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Diffstat (limited to 'arch/arm/vdso/vdsomunge.c')
| -rw-r--r-- | arch/arm/vdso/vdsomunge.c | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/arch/arm/vdso/vdsomunge.c b/arch/arm/vdso/vdsomunge.c new file mode 100644 index 000000000..aedec81d1 --- /dev/null +++ b/arch/arm/vdso/vdsomunge.c @@ -0,0 +1,211 @@ +/* + * 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 <byteswap.h> +#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> + +#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 ? bswap_32(word) : word; +} + +static Elf32_Half read_elf_half(Elf32_Half half, bool swap) +{ + return swap ? bswap_16(half) : half; +} + +static void write_elf_word(Elf32_Word val, Elf32_Word *dst, bool swap) +{ + *dst = swap ? bswap_32(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; +} |