[kvm-unit-tests PATCH v5 07/11] new arm/tlbflush-test: TLB torture test

Alex Bennée
2015-07-31T15:54:30Z

This adds a fairly brain dead torture test for TLB flushes intended for
stressing the MTTCG QEMU build. It takes the usual -smp option for
multiple CPUs.

By default it CPU0 will do a TLBIALL flush after each cycle. You can
pass options via -append to control additional aspects of the test:

- "page" flush each page in turn (one per function)
- "self" do the flush after each computation cycle
- "verbose" report progress on each computation cycle

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

---
v2
- rename to tlbflush-test
- made makefile changes cleaner
- added self/other flush mode
- create specific prefix
- whitespace fixes
---
arm/tlbflush-test.c | 194 +++++++++++++++++++++++++++++++++++++++++++
config/config-arm-common.mak | 7 +-
2 files changed, 198 insertions(+), 3 deletions(-)
create mode 100644 arm/tlbflush-test.c

diff --git a/arm/tlbflush-test.c b/arm/tlbflush-test.c
new file mode 100644
index 0000000..0375ad9
--- /dev/null
+++ b/arm/tlbflush-test.c
@@ -0,0 +1,194 @@
+#include <libcflat.h>
+#include <asm/smp.h>
+#include <asm/cpumask.h>
+#include <asm/barrier.h>
+#include <asm/mmu.h>
+
+#define SEQ_LENGTH 10
+#define SEQ_HASH 0x7cd707fe
+
+static cpumask_t smp_test_complete;
+static int flush_count = 1000000;
+static int flush_self = 0;
+static int flush_page = 0;
+static int flush_verbose = 0;
+
+/* Work functions
+ *
+ * These work functions need to be:
+ *
+ * - page aligned, so we can flush one function at a time
+ * - have branches, so QEMU TCG generates multiple basic blocks
+ * - call across pages, so we exercise the TCG basic block slow path
+ */
+
+/* Adler32 */
+__attribute__((aligned(PAGE_SIZE))) uint32_t hash_array(const void *buf,
+ size_t buflen)
+{
+ const uint8_t *data = (uint8_t *) buf;
+ uint32_t s1 = 1;
+ uint32_t s2 = 0;
+
+ for (size_t n = 0; n < buflen; n++) {
+ s1 = (s1 + data[n]) % 65521;
+ s2 = (s2 + s1) % 65521;
+ }
+ return (s2 << 16) | s1;
+}
+
+__attribute__((aligned(PAGE_SIZE))) void create_fib_sequence(int length,
+ unsigned int *array)
+{
+ int i;
+
+ /* first two values */
+ array[0] = 0;
+ array[1] = 1;
+ for (i=2; i<length; i++) {
+ array[i] = array[i-2] + array[i-1];
+ }
+}
+
+__attribute__((aligned(PAGE_SIZE))) unsigned long long factorial(unsigned int n)
+{
+ unsigned int i;
+ unsigned long long fac = 1;
+ for (i=1; i<=n; i++)
+ {
+ fac = fac * i;
+ }
+ return fac;
+}
+
+__attribute__((aligned(PAGE_SIZE))) void factorial_array
+(unsigned int n, unsigned int *input, unsigned long long *output)
+{
+ unsigned int i;
+ for (i=0; i<n; i++) {
+ output[i] = factorial(input[i]);
+ }
+}
+
+__attribute__((aligned(PAGE_SIZE))) unsigned int do_computation(void)
+{
+ unsigned int fib_array[SEQ_LENGTH];
+ unsigned long long facfib_array[SEQ_LENGTH];
+ uint32_t fib_hash, facfib_hash;
+
+ create_fib_sequence(SEQ_LENGTH, &fib_array[0]);
+ fib_hash = hash_array(&fib_array[0], sizeof(fib_array));
+ factorial_array(SEQ_LENGTH, &fib_array[0], &facfib_array[0]);
+ facfib_hash = hash_array(&facfib_array[0], sizeof(facfib_array));
+
+ return (fib_hash ^ facfib_hash);
+}
+
+/* This provides a table of the work functions so we can flush each
+ * page individually
+ */
+static void * pages[] = {&hash_array, &create_fib_sequence, &factorial,
+ &factorial_array, &do_computation};
+
+static void do_flush(int i)
+{
+ if (flush_page) {
+ flush_tlb_page((unsigned long)pages[i % ARRAY_SIZE(pages)]);
+ } else {
+ flush_tlb_all();
+ }
+}
+
+
+static void just_compute(void)
+{
+ int i, errors = 0;
+ int cpu = smp_processor_id();
+
+ uint32_t result;
+
+ printf("CPU%d online\n", cpu);
+
+ for (i=0; i < flush_count; i++) {
+ result = do_computation();
+
+ if (result != SEQ_HASH) {
+ errors++;
+ printf("CPU%d: seq%d 0x%x!=0x%x\n",
+ cpu, i, result, SEQ_HASH);
+ }
+
+ if (flush_verbose && (i % 1000) == 0) {
+ printf("CPU%d: seq%d\n", cpu, i);
+ }
+
+ if (flush_self) {
+ do_flush(i);
+ }
+ }
+
+ report("CPU%d: Done - Errors: %d\n", errors == 0, cpu, errors);
+
+ cpumask_set_cpu(cpu, &smp_test_complete);
+ if (cpu != 0)
+ halt();
+}
+
+static void just_flush(void)
+{
+ int cpu = smp_processor_id();
+ int i = 0;
+
+ /* set our CPU as done, keep flushing until everyone else
+ finished */
+ cpumask_set_cpu(cpu, &smp_test_complete);
+
+ while (!cpumask_full(&smp_test_complete)) {
+ do_flush(i++);
+ }
+
+ report("CPU%d: Done - Triggered %d flushes\n", true, cpu, i);
+}
+
+int main(int argc, char **argv)
+{
+ int cpu, i;
+ char prefix[100];
+
+ for (i=0; i<argc; i++) {
+ char *arg = argv[i];
+
+ if (strcmp(arg, "page") == 0) {
+ flush_page = 1;
+ }
+
+ if (strcmp(arg, "self") == 0) {
+ flush_self = 1;
+ }
+
+ if (strcmp(arg, "verbose") == 0) {
+ flush_verbose = 1;
+ }
+ }
+
+ snprintf(prefix, sizeof(prefix), "tlbflush_%s_%s",
+ flush_page?"page":"all",
+ flush_self?"self":"other");
+ report_prefix_push(prefix);
+
+ for_each_present_cpu(cpu) {
+ if (cpu == 0)
+ continue;
+ smp_boot_secondary(cpu, just_compute);
+ }
+
+ if (flush_self)
+ just_compute();
+ else
+ just_flush();
+
+ while (!cpumask_full(&smp_test_complete))
+ cpu_relax();
+
+ return report_summary();
+}
diff --git a/config/config-arm-common.mak b/config/config-arm-common.mak
index 0674daa..164199b 100644
--- a/config/config-arm-common.mak
+++ b/config/config-arm-common.mak
@@ -9,9 +9,9 @@ ifeq ($(LOADADDR),)
LOADADDR = 0x40000000
endif

-tests-common = \
- $(TEST_DIR)/selftest.flat \
- $(TEST_DIR)/spinlock-test.flat
+tests-common = $(TEST_DIR)/selftest.flat
+tests-common += $(TEST_DIR)/spinlock-test.flat
+tests-common += $(TEST_DIR)/tlbflush-test.flat

all: test_cases

@@ -72,3 +72,4 @@ test_cases: $(generated_files) $(tests-common) $(tests)

$(TEST_DIR)/selftest.elf: $(cstart.o) $(TEST_DIR)/selftest.o
$(TEST_DIR)/spinlock-test.elf: $(cstart.o) $(TEST_DIR)/spinlock-test.o
+$(TEST_DIR)/tlbflush-test.elf: $(cstart.o) $(TEST_DIR)/tlbflush-test.o
--
2.5.0