[igt-dev] [PATCH i-g-t v2 3/3] tests/i915/gem_mmap_offset: Add new API test for gem_mmap_offset

[Chris Wilson]

Quoting Zbigniew Kempczyński (2019-11-25 11:05:37)
> From: Lukasz Kalamarz <lukasz.kalamarz at intel.com>
> 
> Few simple tests which tries to create / mmap buffer objects
> using GEM_MMAP_OFFSET uAPI.
> 
> v2: change from WC -> WB (according to Chris review comment)
> 
> Signed-off-by: Lukasz Kalamarz <lukasz.kalamarz at intel.com>
> Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Vanshidhar Konda <vanshidhar.r.konda at intel.com>
> ---
>  tests/Makefile.sources       |   3 +
>  tests/i915/gem_mmap_offset.c | 126 +++++++++++++++++++++++++++++++++++
>  tests/meson.build            |   1 +
>  3 files changed, 130 insertions(+)
>  create mode 100644 tests/i915/gem_mmap_offset.c
> 
> diff --git a/tests/Makefile.sources b/tests/Makefile.sources
> index 27801c89..9c6c3933 100644
> --- a/tests/Makefile.sources
> +++ b/tests/Makefile.sources
> @@ -320,6 +320,9 @@ gem_mmap_SOURCES = i915/gem_mmap.c
>  TESTS_progs += gem_mmap_gtt
>  gem_mmap_gtt_SOURCES = i915/gem_mmap_gtt.c
>  
> +TESTS_progs += gem_mmap_offset
> +gem_mmap_offset_SOURCES = i915/gem_mmap_offset.c
> +
>  TESTS_progs += gem_mmap_offset_exhaustion
>  gem_mmap_offset_exhaustion_SOURCES = i915/gem_mmap_offset_exhaustion.c
>  
> diff --git a/tests/i915/gem_mmap_offset.c b/tests/i915/gem_mmap_offset.c
> new file mode 100644
> index 00000000..12417ae9
> --- /dev/null
> +++ b/tests/i915/gem_mmap_offset.c
> @@ -0,0 +1,126 @@
> +/*
> + * Copyright © 2019 Intel Corporation
> + *
> + * 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 <errno.h>
> +#include <sys/stat.h>
> +#include <sys/ioctl.h>
> +#include "drm.h"
> +
> +IGT_TEST_DESCRIPTION("Basic MMAP_OFFSET IOCTL tests for mem regions\n");
> +
> +static int mmap_offset_ioctl(int fd, struct local_i915_gem_mmap_offset *arg)
> +{
> +       int err = 0;
> +
> +       if (igt_ioctl(fd, LOCAL_IOCTL_I915_GEM_MMAP_OFFSET, arg))
> +               err = -errno;
> +
> +       errno = 0;
> +       return err;
> +}
> +
> +static void mmap_offset_bad_object(int fd)
> +{
> +       uint32_t real_handle;
> +       uint32_t handles[20];
> +       int i = 0;
> +
> +       real_handle = gem_create(fd, 4096);
> +
> +       handles[i++] = 0xdeadbeef;
> +       for (int bit = 0; bit < 16; bit++)
> +               handles[i++] = real_handle | (1 << (bit + 16));
> +       handles[i] = real_handle + 1;
> +
> +       for (; i >= 0; i--) {
> +               struct local_i915_gem_mmap_offset arg = {
> +                       .handle = handles[i],
> +                       .flags = LOCAL_I915_MMAP_OFFSET_WB,
> +               };
> +
> +               igt_debug("Trying MMAP IOCTL with handle %x\n",
> +                         handles[i]);
> +               igt_assert_eq(mmap_offset_ioctl(fd, &arg),
> +                             -ENOENT);
> +       }
> +
> +       gem_close(fd, real_handle);
> +}
> +
> +static void mmap_offset_basic(int fd)
> +{
> +       uint64_t flags;
> +       uint32_t handle, obj_size;
> +       uint8_t *expected, *buf, *addr;
> +
> +       obj_size = 4096;
> +       handle = gem_create(fd, obj_size);
> +       flags = LOCAL_I915_MMAP_OFFSET_WC;

Hmm, was about to say missed one...

> +       addr = __gem_mmap_offset(fd, handle, 0, obj_size,
> +                                PROT_READ | PROT_WRITE,
> +                                flags);
> +       igt_assert(addr);
> +
> +       igt_debug("Testing contents of newly created object.\n");
> +       expected = calloc(obj_size, sizeof(*expected));
> +       igt_assert_eq(memcmp(addr, expected, obj_size), 0);
> +       free(expected);
> +
> +       igt_debug("Testing coherency of writes and mmap reads.\n");
> +       buf = calloc(obj_size, sizeof(*buf));
> +       memset(buf + 1024, 0x01, 1024);
> +       gem_write(fd, handle, 0, buf, obj_size);
> +       igt_assert_eq(memcmp(buf, addr, obj_size), 0);

But you have a coherency check here, when all I was expecting was
...

> +
> +       igt_debug("Testing that mapping stays after close\n");
> +       gem_close(fd, handle);
> +       igt_assert_eq(memcmp(buf, addr, obj_size), 0);
> +       free(buf);
> +
> +       igt_debug("Testing unmapping\n");
> +       munmap(addr, obj_size);

... this mmap exists after gem_close().

I'd strongly advocate making these two independent tests. As the
mmap-vs-gem_close deserves more thorough probing as it is a source of
kernel use-after-frees (see gem_mmap_gtt::test_close_race) And
flink_race etc. But before we get into the prolonged races a simple
mmap-exists-after-close is a good basic test.
-Chris