[PATCH 3/3] tests/tcg: Add riscv test for interrupted vector ops

[Nicholas Piggin <npiggin@gmail.com>]

riscv vector instructions can be interrupted with a trap, and partial
completion is recorded in the vstart register. Some causes are
implementation dependent, for example an asynchronous interrupt (which I
don't think TCG allows). Others are architectural, typically memory
access faults on vector load/store instructions.

Add some TCG tests for interrupting vector load instructions and
resuming partially completed ones.

This would have caught a recent (now reverted) regression in vector
stride load implementation, commit 28c12c1f2f50d ("Generate strided
vector loads/stores with tcg nodes.")

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 tests/tcg/riscv64/Makefile.target      |   5 +
 tests/tcg/riscv64/test-interrupted-v.c | 208 +++++++++++++++++++++++++
 2 files changed, 213 insertions(+)
 create mode 100644 tests/tcg/riscv64/test-interrupted-v.c

diff --git a/tests/tcg/riscv64/Makefile.target b/tests/tcg/riscv64/Makefile.target
index 19a49b6467..8f4690ac57 100644
--- a/tests/tcg/riscv64/Makefile.target
+++ b/tests/tcg/riscv64/Makefile.target
@@ -23,3 +23,8 @@ run-test-fcvtmod: QEMU_OPTS += -cpu rv64,d=true,zfa=true
 TESTS += test-vstart-overflow
 test-vstart-overflow: CFLAGS += -march=rv64gcv
 run-test-vstart-overflow: QEMU_OPTS += -cpu rv64,v=on
+
+# Test for interrupted vector instructions
+TESTS += test-interrupted-v
+test-interrupted-v: CFLAGS += -march=rv64gcv
+run-test-interrupted-v: QEMU_OPTS += -cpu rv64,v=on
diff --git a/tests/tcg/riscv64/test-interrupted-v.c b/tests/tcg/riscv64/test-interrupted-v.c
new file mode 100644
index 0000000000..db4fb6092f
--- /dev/null
+++ b/tests/tcg/riscv64/test-interrupted-v.c
@@ -0,0 +1,208 @@
+/*
+ * Test for interrupted vector operations.
+ *
+ * Some vector instructions can be interrupted partially complete, vstart will
+ * be set to where the operation has progressed to, and the instruction can be
+ * re-executed with vstart != 0. It is implementation dependent as to what
+ * instructions can be interrupted and what vstart values are permitted when
+ * executing them. Vector memory operations can typically be interrupted
+ * (as they can take page faults), so these are easy to test.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <stdio.h>
+#include <assert.h>
+#include <signal.h>
+#include <unistd.h>
+#include <riscv_vector.h>
+
+static unsigned long page_size;
+
+static volatile int nr_segv;
+static volatile unsigned long fault_start, fault_end;
+
+/*
+ * Careful: qemu-user does not save/restore vector state in
+ * signals yet, so any library or compiler autovec code will
+ * corrupt our test.
+ *
+ * Do only minimal work in the signal handler.
+ */
+static void SEGV_handler(int signo, siginfo_t *info, void *context)
+{
+    unsigned long page = (unsigned long)info->si_addr &
+                             ~(unsigned long)(page_size - 1);
+
+    assert((unsigned long)info->si_addr >= fault_start);
+    assert((unsigned long)info->si_addr < fault_end);
+    mprotect((void *)page, page_size, PROT_READ);
+    nr_segv++;
+}
+
+/* Use noinline to make generated code easier to inspect */
+static __attribute__((noinline))
+uint8_t unit_load(uint8_t *mem, size_t nr, bool ff)
+{
+    size_t vl;
+    vuint8m1_t vec, redvec, sum;
+
+    vl = __riscv_vsetvl_e8m1(nr);
+    if (ff) {
+        vec = __riscv_vle8ff_v_u8m1(mem, &vl, vl);
+    } else {
+        vec = __riscv_vle8_v_u8m1(mem, vl);
+    }
+    redvec = __riscv_vmv_v_x_u8m1(0, vl);
+    sum = __riscv_vredsum_vs_u8m1_u8m1(vec, redvec, vl);
+    return __riscv_vmv_x_s_u8m1_u8(sum);
+}
+
+static __attribute__((noinline))
+uint8_t seg2_load(uint8_t *mem, size_t nr, bool ff)
+{
+    size_t vl;
+    vuint8m1x2_t segvec;
+    vuint8m1_t vec, redvec, sum;
+
+    vl = __riscv_vsetvl_e8m1(nr);
+    if (ff) {
+        segvec = __riscv_vlseg2e8ff_v_u8m1x2(mem, &vl, vl);
+    } else {
+        segvec = __riscv_vlseg2e8_v_u8m1x2(mem, vl);
+    }
+    vec = __riscv_vadd_vv_u8m1(__riscv_vget_v_u8m1x2_u8m1(segvec, 0),
+                   __riscv_vget_v_u8m1x2_u8m1(segvec, 1), vl);
+    redvec = __riscv_vmv_v_x_u8m1(0, vl);
+    sum = __riscv_vredsum_vs_u8m1_u8m1(vec, redvec, vl);
+    return __riscv_vmv_x_s_u8m1_u8(sum);
+}
+
+static __attribute__((noinline))
+uint8_t strided_load(uint8_t *mem, size_t nr, size_t stride)
+{
+    size_t vl;
+    vuint8m1_t vec, redvec, sum;
+
+    vl = __riscv_vsetvl_e8m1(nr);
+    vec = __riscv_vlse8_v_u8m1(mem, stride, vl);
+    redvec = __riscv_vmv_v_x_u8m1(0, vl);
+    sum = __riscv_vredsum_vs_u8m1_u8m1(vec, redvec, vl);
+    return __riscv_vmv_x_s_u8m1_u8(sum);
+}
+
+static __attribute__((noinline))
+uint8_t indexed_load(uint8_t *mem, size_t nr, uint32_t *indices)
+{
+    size_t vl;
+    vuint32m4_t idx;
+    vuint8m1_t vec, redvec, sum;
+
+    vl = __riscv_vsetvl_e8m1(nr);
+    idx = __riscv_vle32_v_u32m4(indices, vl);
+    vec = __riscv_vloxei32_v_u8m1(mem, idx, vl);
+    redvec = __riscv_vmv_v_x_u8m1(0, vl);
+    sum = __riscv_vredsum_vs_u8m1_u8m1(vec, redvec, vl);
+    return __riscv_vmv_x_s_u8m1_u8(sum);
+}
+
+/* Use e8 elements, 128-bit vectors */
+#define NR_ELEMS 16
+
+static int run_interrupted_v_tests(void)
+{
+    struct sigaction act = { 0 };
+    uint8_t *mem;
+    uint32_t indices[NR_ELEMS];
+    int i;
+
+    page_size = sysconf(_SC_PAGESIZE);
+
+    act.sa_flags = SA_SIGINFO;
+    act.sa_sigaction = &SEGV_handler;
+    if (sigaction(SIGSEGV, &act, NULL) == -1) {
+        perror("sigaction");
+        exit(EXIT_FAILURE);
+    }
+
+    mem = mmap(NULL, NR_ELEMS * page_size, PROT_READ | PROT_WRITE,
+               MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+    assert(mem != MAP_FAILED);
+    madvise(mem, NR_ELEMS * page_size, MADV_NOHUGEPAGE);
+
+    /* Unit-stride tests load memory crossing a page boundary */
+    memset(mem, 0, NR_ELEMS * page_size);
+    for (i = 0; i < NR_ELEMS; i++) {
+        mem[page_size - NR_ELEMS + i] = 3;
+    }
+    for (i = 0; i < NR_ELEMS; i++) {
+        mem[page_size + i] = 5;
+    }
+
+    nr_segv = 0;
+    fault_start = (unsigned long)&mem[page_size - (NR_ELEMS / 2)];
+    fault_end = fault_start + NR_ELEMS;
+    mprotect(mem, page_size * 2, PROT_NONE);
+    assert(unit_load(&mem[page_size - (NR_ELEMS / 2)], NR_ELEMS, false)
+                    == 8 * NR_ELEMS / 2);
+    assert(nr_segv == 2);
+
+    nr_segv = 0;
+    fault_start = (unsigned long)&mem[page_size - NR_ELEMS];
+    fault_end = fault_start + NR_ELEMS * 2;
+    mprotect(mem, page_size * 2, PROT_NONE);
+    assert(seg2_load(&mem[page_size - NR_ELEMS], NR_ELEMS, false)
+                    == 8 * NR_ELEMS);
+    assert(nr_segv == 2);
+
+    nr_segv = 0;
+    fault_start = (unsigned long)&mem[page_size - (NR_ELEMS / 2)];
+    fault_end = fault_start + (NR_ELEMS / 2);
+    mprotect(mem, page_size * 2, PROT_NONE);
+    assert(unit_load(&mem[page_size - (NR_ELEMS / 2)], NR_ELEMS, true)
+                    == 3 * NR_ELEMS / 2);
+    assert(nr_segv == 1); /* fault-first does not fault the second page */
+
+    nr_segv = 0;
+    fault_start = (unsigned long)&mem[page_size - NR_ELEMS];
+    fault_end = fault_start + NR_ELEMS;
+    mprotect(mem, page_size * 2, PROT_NONE);
+    assert(seg2_load(&mem[page_size - NR_ELEMS], NR_ELEMS * 2, true)
+                    == 3 * NR_ELEMS);
+    assert(nr_segv == 1); /* fault-first does not fault the second page */
+
+    /* Following tests load one element from first byte of each page */
+    mprotect(mem, page_size * 2, PROT_READ | PROT_WRITE);
+    memset(mem, 0, NR_ELEMS * page_size);
+    for (i = 0; i < NR_ELEMS; i++) {
+        mem[i * page_size] = 3;
+        indices[i] = i * page_size;
+    }
+
+    nr_segv = 0;
+    fault_start = (unsigned long)mem;
+    fault_end = fault_start + NR_ELEMS * page_size;
+    mprotect(mem, NR_ELEMS * page_size, PROT_NONE);
+    assert(strided_load(mem, NR_ELEMS, page_size) == 3 * NR_ELEMS);
+    assert(nr_segv == NR_ELEMS);
+
+    nr_segv = 0;
+    fault_start = (unsigned long)mem;
+    fault_end = fault_start + NR_ELEMS * page_size;
+    mprotect(mem, NR_ELEMS * page_size, PROT_NONE);
+    assert(indexed_load(mem, NR_ELEMS, indices) == 3 * NR_ELEMS);
+    assert(nr_segv == NR_ELEMS);
+
+    munmap(mem, NR_ELEMS * page_size);
+
+    return 0;
+}
+
+int main(void)
+{
+    return run_interrupted_v_tests();
+}
-- 
2.51.0