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@xxxxxxxxxx>
CC: Mark Rutland <mark.rutland@xxxxxxx>
Message-Id: <20211118184650.661575-7-alex.bennee@xxxxxxxxxx>
---
v9
- move tests back into unittests.cfg (with nodefault mttcg)
- replace printf with report_info
- drop accel = tcg
---
arm/Makefile.common | 1 +
arm/tlbflush-code.c | 209 ++++++++++++++++++++++++++++++++++++++++++++
arm/unittests.cfg | 25 ++++++
3 files changed, 235 insertions(+)
create mode 100644 arm/tlbflush-code.c
diff --git a/arm/Makefile.common b/arm/Makefile.common
index 99bcf3fc..e3f04f2d 100644
--- a/arm/Makefile.common
+++ b/arm/Makefile.common
@@ -12,6 +12,7 @@ tests-common += $(TEST_DIR)/gic.flat
tests-common += $(TEST_DIR)/psci.flat
tests-common += $(TEST_DIR)/sieve.flat
tests-common += $(TEST_DIR)/pl031.flat
+tests-common += $(TEST_DIR)/tlbflush-code.flat
tests-all = $(tests-common) $(tests)
all: directories $(tests-all)
diff --git a/arm/tlbflush-code.c b/arm/tlbflush-code.c
new file mode 100644
index 00000000..bf9eb111
--- /dev/null
+++ b/arm/tlbflush-code.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * TLB Flush Race Tests
+ *
+ * These tests are designed to test for incorrect TLB flush semantics
+ * under emulation. The initial CPU will set all the others working a
+ * compuation task and will then trigger TLB flushes across the
+ * system. It doesn't actually need to re-map anything but the flushes
+ * themselves will trigger QEMU's TCG self-modifying code detection
+ * which will invalidate any generated code causing re-translation.
+ * Eventually the code buffer will fill and a general tb_lush() will
+ * be triggered.
+ *
+ * Copyright (C) 2016-2021, Linaro, Alex Bennée <alex.bennee@xxxxxxxxxx>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.
+ */
+
+#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 bool flush_self;
+static bool flush_page;
+static bool flush_verbose;
+
+/*
+ * 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))) static
+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))) static
+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))) static
+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))) static
+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))) static
+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;
+
+ report_info("CPU%d online", cpu);
+
+ for (i = 0 ; i < flush_count; i++) {
+ result = do_computation();
+
+ if (result != SEQ_HASH) {
+ errors++;
+ report_info("CPU%d: seq%d 0x%"PRIx32"!=0x%x",
+ cpu, i, result, SEQ_HASH);
+ }
+
+ if (flush_verbose && (i % 1000) == 0)
+ report_info("CPU%d: seq%d", cpu, i);
+
+ if (flush_self)
+ do_flush(i);
+ }
+
+ report(errors == 0, "CPU%d: Done - Errors: %d", 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_info("CPU%d: Done - Triggered %d flushes", 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 = true;
+
+ if (strcmp(arg, "self") == 0)
+ flush_self = true;
+
+ if (strcmp(arg, "verbose") == 0)
+ flush_verbose = true;
+ }
+
+ 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/arm/unittests.cfg b/arm/unittests.cfg
index 945c2d07..34c8a95b 100644
--- a/arm/unittests.cfg
+++ b/arm/unittests.cfg
@@ -241,3 +241,28 @@ arch = arm64
file = cache.flat
arch = arm64
groups = cache
+
+# TLB Torture Tests
+[tlbflush-code::all_other]
+file = tlbflush-code.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+groups = nodefault mttcg
+
+[tlbflush-code::page_other]
+file = tlbflush-code.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'page'
+groups = nodefault mttcg
+
+[tlbflush-code::all_self]
+file = tlbflush-code.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'self'
+groups = nodefault mttcg
+
+[tlbflush-code::page_self]
+file = tlbflush-code.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'page self'
+groups = nodefault mttcg
+
--
2.30.2
