/*
 * Copyright © 2015-2018 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.
 */

#undef _FILE_OFFSET_BITS /* prevent #define open open64 */

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <stdarg.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <sys/sysmacros.h>
#include <dlfcn.h>
#include <pthread.h>
#include <i915_drm.h>

#include "util/hash_table.h"

#define INTEL_LOG_TAG "INTEL-SANITIZE-GPU"
#include "common/intel_log.h"
#include "common/gen_clflush.h"

static int (*libc_open)(const char *pathname, int flags, mode_t mode);
static int (*libc_close)(int fd);
static int (*libc_ioctl)(int fd, unsigned long request, void *argp);
static int (*libc_fcntl)(int fd, int cmd, int param);

#define DRM_MAJOR 226

/* TODO: we want to make sure that the padding forces
 * the BO to take another page on the (PP)GTT; 4KB
 * may or may not be the page size for the BO. Indeed,
 * depending on GPU, kernel version and GEM size, the
 * page size can be one of 4KB, 64KB or 2M.
 */
#define PADDING_SIZE 4096

struct refcnt_hash_table {
   struct hash_table *t;
   int refcnt;
};

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
#define MUTEX_LOCK() do {                        \
   if (unlikely(pthread_mutex_lock(&mutex))) {   \
      intel_loge("mutex_lock failed");           \
      abort();                                   \
   }                                             \
} while (0)
#define MUTEX_UNLOCK() do {                      \
   if (unlikely(pthread_mutex_unlock(&mutex))) { \
      intel_loge("mutex_unlock failed");         \
      abort();                                   \
   }                                             \
} while (0)

static struct hash_table *fds_to_bo_sizes = NULL;

static inline struct hash_table*
bo_size_table(int fd)
{
   struct hash_entry *e = _mesa_hash_table_search(fds_to_bo_sizes,
                                                  (void*)(uintptr_t)fd);
   return e ? ((struct refcnt_hash_table*)e->data)->t : NULL;
}

static inline uint64_t
bo_size(int fd, uint32_t handle)
{
   struct hash_table *t = bo_size_table(fd);
   if (!t)
      return UINT64_MAX;
   struct hash_entry *e = _mesa_hash_table_search(t, (void*)(uintptr_t)handle);
   return e ? (uint64_t)e->data : UINT64_MAX;
}

static inline bool
is_drm_fd(int fd)
{
   return !!bo_size_table(fd);
}

static inline void
add_drm_fd(int fd)
{
   struct refcnt_hash_table *r = malloc(sizeof(*r));
   r->refcnt = 1;
   r->t = _mesa_hash_table_create(NULL, _mesa_hash_pointer,
                                  _mesa_key_pointer_equal);
   _mesa_hash_table_insert(fds_to_bo_sizes, (void*)(uintptr_t)fd,
                           (void*)(uintptr_t)r);
}

static inline void
dup_drm_fd(int old_fd, int new_fd)
{
   struct hash_entry *e = _mesa_hash_table_search(fds_to_bo_sizes,
                                                  (void*)(uintptr_t)old_fd);
   struct refcnt_hash_table *r = e->data;
   r->refcnt++;
   _mesa_hash_table_insert(fds_to_bo_sizes, (void*)(uintptr_t)new_fd,
                           (void*)(uintptr_t)r);
}

static inline void
del_drm_fd(int fd)
{
   struct hash_entry *e = _mesa_hash_table_search(fds_to_bo_sizes,
                                                  (void*)(uintptr_t)fd);
   struct refcnt_hash_table *r = e->data;
   if (!--r->refcnt) {
      _mesa_hash_table_remove(fds_to_bo_sizes, e);
      _mesa_hash_table_destroy(r->t, NULL);
      free(r);
   }
}

/* Our goal is not to have noise good enough for cryto,
 * but instead values that are unique-ish enough that
 * it is incredibly unlikely that a buffer overwrite
 * will produce the exact same values.
 */
static uint8_t
next_noise_value(uint8_t prev_noise)
{
   uint32_t v = prev_noise;
   return (v * 103u + 227u) & 0xFF;
}

static void
fill_noise_buffer(uint8_t *dst, uint8_t start, uint32_t length)
{
   for(uint32_t i = 0; i < length; ++i) {
      dst[i] = start;
      start = next_noise_value(start);
   }
}

static bool
padding_is_good(int fd, uint32_t handle)
{
   struct drm_i915_gem_mmap mmap_arg = {
      .handle = handle,
      .offset = bo_size(fd, handle),
      .size = PADDING_SIZE,
      .flags = 0,
   };

   /* Unknown bo, maybe prime or userptr. Ignore */
   if (mmap_arg.offset == UINT64_MAX)
      return true;

   uint8_t *mapped;
   int ret;
   uint8_t expected_value;

   ret = libc_ioctl(fd, DRM_IOCTL_I915_GEM_MMAP, &mmap_arg);
   if (ret != 0) {
      intel_logd("Unable to map buffer %d for pad checking.", handle);
      return false;
   }

   mapped = (uint8_t*) (uintptr_t) mmap_arg.addr_ptr;
   /* bah-humbug, we need to see the latest contents and
    * if the bo is not cache coherent we likely need to
    * invalidate the cache lines to get it.
    */
   gen_invalidate_range(mapped, PADDING_SIZE);

   expected_value = handle & 0xFF;
   for (uint32_t i = 0; i < PADDING_SIZE; ++i) {
      if (expected_value != mapped[i]) {
         munmap(mapped, PADDING_SIZE);
         return false;
      }
      expected_value = next_noise_value(expected_value);
   }
   munmap(mapped, PADDING_SIZE);

   return true;
}

static int
create_with_padding(int fd, struct drm_i915_gem_create *create)
{
   create->size += PADDING_SIZE;
   int ret = libc_ioctl(fd, DRM_IOCTL_I915_GEM_CREATE, create);
   create->size -= PADDING_SIZE;

   if (ret != 0)
      return ret;

   uint8_t *noise_values;
   struct drm_i915_gem_mmap mmap_arg = {
      .handle = create->handle,
      .offset = create->size,
      .size = PADDING_SIZE,
      .flags = 0,
   };

   ret = libc_ioctl(fd, DRM_IOCTL_I915_GEM_MMAP, &mmap_arg);
   if (ret != 0)
      return 0;

   noise_values = (uint8_t*) (uintptr_t) mmap_arg.addr_ptr;
   fill_noise_buffer(noise_values, create->handle & 0xFF,
                     PADDING_SIZE);
   munmap(noise_values, PADDING_SIZE);

   _mesa_hash_table_insert(bo_size_table(fd), (void*)(uintptr_t)create->handle,
                           (void*)(uintptr_t)create->size);

   return 0;
}

static int
exec_and_check_padding(int fd, unsigned long request,
                       struct drm_i915_gem_execbuffer2 *exec)
{
   int ret = libc_ioctl(fd, request, exec);
   if (ret != 0)
      return ret;

   struct drm_i915_gem_exec_object2 *objects =
      (void*)(uintptr_t)exec->buffers_ptr;
   uint32_t batch_bo = exec->flags & I915_EXEC_BATCH_FIRST ? objects[0].handle :
      objects[exec->buffer_count - 1].handle;

   struct drm_i915_gem_wait wait = {
      .bo_handle = batch_bo,
      .timeout_ns = -1,
   };
   ret = libc_ioctl(fd, DRM_IOCTL_I915_GEM_WAIT, &wait);
   if (ret != 0)
      return ret;

   bool detected_out_of_bounds_write = false;

   for (int i = 0; i < exec->buffer_count; i++) {
      uint32_t handle = objects[i].handle;

      if (!padding_is_good(fd, handle)) {
         detected_out_of_bounds_write = true;
         intel_loge("Detected buffer out-of-bounds write in bo %d", handle);
      }
   }

   if (unlikely(detected_out_of_bounds_write)) {
      abort();
   }

   return 0;
}

static int
gem_close(int fd, struct drm_gem_close *close)
{
   int ret = libc_ioctl(fd, DRM_IOCTL_GEM_CLOSE, close);
   if (ret != 0)
      return ret;

   struct hash_table *t = bo_size_table(fd);
   struct hash_entry *e =
      _mesa_hash_table_search(t, (void*)(uintptr_t)close->handle);

   if (e)
      _mesa_hash_table_remove(t, e);

   return 0;
}

static bool
is_i915(int fd) {
   struct stat stat;
   if (fstat(fd, &stat))
      return false;

   if (!S_ISCHR(stat.st_mode) || major(stat.st_rdev) != DRM_MAJOR)
      return false;

   char name[5] = "";
   drm_version_t version = {
      .name = name,
      .name_len = sizeof(name) - 1,
   };
   if (libc_ioctl(fd, DRM_IOCTL_VERSION, &version))
      return false;

   return strcmp("i915", name) == 0;
}

__attribute__ ((visibility ("default"))) int
open(const char *path, int flags, ...)
{
   va_list args;
   mode_t mode;

   va_start(args, flags);
   mode = va_arg(args, int);
   va_end(args);

   int fd = libc_open(path, flags, mode);

   MUTEX_LOCK();

   if (fd >= 0 && is_i915(fd))
      add_drm_fd(fd);

   MUTEX_UNLOCK();

   return fd;
}

__attribute__ ((visibility ("default"), alias ("open"))) int
open64(const char *path, int flags, ...);

__attribute__ ((visibility ("default"))) int
close(int fd)
{
   MUTEX_LOCK();

   if (is_drm_fd(fd))
      del_drm_fd(fd);

   MUTEX_UNLOCK();

   return libc_close(fd);
}

__attribute__ ((visibility ("default"))) int
fcntl(int fd, int cmd, ...)
{
   va_list args;
   int param;

   va_start(args, cmd);
   param = va_arg(args, int);
   va_end(args);

   int res = libc_fcntl(fd, cmd, param);

   MUTEX_LOCK();

   if (is_drm_fd(fd) && cmd == F_DUPFD_CLOEXEC)
      dup_drm_fd(fd, res);

   MUTEX_UNLOCK();

   return res;
}

__attribute__ ((visibility ("default"))) int
ioctl(int fd, unsigned long request, ...)
{
   int res;
   va_list args;
   void *argp;

   MUTEX_LOCK();

   va_start(args, request);
   argp = va_arg(args, void *);
   va_end(args);

   if (_IOC_TYPE(request) == DRM_IOCTL_BASE && !is_drm_fd(fd) && is_i915(fd)) {
      intel_loge("missed drm fd %d", fd);
      add_drm_fd(fd);
   }

   if (is_drm_fd(fd)) {
      switch (request) {
      case DRM_IOCTL_GEM_CLOSE:
         res = gem_close(fd, (struct drm_gem_close*)argp);
         goto out;

      case DRM_IOCTL_I915_GEM_CREATE:
         res = create_with_padding(fd, (struct drm_i915_gem_create*)argp);
         goto out;

      case DRM_IOCTL_I915_GEM_EXECBUFFER2:
      case DRM_IOCTL_I915_GEM_EXECBUFFER2_WR:
         res = exec_and_check_padding(fd, request,
                                      (struct drm_i915_gem_execbuffer2*)argp);
         goto out;

      default:
         break;
      }
   }
   res = libc_ioctl(fd, request, argp);

 out:
   MUTEX_UNLOCK();
   return res;
}

static void __attribute__ ((constructor))
init(void)
{
   fds_to_bo_sizes = _mesa_hash_table_create(NULL, _mesa_hash_pointer,
                                             _mesa_key_pointer_equal);
   libc_open = dlsym(RTLD_NEXT, "open");
   libc_close = dlsym(RTLD_NEXT, "close");
   libc_fcntl = dlsym(RTLD_NEXT, "fcntl");
   libc_ioctl = dlsym(RTLD_NEXT, "ioctl");
}
