diff options
| -rw-r--r-- | drivers/misc/lkdtm/Makefile | 2 | ||||
| -rw-r--r-- | drivers/misc/lkdtm/bugs.c | 16 | ||||
| -rw-r--r-- | drivers/misc/lkdtm/core.c | 6 | ||||
| -rwxr-xr-x | tools/testing/selftests/lkdtm/stack-entropy.sh | 16 |
4 files changed, 30 insertions, 10 deletions
diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile index aa12097668d3..e2984ce51fe4 100644 --- a/drivers/misc/lkdtm/Makefile +++ b/drivers/misc/lkdtm/Makefile @@ -20,7 +20,7 @@ CFLAGS_REMOVE_rodata.o += $(CC_FLAGS_LTO) OBJCOPYFLAGS := OBJCOPYFLAGS_rodata_objcopy.o := \ - --rename-section .noinstr.text=.rodata,alloc,readonly,load + --rename-section .noinstr.text=.rodata,alloc,readonly,load,contents targets += rodata.o rodata_objcopy.o $(obj)/rodata_objcopy.o: $(obj)/rodata.o FORCE $(call if_changed,objcopy) diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c index f4cb94a9aa9c..f21854ac5cc2 100644 --- a/drivers/misc/lkdtm/bugs.c +++ b/drivers/misc/lkdtm/bugs.c @@ -41,20 +41,22 @@ static DEFINE_SPINLOCK(lock_me_up); * Make sure compiler does not optimize this function or stack frame away: * - function marked noinline * - stack variables are marked volatile - * - stack variables are written (memset()) and read (pr_info()) - * - function has external effects (pr_info()) - * */ + * - stack variables are written (memset()) and read (buf[..] passed as arg) + * - function may have external effects (memzero_explicit()) + * - no tail recursion possible + */ static int noinline recursive_loop(int remaining) { volatile char buf[REC_STACK_SIZE]; + volatile int ret; memset((void *)buf, remaining & 0xFF, sizeof(buf)); - pr_info("loop %d/%d ...\n", (int)buf[remaining % sizeof(buf)], - recur_count); if (!remaining) - return 0; + ret = 0; else - return recursive_loop(remaining - 1); + ret = recursive_loop((int)buf[remaining % sizeof(buf)] - 1); + memzero_explicit((void *)buf, sizeof(buf)); + return ret; } /* If the depth is negative, use the default, otherwise keep parameter. */ diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c index 609d9ee2acc0..d4c6cdced37b 100644 --- a/drivers/misc/lkdtm/core.c +++ b/drivers/misc/lkdtm/core.c @@ -212,7 +212,11 @@ module_param(cpoint_count, int, 0644); MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\ "crash point is to be hit to trigger action"); -/* For test debug reporting. */ +/* + * For test debug reporting when CI systems provide terse summaries. + * TODO: Remove this once reasonable reporting exists in most CI systems: + * https://lore.kernel.org/lkml/CAHk-=wiFvfkoFixTapvvyPMN9pq5G-+Dys2eSyBa1vzDGAO5+A@mail.gmail.com + */ char *lkdtm_kernel_info; /* Return the crashtype number or NULL if the name is invalid */ diff --git a/tools/testing/selftests/lkdtm/stack-entropy.sh b/tools/testing/selftests/lkdtm/stack-entropy.sh index 1b4d95d575f8..14fedeef762e 100755 --- a/tools/testing/selftests/lkdtm/stack-entropy.sh +++ b/tools/testing/selftests/lkdtm/stack-entropy.sh @@ -4,13 +4,27 @@ # Measure kernel stack entropy by sampling via LKDTM's REPORT_STACK test. set -e samples="${1:-1000}" +TRIGGER=/sys/kernel/debug/provoke-crash/DIRECT +KSELFTEST_SKIP_TEST=4 + +# Verify we have LKDTM available in the kernel. +if [ ! -r $TRIGGER ] ; then + /sbin/modprobe -q lkdtm || true + if [ ! -r $TRIGGER ] ; then + echo "Cannot find $TRIGGER (missing CONFIG_LKDTM?)" + else + echo "Cannot write $TRIGGER (need to run as root?)" + fi + # Skip this test + exit $KSELFTEST_SKIP_TEST +fi # Capture dmesg continuously since it may fill up depending on sample size. log=$(mktemp -t stack-entropy-XXXXXX) dmesg --follow >"$log" & pid=$! report=-1 for i in $(seq 1 $samples); do - echo "REPORT_STACK" >/sys/kernel/debug/provoke-crash/DIRECT + echo "REPORT_STACK" > $TRIGGER if [ -t 1 ]; then percent=$(( 100 * $i / $samples )) if [ "$percent" -ne "$report" ]; then |