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/*
* The PCI Library -- Physical memory mapping for POSIX systems
*
* Copyright (c) 2023 Pali Rohár <pali@kernel.org>
*
* Can be freely distributed and used under the terms of the GNU GPL v2+
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/*
* Tell 32-bit platforms that we are interested in 64-bit variant of off_t type
* as 32-bit variant of off_t type is signed and so it cannot represent all
* possible 32-bit offsets. It is required because off_t type is used by mmap().
*/
#define _FILE_OFFSET_BITS 64
#include "internal.h"
#include "physmem.h"
#include <limits.h>
#include <errno.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#ifndef OFF_MAX
#define OFF_MAX (off_t)((1ULL << (sizeof(off_t) * CHAR_BIT - 1)) - 1)
#endif
struct physmem {
int fd;
};
void
physmem_init_config(struct pci_access *a)
{
pci_define_param(a, "devmem.path", PCI_PATH_DEVMEM_DEVICE, "Path to the /dev/mem device");
}
int
physmem_access(struct pci_access *a, int w)
{
const char *devmem = pci_get_param(a, "devmem.path");
a->debug("checking access permission of physical memory device %s for %s mode...", devmem, w ? "read/write" : "read-only");
return access(devmem, R_OK | (w ? W_OK : 0));
}
struct physmem *
physmem_open(struct pci_access *a, int w)
{
const char *devmem = pci_get_param(a, "devmem.path");
struct physmem *physmem = pci_malloc(a, sizeof(struct physmem));
a->debug("trying to open physical memory device %s in %s mode...", devmem, w ? "read/write" : "read-only");
physmem->fd = open(devmem, (w ? O_RDWR : O_RDONLY) | O_DSYNC); /* O_DSYNC bypass CPU cache for mmap() on Linux */
if (physmem->fd < 0)
{
pci_mfree(physmem);
return NULL;
}
return physmem;
}
void
physmem_close(struct physmem *physmem)
{
close(physmem->fd);
pci_mfree(physmem);
}
long
physmem_get_pagesize(struct physmem *physmem UNUSED)
{
return sysconf(_SC_PAGESIZE);
}
void *
physmem_map(struct physmem *physmem, u64 addr, size_t length, int w)
{
if (addr > OFF_MAX)
{
errno = EOVERFLOW;
return (void *)-1;
}
return mmap(NULL, length, PROT_READ | (w ? PROT_WRITE : 0), MAP_SHARED, physmem->fd, addr);
}
int
physmem_unmap(struct physmem *physmem UNUSED, void *ptr, size_t length)
{
return munmap(ptr, length);
}
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