Ciro Santilli has uploaded this change for review. (
https://gem5-review.googlesource.com/c/public/gem5/+/30634 )
Change subject: tests: add arm64/futex_ldxr_stxr.c
......................................................................
tests: add arm64/futex_ldxr_stxr.c
For: https://gem5.atlassian.net/browse/GEM5-537
Change-Id: I943d78f797685f253b7095847a254767c79a2421
---
A tests/test-progs/arm64/futex_ldxr_stxr.c
1 file changed, 126 insertions(+), 0 deletions(-)
diff --git a/tests/test-progs/arm64/futex_ldxr_stxr.c
b/tests/test-progs/arm64/futex_ldxr_stxr.c
new file mode 100644
index 0000000..b044494
--- /dev/null
+++ b/tests/test-progs/arm64/futex_ldxr_stxr.c
@@ -0,0 +1,126 @@
+/* Copyright (c) 2020 ARM Limited
+ * All rights reserved
+ *
+ * The license below extends only to copyright in the software and shall
+ * not be construed as granting a license to any other intellectual
+ * property including but not limited to intellectual property relating
+ * to a hardware implementation of the functionality of the software
+ * licensed hereunder. You may use the software subject to the license
+ * terms below provided that you ensure that this notice is replicated
+ * unmodified and in its entirety in all distributions of the software,
+ * modified or unmodified, in source code or in binary form.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Correct outcome:
+ * Exiting @ tick 18446744073709551615 because simulate() limit reached
+ * Incorrect behaviour due to: https://gem5.atlassian.net/browse/GEM5-537
+ * Exits successfully. */
+
+#define _GNU_SOURCE
+#include <assert.h>
+#include <inttypes.h>
+#include <linux/futex.h>
+#include <pthread.h>
+#include <stdatomic.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#define LDXR_OPS_SIZE 1024
+static int futex1 = 1;
+static int futex2 = 1;
+/* We do this to ensure that those two varibles are well separated.
+ * If they are too close (same cache line?), then the str to ldxr_done
+ * can make CPU1 lose the lock. */
+static uint64_t ldxr_ops[LDXR_OPS_SIZE];
+static uint64_t *ldxr_done = ldxr_ops;
+static uint64_t *ldxr_var = ldxr_ops + LDXR_OPS_SIZE - 1;
+
+void __attribute__ ((noinline)) busy_loop(
+ unsigned long long max,
+ unsigned long long max2
+) {
+ for (unsigned long long i = 0; i < max2; i++) {
+ for (unsigned long long j = 0; j < max; j++) {
+ __asm__ __volatile__ ("" : "+g" (i), "+g" (j) : :);
+ }
+ }
+}
+
+static int
+futex(int *uaddr, int futex_op, int val,
+ const struct timespec *timeout, int *uaddr2, int val3)
+{
+ register uint64_t x0 __asm__ ("x0") = (uint64_t)uaddr;
+ register uint64_t x1 __asm__ ("x1") = futex_op;
+ register uint64_t x2 __asm__ ("x2") = val;
+ register const struct timespec *x3 __asm__ ("x3") = timeout;
+ register int *x4 __asm__ ("x4") = uaddr2;
+ register uint64_t x5 __asm__ ("x5") = val3;
+ register uint64_t x8 __asm__ ("x8") = SYS_futex; /* syscall number */
+ __asm__ __volatile__ (
+ "svc 0;"
+ : "+r" (x0)
+ : "r" (x1), "r" (x2), "r" (x3), "r" (x4), "r" (x5), "r" (x8)
+ : "memory"
+ );
+ return x0;
+}
+
+void* thread_main(void *arg) {
+ (void)arg;
+ __asm__ __volatile__ (
+ "ldxr x0, [%[ldxr_var]];mov %[ldxr_done], 1"
+ : [ldxr_done] "=r" (*ldxr_done)
+ : [ldxr_var] "r" (ldxr_var)
+ : "x0", "memory"
+ );
+ futex(&futex1, FUTEX_WAIT, futex1, NULL, NULL, 0);
+ futex(&futex2, FUTEX_WAIT, futex2, NULL, NULL, 0);
+ return NULL;
+}
+
+int main(void) {
+ pthread_t thread;
+ pthread_create(&thread, NULL, thread_main, NULL);
+ while (!*ldxr_done) {}
+ /* Wait for thread1 to sleep on futex1. Works because */
+ busy_loop(1000, 1);
+ /* Try to wake up the thread with an LLSC event.
+ * It should not wake up in a correct implementation,
+ * but it used to happen in gem5 before it was fixed. */
+ __asm__ __volatile__ (
+ "mov x0, 1;ldxr x0, [%0]; stxr w1, x0, [%0]"
+ :
+ : "r" (ldxr_var) : "x0", "x1", "memory"
+ );
+ /* Wait for thread1 to sleep on futex2. */
+ busy_loop(1000, 1);
+ /* Before it was fixed in gem5, this would wrongly wake a futex2
+ * because the previous futex1 was woken up via LLSC. */
+ futex(&futex1, FUTEX_WAKE, 1, NULL, NULL, 0);
+ assert(!pthread_join(thread, NULL));
+}
--
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Gerrit-Project: public/gem5
Gerrit-Branch: develop
Gerrit-Change-Id: I943d78f797685f253b7095847a254767c79a2421
Gerrit-Change-Number: 30634
Gerrit-PatchSet: 1
Gerrit-Owner: Ciro Santilli <ciro.santi...@arm.com>
Gerrit-MessageType: newchange
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