These tests are not really aimed at KVM at all but exist to stretch
QEMU's TCG code generator. In particular these exercise the ability of
the TCG to:
* Chain TranslationBlocks together (tight)
* Handle heavy usage of the tb_jump_cache (paged)
* Pathological case of computed local jumps (computed)
In addition the tests can be varied by adding IPI IRQs or SMC sequences
into the mix to stress the tcg_exit and invalidation mechanisms.
To explicitly stress the tb_flush() mechanism you can use the mod/rounds
parameters to force more frequent tb invalidation. Combined with setting
-tb-size 1 in QEMU to limit the code generation buffer size.
Signed-off-by: Alex Bennée <alex.bennee@xxxxxxxxxx>
Message-Id: <20211118184650.661575-11-alex.bennee@xxxxxxxxxx>
---
v9
- moved back to unittests.cfg
- fixed some missing accel tags
- s/printf/report_info/
- clean up some comment blocks
---
arm/Makefile.arm | 2 +
arm/Makefile.arm64 | 2 +
arm/Makefile.common | 1 +
arm/tcg-test-asm.S | 171 ++++++++++++++++++++++
arm/tcg-test-asm64.S | 170 ++++++++++++++++++++++
arm/tcg-test.c | 340 +++++++++++++++++++++++++++++++++++++++++++
arm/unittests.cfg | 84 +++++++++++
7 files changed, 770 insertions(+)
create mode 100644 arm/tcg-test-asm.S
create mode 100644 arm/tcg-test-asm64.S
create mode 100644 arm/tcg-test.c
diff --git a/arm/Makefile.arm b/arm/Makefile.arm
index 01fd4c7b..6af61033 100644
--- a/arm/Makefile.arm
+++ b/arm/Makefile.arm
@@ -37,4 +37,6 @@ tests =
include $(SRCDIR)/$(TEST_DIR)/Makefile.common
+$(TEST_DIR)/tcg-test.elf: $(cstart.o) $(TEST_DIR)/tcg-test.o $(TEST_DIR)/tcg-test-asm.o
+
arch_clean: arm_clean
diff --git a/arm/Makefile.arm64 b/arm/Makefile.arm64
index 42e18e77..72da5033 100644
--- a/arm/Makefile.arm64
+++ b/arm/Makefile.arm64
@@ -35,5 +35,7 @@ tests += $(TEST_DIR)/debug.flat
include $(SRCDIR)/$(TEST_DIR)/Makefile.common
+$(TEST_DIR)/tcg-test.elf: $(cstart.o) $(TEST_DIR)/tcg-test.o $(TEST_DIR)/tcg-test-asm64.o
+
arch_clean: arm_clean
$(RM) lib/arm64/.*.d
diff --git a/arm/Makefile.common b/arm/Makefile.common
index 0a2bdcfc..0b81fa72 100644
--- a/arm/Makefile.common
+++ b/arm/Makefile.common
@@ -14,6 +14,7 @@ tests-common += $(TEST_DIR)/pl031.flat
tests-common += $(TEST_DIR)/tlbflush-code.flat
tests-common += $(TEST_DIR)/locking-test.flat
tests-common += $(TEST_DIR)/barrier-litmus-test.flat
+tests-common += $(TEST_DIR)/tcg-test.flat
tests-all = $(tests-common) $(tests)
all: directories $(tests-all)
diff --git a/arm/tcg-test-asm.S b/arm/tcg-test-asm.S
new file mode 100644
index 00000000..f58fac08
--- /dev/null
+++ b/arm/tcg-test-asm.S
@@ -0,0 +1,171 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * TCG Test assembler functions for armv7 tests.
+ *
+ * Copyright (C) 2016, Linaro Ltd, Alex Bennée <alex.bennee@xxxxxxxxxx>
+ *
+ * These helper functions are written in pure asm to control the size
+ * of the basic blocks and ensure they fit neatly into page
+ * aligned chunks. The pattern of branches they follow is determined by
+ * the 32 bit seed they are passed. It should be the same for each set.
+ *
+ * Calling convention
+ * - r0, iterations
+ * - r1, jump pattern
+ * - r2-r3, scratch
+ *
+ * Returns r0
+ */
+
+.arm
+
+.section .text
+
+/*
+ * Tight - all blocks should quickly be patched and should run
+ * very fast unless irqs or smc gets in the way
+ */
+
+.global tight_start
+tight_start:
+ subs r0, r0, #1
+ beq tight_end
+
+ ror r1, r1, #1
+ tst r1, #1
+ beq tightA
+ b tight_start
+
+tightA:
+ subs r0, r0, #1
+ beq tight_end
+
+ ror r1, r1, #1
+ tst r1, #1
+ beq tightB
+ b tight_start
+
+tightB:
+ subs r0, r0, #1
+ beq tight_end
+
+ ror r1, r1, #1
+ tst r1, #1
+ beq tight_start
+ b tightA
+
+.global tight_end
+tight_end:
+ mov pc, lr
+
+/*
+ * Computed jumps cannot be hardwired into the basic blocks so each one
+ * will either cause an exit for the main execution loop or trigger an
+ * inline look up for the next block.
+ *
+ * There is some caching which should ameliorate the cost a little.
+ */
+
+ /* Align << 13 == 4096 byte alignment */
+ .align 13
+ .global computed_start
+computed_start:
+ subs r0, r0, #1
+ beq computed_end
+
+ /* Jump table */
+ ror r1, r1, #1
+ and r2, r1, #1
+ adr r3, computed_jump_table
+ ldr r2, [r3, r2, lsl #2]
+ mov pc, r2
+
+ b computed_err
+
+computed_jump_table:
+ .word computed_start
+ .word computedA
+
+computedA:
+ subs r0, r0, #1
+ beq computed_end
+
+ /* Jump into code */
+ ror r1, r1, #1
+ and r2, r1, #1
+ adr r3, 1f
+ add r3, r2, lsl #2
+ mov pc, r3
+1: b computed_start
+ b computedB
+
+ b computed_err
+
+
+computedB:
+ subs r0, r0, #1
+ beq computed_end
+ ror r1, r1, #1
+
+ /* Conditional register load */
+ adr r3, computedA
+ tst r1, #1
+ adreq r3, computed_start
+ mov pc, r3
+
+ b computed_err
+
+computed_err:
+ mov r0, #1
+ .global computed_end
+computed_end:
+ mov pc, lr
+
+
+/*
+ * Page hoping
+ *
+ * Each block is in a different page, hence the blocks never get joined
+ */
+ /* Align << 13 == 4096 byte alignment */
+ .align 13
+ .global paged_start
+paged_start:
+ subs r0, r0, #1
+ beq paged_end
+
+ ror r1, r1, #1
+ tst r1, #1
+ beq pagedA
+ b paged_start
+
+ /* Align << 13 == 4096 byte alignment */
+ .align 13
+pagedA:
+ subs r0, r0, #1
+ beq paged_end
+
+ ror r1, r1, #1
+ tst r1, #1
+ beq pagedB
+ b paged_start
+
+ /* Align << 13 == 4096 byte alignment */
+ .align 13
+pagedB:
+ subs r0, r0, #1
+ beq paged_end
+
+ ror r1, r1, #1
+ tst r1, #1
+ beq paged_start
+ b pagedA
+
+ /* Align << 13 == 4096 byte alignment */
+ .align 13
+.global paged_end
+paged_end:
+ mov pc, lr
+
+.global test_code_end
+test_code_end:
diff --git a/arm/tcg-test-asm64.S b/arm/tcg-test-asm64.S
new file mode 100644
index 00000000..e69a8c72
--- /dev/null
+++ b/arm/tcg-test-asm64.S
@@ -0,0 +1,170 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * TCG Test assembler functions for armv8 tests.
+ *
+ * Copyright (C) 2016, Linaro Ltd, Alex Bennée <alex.bennee@xxxxxxxxxx>
+ *
+ * These helper functions are written in pure asm to control the size
+ * of the basic blocks and ensure they fit neatly into page
+ * aligned chunks. The pattern of branches they follow is determined by
+ * the 32 bit seed they are passed. It should be the same for each set.
+ *
+ * Calling convention
+ * - x0, iterations
+ * - x1, jump pattern
+ * - x2-x3, scratch
+ *
+ * Returns x0
+ */
+
+.section .text
+
+/*
+ * Tight - all blocks should quickly be patched and should run
+ * very fast unless irqs or smc gets in the way
+ */
+
+.global tight_start
+tight_start:
+ subs x0, x0, #1
+ beq tight_end
+
+ ror x1, x1, #1
+ tst x1, #1
+ beq tightA
+ b tight_start
+
+tightA:
+ subs x0, x0, #1
+ beq tight_end
+
+ ror x1, x1, #1
+ tst x1, #1
+ beq tightB
+ b tight_start
+
+tightB:
+ subs x0, x0, #1
+ beq tight_end
+
+ ror x1, x1, #1
+ tst x1, #1
+ beq tight_start
+ b tightA
+
+.global tight_end
+tight_end:
+ ret
+
+/*
+ * Computed jumps cannot be hardwired into the basic blocks so each one
+ * will either cause an exit for the main execution loop or trigger an
+ * inline look up for the next block.
+ *
+ * There is some caching which should ameliorate the cost a little.
+ */
+
+ /* Align << 13 == 4096 byte alignment */
+ .align 13
+ .global computed_start
+computed_start:
+ subs x0, x0, #1
+ beq computed_end
+
+ /* Jump table */
+ ror x1, x1, #1
+ and x2, x1, #1
+ adr x3, computed_jump_table
+ ldr x2, [x3, x2, lsl #3]
+ br x2
+
+ b computed_err
+
+computed_jump_table:
+ .quad computed_start
+ .quad computedA
+
+computedA:
+ subs x0, x0, #1
+ beq computed_end
+
+ /* Jump into code */
+ ror x1, x1, #1
+ and x2, x1, #1
+ adr x3, 1f
+ add x3, x3, x2, lsl #2
+ br x3
+1: b computed_start
+ b computedB
+
+ b computed_err
+
+
+computedB:
+ subs x0, x0, #1
+ beq computed_end
+ ror x1, x1, #1
+
+ /* Conditional register load */
+ adr x2, computedA
+ adr x3, computed_start
+ tst x1, #1
+ csel x2, x3, x2, eq
+ br x2
+
+ b computed_err
+
+computed_err:
+ mov x0, #1
+ .global computed_end
+computed_end:
+ ret
+
+
+/*
+ * Page hoping
+ *
+ * Each block is in a different page, hence the blocks never get joined
+ */
+ /* Align << 13 == 4096 byte alignment */
+ .align 13
+ .global paged_start
+paged_start:
+ subs x0, x0, #1
+ beq paged_end
+
+ ror x1, x1, #1
+ tst x1, #1
+ beq pagedA
+ b paged_start
+
+ /* Align << 13 == 4096 byte alignment */
+ .align 13
+pagedA:
+ subs x0, x0, #1
+ beq paged_end
+
+ ror x1, x1, #1
+ tst x1, #1
+ beq pagedB
+ b paged_start
+
+ /* Align << 13 == 4096 byte alignment */
+ .align 13
+pagedB:
+ subs x0, x0, #1
+ beq paged_end
+
+ ror x1, x1, #1
+ tst x1, #1
+ beq paged_start
+ b pagedA
+
+ /* Align << 13 == 4096 byte alignment */
+ .align 13
+.global paged_end
+paged_end:
+ ret
+
+.global test_code_end
+test_code_end:
diff --git a/arm/tcg-test.c b/arm/tcg-test.c
new file mode 100644
index 00000000..d04d56e4
--- /dev/null
+++ b/arm/tcg-test.c
@@ -0,0 +1,340 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * ARM TCG Tests
+ *
+ * These tests are explicitly aimed at stretching the QEMU TCG engine.
+ */
+
+#include <libcflat.h>
+#include <asm/processor.h>
+#include <asm/smp.h>
+#include <asm/cpumask.h>
+#include <asm/barrier.h>
+#include <asm/mmu.h>
+#include <asm/gic.h>
+
+#include <prng.h>
+
+#define MAX_CPUS 8
+
+/* These entry points are in the assembly code */
+extern int tight_start(uint32_t count, uint32_t pattern);
+extern int computed_start(uint32_t count, uint32_t pattern);
+extern int paged_start(uint32_t count, uint32_t pattern);
+extern uint32_t tight_end;
+extern uint32_t computed_end;
+extern uint32_t paged_end;
+extern unsigned long test_code_end;
+
+typedef int (*test_fn)(uint32_t count, uint32_t pattern);
+
+typedef struct {
+ const char *test_name;
+ bool should_pass;
+ test_fn start_fn;
+ uint32_t *code_end;
+} test_descr_t;
+
+/* Test array */
+static test_descr_t tests[] = {
+ /*
+ * Tight chain.
+ *
+ * These are a bunch of basic blocks that have fixed branches in
+ * a page aligned space. The branches taken are decided by a
+ * psuedo-random bitmap for each CPU.
+ *
+ * Once the basic blocks have been chained together by the TCG they
+ * should run until they reach their block count. This will be the
+ * most efficient mode in which generated code is run. The only other
+ * exits will be caused by interrupts or TB invalidation.
+ */
+ { "tight", true, tight_start, &tight_end },
+ /*
+ * Computed jumps.
+ *
+ * A bunch of basic blocks which just do computed jumps so the basic
+ * block is never chained but they are all within a page (maybe not
+ * required). This will exercise the cache lookup but not the new
+ * generation.
+ */
+ { "computed", true, computed_start, &computed_end },
+ /*
+ * Page ping pong.
+ *
+ * Have the blocks are separated by PAGE_SIZE so they can never
+ * be chained together.
+ *
+ */
+ { "paged", true, paged_start, &paged_end}
+};
+
+static test_descr_t *test;
+
+static int iterations = 1000000;
+static int rounds = 1000;
+static int mod_freq = 5;
+static uint32_t pattern[MAX_CPUS];
+
+/* control flags */
+static int smc;
+static int irq;
+static int check_irq;
+
+/* IRQ accounting */
+#define MAX_IRQ_IDS 16
+static int irqv;
+static unsigned long irq_sent_ts[MAX_CPUS][MAX_CPUS][MAX_IRQ_IDS];
+
+static int irq_recv[MAX_CPUS];
+static int irq_sent[MAX_CPUS];
+static int irq_overlap[MAX_CPUS]; /* if ts > now, i.e a race */
+static int irq_slow[MAX_CPUS]; /* if delay > threshold */
+static unsigned long irq_latency[MAX_CPUS]; /* cumulative time */
+
+static int errors[MAX_CPUS];
+
+static cpumask_t smp_test_complete;
+
+static cpumask_t ready;
+
+static void wait_on_ready(void)
+{
+ cpumask_set_cpu(smp_processor_id(), &ready);
+ while (!cpumask_full(&ready))
+ cpu_relax();
+}
+
+/*
+ * This triggers TCGs SMC detection by writing values to the executing
+ * code pages. We are not actually modifying the instructions and the
+ * underlying code will remain unchanged. However this should trigger
+ * invalidation of the Translation Blocks
+ */
+
+static void trigger_smc_detection(uint32_t *start, uint32_t *end)
+{
+ volatile uint32_t *ptr = start;
+
+ while (ptr < end) {
+ uint32_t inst = *ptr;
+ *ptr++ = inst;
+ }
+}
+
+/* Handler for receiving IRQs */
+
+static void irq_handler(struct pt_regs *regs __unused)
+{
+ unsigned long then, now = get_cntvct();
+ int cpu = smp_processor_id();
+ u32 irqstat = gic_read_iar();
+ u32 irqnr = gic_iar_irqnr(irqstat);
+
+ if (irqnr != GICC_INT_SPURIOUS) {
+ unsigned int src_cpu = (irqstat >> 10) & 0x7;
+
+ gic_write_eoir(irqstat);
+ irq_recv[cpu]++;
+
+ then = irq_sent_ts[src_cpu][cpu][irqnr];
+
+ if (then > now) {
+ irq_overlap[cpu]++;
+ } else {
+ unsigned long latency = (now - then);
+
+ if (latency > 30000)
+ irq_slow[cpu]++;
+ else
+ irq_latency[cpu] += latency;
+ }
+ }
+}
+
+/*
+ * This triggers cross-CPU IRQs. Each IRQ should cause the basic block
+ * execution to finish the main run-loop get entered again.
+ */
+static int send_cross_cpu_irqs(int this_cpu, int irq)
+{
+ int cpu, sent = 0;
+ cpumask_t mask;
+
+ cpumask_copy(&mask, &cpu_present_mask);
+
+ for_each_present_cpu(cpu) {
+ if (cpu != this_cpu) {
+ irq_sent_ts[this_cpu][cpu][irq] = get_cntvct();
+ cpumask_clear_cpu(cpu, &mask);
+ sent++;
+ }
+ }
+
+ gic_ipi_send_mask(irq, &mask);
+
+ return sent;
+}
+
+static void do_test(void)
+{
+ int cpu = smp_processor_id();
+ int i, irq_id = 0;
+
+ report_info("CPU%d: online and setting up with pattern 0x%"PRIx32,
+ cpu, pattern[cpu]);
+
+ if (irq) {
+ gic_enable_defaults();
+#ifdef __arm__
+ install_exception_handler(EXCPTN_IRQ, irq_handler);
+#else
+ install_irq_handler(EL1H_IRQ, irq_handler);
+#endif
+ local_irq_enable();
+
+ wait_on_ready();
+ }
+
+ for (i = 0; i < rounds; i++) {
+ /* Enter the blocks */
+ errors[cpu] += test->start_fn(iterations, pattern[cpu]);
+
+ if ((i + cpu) % mod_freq == 0) {
+ if (smc)
+ trigger_smc_detection((uint32_t *) test->start_fn,
+ test->code_end);
+
+ if (irq) {
+ irq_sent[cpu] += send_cross_cpu_irqs(cpu, irq_id);
+ irq_id++;
+ irq_id = irq_id % 15;
+ }
+ }
+ }
+
+ /* ensure everything complete before we finish */
+ smp_wmb();
+
+ cpumask_set_cpu(cpu, &smp_test_complete);
+ if (cpu != 0)
+ halt();
+}
+
+static void report_irq_stats(int cpu)
+{
+ int recv = irq_recv[cpu];
+ int race = irq_overlap[cpu];
+ int slow = irq_slow[cpu];
+
+ unsigned long avg_latency = irq_latency[cpu] / (recv - (race + slow));
+
+ report_info("CPU%d: %d irqs (%d races, %d slow, %ld ticks avg latency)",
+ cpu, recv, race, slow, avg_latency);
+}
+
+
+static void setup_and_run_tcg_test(void)
+{
+ static const unsigned char seed[] = "tcg-test";
+ struct isaac_ctx prng_context;
+ int cpu;
+ int total_err = 0, total_sent = 0, total_recv = 0;
+
+ isaac_init(&prng_context, &seed[0], sizeof(seed));
+
+ /* boot other CPUs */
+ for_each_present_cpu(cpu) {
+ pattern[cpu] = isaac_next_uint32(&prng_context);
+
+ if (cpu == 0)
+ continue;
+
+ smp_boot_secondary(cpu, do_test);
+ }
+
+ do_test();
+
+ while (!cpumask_full(&smp_test_complete))
+ cpu_relax();
+
+ /* Ensure everything completes before we check the data */
+ smp_mb();
+
+ /* Now total up errors and irqs */
+ for_each_present_cpu(cpu) {
+ total_err += errors[cpu];
+ total_sent += irq_sent[cpu];
+ total_recv += irq_recv[cpu];
+
+ if (check_irq)
+ report_irq_stats(cpu);
+ }
+
+ if (check_irq)
+ report(total_sent == total_recv && total_err == 0,
+ "%d IRQs sent, %d received, %d errors\n",
+ total_sent, total_recv, total_err == 0);
+ else
+ report(total_err == 0, "%d errors, IRQs not checked", total_err);
+}
+
+int main(int argc, char **argv)
+{
+ int i;
+ unsigned int j;
+
+ for (i = 0; i < argc; i++) {
+ char *arg = argv[i];
+
+ for (j = 0; j < ARRAY_SIZE(tests); j++) {
+ if (strcmp(arg, tests[j].test_name) == 0)
+ test = &tests[j];
+ }
+
+ /* Test modifiers */
+ if (strstr(arg, "mod=") != NULL) {
+ char *p = strstr(arg, "=");
+
+ mod_freq = atol(p+1);
+ }
+
+ if (strstr(arg, "rounds=") != NULL) {
+ char *p = strstr(arg, "=");
+
+ rounds = atol(p+1);
+ }
+
+ if (strcmp(arg, "smc") == 0) {
+ unsigned long test_start = (unsigned long) &tight_start;
+ unsigned long test_end = (unsigned long) &test_code_end;
+
+ smc = 1;
+ mmu_set_range_ptes(mmu_idmap, test_start, test_start,
+ test_end, __pgprot(PTE_WBWA));
+
+ report_prefix_push("smc");
+ }
+
+ if (strcmp(arg, "irq") == 0) {
+ irq = 1;
+ if (!gic_init())
+ report_abort("No supported gic present!");
+ irqv = gic_version();
+ report_prefix_push("irq");
+ }
+
+ if (strcmp(arg, "check_irq") == 0)
+ check_irq = 1;
+ }
+
+ if (test) {
+ /* ensure args visible to all cores */
+ smp_mb();
+ setup_and_run_tcg_test();
+ } else {
+ report(false, "Unknown test");
+ }
+
+ return report_summary();
+}
diff --git a/arm/unittests.cfg b/arm/unittests.cfg
index 3d73e308..5b46ff5b 100644
--- a/arm/unittests.cfg
+++ b/arm/unittests.cfg
@@ -361,3 +361,87 @@ smp = 2
extra_params = -append 'sal_barrier'
groups = nodefault mttcg barrier
+# TCG Tests
+[tcg::tight]
+file = tcg-test.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'tight'
+groups = nodefault mttcg
+accel = tcg
+
+[tcg::tight-smc]
+file = tcg-test.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'tight smc' -accel tcg,tb-size=1
+groups = nodefault mttcg
+accel = tcg
+
+[tcg::tight-irq]
+file = tcg-test.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'tight irq'
+groups = nodefault mttcg
+accel = tcg
+
+[tcg::tight-smc-irq]
+file = tcg-test.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'tight smc irq'
+groups = nodefault mttcg
+accel = tcg
+
+[tcg::computed]
+file = tcg-test.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'computed'
+groups = nodefault mttcg
+accel = tcg
+
+[tcg::computed-smc]
+file = tcg-test.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'computed smc'
+groups = nodefault mttcg
+accel = tcg
+
+[tcg::computed-irq]
+file = tcg-test.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'computed irq'
+groups = nodefault mttcg
+accel = tcg
+
+[tcg::computed-smc-irq]
+file = tcg-test.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'computed smc irq'
+groups = nodefault mttcg
+accel = tcg
+
+[tcg::paged]
+file = tcg-test.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'paged'
+groups = nodefault mttcg
+accel = tcg
+
+[tcg::paged-smc]
+file = tcg-test.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'paged smc'
+groups = nodefault mttcg
+accel = tcg
+
+[tcg::paged-irq]
+file = tcg-test.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'paged irq'
+groups = nodefault mttcg
+accel = tcg
+
+[tcg::paged-smc-irq]
+file = tcg-test.flat
+smp = $(($MAX_SMP>4?4:$MAX_SMP))
+extra_params = -append 'paged smc irq'
+groups = nodefault mttcg
+accel = tcg
--
2.39.2
