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/*
* Copyright 2015 Mentor Graphics Corporation.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; version 2 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*
* vdsomunge - Host program which produces a shared object
* architecturally specified to be usable by both soft- and hard-float
* programs.
*
* The Procedure Call Standard for the ARM Architecture (ARM IHI
* 0042E) says:
*
* 6.4.1 VFP and Base Standard Compatibility
*
* Code compiled for the VFP calling standard is compatible with
* the base standard (and vice-versa) if no floating-point or
* containerized vector arguments or results are used.
*
* And ELF for the ARM Architecture (ARM IHI 0044E) (Table 4-2) says:
*
* If both EF_ARM_ABI_FLOAT_XXXX bits are clear, conformance to the
* base procedure-call standard is implied.
*
* The VDSO is built with -msoft-float, as with the rest of the ARM
* kernel, and uses no floating point arguments or results. The build
* process will produce a shared object that may or may not have the
* EF_ARM_ABI_FLOAT_SOFT flag set (it seems to depend on the binutils
* version; binutils starting with 2.24 appears to set it). The
* EF_ARM_ABI_FLOAT_HARD flag should definitely not be set, and this
* program will error out if it is.
*
* If the soft-float flag is set, this program clears it. That's all
* it does.
*/
#include <elf.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#define swab16(x) \
((((x) & 0x00ff) << 8) | \
(((x) & 0xff00) >> 8))
#define swab32(x) \
((((x) & 0x000000ff) << 24) | \
(((x) & 0x0000ff00) << 8) | \
(((x) & 0x00ff0000) >> 8) | \
(((x) & 0xff000000) >> 24))
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define HOST_ORDER ELFDATA2LSB
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
#define HOST_ORDER ELFDATA2MSB
#endif
/* Some of the ELF constants we'd like to use were added to <elf.h>
* relatively recently.
*/
#ifndef EF_ARM_EABI_VER5
#define EF_ARM_EABI_VER5 0x05000000
#endif
#ifndef EF_ARM_ABI_FLOAT_SOFT
#define EF_ARM_ABI_FLOAT_SOFT 0x200
#endif
#ifndef EF_ARM_ABI_FLOAT_HARD
#define EF_ARM_ABI_FLOAT_HARD 0x400
#endif
static int failed;
static const char *argv0;
static const char *outfile;
static void fail(const char *fmt, ...)
{
va_list ap;
failed = 1;
fprintf(stderr, "%s: ", argv0);
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
exit(EXIT_FAILURE);
}
static void cleanup(void)
{
if (failed && outfile != NULL)
unlink(outfile);
}
static Elf32_Word read_elf_word(Elf32_Word word, bool swap)
{
return swap ? swab32(word) : word;
}
static Elf32_Half read_elf_half(Elf32_Half half, bool swap)
{
return swap ? swab16(half) : half;
}
static void write_elf_word(Elf32_Word val, Elf32_Word *dst, bool swap)
{
*dst = swap ? swab32(val) : val;
}
int main(int argc, char **argv)
{
const Elf32_Ehdr *inhdr;
bool clear_soft_float;
const char *infile;
Elf32_Word e_flags;
const void *inbuf;
struct stat stat;
void *outbuf;
bool swap;
int outfd;
int infd;
atexit(cleanup);
argv0 = argv[0];
if (argc != 3)
fail("Usage: %s [infile] [outfile]\n", argv[0]);
infile = argv[1];
outfile = argv[2];
infd = open(infile, O_RDONLY);
if (infd < 0)
fail("Cannot open %s: %s\n", infile, strerror(errno));
if (fstat(infd, &stat) != 0)
fail("Failed stat for %s: %s\n", infile, strerror(errno));
inbuf = mmap(NULL, stat.st_size, PROT_READ, MAP_PRIVATE, infd, 0);
if (inbuf == MAP_FAILED)
fail("Failed to map %s: %s\n", infile, strerror(errno));
close(infd);
inhdr = inbuf;
if (memcmp(&inhdr->e_ident, ELFMAG, SELFMAG) != 0)
fail("Not an ELF file\n");
if (inhdr->e_ident[EI_CLASS] != ELFCLASS32)
fail("Unsupported ELF class\n");
swap = inhdr->e_ident[EI_DATA] != HOST_ORDER;
if (read_elf_half(inhdr->e_type, swap) != ET_DYN)
fail("Not a shared object\n");
if (read_elf_half(inhdr->e_machine, swap) != EM_ARM)
fail("Unsupported architecture %#x\n", inhdr->e_machine);
e_flags = read_elf_word(inhdr->e_flags, swap);
if (EF_ARM_EABI_VERSION(e_flags) != EF_ARM_EABI_VER5) {
fail("Unsupported EABI version %#x\n",
EF_ARM_EABI_VERSION(e_flags));
}
if (e_flags & EF_ARM_ABI_FLOAT_HARD)
fail("Unexpected hard-float flag set in e_flags\n");
clear_soft_float = !!(e_flags & EF_ARM_ABI_FLOAT_SOFT);
outfd = open(outfile, O_RDWR | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
if (outfd < 0)
fail("Cannot open %s: %s\n", outfile, strerror(errno));
if (ftruncate(outfd, stat.st_size) != 0)
fail("Cannot truncate %s: %s\n", outfile, strerror(errno));
outbuf = mmap(NULL, stat.st_size, PROT_READ | PROT_WRITE, MAP_SHARED,
outfd, 0);
if (outbuf == MAP_FAILED)
fail("Failed to map %s: %s\n", outfile, strerror(errno));
close(outfd);
memcpy(outbuf, inbuf, stat.st_size);
if (clear_soft_float) {
Elf32_Ehdr *outhdr;
outhdr = outbuf;
e_flags &= ~EF_ARM_ABI_FLOAT_SOFT;
write_elf_word(e_flags, &outhdr->e_flags, swap);
}
if (msync(outbuf, stat.st_size, MS_SYNC) != 0)
fail("Failed to sync %s: %s\n", outfile, strerror(errno));
return EXIT_SUCCESS;
}
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