linux/arch/mips/vdso/genvdso.c
Guoyun Sun ad1df95419
mips/vdso: Support mremap() for vDSO
vDSO VMA address is saved in mm_context for the purpose of using
restorer from vDSO page to return to userspace after signal handling.

In Checkpoint Restore in Userspace (CRIU) project we place vDSO VMA
on restore back to the place where it was on the dump.

Make vDSO code track the VMA address by supplying .mremap() fops
the same way it's done for x86 and arm by:
commit b059a453b1 ("x86/vdso: Add mremap hook to vm_special_mapping")
commit 739586951b ("arm64/vdso: Support mremap() for vDSO").

Signed-off-by: Guoyun Sun <sunguoyun@loongson.cn>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Allison Randal <allison@lohutok.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
2020-01-15 10:44:14 -08:00

303 lines
7.8 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2015 Imagination Technologies
* Author: Alex Smith <alex.smith@imgtec.com>
*/
/*
* This tool is used to generate the real VDSO images from the raw image. It
* first patches up the MIPS ABI flags and GNU attributes sections defined in
* elf.S to have the correct name and type. It then generates a C source file
* to be compiled into the kernel containing the VDSO image data and a
* mips_vdso_image struct for it, including symbol offsets extracted from the
* image.
*
* We need to be passed both a stripped and unstripped VDSO image. The stripped
* image is compiled into the kernel, but we must also patch up the unstripped
* image's ABI flags sections so that it can be installed and used for
* debugging.
*/
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <byteswap.h>
#include <elf.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/* Define these in case the system elf.h is not new enough to have them. */
#ifndef SHT_GNU_ATTRIBUTES
# define SHT_GNU_ATTRIBUTES 0x6ffffff5
#endif
#ifndef SHT_MIPS_ABIFLAGS
# define SHT_MIPS_ABIFLAGS 0x7000002a
#endif
enum {
ABI_O32 = (1 << 0),
ABI_N32 = (1 << 1),
ABI_N64 = (1 << 2),
ABI_ALL = ABI_O32 | ABI_N32 | ABI_N64,
};
/* Symbols the kernel requires offsets for. */
static struct {
const char *name;
const char *offset_name;
unsigned int abis;
} vdso_symbols[] = {
{ "__vdso_sigreturn", "off_sigreturn", ABI_O32 },
{ "__vdso_rt_sigreturn", "off_rt_sigreturn", ABI_ALL },
{}
};
static const char *program_name;
static const char *vdso_name;
static unsigned char elf_class;
static unsigned int elf_abi;
static bool need_swap;
static FILE *out_file;
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
# define HOST_ORDER ELFDATA2LSB
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
# define HOST_ORDER ELFDATA2MSB
#endif
#define BUILD_SWAP(bits) \
static uint##bits##_t swap_uint##bits(uint##bits##_t val) \
{ \
return need_swap ? bswap_##bits(val) : val; \
}
BUILD_SWAP(16)
BUILD_SWAP(32)
BUILD_SWAP(64)
#define __FUNC(name, bits) name##bits
#define _FUNC(name, bits) __FUNC(name, bits)
#define FUNC(name) _FUNC(name, ELF_BITS)
#define __ELF(x, bits) Elf##bits##_##x
#define _ELF(x, bits) __ELF(x, bits)
#define ELF(x) _ELF(x, ELF_BITS)
/*
* Include genvdso.h twice with ELF_BITS defined differently to get functions
* for both ELF32 and ELF64.
*/
#define ELF_BITS 64
#include "genvdso.h"
#undef ELF_BITS
#define ELF_BITS 32
#include "genvdso.h"
#undef ELF_BITS
static void *map_vdso(const char *path, size_t *_size)
{
int fd;
struct stat stat;
void *addr;
const Elf32_Ehdr *ehdr;
fd = open(path, O_RDWR);
if (fd < 0) {
fprintf(stderr, "%s: Failed to open '%s': %s\n", program_name,
path, strerror(errno));
return NULL;
}
if (fstat(fd, &stat) != 0) {
fprintf(stderr, "%s: Failed to stat '%s': %s\n", program_name,
path, strerror(errno));
return NULL;
}
addr = mmap(NULL, stat.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
0);
if (addr == MAP_FAILED) {
fprintf(stderr, "%s: Failed to map '%s': %s\n", program_name,
path, strerror(errno));
return NULL;
}
/* ELF32/64 header formats are the same for the bits we're checking. */
ehdr = addr;
if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0) {
fprintf(stderr, "%s: '%s' is not an ELF file\n", program_name,
path);
return NULL;
}
elf_class = ehdr->e_ident[EI_CLASS];
switch (elf_class) {
case ELFCLASS32:
case ELFCLASS64:
break;
default:
fprintf(stderr, "%s: '%s' has invalid ELF class\n",
program_name, path);
return NULL;
}
switch (ehdr->e_ident[EI_DATA]) {
case ELFDATA2LSB:
case ELFDATA2MSB:
need_swap = ehdr->e_ident[EI_DATA] != HOST_ORDER;
break;
default:
fprintf(stderr, "%s: '%s' has invalid ELF data order\n",
program_name, path);
return NULL;
}
if (swap_uint16(ehdr->e_machine) != EM_MIPS) {
fprintf(stderr,
"%s: '%s' has invalid ELF machine (expected EM_MIPS)\n",
program_name, path);
return NULL;
} else if (swap_uint16(ehdr->e_type) != ET_DYN) {
fprintf(stderr,
"%s: '%s' has invalid ELF type (expected ET_DYN)\n",
program_name, path);
return NULL;
}
*_size = stat.st_size;
return addr;
}
static bool patch_vdso(const char *path, void *vdso)
{
if (elf_class == ELFCLASS64)
return patch_vdso64(path, vdso);
else
return patch_vdso32(path, vdso);
}
static bool get_symbols(const char *path, void *vdso)
{
if (elf_class == ELFCLASS64)
return get_symbols64(path, vdso);
else
return get_symbols32(path, vdso);
}
int main(int argc, char **argv)
{
const char *dbg_vdso_path, *vdso_path, *out_path;
void *dbg_vdso, *vdso;
size_t dbg_vdso_size, vdso_size, i;
program_name = argv[0];
if (argc < 4 || argc > 5) {
fprintf(stderr,
"Usage: %s <debug VDSO> <stripped VDSO> <output file> [<name>]\n",
program_name);
return EXIT_FAILURE;
}
dbg_vdso_path = argv[1];
vdso_path = argv[2];
out_path = argv[3];
vdso_name = (argc > 4) ? argv[4] : "";
dbg_vdso = map_vdso(dbg_vdso_path, &dbg_vdso_size);
if (!dbg_vdso)
return EXIT_FAILURE;
vdso = map_vdso(vdso_path, &vdso_size);
if (!vdso)
return EXIT_FAILURE;
/* Patch both the VDSOs' ABI flags sections. */
if (!patch_vdso(dbg_vdso_path, dbg_vdso))
return EXIT_FAILURE;
if (!patch_vdso(vdso_path, vdso))
return EXIT_FAILURE;
if (msync(dbg_vdso, dbg_vdso_size, MS_SYNC) != 0) {
fprintf(stderr, "%s: Failed to sync '%s': %s\n", program_name,
dbg_vdso_path, strerror(errno));
return EXIT_FAILURE;
} else if (msync(vdso, vdso_size, MS_SYNC) != 0) {
fprintf(stderr, "%s: Failed to sync '%s': %s\n", program_name,
vdso_path, strerror(errno));
return EXIT_FAILURE;
}
out_file = fopen(out_path, "w");
if (!out_file) {
fprintf(stderr, "%s: Failed to open '%s': %s\n", program_name,
out_path, strerror(errno));
return EXIT_FAILURE;
}
fprintf(out_file, "/* Automatically generated - do not edit */\n");
fprintf(out_file, "#include <linux/linkage.h>\n");
fprintf(out_file, "#include <linux/mm.h>\n");
fprintf(out_file, "#include <asm/vdso.h>\n");
fprintf(out_file, "static int vdso_mremap(\n");
fprintf(out_file, " const struct vm_special_mapping *sm,\n");
fprintf(out_file, " struct vm_area_struct *new_vma)\n");
fprintf(out_file, "{\n");
fprintf(out_file, " unsigned long new_size =\n");
fprintf(out_file, " new_vma->vm_end - new_vma->vm_start;\n");
fprintf(out_file, " if (vdso_image.size != new_size)\n");
fprintf(out_file, " return -EINVAL;\n");
fprintf(out_file, " current->mm->context.vdso =\n");
fprintf(out_file, " (void __user *)(new_vma->vm_start);\n");
fprintf(out_file, " return 0;\n");
fprintf(out_file, "}\n");
/* Write out the stripped VDSO data. */
fprintf(out_file,
"static unsigned char vdso_data[PAGE_ALIGN(%zu)] __page_aligned_data = {\n\t",
vdso_size);
for (i = 0; i < vdso_size; i++) {
if (!(i % 10))
fprintf(out_file, "\n\t");
fprintf(out_file, "0x%02x, ", ((unsigned char *)vdso)[i]);
}
fprintf(out_file, "\n};\n");
/* Preallocate a page array. */
fprintf(out_file,
"static struct page *vdso_pages[PAGE_ALIGN(%zu) / PAGE_SIZE];\n",
vdso_size);
fprintf(out_file, "struct mips_vdso_image vdso_image%s%s = {\n",
(vdso_name[0]) ? "_" : "", vdso_name);
fprintf(out_file, "\t.data = vdso_data,\n");
fprintf(out_file, "\t.size = PAGE_ALIGN(%zu),\n", vdso_size);
fprintf(out_file, "\t.mapping = {\n");
fprintf(out_file, "\t\t.name = \"[vdso]\",\n");
fprintf(out_file, "\t\t.pages = vdso_pages,\n");
fprintf(out_file, "\t\t.mremap = vdso_mremap,\n");
fprintf(out_file, "\t},\n");
/* Calculate and write symbol offsets to <output file> */
if (!get_symbols(dbg_vdso_path, dbg_vdso)) {
unlink(out_path);
return EXIT_FAILURE;
}
fprintf(out_file, "};\n");
return EXIT_SUCCESS;
}