The test creates a buffer, sets it as DONTNEED via madvise, tries to
trigger a purge of buffers and then accesses the buffer via a user-space
mapping. This should generate a bus error, but due to a bug in the
kernel driver it fails to invalidate the mapping when the buffer is
purged.
Signed-off-by: Neil Roberts <nroberts@xxxxxxxxxx>
---
tests/meson.build | 1 +
tests/panfrost_purgemap.c | 146 ++++++++++++++++++++++++++++++++++++++
2 files changed, 147 insertions(+)
create mode 100644 tests/panfrost_purgemap.c
diff --git a/tests/meson.build b/tests/meson.build
index 825e0183..af24427a 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -82,6 +82,7 @@ test_progs = [
'panfrost_get_param',
'panfrost_gem_new',
'panfrost_prime',
+ 'panfrost_purgemap',
'panfrost_submit',
'prime_busy',
'prime_mmap',
diff --git a/tests/panfrost_purgemap.c b/tests/panfrost_purgemap.c
new file mode 100644
index 00000000..096fb95a
--- /dev/null
+++ b/tests/panfrost_purgemap.c
@@ -0,0 +1,146 @@
+/*
+ * Copyright © 2021 Igalia
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "igt.h"
+#include "igt_panfrost.h"
+#include "igt_syncobj.h"
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <setjmp.h>
+#include <signal.h>
+#include "panfrost-job.h"
+#include "panfrost_drm.h"
+
+IGT_TEST_DESCRIPTION("Checks that accessing an mmapping of a buffer that has "
+ "been purged causes a bus fault signal.");
+
+#define BUF_SIZE (32 * 1024 * 1024)
+
+struct buf_link {
+ struct panfrost_bo *bo;
+ struct buf_link *next;
+};
+
+static jmp_buf jmp;
+
+__noreturn static void sigtrap(int sig)
+{
+ siglongjmp(jmp, sig);
+}
+
+static void
+try_writing_to_mmap(uint8_t *ptr)
+{
+ sighandler_t old_sigsegv, old_sigbus;
+
+ old_sigsegv = signal(SIGSEGV, sigtrap);
+ old_sigbus = signal(SIGBUS, sigtrap);
+
+ switch (sigsetjmp(jmp, SIGBUS | SIGSEGV)) {
+ case SIGBUS:
+ break;
+ case 0:
+ *ptr = 0;
+ default:
+ igt_assert(!"reached");
+ break;
+ }
+
+ signal(SIGBUS, old_sigsegv);
+ signal(SIGSEGV, old_sigbus);
+}
+
+static void
+trigger_purge(int fd, struct panfrost_bo *madv_bo)
+{
+ struct buf_link *buf_list = NULL, *next, *buf;
+ bool retained;
+
+ /* Try to trigger a purge by allocating buffers until the main
+ * buffer is no longer retained. This should probably be
+ * replaced with a more reliable way to do this such as a
+ * debugfs trigger.
+ */
+
+ while (true) {
+ /* Mark the buffer as purgeable */
+ retained = igt_panfrost_bo_madvise(fd,
+ madv_bo,
+ PANFROST_MADV_DONTNEED);
+ igt_assert(retained);
+
+ buf = malloc(sizeof(*buf));
+ buf->bo = igt_panfrost_gem_new(fd, BUF_SIZE);
+ buf->next = buf_list;
+ buf_list = buf;
+
+ /* Check if that caused the buffer to be purged */
+ retained = igt_panfrost_bo_madvise(fd,
+ madv_bo,
+ PANFROST_MADV_WILLNEED);
+
+ if (!retained)
+ break;
+ }
+
+ /* Free all the temporary buffers that we created */
+ for (buf = buf_list; buf; buf = next) {
+ next = buf->next;
+ igt_panfrost_free_bo(fd, buf->bo);
+ free(buf);
+ }
+}
+
+igt_simple_main
+{
+ int fd;
+ struct panfrost_bo *bo;
+
+ fd = drm_open_driver(DRIVER_PANFROST);
+
+ bo = igt_panfrost_gem_new(fd, BUF_SIZE);
+
+ igt_panfrost_bo_mmap(fd, bo);
+
+ /* Write to the buffer to make sure the first page is
+ * paged in
+ */
+ memset(bo->map, 42, 64);
+
+ /* Try to cause the buffer to be purged */
+ trigger_purge(fd, bo);
+
+ /* Write through the mapping. This should cause a bus fault. */
+ try_writing_to_mmap(bo->map);
+
+ igt_panfrost_free_bo(fd, bo);
+
+ close(fd);
+}
--
2.29.2
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