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/**************************************************************************
*
* Copyright 2021 Snap Inc.
* SPDX-License-Identifier: MIT
*
* 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 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.
*
**************************************************************************/
/*
* Memory fd wrappers.
*/
#include "detect_os.h"
#if DETECT_OS_UNIX
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#include "anon_file.h"
#include "mesa-sha1.h"
#include "u_math.h"
#include "os_memory.h"
/* (Re)define UUID_SIZE to avoid including vulkan.h (or p_defines.h) here. */
#define UUID_SIZE 16
struct memory_header {
size_t size;
size_t offset;
uint8_t uuid[UUID_SIZE];
};
static void
get_driver_id_sha1_hash(uint8_t sha1[SHA1_DIGEST_LENGTH], const char *driver_id) {
struct mesa_sha1 sha1_ctx;
_mesa_sha1_init(&sha1_ctx);
_mesa_sha1_update(&sha1_ctx, driver_id, strlen(driver_id));
_mesa_sha1_final(&sha1_ctx, sha1);
}
/**
* Imports memory from a file descriptor
*/
bool
os_import_memory_fd(int fd, void **ptr, uint64_t *size, char const *driver_id)
{
void *mapped_ptr;
struct memory_header header;
lseek(fd, 0, SEEK_SET);
int bytes_read = read(fd, &header, sizeof(header));
if(bytes_read != sizeof(header))
return false;
// Check the uuid we put after the sizes in order to verify that the fd
// is a memfd that we created and not some random fd.
uint8_t sha1[SHA1_DIGEST_LENGTH];
get_driver_id_sha1_hash(sha1, driver_id);
assert(SHA1_DIGEST_LENGTH >= UUID_SIZE);
if (memcmp(header.uuid, sha1, UUID_SIZE)) {
return false;
}
mapped_ptr = mmap(NULL, header.size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
if (mapped_ptr == MAP_FAILED) {
return false;
}
*ptr = (void*)((uintptr_t)mapped_ptr + header.offset);
// the offset does not count as part of the size
*size = header.size - header.offset;
return true;
}
/**
* Return memory on given byte alignment
*/
void *
os_malloc_aligned_fd(size_t size, size_t alignment, int *fd, char const *fd_name, char const *driver_id)
{
void *ptr, *buf;
int mem_fd;
size_t alloc_size, offset;
*fd = -1;
/*
* Calculate
*
* alloc_size = size + alignment + sizeof(struct memory_header) + sizeof(size_t)
*
* while checking for overflow.
*/
const size_t header_size = sizeof(struct memory_header) + sizeof(size_t);
if (add_overflow_size_t(size, alignment, &alloc_size) ||
add_overflow_size_t(alloc_size, header_size, &alloc_size))
return NULL;
mem_fd = os_create_anonymous_file(alloc_size, fd_name);
if(mem_fd < 0)
return NULL;
#if defined(HAVE_MEMFD_CREATE) || defined(ANDROID)
// Seal fd, so no one can grow or shrink the memory.
if (fcntl(mem_fd, F_ADD_SEALS, F_SEAL_SHRINK | F_SEAL_GROW | F_SEAL_SEAL) != 0)
goto fail;
#endif
ptr = mmap(NULL, alloc_size, PROT_READ | PROT_WRITE, MAP_SHARED, mem_fd, 0);
if (ptr == MAP_FAILED)
goto fail;
// Save the size and offset at the start, so we have all we need to unmap the memory
// and we are able to find the start of the actual data-section. Also save the
// offset directly before the data-section, so we can find the start of the mapped memory.
// | size | offset | ... padding ... | offset | ... data ... |
// ^ ^ ^
// 0 offset size
buf = (char *)(((uintptr_t)ptr + header_size + alignment - 1) & ~((uintptr_t)(alignment - 1)));
offset = (size_t)((uintptr_t)buf - (uintptr_t)ptr);
struct memory_header* header = (struct memory_header*)ptr;
header->size = alloc_size;
header->offset = offset;
((size_t*)buf)[-1] = offset;
// Add the hash of the driver_id as a uuid to the header in order to identify the memory
// when importing.
uint8_t sha1[SHA1_DIGEST_LENGTH];
get_driver_id_sha1_hash(sha1, driver_id);
assert(SHA1_DIGEST_LENGTH >= UUID_SIZE);
memcpy(header->uuid, sha1, UUID_SIZE);
*fd = mem_fd;
return buf;
fail:
close(mem_fd);
return NULL;
}
/**
* Free memory returned by os_malloc_aligned_fd().
*/
void
os_free_fd(void *ptr)
{
if (ptr) {
size_t offset = ((size_t*)ptr)[-1];
struct memory_header* header = (struct memory_header*)((uintptr_t)ptr - offset);
// check if the offset at the beginning of the memory
// is the same as the one we saved directly before the data.
assert(offset == header->offset);
munmap(header, header->size);
}
}
#endif
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