diff options
| -rw-r--r-- | drivers/misc/lkdtm.h | 2 | ||||
| -rw-r--r-- | drivers/misc/lkdtm_core.c | 2 | ||||
| -rw-r--r-- | drivers/misc/lkdtm_refcount.c | 44 |
3 files changed, 48 insertions, 0 deletions
diff --git a/drivers/misc/lkdtm.h b/drivers/misc/lkdtm.h index 04ff8b23b3b0..063f5d651076 100644 --- a/drivers/misc/lkdtm.h +++ b/drivers/misc/lkdtm.h @@ -61,6 +61,8 @@ void lkdtm_REFCOUNT_INC_NOT_ZERO_SATURATED(void); void lkdtm_REFCOUNT_ADD_NOT_ZERO_SATURATED(void); void lkdtm_REFCOUNT_DEC_AND_TEST_SATURATED(void); void lkdtm_REFCOUNT_SUB_AND_TEST_SATURATED(void); +void lkdtm_REFCOUNT_TIMING(void); +void lkdtm_ATOMIC_TIMING(void); /* lkdtm_rodata.c */ void lkdtm_rodata_do_nothing(void); diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c index 156a1a07c3db..51decc07eeda 100644 --- a/drivers/misc/lkdtm_core.c +++ b/drivers/misc/lkdtm_core.c @@ -238,6 +238,8 @@ struct crashtype crashtypes[] = { CRASHTYPE(REFCOUNT_ADD_NOT_ZERO_SATURATED), CRASHTYPE(REFCOUNT_DEC_AND_TEST_SATURATED), CRASHTYPE(REFCOUNT_SUB_AND_TEST_SATURATED), + CRASHTYPE(REFCOUNT_TIMING), + CRASHTYPE(ATOMIC_TIMING), CRASHTYPE(USERCOPY_HEAP_SIZE_TO), CRASHTYPE(USERCOPY_HEAP_SIZE_FROM), CRASHTYPE(USERCOPY_HEAP_FLAG_TO), diff --git a/drivers/misc/lkdtm_refcount.c b/drivers/misc/lkdtm_refcount.c index 313abea4bf9d..29af0152a337 100644 --- a/drivers/misc/lkdtm_refcount.c +++ b/drivers/misc/lkdtm_refcount.c @@ -354,3 +354,47 @@ void lkdtm_REFCOUNT_SUB_AND_TEST_SATURATED(void) check_saturated(&sat); } + +/* Used to time the existing atomic_t when used for reference counting */ +void lkdtm_ATOMIC_TIMING(void) +{ + unsigned int i; + atomic_t count = ATOMIC_INIT(1); + + for (i = 0; i < INT_MAX - 1; i++) + atomic_inc(&count); + + for (i = INT_MAX; i > 0; i--) + if (atomic_dec_and_test(&count)) + break; + + if (i != 1) + pr_err("atomic timing: out of sync up/down cycle: %u\n", i - 1); + else + pr_info("atomic timing: done\n"); +} + +/* + * This can be compared to ATOMIC_TIMING when implementing fast refcount + * protections. Looking at the number of CPU cycles tells the real story + * about performance. For example: + * cd /sys/kernel/debug/provoke-crash + * perf stat -B -- cat <(echo REFCOUNT_TIMING) > DIRECT + */ +void lkdtm_REFCOUNT_TIMING(void) +{ + unsigned int i; + refcount_t count = REFCOUNT_INIT(1); + + for (i = 0; i < INT_MAX - 1; i++) + refcount_inc(&count); + + for (i = INT_MAX; i > 0; i--) + if (refcount_dec_and_test(&count)) + break; + + if (i != 1) + pr_err("refcount: out of sync up/down cycle: %u\n", i - 1); + else + pr_info("refcount timing: done\n"); +} |