[igt-dev] [PATCH i-g-t v2] igt/gem_userptr: Check read-only mappings
Tvrtko Ursulin
tvrtko.ursulin at linux.intel.com
Fri Jul 13 14:51:50 UTC 2018
On 13/07/2018 11:59, Chris Wilson wrote:
> Setup a userptr object that only has a read-only mapping back to a file
> store (memfd). Then attempt to write into that mapping using the GPU and
> assert that those writes do not land (while also writing via a writable
> userptr mapping into the same memfd to verify that the GPU is working!)
>
> v2: Pull the random batch construction into a routine to avoid
> duplication.
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> ---
> configure.ac | 1 +
> lib/ioctl_wrappers.c | 4 +-
> lib/ioctl_wrappers.h | 4 +-
> lib/meson.build | 1 +
> meson.build | 1 +
> tests/Makefile.am | 4 +-
> tests/gem_userptr_blits.c | 365 +++++++++++++++++++++++++++++++++++++-
> 7 files changed, 370 insertions(+), 10 deletions(-)
>
> diff --git a/configure.ac b/configure.ac
> index 1ee4e90e9..195963d4f 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -125,6 +125,7 @@ PKG_CHECK_MODULES(PCIACCESS, [pciaccess >= 0.10])
> PKG_CHECK_MODULES(KMOD, [libkmod])
> PKG_CHECK_MODULES(PROCPS, [libprocps])
> PKG_CHECK_MODULES(LIBUNWIND, [libunwind])
> +PKG_CHECK_MODULES(SSL, [openssl])
> PKG_CHECK_MODULES(VALGRIND, [valgrind], [have_valgrind=yes], [have_valgrind=no])
>
> if test x$have_valgrind = xyes; then
> diff --git a/lib/ioctl_wrappers.c b/lib/ioctl_wrappers.c
> index 79db44a8c..d5d2a4e4c 100644
> --- a/lib/ioctl_wrappers.c
> +++ b/lib/ioctl_wrappers.c
> @@ -869,7 +869,7 @@ int gem_madvise(int fd, uint32_t handle, int state)
> return madv.retained;
> }
>
> -int __gem_userptr(int fd, void *ptr, int size, int read_only, uint32_t flags, uint32_t *handle)
> +int __gem_userptr(int fd, void *ptr, uint64_t size, int read_only, uint32_t flags, uint32_t *handle)
> {
> struct drm_i915_gem_userptr userptr;
>
> @@ -898,7 +898,7 @@ int __gem_userptr(int fd, void *ptr, int size, int read_only, uint32_t flags, ui
> *
> * Returns userptr handle for the GEM object.
> */
> -void gem_userptr(int fd, void *ptr, int size, int read_only, uint32_t flags, uint32_t *handle)
> +void gem_userptr(int fd, void *ptr, uint64_t size, int read_only, uint32_t flags, uint32_t *handle)
> {
> igt_assert_eq(__gem_userptr(fd, ptr, size, read_only, flags, handle), 0);
> }
> diff --git a/lib/ioctl_wrappers.h b/lib/ioctl_wrappers.h
> index b966f72c9..8e2cd380b 100644
> --- a/lib/ioctl_wrappers.h
> +++ b/lib/ioctl_wrappers.h
> @@ -133,8 +133,8 @@ struct local_i915_gem_userptr {
> #define LOCAL_I915_USERPTR_UNSYNCHRONIZED (1<<31)
> uint32_t handle;
> };
> -void gem_userptr(int fd, void *ptr, int size, int read_only, uint32_t flags, uint32_t *handle);
> -int __gem_userptr(int fd, void *ptr, int size, int read_only, uint32_t flags, uint32_t *handle);
> +void gem_userptr(int fd, void *ptr, uint64_t size, int read_only, uint32_t flags, uint32_t *handle);
> +int __gem_userptr(int fd, void *ptr, uint64_t size, int read_only, uint32_t flags, uint32_t *handle);
>
> void gem_sw_finish(int fd, uint32_t handle);
>
> diff --git a/lib/meson.build b/lib/meson.build
> index 1a355414e..939167f91 100644
> --- a/lib/meson.build
> +++ b/lib/meson.build
> @@ -62,6 +62,7 @@ lib_deps = [
> pthreads,
> math,
> realtime,
> + ssl,
> ]
>
> if libdrm_intel.found()
> diff --git a/meson.build b/meson.build
> index 59e729723..8d4d75cfa 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -98,6 +98,7 @@ pciaccess = dependency('pciaccess', version : '>=0.10')
> libkmod = dependency('libkmod')
> libprocps = dependency('libprocps', required : true)
> libunwind = dependency('libunwind', required : true)
> +ssl = dependency('openssl', required : true)
>
> valgrind = null_dep
> valgrindinfo = 'No'
> diff --git a/tests/Makefile.am b/tests/Makefile.am
> index 69300448a..0b4c45b04 100644
> --- a/tests/Makefile.am
> +++ b/tests/Makefile.am
> @@ -126,8 +126,8 @@ gem_tiled_swapping_CFLAGS = $(AM_CFLAGS) $(THREAD_CFLAGS)
> gem_tiled_swapping_LDADD = $(LDADD) -lpthread
> prime_self_import_CFLAGS = $(AM_CFLAGS) $(THREAD_CFLAGS)
> prime_self_import_LDADD = $(LDADD) -lpthread
> -gem_userptr_blits_CFLAGS = $(AM_CFLAGS) $(THREAD_CFLAGS)
> -gem_userptr_blits_LDADD = $(LDADD) -lpthread
> +gem_userptr_blits_CFLAGS = $(AM_CFLAGS) $(THREAD_CFLAGS) $(SSL_CFLAGS)
> +gem_userptr_blits_LDADD = $(LDADD) $(SSL_LIBS) -lpthread
> perf_pmu_LDADD = $(LDADD) $(top_builddir)/lib/libigt_perf.la
>
> gem_eio_LDADD = $(LDADD) -lrt
> diff --git a/tests/gem_userptr_blits.c b/tests/gem_userptr_blits.c
> index 7e3b6ef38..909dd19df 100644
> --- a/tests/gem_userptr_blits.c
> +++ b/tests/gem_userptr_blits.c
> @@ -43,13 +43,17 @@
> #include <fcntl.h>
> #include <inttypes.h>
> #include <errno.h>
> +#include <setjmp.h>
> #include <sys/stat.h>
> #include <sys/time.h>
> #include <sys/mman.h>
> +#include <openssl/sha.h>
> #include <signal.h>
> #include <pthread.h>
> #include <time.h>
>
> +#include <linux/memfd.h>
> +
> #include "drm.h"
> #include "i915_drm.h"
>
> @@ -238,6 +242,57 @@ blit(int fd, uint32_t dst, uint32_t src, uint32_t *all_bo, int n_bo)
> return ret;
> }
>
> +static void store_dword(int fd, uint32_t target,
> + uint32_t offset, uint32_t value)
> +{
> + const int gen = intel_gen(intel_get_drm_devid(fd));
> + struct drm_i915_gem_exec_object2 obj[2];
> + struct drm_i915_gem_relocation_entry reloc;
> + struct drm_i915_gem_execbuffer2 execbuf;
> + uint32_t batch[16];
> + int i;
> +
> + memset(&execbuf, 0, sizeof(execbuf));
> + execbuf.buffers_ptr = to_user_pointer(obj);
> + execbuf.buffer_count = ARRAY_SIZE(obj);
> + execbuf.flags = 0;
> + if (gen < 6)
> + execbuf.flags |= I915_EXEC_SECURE;
> +
> + memset(obj, 0, sizeof(obj));
> + obj[0].handle = target;
> + obj[1].handle = gem_create(fd, 4096);
> +
> + memset(&reloc, 0, sizeof(reloc));
> + reloc.target_handle = obj[0].handle;
> + reloc.presumed_offset = 0;
> + reloc.offset = sizeof(uint32_t);
> + reloc.delta = offset;
> + reloc.read_domains = I915_GEM_DOMAIN_RENDER;
> + reloc.write_domain = I915_GEM_DOMAIN_RENDER;
> + obj[1].relocs_ptr = to_user_pointer(&reloc);
> + obj[1].relocation_count = 1;
> +
> + i = 0;
> + batch[i] = MI_STORE_DWORD_IMM | (gen < 6 ? 1 << 22 : 0);
> + if (gen >= 8) {
> + batch[++i] = offset;
> + batch[++i] = 0;
> + } else if (gen >= 4) {
> + batch[++i] = 0;
> + batch[++i] = offset;
> + reloc.offset += sizeof(uint32_t);
> + } else {
> + batch[i]--;
> + batch[++i] = offset;
> + }
> + batch[++i] = value;
> + batch[++i] = MI_BATCH_BUFFER_END;
> + gem_write(fd, obj[1].handle, 0, batch, sizeof(batch));
> + gem_execbuf(fd, &execbuf);
> + gem_close(fd, obj[1].handle);
> +}
> +
> static uint32_t
> create_userptr(int fd, uint32_t val, uint32_t *ptr)
> {
> @@ -941,6 +996,303 @@ static int test_dmabuf(void)
> return 0;
> }
>
> +static void store_dword_rand(int i915, unsigned int engine,
> + uint32_t target, uint64_t sz,
> + int count)
> +{
> + const int gen = intel_gen(intel_get_drm_devid(i915));
> + struct drm_i915_gem_relocation_entry *reloc;
> + struct drm_i915_gem_exec_object2 obj[2];
> + struct drm_i915_gem_execbuffer2 exec;
> + unsigned int batchsz;
> + uint32_t *batch;
> + int i;
> +
> + batchsz = count * 16 + 4;
> + batchsz = ALIGN(batchsz, 4096);
> +
> + reloc = calloc(sizeof(*reloc), count);
> +
> + memset(obj, 0, sizeof(obj));
> + obj[0].handle = target;
> + obj[0].flags = LOCAL_EXEC_OBJECT_SUPPORTS_48B;
> + obj[1].handle = gem_create(i915, batchsz);
> + obj[1].relocation_count = count;
> + obj[1].relocs_ptr = to_user_pointer(reloc);
> +
> + batch = gem_mmap__wc(i915, obj[1].handle, 0, batchsz, PROT_WRITE);
> +
> + memset(&exec, 0, sizeof(exec));
> + exec.buffer_count = 2;
> + exec.buffers_ptr = to_user_pointer(obj);
> + exec.flags = engine;
> + if (gen < 6)
> + exec.flags |= I915_EXEC_SECURE;
> +
> + i = 0;
> + for (int n = 0; n < count; n++) {
> + uint64_t offset;
> +
> + reloc[n].target_handle = obj[0].handle;
> + reloc[n].delta = rand() % (sz / 4) * 4;
> + reloc[n].offset = (i + 1) * sizeof(uint32_t);
> + reloc[n].presumed_offset = obj[0].offset;
> + reloc[n].read_domains = I915_GEM_DOMAIN_RENDER;
> + reloc[n].write_domain = I915_GEM_DOMAIN_RENDER;
> +
> + offset = reloc[n].presumed_offset + reloc[n].delta;
> +
> + batch[i] = MI_STORE_DWORD_IMM | (gen < 6 ? 1 << 22 : 0);
> + if (gen >= 8) {
> + batch[++i] = offset;
> + batch[++i] = offset >> 32;
> + } else if (gen >= 4) {
> + batch[++i] = 0;
> + batch[++i] = offset;
> + reloc[n].offset += sizeof(uint32_t);
> + } else {
> + batch[i]--;
> + batch[++i] = offset;
> + }
> + batch[++i] = rand();
> + i++;
> + }
> + batch[i] = MI_BATCH_BUFFER_END;
> + igt_assert(i * sizeof(uint32_t) < batchsz);
> + munmap(batch, batchsz);
> +
> + gem_execbuf(i915, &exec);
> +
> + gem_close(i915, obj[1].handle);
> + free(reloc);
> +}
> +
> +static void test_readonly(int i915)
> +{
> + unsigned char orig[SHA_DIGEST_LENGTH];
> + uint64_t aperture_size;
> + uint32_t whandle, rhandle;
> + size_t sz, total;
> + void *pages, *space;
> + int memfd;
> +
> + /*
> + * A small batch of pages; small enough to cheaply check for stray
> + * writes but large enough that we don't create too many VMA pointing
> + * back to this set from the large arena. The limit on total number
> + * of VMA for a process is 65,536 (at least on this kernel).
> + *
> + * We then write from the GPU through the large arena into the smaller
> + * backing storage, which we can cheaply check to see if those writes
> + * have landed (using a SHA1sum). Repeating the same random GPU writes
> + * though a read-only handle to confirm that this time the writes are
> + * discarded and the backing store unchanged.
> + */
> + sz = 16 << 12;
> + memfd = memfd_create("pages", 0);
> + igt_require(memfd != -1);
> + igt_require(ftruncate(memfd, sz) == 0);
> +
> + pages = mmap(NULL, sz, PROT_WRITE, MAP_SHARED, memfd, 0);
> + igt_assert(pages != MAP_FAILED);
> +
> + igt_require(__gem_userptr(i915, pages, sz, true, userptr_flags, &rhandle) == 0);
> + gem_close(i915, rhandle);
> +
> + gem_userptr(i915, pages, sz, false, userptr_flags, &whandle);
> +
> + /*
> + * We have only a 31bit delta which we use for generating
> + * the target address for MI_STORE_DWORD_IMM, so our maximum
> + * usuable object size is only 2GiB. For now.
> + */
> + total = 2048ull << 20;
> + aperture_size = gem_aperture_size(i915) / 2;
> + if (aperture_size < total)
> + total = aperture_size;
> + total = total / sz * sz;
> + igt_info("Using a %'zuB (%'zu pages) arena onto %zu pages\n",
> + total, total >> 12, sz >> 12);
> +
> + /* Create an arena all pointing to the same set of pages */
> + space = mmap(NULL, total, PROT_READ, MAP_ANON | MAP_SHARED, -1, 0);
> + igt_require(space != MAP_FAILED);
> + for (size_t offset = 0; offset < total; offset += sz) {
> + igt_assert(mmap(space + offset, sz,
> + PROT_WRITE, MAP_SHARED | MAP_FIXED,
> + memfd, 0) != MAP_FAILED);
> + *(uint32_t *)(space + offset) = offset;
> + }
> + igt_assert_eq_u32(*(uint32_t *)pages, (uint32_t)(total - sz));
> + igt_assert(mlock(space, total) == 0);
> + close(memfd);
> +
> + /* Check we can create a normal userptr bo wrapping the wrapper */
> + gem_userptr(i915, space, total, false, userptr_flags, &rhandle);
> + gem_set_domain(i915, rhandle, I915_GEM_DOMAIN_CPU, 0);
> + for (size_t offset = 0; offset < total; offset += sz)
> + store_dword(i915, rhandle, offset + 4, offset / sz);
> + gem_sync(i915, rhandle);
> + igt_assert_eq_u32(*(uint32_t *)(pages + 0), (uint32_t)(total - sz));
> + igt_assert_eq_u32(*(uint32_t *)(pages + 4), (uint32_t)(total / sz - 1));
> + gem_close(i915, rhandle);
> +
> + /* Now enforce read-only henceforth */
> + igt_assert(mprotect(space, total, PROT_READ) == 0);
If rhandle was still alive, would this trigger the mmu notifier
invalidation? Something to check maybe, if there is such hook.
> +
> + SHA1(pages, sz, orig);
> + igt_fork(child, 1) {
> + unsigned int engine;
> +
> + gem_userptr(i915, space, total, true, userptr_flags, &rhandle);
> +
> + for_each_engine(i915, engine) {
> + unsigned char ref[SHA_DIGEST_LENGTH];
> + unsigned char result[SHA_DIGEST_LENGTH];
> +
> + /* First tweak the backing store through the write */
> + store_dword_rand(i915, engine, whandle, sz, 1024);
> + gem_sync(i915, whandle);
> + SHA1(pages, sz, ref);
> +
> + /* Check some writes did land */
> + igt_assert(memcmp(ref, orig, sizeof(ref)));
> + memcpy(orig, ref, sizeof(orig));
> +
> + /* Now try the same through the read-only handle */
> + store_dword_rand(i915, engine, rhandle, total, 1024);
> + gem_sync(i915, rhandle);
> + SHA1(pages, sz, result);
> +
> + /*
> + * As the writes into the read-only GPU bo should fail,
> + * the SHA1 hash of the backing store should be
> + * unaffected.
> + */
> + igt_assert(memcmp(ref, result, SHA_DIGEST_LENGTH) == 0);
> + }
> +
> + gem_close(i915, rhandle);
> + }
> + igt_waitchildren();
> +
> + munmap(space, total);
> + munmap(pages, sz);
> +}
> +
> +static jmp_buf sigjmp;
> +static void sigjmp_handler(int sig)
> +{
> + siglongjmp(sigjmp, sig);
> +}
> +
> +static void test_readonly_mmap(int i915)
> +{
> + unsigned char original[SHA_DIGEST_LENGTH];
> + unsigned char result[SHA_DIGEST_LENGTH];
> + uint32_t handle;
> + uint32_t sz;
> + void *pages;
> + void *ptr;
> + int sig;
> +
> + /*
> + * A quick check to ensure that we cannot circumvent the
> + * read-only nature of our memory by creating a GTT mmap into
> + * the pages. Imagine receiving a readonly SHM segment from
> + * another process, or a readonly file mmap, it must remain readonly
> + * on the GPU as well.
> + */
> +
> + igt_require(igt_setup_clflush());
> +
> + sz = 16 << 12;
> + pages = mmap(NULL, sz, PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
> + igt_assert(pages != MAP_FAILED);
> +
> + igt_require(__gem_userptr(i915, pages, sz, true, userptr_flags, &handle) == 0);
> + gem_set_caching(i915, handle, 0);
> +
> + memset(pages, 0xa5, sz);
> + igt_clflush_range(pages, sz);
> + SHA1(pages, sz, original);
> +
> + ptr = __gem_mmap__gtt(i915, handle, sz, PROT_WRITE);
> + igt_assert(ptr == NULL);
> +
> + ptr = gem_mmap__gtt(i915, handle, sz, PROT_READ);
> + gem_close(i915, handle);
> +
> + /* Check that a write into the GTT readonly map fails */
> + if (!(sig = sigsetjmp(sigjmp, 1))) {
> + signal(SIGBUS, sigjmp_handler);
> + signal(SIGSEGV, sigjmp_handler);
> + memset(ptr, 0x5a, sz);
> + igt_assert(0);
> + }
> + igt_assert_eq(sig, SIGSEGV);
> +
> + /* Check that we disallow removing the readonly protection */
What does it mean that we are disallowing it? Is it more that we are
oblivious to it (form the userptr bo point of view)?
> + igt_assert(mprotect(ptr, sz, PROT_WRITE));
> + if (!(sig = sigsetjmp(sigjmp, 1))) {
> + signal(SIGBUS, sigjmp_handler);
> + signal(SIGSEGV, sigjmp_handler);
> + memset(ptr, 0x5a, sz);
> + igt_assert(0);
> + }
> + igt_assert_eq(sig, SIGSEGV);
> +
> + /* A single read from the GTT pointer to prove that works */
> + igt_assert_eq_u32(*(uint8_t *)ptr, 0xa5);
> + munmap(ptr, sz);
> +
> + /* Double check that the kernel did indeed not let any writes through */
> + igt_clflush_range(pages, sz);
> + SHA1(pages, sz, result);
> + igt_assert(!memcmp(original, result, sizeof(original)));
> +
> + munmap(pages, sz);
> +}
> +
> +static void test_readonly_pwrite(int i915)
> +{
> + unsigned char original[SHA_DIGEST_LENGTH];
> + unsigned char result[SHA_DIGEST_LENGTH];
> + uint32_t handle;
> + uint32_t sz;
> + void *pages;
> +
> + /*
> + * Same as for GTT mmapings, we cannot alone ourselves to
> + * circumvent readonly protection on a piece of memory via the
> + * pwrite ioctl.
> + */
> +
> + igt_require(igt_setup_clflush());
> +
> + sz = 16 << 12;
> + pages = mmap(NULL, sz, PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);
> + igt_assert(pages != MAP_FAILED);
> +
> + igt_require(__gem_userptr(i915, pages, sz, true, userptr_flags, &handle) == 0);
> + memset(pages, 0xa5, sz);
> + SHA1(pages, sz, original);
> +
> + for (int page = 0; page < 16; page++) {
> + char data[4096];
> +
> + memset(data, page, sizeof(data));
> + igt_assert_eq(__gem_write(i915, handle, page << 12, data, sizeof(data)), -EINVAL);
> + }
> +
> + gem_close(i915, handle);
> +
> + SHA1(pages, sz, result);
> + igt_assert(!memcmp(original, result, sizeof(original)));
> +
> + munmap(pages, sz);
> +}
> +
> static int test_usage_restrictions(int fd)
> {
> void *ptr;
> @@ -961,10 +1313,6 @@ static int test_usage_restrictions(int fd)
> ret = __gem_userptr(fd, (char *)ptr + 1, PAGE_SIZE - 1, 0, userptr_flags, &handle);
> igt_assert_neq(ret, 0);
>
> - /* Read-only not supported. */
> - ret = __gem_userptr(fd, (char *)ptr, PAGE_SIZE, 1, userptr_flags, &handle);
> - igt_assert_neq(ret, 0);
> -
> free(ptr);
>
> return 0;
> @@ -1502,6 +1850,15 @@ int main(int argc, char **argv)
> igt_subtest("dmabuf-unsync")
> test_dmabuf();
>
> + igt_subtest("readonly-unsync")
> + test_readonly(fd);
> +
> + igt_subtest("readonly-mmap-unsync")
> + test_readonly_mmap(fd);
> +
> + igt_subtest("readonly-pwrite-unsync")
> + test_readonly_pwrite(fd);
> +
> for (unsigned flags = 0; flags < ALL_FORKING_EVICTIONS + 1; flags++) {
> igt_subtest_f("forked-unsync%s%s%s-%s",
> flags & FORKING_EVICTIONS_SWAPPING ? "-swapping" : "",
>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Regards,
Tvrtko
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