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kcsan: Add ability to pass instruction pointer of access to reporting
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Add the ability to pass an explicitly set instruction pointer of access
from check_access() all the way through to reporting.

In preparation of using it in reporting.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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Marco Elver authored and Paul E. McKenney committed Sep 13, 2021
1 parent ade3a58 commit 55a55fe
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Showing 3 changed files with 45 additions and 38 deletions.
55 changes: 30 additions & 25 deletions kernel/kcsan/core.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -350,6 +350,7 @@ void kcsan_restore_irqtrace(struct task_struct *task)
static noinline void kcsan_found_watchpoint(const volatile void *ptr,
size_t size,
int type,
unsigned long ip,
atomic_long_t *watchpoint,
long encoded_watchpoint)
{
Expand Down Expand Up @@ -396,7 +397,7 @@ static noinline void kcsan_found_watchpoint(const volatile void *ptr,

if (consumed) {
kcsan_save_irqtrace(current);
kcsan_report_set_info(ptr, size, type, watchpoint - watchpoints);
kcsan_report_set_info(ptr, size, type, ip, watchpoint - watchpoints);
kcsan_restore_irqtrace(current);
} else {
/*
Expand All @@ -416,7 +417,7 @@ static noinline void kcsan_found_watchpoint(const volatile void *ptr,
}

static noinline void
kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type, unsigned long ip)
{
const bool is_write = (type & KCSAN_ACCESS_WRITE) != 0;
const bool is_assert = (type & KCSAN_ACCESS_ASSERT) != 0;
Expand Down Expand Up @@ -568,8 +569,8 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
if (is_assert && value_change == KCSAN_VALUE_CHANGE_TRUE)
atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_ASSERT_FAILURES]);

kcsan_report_known_origin(ptr, size, type, value_change,
watchpoint - watchpoints,
kcsan_report_known_origin(ptr, size, type, ip,
value_change, watchpoint - watchpoints,
old, new, access_mask);
} else if (value_change == KCSAN_VALUE_CHANGE_TRUE) {
/* Inferring a race, since the value should not have changed. */
Expand All @@ -578,8 +579,10 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
if (is_assert)
atomic_long_inc(&kcsan_counters[KCSAN_COUNTER_ASSERT_FAILURES]);

if (IS_ENABLED(CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN) || is_assert)
kcsan_report_unknown_origin(ptr, size, type, old, new, access_mask);
if (IS_ENABLED(CONFIG_KCSAN_REPORT_RACE_UNKNOWN_ORIGIN) || is_assert) {
kcsan_report_unknown_origin(ptr, size, type, ip,
old, new, access_mask);
}
}

/*
Expand All @@ -596,8 +599,8 @@ kcsan_setup_watchpoint(const volatile void *ptr, size_t size, int type)
user_access_restore(ua_flags);
}

static __always_inline void check_access(const volatile void *ptr, size_t size,
int type)
static __always_inline void
check_access(const volatile void *ptr, size_t size, int type, unsigned long ip)
{
const bool is_write = (type & KCSAN_ACCESS_WRITE) != 0;
atomic_long_t *watchpoint;
Expand Down Expand Up @@ -625,13 +628,12 @@ static __always_inline void check_access(const volatile void *ptr, size_t size,
*/

if (unlikely(watchpoint != NULL))
kcsan_found_watchpoint(ptr, size, type, watchpoint,
encoded_watchpoint);
kcsan_found_watchpoint(ptr, size, type, ip, watchpoint, encoded_watchpoint);
else {
struct kcsan_ctx *ctx = get_ctx(); /* Call only once in fast-path. */

if (unlikely(should_watch(ptr, size, type, ctx)))
kcsan_setup_watchpoint(ptr, size, type);
kcsan_setup_watchpoint(ptr, size, type, ip);
else if (unlikely(ctx->scoped_accesses.prev))
kcsan_check_scoped_accesses();
}
Expand Down Expand Up @@ -757,7 +759,7 @@ kcsan_begin_scoped_access(const volatile void *ptr, size_t size, int type,
{
struct kcsan_ctx *ctx = get_ctx();

__kcsan_check_access(ptr, size, type);
check_access(ptr, size, type, _RET_IP_);

ctx->disable_count++; /* Disable KCSAN, in case list debugging is on. */

Expand Down Expand Up @@ -802,7 +804,7 @@ EXPORT_SYMBOL(kcsan_end_scoped_access);

void __kcsan_check_access(const volatile void *ptr, size_t size, int type)
{
check_access(ptr, size, type);
check_access(ptr, size, type, _RET_IP_);
}
EXPORT_SYMBOL(__kcsan_check_access);

Expand All @@ -823,7 +825,7 @@ EXPORT_SYMBOL(__kcsan_check_access);
void __tsan_read##size(void *ptr); \
void __tsan_read##size(void *ptr) \
{ \
check_access(ptr, size, 0); \
check_access(ptr, size, 0, _RET_IP_); \
} \
EXPORT_SYMBOL(__tsan_read##size); \
void __tsan_unaligned_read##size(void *ptr) \
Expand All @@ -832,7 +834,7 @@ EXPORT_SYMBOL(__kcsan_check_access);
void __tsan_write##size(void *ptr); \
void __tsan_write##size(void *ptr) \
{ \
check_access(ptr, size, KCSAN_ACCESS_WRITE); \
check_access(ptr, size, KCSAN_ACCESS_WRITE, _RET_IP_); \
} \
EXPORT_SYMBOL(__tsan_write##size); \
void __tsan_unaligned_write##size(void *ptr) \
Expand All @@ -842,7 +844,8 @@ EXPORT_SYMBOL(__kcsan_check_access);
void __tsan_read_write##size(void *ptr) \
{ \
check_access(ptr, size, \
KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE); \
KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE, \
_RET_IP_); \
} \
EXPORT_SYMBOL(__tsan_read_write##size); \
void __tsan_unaligned_read_write##size(void *ptr) \
Expand All @@ -858,14 +861,14 @@ DEFINE_TSAN_READ_WRITE(16);
void __tsan_read_range(void *ptr, size_t size);
void __tsan_read_range(void *ptr, size_t size)
{
check_access(ptr, size, 0);
check_access(ptr, size, 0, _RET_IP_);
}
EXPORT_SYMBOL(__tsan_read_range);

void __tsan_write_range(void *ptr, size_t size);
void __tsan_write_range(void *ptr, size_t size)
{
check_access(ptr, size, KCSAN_ACCESS_WRITE);
check_access(ptr, size, KCSAN_ACCESS_WRITE, _RET_IP_);
}
EXPORT_SYMBOL(__tsan_write_range);

Expand All @@ -886,7 +889,8 @@ EXPORT_SYMBOL(__tsan_write_range);
IS_ALIGNED((unsigned long)ptr, size); \
if (IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS) && is_atomic) \
return; \
check_access(ptr, size, is_atomic ? KCSAN_ACCESS_ATOMIC : 0); \
check_access(ptr, size, is_atomic ? KCSAN_ACCESS_ATOMIC : 0, \
_RET_IP_); \
} \
EXPORT_SYMBOL(__tsan_volatile_read##size); \
void __tsan_unaligned_volatile_read##size(void *ptr) \
Expand All @@ -901,7 +905,8 @@ EXPORT_SYMBOL(__tsan_write_range);
return; \
check_access(ptr, size, \
KCSAN_ACCESS_WRITE | \
(is_atomic ? KCSAN_ACCESS_ATOMIC : 0)); \
(is_atomic ? KCSAN_ACCESS_ATOMIC : 0), \
_RET_IP_); \
} \
EXPORT_SYMBOL(__tsan_volatile_write##size); \
void __tsan_unaligned_volatile_write##size(void *ptr) \
Expand Down Expand Up @@ -955,7 +960,7 @@ EXPORT_SYMBOL(__tsan_init);
u##bits __tsan_atomic##bits##_load(const u##bits *ptr, int memorder) \
{ \
if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) { \
check_access(ptr, bits / BITS_PER_BYTE, KCSAN_ACCESS_ATOMIC); \
check_access(ptr, bits / BITS_PER_BYTE, KCSAN_ACCESS_ATOMIC, _RET_IP_); \
} \
return __atomic_load_n(ptr, memorder); \
} \
Expand All @@ -965,7 +970,7 @@ EXPORT_SYMBOL(__tsan_init);
{ \
if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) { \
check_access(ptr, bits / BITS_PER_BYTE, \
KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC); \
KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ATOMIC, _RET_IP_); \
} \
__atomic_store_n(ptr, v, memorder); \
} \
Expand All @@ -978,7 +983,7 @@ EXPORT_SYMBOL(__tsan_init);
if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) { \
check_access(ptr, bits / BITS_PER_BYTE, \
KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | \
KCSAN_ACCESS_ATOMIC); \
KCSAN_ACCESS_ATOMIC, _RET_IP_); \
} \
return __atomic_##op##suffix(ptr, v, memorder); \
} \
Expand Down Expand Up @@ -1010,7 +1015,7 @@ EXPORT_SYMBOL(__tsan_init);
if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) { \
check_access(ptr, bits / BITS_PER_BYTE, \
KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | \
KCSAN_ACCESS_ATOMIC); \
KCSAN_ACCESS_ATOMIC, _RET_IP_); \
} \
return __atomic_compare_exchange_n(ptr, exp, val, weak, mo, fail_mo); \
} \
Expand All @@ -1025,7 +1030,7 @@ EXPORT_SYMBOL(__tsan_init);
if (!IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) { \
check_access(ptr, bits / BITS_PER_BYTE, \
KCSAN_ACCESS_COMPOUND | KCSAN_ACCESS_WRITE | \
KCSAN_ACCESS_ATOMIC); \
KCSAN_ACCESS_ATOMIC, _RET_IP_); \
} \
__atomic_compare_exchange_n(ptr, &exp, val, 0, mo, fail_mo); \
return exp; \
Expand Down
8 changes: 4 additions & 4 deletions kernel/kcsan/kcsan.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -121,22 +121,22 @@ enum kcsan_value_change {
* to be consumed by the reporting thread. No report is printed yet.
*/
void kcsan_report_set_info(const volatile void *ptr, size_t size, int access_type,
int watchpoint_idx);
unsigned long ip, int watchpoint_idx);

/*
* The calling thread observed that the watchpoint it set up was hit and
* consumed: print the full report based on information set by the racing
* thread.
*/
void kcsan_report_known_origin(const volatile void *ptr, size_t size, int access_type,
enum kcsan_value_change value_change, int watchpoint_idx,
u64 old, u64 new, u64 mask);
unsigned long ip, enum kcsan_value_change value_change,
int watchpoint_idx, u64 old, u64 new, u64 mask);

/*
* No other thread was observed to race with the access, but the data value
* before and after the stall differs. Reports a race of "unknown origin".
*/
void kcsan_report_unknown_origin(const volatile void *ptr, size_t size, int access_type,
u64 old, u64 new, u64 mask);
unsigned long ip, u64 old, u64 new, u64 mask);

#endif /* _KERNEL_KCSAN_KCSAN_H */
20 changes: 11 additions & 9 deletions kernel/kcsan/report.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@ struct access_info {
int access_type;
int task_pid;
int cpu_id;
unsigned long ip;
};

/*
Expand Down Expand Up @@ -576,21 +577,22 @@ static bool prepare_report_consumer(unsigned long *flags,
}

static struct access_info prepare_access_info(const volatile void *ptr, size_t size,
int access_type)
int access_type, unsigned long ip)
{
return (struct access_info) {
.ptr = ptr,
.size = size,
.access_type = access_type,
.task_pid = in_task() ? task_pid_nr(current) : -1,
.cpu_id = raw_smp_processor_id()
.cpu_id = raw_smp_processor_id(),
.ip = ip,
};
}

void kcsan_report_set_info(const volatile void *ptr, size_t size, int access_type,
int watchpoint_idx)
unsigned long ip, int watchpoint_idx)
{
const struct access_info ai = prepare_access_info(ptr, size, access_type);
const struct access_info ai = prepare_access_info(ptr, size, access_type, ip);
unsigned long flags;

kcsan_disable_current();
Expand All @@ -603,10 +605,10 @@ void kcsan_report_set_info(const volatile void *ptr, size_t size, int access_typ
}

void kcsan_report_known_origin(const volatile void *ptr, size_t size, int access_type,
enum kcsan_value_change value_change, int watchpoint_idx,
u64 old, u64 new, u64 mask)
unsigned long ip, enum kcsan_value_change value_change,
int watchpoint_idx, u64 old, u64 new, u64 mask)
{
const struct access_info ai = prepare_access_info(ptr, size, access_type);
const struct access_info ai = prepare_access_info(ptr, size, access_type, ip);
struct other_info *other_info = &other_infos[watchpoint_idx];
unsigned long flags = 0;

Expand Down Expand Up @@ -637,9 +639,9 @@ void kcsan_report_known_origin(const volatile void *ptr, size_t size, int access
}

void kcsan_report_unknown_origin(const volatile void *ptr, size_t size, int access_type,
u64 old, u64 new, u64 mask)
unsigned long ip, u64 old, u64 new, u64 mask)
{
const struct access_info ai = prepare_access_info(ptr, size, access_type);
const struct access_info ai = prepare_access_info(ptr, size, access_type, ip);
unsigned long flags;

kcsan_disable_current();
Expand Down

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