, avoiding compiler optimizations; b) to document which writes are * meant to propagate to the reader critical section. This is necessary because @@ -465,7 +465,7 @@ static inline unsigned read_seqbegin(const seqlock_t *sl) { unsigned ret = read_seqcount_begin(&sl->seqcount); - kcsan_atomic_next(0); /* non-raw usage, assume closing read_seqretry */ + kcsan_atomic_next(0); /* non-raw usage, assume closing read_seqretry() */ kcsan_flat_atomic_begin(); return ret; } @@ -473,7 +473,7 @@ static inline unsigned read_seqbegin(const seqlock_t *sl) static inline unsigned read_seqretry(const seqlock_t *sl, unsigned start) { /* - * Assume not nested: read_seqretry may be called multiple times when + * Assume not nested: read_seqretry() may be called multiple times when * completing read critical section. */ kcsan_flat_atomic_end(); diff --git a/kernel/kcsan/atomic.h b/kernel/kcsan/atomic.h index c9c3fe628011..576e03ddd6a3 100644 --- a/kernel/kcsan/atomic.h +++ b/kernel/kcsan/atomic.h @@ -6,7 +6,7 @@ #include <linux/jiffies.h> /* - * Helper that returns true if access to ptr should be considered as an atomic + * Helper that returns true if access to @ptr should be considered an atomic * access, even though it is not explicitly atomic. * * List all volatile globals that have been observed in races, to suppress diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c index d9410d58c93e..3314fc29e236 100644 --- a/kernel/kcsan/core.c +++ b/kernel/kcsan/core.c @@ -19,10 +19,10 @@ bool kcsan_enabled; /* Per-CPU kcsan_ctx for interrupts */ static DEFINE_PER_CPU(struct kcsan_ctx, kcsan_cpu_ctx) = { - .disable_count = 0, - .atomic_next = 0, - .atomic_nest_count = 0, - .in_flat_atomic = false, + .disable_count = 0, + .atomic_next = 0, + .atomic_nest_count = 0, + .in_flat_atomic = false, }; /* @@ -50,11 +50,11 @@ static DEFINE_PER_CPU(struct kcsan_ctx, kcsan_cpu_ctx) = { * slot=9: [10, 11, 9] * slot=63: [64, 65, 63] */ -#define NUM_SLOTS (1 + 2 * KCSAN_CHECK_ADJACENT) +#define NUM_SLOTS (1 + 2*KCSAN_CHECK_ADJACENT) #define SLOT_IDX(slot, i) (slot + ((i + KCSAN_CHECK_ADJACENT) % NUM_SLOTS)) /* - * SLOT_IDX_FAST is used in fast-path. Not first checking the address's primary + * SLOT_IDX_FAST is used in the fast-path. Not first checking the address's primary * slot (middle) is fine if we assume that data races occur rarely. The set of * indices {SLOT_IDX(slot, i) | i in [0, NUM_SLOTS)} is equivalent to * {SLOT_IDX_FAST(slot, i) | i in [0, NUM_SLOTS)}. @@ -68,9 +68,9 @@ static DEFINE_PER_CPU(struct kcsan_ctx, kcsan_cpu_ctx) = { * zero-initialized state matches INVALID_WATCHPOINT. * * Add NUM_SLOTS-1 entries to account for overflow; this helps avoid having to - * use more complicated SLOT_IDX_FAST calculation with modulo in fast-path. + * use more complicated SLOT_IDX_FAST calculation with modulo in the fast-path. */ -static atomic_long_t watchpoints[CONFIG_KCSAN_NUM_WATCHPOINTS + NUM_SLOTS - 1]; +static atomic_long_t watchpoints[CONFIG_KCSAN_NUM_WATCHPOINTS + NUM_SLOTS-1]; /* * Instructions to skip watching counter, used in should_watch(). We use a @@ -78,7 +78,8 @@ static atomic_long_t watchpoints[CONFIG_KCSAN_NUM_WATCHPOINTS + NUM_SLOTS - 1]; */ static DEFINE_PER_CPU(long, kcsan_skip); -static inline atomic_long_t *find_watchpoint(unsigned long addr, size_t size, +static inline atomic_long_t *find_watchpoint(unsigned long addr, + size_t size, bool expect_write, long *encoded_watchpoint) { @@ -110,8 +111,8 @@ static inline atomic_long_t *find_watchpoint(unsigned long addr, size_t size, return NULL; } -static inline atomic_long_t *insert_watchpoint(unsigned long addr, size_t size, - bool is_write) +static inline atomic_long_t * +insert_watchpoint(unsigned long addr, size_t size, bool is_write) { const int slot = watchpoint_slot(addr); const long encoded_watchpoint = encode_watchpoint(addr, size, is_write); @@ -120,21 +121,16 @@ static inline atomic_long_t *insert_watchpoint(unsigned long addr, size_t size, /* Check slot index logic, ensuring we stay within array bounds. */ BUILD_BUG_ON(SLOT_IDX(0, 0) != KCSAN_CHECK_ADJACENT); - BUILD_BUG_ON(SLOT_IDX(0, KCSAN_CHECK_ADJACENT + 1) != 0); - BUILD_BUG_ON(SLOT_IDX(CONFIG_KCSAN_NUM_WATCHPOINTS - 1, - KCSAN_CHECK_ADJACENT) != - ARRAY_SIZE(watchpoints) - 1); - BUILD_BUG_ON(SLOT_IDX(CONFIG_KCSAN_NUM_WATCHPOINTS - 1, - KCSAN_CHECK_ADJACENT + 1) != - ARRAY_SIZE(watchpoints) - NUM_SLOTS); + BUILD_BUG_ON(SLOT_IDX(0, KCSAN_CHECK_ADJACENT+1) != 0); + BUILD_BUG_ON(SLOT_IDX(CONFIG_KCSAN_NUM_WATCHPOINTS-1, KCSAN_CHECK_ADJACENT) != ARRAY_SIZE(watchpoints)-1); + BUILD_BUG_ON(SLOT_IDX(CONFIG_KCSAN_NUM_WATCHPOINTS-1, KCSAN_CHECK_ADJACENT+1) != ARRAY_SIZE(watchpoints) - NUM_SLOTS); for (i = 0; i < NUM_SLOTS; ++i) { long expect_val = INVALID_WATCHPOINT; /* Try to acquire this slot. */ watchpoint = &watchpoints[SLOT_IDX(slot, i)]; - if (atomic_long_try_cmpxchg_relaxed(watchpoint, &expect_val, - encoded_watchpoint)) + if (atomic_long_try_cmpxchg_relaxed(watchpoint, &expect_val, encoded_watchpoint)) return watchpoint; } @@ -150,11 +146,10 @@ static inline atomic_long_t *insert_watchpoint(unsigned long addr, size_t size, * 2. the thread that set up the watchpoint already removed it; * 3. the watchpoint was removed and then re-used. */ -static inline bool try_consume_watchpoint(atomic_long_t *watchpoint, - long encoded_watchpoint) +static inline bool +try_consume_watchpoint(atomic_long_t *watchpoint, long encoded_watchpoint) { - return atomic_long_try_cmpxchg_relaxed(watchpoint, &encoded_watchpoint, - CONSUMED_WATCHPOINT); + return atomic_long_try_cmpxchg_relaxed(watchpoint, &encoded_watchpoint, CONSUMED_WATCHPOINT); } /* @@ -162,14 +157,13 @@ static inline bool try_consume_watchpoint(atomic_long_t *watchpoint, */ static inline bool remove_watchpoint(atomic_long_t *watchpoint) { - return atomic_long_xchg_relaxed(watchpoint, INVALID_WATCHPOINT) != - CONSUMED_WATCHPOINT; + return atomic_long_xchg_relaxed(watchpoint, INVALID_WATCHPOINT) != CONSUMED_WATCHPOINT; } static inline struct kcsan_ctx *get_ctx(void) { /* - * In interrupt, use raw_cpu_ptr to avoid unnecessary checks, that would + * In interrupts, use raw_cpu_ptr to avoid unnecessary checks, that would * also result in calls that generate warnings in uaccess regions. */ return in_task() ? ¤t->kcsan_ctx : raw_cpu_ptr(&kcsan_cpu_ctx); @@ -260,7 +254,8 @@ static inline unsigned int get_delay(void) */ static noinline void kcsan_found_watchpoint(const volatile void *ptr, - size_t size, bool is_write, + size_t size, + bool is_write, atomic_long_t *watchpoint, long encoded_watchpoint) { @@ -296,8 +291,8 @@ static noinline void kcsan_found_watchpoint(const volatile void *ptr, user_access_restore(flags); } -static noinline void kcsan_setup_watchpoint(const volatile void *ptr, - size_t size, bool is_write) +static noinline void +kcsan_setup_watchpoint(const volatile void *ptr, size_t size, bool is_write) { atomic_long_t *watchpoint; union { @@ -346,8 +341,8 @@ static noinline void kcsan_setup_watchpoint(const volatile void *ptr, watchpoint = insert_watchpoint((unsigned long)ptr, size, is_write); if (watchpoint == NULL) { /* - * Out of capacity: the size of `watchpoints`, and the frequency - * with which `should_watch()` returns true should be tweaked so + * Out of capacity: the size of 'watchpoints', and the frequency + * with which should_watch() returns true should be tweaked so * that this case happens very rarely. */ kcsan_counter_inc(KCSAN_COUNTER_NO_CAPACITY); diff --git a/kernel/kcsan/debugfs.c b/kernel/kcsan/debugfs.c index 041d520a0183..bec42dab32ee 100644 --- a/kernel/kcsan/debugfs.c +++ b/kernel/kcsan/debugfs.c @@ -24,39 +24,31 @@ static atomic_long_t counters[KCSAN_COUNTER_COUNT]; * whitelist or blacklist. */ static struct { - unsigned long *addrs; /* array of addresses */ - size_t size; /* current size */ - int used; /* number of elements used */ - bool sorted; /* if elements are sorted */ - bool whitelist; /* if list is a blacklist or whitelist */ + unsigned long *addrs; /* array of addresses */ + size_t size; /* current size */ + int used; /* number of elements used */ + bool sorted; /* if elements are sorted */ + bool whitelist; /* if list is a blacklist or whitelist */ } report_filterlist = { - .addrs = NULL, - .size = 8, /* small initial size */ - .used = 0, - .sorted = false, - .whitelist = false, /* default is blacklist */ + .addrs = NULL, + .size = 8, /* small initial size */ + .used = 0, + .sorted = false, + .whitelist = false, /* default is blacklist */ }; static DEFINE_SPINLOCK(report_filterlist_lock); static const char *counter_to_name(enum kcsan_counter_id id) { switch (id) { - case KCSAN_COUNTER_USED_WATCHPOINTS: - return "used_watchpoints"; - case KCSAN_COUNTER_SETUP_WATCHPOINTS: - return "setup_watchpoints"; - case KCSAN_COUNTER_DATA_RACES: - return "data_races"; - case KCSAN_COUNTER_NO_CAPACITY: - return "no_capacity"; - case KCSAN_COUNTER_REPORT_RACES: - return "report_races"; - case KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN: - return "races_unknown_origin"; - case KCSAN_COUNTER_UNENCODABLE_ACCESSES: - return "unencodable_accesses"; - case KCSAN_COUNTER_ENCODING_FALSE_POSITIVES: - return "encoding_false_positives"; + case KCSAN_COUNTER_USED_WATCHPOINTS: return "used_watchpoints"; + case KCSAN_COUNTER_SETUP_WATCHPOINTS: return "setup_watchpoints"; + case KCSAN_COUNTER_DATA_RACES: return "data_races"; + case KCSAN_COUNTER_NO_CAPACITY: return "no_capacity"; + case KCSAN_COUNTER_REPORT_RACES: return "report_races"; + case KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN: return "races_unknown_origin"; + case KCSAN_COUNTER_UNENCODABLE_ACCESSES: return "unencodable_accesses"; + case KCSAN_COUNTER_ENCODING_FALSE_POSITIVES: return "encoding_false_positives"; case KCSAN_COUNTER_COUNT: BUG(); } @@ -116,7 +108,7 @@ bool kcsan_skip_report_debugfs(unsigned long func_addr) if (!kallsyms_lookup_size_offset(func_addr, &symbolsize, &offset)) return false; - func_addr -= offset; /* get function start */ + func_addr -= offset; /* Get function start */ spin_lock_irqsave(&report_filterlist_lock, flags); if (report_filterlist.used == 0) @@ -195,6 +187,7 @@ static ssize_t insert_report_filterlist(const char *func) out: spin_unlock_irqrestore(&report_filterlist_lock, flags); + return ret; } @@ -226,8 +219,8 @@ static int debugfs_open(struct inode *inode, struct file *file) return single_open(file, show_info, NULL); } -static ssize_t debugfs_write(struct file *file, const char __user *buf, - size_t count, loff_t *off) +static ssize_t +debugfs_write(struct file *file, const char __user *buf, size_t count, loff_t *off) { char kbuf[KSYM_NAME_LEN]; char *arg; @@ -264,10 +257,13 @@ static ssize_t debugfs_write(struct file *file, const char __user *buf, return count; } -static const struct file_operations debugfs_ops = { .read = seq_read, - .open = debugfs_open, - .write = debugfs_write, - .release = single_release }; +static const struct file_operations debugfs_ops = +{ + .read = seq_read, + .open = debugfs_open, + .write = debugfs_write, + .release = single_release +}; void __init kcsan_debugfs_init(void) { diff --git a/kernel/kcsan/encoding.h b/kernel/kcsan/encoding.h index e17bdac0e54b..b63890e86449 100644 --- a/kernel/kcsan/encoding.h +++ b/kernel/kcsan/encoding.h @@ -10,7 +10,8 @@ #include "kcsan.h" #define SLOT_RANGE PAGE_SIZE -#define INVALID_WATCHPOINT 0 + +#define INVALID_WATCHPOINT 0 #define CONSUMED_WATCHPOINT 1 /* @@ -34,24 +35,24 @@ * Both these are assumed to be very unlikely. However, in case it still happens * happens, the report logic will filter out the false positive (see report.c). */ -#define WATCHPOINT_ADDR_BITS (BITS_PER_LONG - 1 - WATCHPOINT_SIZE_BITS) +#define WATCHPOINT_ADDR_BITS (BITS_PER_LONG-1 - WATCHPOINT_SIZE_BITS) /* * Masks to set/retrieve the encoded data. */ -#define WATCHPOINT_WRITE_MASK BIT(BITS_PER_LONG - 1) +#define WATCHPOINT_WRITE_MASK BIT(BITS_PER_LONG-1) #define WATCHPOINT_SIZE_MASK \ - GENMASK(BITS_PER_LONG - 2, BITS_PER_LONG - 2 - WATCHPOINT_SIZE_BITS) + GENMASK(BITS_PER_LONG-2, BITS_PER_LONG-2 - WATCHPOINT_SIZE_BITS) #define WATCHPOINT_ADDR_MASK \ - GENMASK(BITS_PER_LONG - 3 - WATCHPOINT_SIZE_BITS, 0) + GENMASK(BITS_PER_LONG-3 - WATCHPOINT_SIZE_BITS, 0) static inline bool check_encodable(unsigned long addr, size_t size) { return size <= MAX_ENCODABLE_SIZE; } -static inline long encode_watchpoint(unsigned long addr, size_t size, - bool is_write) +static inline long +encode_watchpoint(unsigned long addr, size_t size, bool is_write) { return (long)((is_write ? WATCHPOINT_WRITE_MASK : 0) | (size << WATCHPOINT_ADDR_BITS) | @@ -59,17 +60,17 @@ static inline long encode_watchpoint(unsigned long addr, size_t size, } static inline bool decode_watchpoint(long watchpoint, - unsigned long *addr_masked, size_t *size, + unsigned long *addr_masked, + size_t *size, bool *is_write) { if (watchpoint == INVALID_WATCHPOINT || watchpoint == CONSUMED_WATCHPOINT) return false; - *addr_masked = (unsigned long)watchpoint & WATCHPOINT_ADDR_MASK; - *size = ((unsigned long)watchpoint & WATCHPOINT_SIZE_MASK) >> - WATCHPOINT_ADDR_BITS; - *is_write = !!((unsigned long)watchpoint & WATCHPOINT_WRITE_MASK); + *addr_masked = (unsigned long)watchpoint & WATCHPOINT_ADDR_MASK; + *size = ((unsigned long)watchpoint & WATCHPOINT_SIZE_MASK) >> WATCHPOINT_ADDR_BITS; + *is_write = !!((unsigned long)watchpoint & WATCHPOINT_WRITE_MASK); return true; } diff --git a/kernel/kcsan/kcsan.h b/kernel/kcsan/kcsan.h index 1bb2f1c0d61e..d3b9a96ac8a4 100644 --- a/kernel/kcsan/kcsan.h +++ b/kernel/kcsan/kcsan.h @@ -72,14 +72,14 @@ enum kcsan_counter_id { /* * Increment/decrement counter with given id; avoid calling these in fast-path. */ -void kcsan_counter_inc(enum kcsan_counter_id id); -void kcsan_counter_dec(enum kcsan_counter_id id); +extern void kcsan_counter_inc(enum kcsan_counter_id id); +extern void kcsan_counter_dec(enum kcsan_counter_id id); /* * Returns true if data races in the function symbol that maps to func_addr * (offsets are ignored) should *not* be reported. */ -bool kcsan_skip_report_debugfs(unsigned long func_addr); +extern bool kcsan_skip_report_debugfs(unsigned long func_addr); enum kcsan_report_type { /* @@ -99,10 +99,11 @@ enum kcsan_report_type { */ KCSAN_REPORT_RACE_UNKNOWN_ORIGIN, }; + /* * Print a race report from thread that encountered the race. */ -void kcsan_report(const volatile void *ptr, size_t size, bool is_write, - bool value_change, int cpu_id, enum kcsan_report_type type); +extern void kcsan_report(const volatile void *ptr, size_t size, bool is_write, + bool value_change, int cpu_id, enum kcsan_report_type type); #endif /* _KERNEL_KCSAN_KCSAN_H */ diff --git a/kernel/kcsan/report.c b/kernel/kcsan/report.c index ead5610bafa7..0eea05a3135b 100644 --- a/kernel/kcsan/report.c +++ b/kernel/kcsan/report.c @@ -22,13 +22,13 @@ * the reports, with reporting being in the slow-path. */ static struct { - const volatile void *ptr; - size_t size; - bool is_write; - int task_pid; - int cpu_id; - unsigned long stack_entries[NUM_STACK_ENTRIES]; - int num_stack_entries; + const volatile void *ptr; + size_t size; + bool is_write; + int task_pid; + int cpu_id; + unsigned long stack_entries[NUM_STACK_ENTRIES]; + int num_stack_entries; } other_info = { .ptr = NULL }; /* @@ -40,8 +40,8 @@ static DEFINE_SPINLOCK(report_lock); /* * Special rules to skip reporting. */ -static bool skip_report(bool is_write, bool value_change, - unsigned long top_frame) +static bool +skip_report(bool is_write, bool value_change, unsigned long top_frame) { if (IS_ENABLED(CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY) && is_write && !value_change) { @@ -105,6 +105,7 @@ static int sym_strcmp(void *addr1, void *addr2) snprintf(buf1, sizeof(buf1), "%pS", addr1); snprintf(buf2, sizeof(buf2), "%pS", addr2); + return strncmp(buf1, buf2, sizeof(buf1)); } @@ -116,8 +117,7 @@ static bool print_report(const volatile void *ptr, size_t size, bool is_write, enum kcsan_report_type type) { unsigned long stack_entries[NUM_STACK_ENTRIES] = { 0 }; - int num_stack_entries = - stack_trace_save(stack_entries, NUM_STACK_ENTRIES, 1); + int num_stack_entries = stack_trace_save(stack_entries, NUM_STACK_ENTRIES, 1); int skipnr = get_stack_skipnr(stack_entries, num_stack_entries); int other_skipnr; @@ -131,7 +131,7 @@ static bool print_report(const volatile void *ptr, size_t size, bool is_write, other_skipnr = get_stack_skipnr(other_info.stack_entries, other_info.num_stack_entries); - /* value_change is only known for the other thread */ + /* @value_change is only known for the other thread */ if (skip_report(other_info.is_write, value_change, other_info.stack_entries[other_skipnr])) return false; @@ -241,13 +241,12 @@ retry: if (other_info.ptr != NULL) break; /* still in use, retry */ - other_info.ptr = ptr; - other_info.size = size; - other_info.is_write = is_write; - other_info.task_pid = in_task() ? task_pid_nr(current) : -1; - other_info.cpu_id = cpu_id; - other_info.num_stack_entries = stack_trace_save( - other_info.stack_entries, NUM_STACK_ENTRIES, 1); + other_info.ptr = ptr; + other_info.size = size; + other_info.is_write = is_write; + other_info.task_pid = in_task() ? task_pid_nr(current) : -1; + other_info.cpu_id = cpu_id; + other_info.num_stack_entries = stack_trace_save(other_info.stack_entries, NUM_STACK_ENTRIES, 1); spin_unlock_irqrestore(&report_lock, *flags); @@ -299,6 +298,7 @@ retry: } spin_unlock_irqrestore(&report_lock, *flags); + goto retry; } @@ -309,9 +309,7 @@ void kcsan_report(const volatile void *ptr, size_t size, bool is_write, kcsan_disable_current(); if (prepare_report(&flags, ptr, size, is_write, cpu_id, type)) { - if (print_report(ptr, size, is_write, value_change, cpu_id, - type) && - panic_on_warn) + if (print_report(ptr, size, is_write, value_change, cpu_id, type) && panic_on_warn) panic("panic_on_warn set ...\n"); release_report(&flags, type); diff --git a/kernel/kcsan/test.c b/kernel/kcsan/test.c index 0bae63c5ca65..cc6000239dc0 100644 --- a/kernel/kcsan/test.c +++ b/kernel/kcsan/test.c @@ -34,7 +34,7 @@ static bool test_encode_decode(void) if (WARN_ON(!check_encodable(addr, size))) return false; - /* encode and decode */ + /* Encode and decode */ { const long encoded_watchpoint = encode_watchpoint(addr, size, is_write); @@ -42,7 +42,7 @@ static bool test_encode_decode(void) size_t verif_size; bool verif_is_write; - /* check special watchpoints */ + /* Check special watchpoints */ if (WARN_ON(decode_watchpoint( INVALID_WATCHPOINT, &verif_masked_addr, &verif_size, &verif_is_write))) @@ -52,7 +52,7 @@ static bool test_encode_decode(void) &verif_size, &verif_is_write))) return false; - /* check decoding watchpoint returns same data */ + /* Check decoding watchpoint returns same data */ if (WARN_ON(!decode_watchpoint( encoded_watchpoint, &verif_masked_addr, &verif_size, &verif_is_write))) diff --git a/kernel/sched/Makefile b/kernel/sched/Makefile index e9307a9c54e7..5fc9c9b70862 100644 --- a/kernel/sched/Makefile +++ b/kernel/sched/Makefile @@ -7,7 +7,7 @@ endif # that is not a function of syscall inputs. E.g. involuntary context switches. KCOV_INSTRUMENT := n -# There are numerous races here, however, most of them due to plain accesses. +# There are numerous data races here, however, most of them are due to plain accesses. # This would make it even harder for syzbot to find reproducers, because these # bugs trigger without specific input. Disable by default, but should re-enable # eventually. diff --git a/lib/Kconfig.kcsan b/lib/Kconfig.kcsan index 5dd464e52ab4..3f78b1434375 100644 --- a/lib/Kconfig.kcsan +++ b/lib/Kconfig.kcsan @@ -6,7 +6,6 @@ config HAVE_ARCH_KCSAN menuconfig KCSAN bool "KCSAN: watchpoint-based dynamic data race detector" depends on HAVE_ARCH_KCSAN && !KASAN && STACKTRACE - default n help Kernel Concurrency Sanitizer is a dynamic data race detector, which uses a watchpoint-based sampling approach to detect races. See @@ -16,13 +15,12 @@ if KCSAN config KCSAN_DEBUG bool "Debugging of KCSAN internals" - default n config KCSAN_SELFTEST bool "Perform short selftests on boot" default y help - Run KCSAN selftests on boot. On test failure, causes kernel to panic. + Run KCSAN selftests on boot. On test failure, causes the kernel to panic. config KCSAN_EARLY_ENABLE bool "Early enable during boot" @@ -62,7 +60,8 @@ config KCSAN_DELAY_RANDOMIZE default y help If delays should be randomized, where the maximum is KCSAN_UDELAY_*. - If false, the chosen delays are always KCSAN_UDELAY_* defined above. + If false, the chosen delays are always the KCSAN_UDELAY_* values + as defined above. config KCSAN_SKIP_WATCH int "Skip instructions before setting up watchpoint" @@ -86,9 +85,9 @@ config KCSAN_SKIP_WATCH_RANDOMIZE # parameters, to optimize for the common use-case, we avoid this because: (a) # it would impact performance (and we want to avoid static branch for all # {READ,WRITE}_ONCE, atomic_*, bitops, etc.), and (b) complicate the design -# without real benefit. The main purpose of the below options are for use in -# fuzzer configs to control reported data races, and are not expected to be -# switched frequently by a user. +# without real benefit. The main purpose of the below options is for use in +# fuzzer configs to control reported data races, and they are not expected +# to be switched frequently by a user. config KCSAN_REPORT_RACE_UNKNOWN_ORIGIN bool "Report races of unknown origin" @@ -103,13 +102,12 @@ config KCSAN_REPORT_VALUE_CHANGE_ONLY bool "Only report races where watcher observed a data value change" default y help - If enabled and a conflicting write is observed via watchpoint, but + If enabled and a conflicting write is observed via a watchpoint, but the data value of the memory location was observed to remain unchanged, do not report the data race. config KCSAN_IGNORE_ATOMICS bool "Do not instrument marked atomic accesses" - default n help If enabled, never instruments marked atomic accesses. This results in not reporting data races where one access is atomic and the other is |