diff options
| -rw-r--r-- | kernel/kcov.c | 31 | ||||
| -rw-r--r-- | lib/Kconfig.debug | 8 |
2 files changed, 39 insertions, 0 deletions
diff --git a/kernel/kcov.c b/kernel/kcov.c index f0a69d402066..d9d4a0c04185 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -11,6 +11,7 @@ #include <linux/fs.h> #include <linux/hashtable.h> #include <linux/init.h> +#include <linux/jiffies.h> #include <linux/kmsan-checks.h> #include <linux/mm.h> #include <linux/preempt.h> @@ -1058,6 +1059,32 @@ u64 kcov_common_handle(void) } EXPORT_SYMBOL(kcov_common_handle); +#ifdef CONFIG_KCOV_SELFTEST +static void __init selftest(void) +{ + unsigned long start; + + pr_err("running self test\n"); + /* + * Test that interrupts don't produce spurious coverage. + * The coverage callback filters out interrupt code, but only + * after the handler updates preempt count. Some code periodically + * leaks out of that section and leads to spurious coverage. + * It's hard to call the actual interrupt handler directly, + * so we just loop here for a bit waiting for a timer interrupt. + * We set kcov_mode to enable tracing, but don't setup the area, + * so any attempt to trace will crash. Note: we must not call any + * potentially traced functions in this region. + */ + start = jiffies; + current->kcov_mode = KCOV_MODE_TRACE_PC; + while ((jiffies - start) * MSEC_PER_SEC / HZ < 300) + ; + current->kcov_mode = 0; + pr_err("done running self test\n"); +} +#endif + static int __init kcov_init(void) { int cpu; @@ -1077,6 +1104,10 @@ static int __init kcov_init(void) */ debugfs_create_file_unsafe("kcov", 0600, NULL, NULL, &kcov_fops); +#ifdef CONFIG_KCOV_SELFTEST + selftest(); +#endif + return 0; } diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index a30c03a66172..270e367b3e6f 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2173,6 +2173,14 @@ config KCOV_IRQ_AREA_SIZE soft interrupts. This specifies the size of those areas in the number of unsigned long words. +config KCOV_SELFTEST + bool "Perform short selftests on boot" + depends on KCOV + help + Run short KCOV coverage collection selftests on boot. + On test failure, causes the kernel to panic. Recommended to be + enabled, ensuring critical functionality works as intended. + menuconfig RUNTIME_TESTING_MENU bool "Runtime Testing" default y |