diff options
Diffstat (limited to 'arch/x86/tools/relocs.c')
| -rw-r--r-- | arch/x86/tools/relocs.c | 797 |
1 files changed, 797 insertions, 0 deletions
diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c new file mode 100644 index 000000000000..02914706e5b9 --- /dev/null +++ b/arch/x86/tools/relocs.c @@ -0,0 +1,797 @@ +#include <stdio.h> +#include <stdarg.h> +#include <stdlib.h> +#include <stdint.h> +#include <string.h> +#include <errno.h> +#include <unistd.h> +#include <elf.h> +#include <byteswap.h> +#define USE_BSD +#include <endian.h> +#include <regex.h> +#include <tools/le_byteshift.h> + +static void die(char *fmt, ...); + +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) +static Elf32_Ehdr ehdr; +static unsigned long reloc_count, reloc_idx; +static unsigned long *relocs; +static unsigned long reloc16_count, reloc16_idx; +static unsigned long *relocs16; + +struct section { + Elf32_Shdr shdr; + struct section *link; + Elf32_Sym *symtab; + Elf32_Rel *reltab; + char *strtab; +}; +static struct section *secs; + +enum symtype { + S_ABS, + S_REL, + S_SEG, + S_LIN, + S_NSYMTYPES +}; + +static const char * const sym_regex_kernel[S_NSYMTYPES] = { +/* + * Following symbols have been audited. There values are constant and do + * not change if bzImage is loaded at a different physical address than + * the address for which it has been compiled. Don't warn user about + * absolute relocations present w.r.t these symbols. + */ + [S_ABS] = + "^(xen_irq_disable_direct_reloc$|" + "xen_save_fl_direct_reloc$|" + "VDSO|" + "__crc_)", + +/* + * These symbols are known to be relative, even if the linker marks them + * as absolute (typically defined outside any section in the linker script.) + */ + [S_REL] = + "^_end$", +}; + + +static const char * const sym_regex_realmode[S_NSYMTYPES] = { +/* + * These are 16-bit segment symbols when compiling 16-bit code. + */ + [S_SEG] = + "^real_mode_seg$", + +/* + * These are offsets belonging to segments, as opposed to linear addresses, + * when compiling 16-bit code. + */ + [S_LIN] = + "^pa_", +}; + +static const char * const *sym_regex; + +static regex_t sym_regex_c[S_NSYMTYPES]; +static int is_reloc(enum symtype type, const char *sym_name) +{ + return sym_regex[type] && + !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0); +} + +static void regex_init(int use_real_mode) +{ + char errbuf[128]; + int err; + int i; + + if (use_real_mode) + sym_regex = sym_regex_realmode; + else + sym_regex = sym_regex_kernel; + + for (i = 0; i < S_NSYMTYPES; i++) { + if (!sym_regex[i]) + continue; + + err = regcomp(&sym_regex_c[i], sym_regex[i], + REG_EXTENDED|REG_NOSUB); + + if (err) { + regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf); + die("%s", errbuf); + } + } +} + +static void die(char *fmt, ...) +{ + va_list ap; + va_start(ap, fmt); + vfprintf(stderr, fmt, ap); + va_end(ap); + exit(1); +} + +static const char *sym_type(unsigned type) +{ + static const char *type_name[] = { +#define SYM_TYPE(X) [X] = #X + SYM_TYPE(STT_NOTYPE), + SYM_TYPE(STT_OBJECT), + SYM_TYPE(STT_FUNC), + SYM_TYPE(STT_SECTION), + SYM_TYPE(STT_FILE), + SYM_TYPE(STT_COMMON), + SYM_TYPE(STT_TLS), +#undef SYM_TYPE + }; + const char *name = "unknown sym type name"; + if (type < ARRAY_SIZE(type_name)) { + name = type_name[type]; + } + return name; +} + +static const char *sym_bind(unsigned bind) +{ + static const char *bind_name[] = { +#define SYM_BIND(X) [X] = #X + SYM_BIND(STB_LOCAL), + SYM_BIND(STB_GLOBAL), + SYM_BIND(STB_WEAK), +#undef SYM_BIND + }; + const char *name = "unknown sym bind name"; + if (bind < ARRAY_SIZE(bind_name)) { + name = bind_name[bind]; + } + return name; +} + +static const char *sym_visibility(unsigned visibility) +{ + static const char *visibility_name[] = { +#define SYM_VISIBILITY(X) [X] = #X + SYM_VISIBILITY(STV_DEFAULT), + SYM_VISIBILITY(STV_INTERNAL), + SYM_VISIBILITY(STV_HIDDEN), + SYM_VISIBILITY(STV_PROTECTED), +#undef SYM_VISIBILITY + }; + const char *name = "unknown sym visibility name"; + if (visibility < ARRAY_SIZE(visibility_name)) { + name = visibility_name[visibility]; + } + return name; +} + +static const char *rel_type(unsigned type) +{ + static const char *type_name[] = { +#define REL_TYPE(X) [X] = #X + REL_TYPE(R_386_NONE), + REL_TYPE(R_386_32), + REL_TYPE(R_386_PC32), + REL_TYPE(R_386_GOT32), + REL_TYPE(R_386_PLT32), + REL_TYPE(R_386_COPY), + REL_TYPE(R_386_GLOB_DAT), + REL_TYPE(R_386_JMP_SLOT), + REL_TYPE(R_386_RELATIVE), + REL_TYPE(R_386_GOTOFF), + REL_TYPE(R_386_GOTPC), + REL_TYPE(R_386_8), + REL_TYPE(R_386_PC8), + REL_TYPE(R_386_16), + REL_TYPE(R_386_PC16), +#undef REL_TYPE + }; + const char *name = "unknown type rel type name"; + if (type < ARRAY_SIZE(type_name) && type_name[type]) { + name = type_name[type]; + } + return name; +} + +static const char *sec_name(unsigned shndx) +{ + const char *sec_strtab; + const char *name; + sec_strtab = secs[ehdr.e_shstrndx].strtab; + name = "<noname>"; + if (shndx < ehdr.e_shnum) { + name = sec_strtab + secs[shndx].shdr.sh_name; + } + else if (shndx == SHN_ABS) { + name = "ABSOLUTE"; + } + else if (shndx == SHN_COMMON) { + name = "COMMON"; + } + return name; +} + +static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym) +{ + const char *name; + name = "<noname>"; + if (sym->st_name) { + name = sym_strtab + sym->st_name; + } + else { + name = sec_name(sym->st_shndx); + } + return name; +} + + + +#if BYTE_ORDER == LITTLE_ENDIAN +#define le16_to_cpu(val) (val) +#define le32_to_cpu(val) (val) +#endif +#if BYTE_ORDER == BIG_ENDIAN +#define le16_to_cpu(val) bswap_16(val) +#define le32_to_cpu(val) bswap_32(val) +#endif + +static uint16_t elf16_to_cpu(uint16_t val) +{ + return le16_to_cpu(val); +} + +static uint32_t elf32_to_cpu(uint32_t val) +{ + return le32_to_cpu(val); +} + +static void read_ehdr(FILE *fp) +{ + if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) { + die("Cannot read ELF header: %s\n", + strerror(errno)); + } + if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) { + die("No ELF magic\n"); + } + if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) { + die("Not a 32 bit executable\n"); + } + if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) { + die("Not a LSB ELF executable\n"); + } + if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) { + die("Unknown ELF version\n"); + } + /* Convert the fields to native endian */ + ehdr.e_type = elf16_to_cpu(ehdr.e_type); + ehdr.e_machine = elf16_to_cpu(ehdr.e_machine); + ehdr.e_version = elf32_to_cpu(ehdr.e_version); + ehdr.e_entry = elf32_to_cpu(ehdr.e_entry); + ehdr.e_phoff = elf32_to_cpu(ehdr.e_phoff); + ehdr.e_shoff = elf32_to_cpu(ehdr.e_shoff); + ehdr.e_flags = elf32_to_cpu(ehdr.e_flags); + ehdr.e_ehsize = elf16_to_cpu(ehdr.e_ehsize); + ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize); + ehdr.e_phnum = elf16_to_cpu(ehdr.e_phnum); + ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize); + ehdr.e_shnum = elf16_to_cpu(ehdr.e_shnum); + ehdr.e_shstrndx = elf16_to_cpu(ehdr.e_shstrndx); + + if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) { + die("Unsupported ELF header type\n"); + } + if (ehdr.e_machine != EM_386) { + die("Not for x86\n"); + } + if (ehdr.e_version != EV_CURRENT) { + die("Unknown ELF version\n"); + } + if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) { + die("Bad Elf header size\n"); + } + if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) { + die("Bad program header entry\n"); + } + if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) { + die("Bad section header entry\n"); + } + if (ehdr.e_shstrndx >= ehdr.e_shnum) { + die("String table index out of bounds\n"); + } +} + +static void read_shdrs(FILE *fp) +{ + int i; + Elf32_Shdr shdr; + + secs = calloc(ehdr.e_shnum, sizeof(struct section)); + if (!secs) { + die("Unable to allocate %d section headers\n", + ehdr.e_shnum); + } + if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) { + die("Seek to %d failed: %s\n", + ehdr.e_shoff, strerror(errno)); + } + for (i = 0; i < ehdr.e_shnum; i++) { + struct section *sec = &secs[i]; + if (fread(&shdr, sizeof shdr, 1, fp) != 1) + die("Cannot read ELF section headers %d/%d: %s\n", + i, ehdr.e_shnum, strerror(errno)); + sec->shdr.sh_name = elf32_to_cpu(shdr.sh_name); + sec->shdr.sh_type = elf32_to_cpu(shdr.sh_type); + sec->shdr.sh_flags = elf32_to_cpu(shdr.sh_flags); + sec->shdr.sh_addr = elf32_to_cpu(shdr.sh_addr); + sec->shdr.sh_offset = elf32_to_cpu(shdr.sh_offset); + sec->shdr.sh_size = elf32_to_cpu(shdr.sh_size); + sec->shdr.sh_link = elf32_to_cpu(shdr.sh_link); + sec->shdr.sh_info = elf32_to_cpu(shdr.sh_info); + sec->shdr.sh_addralign = elf32_to_cpu(shdr.sh_addralign); + sec->shdr.sh_entsize = elf32_to_cpu(shdr.sh_entsize); + if (sec->shdr.sh_link < ehdr.e_shnum) + sec->link = &secs[sec->shdr.sh_link]; + } + +} + +static void read_strtabs(FILE *fp) +{ + int i; + for (i = 0; i < ehdr.e_shnum; i++) { + struct section *sec = &secs[i]; + if (sec->shdr.sh_type != SHT_STRTAB) { + continue; + } + sec->strtab = malloc(sec->shdr.sh_size); + if (!sec->strtab) { + die("malloc of %d bytes for strtab failed\n", + sec->shdr.sh_size); + } + if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) { + die("Seek to %d failed: %s\n", + sec->shdr.sh_offset, strerror(errno)); + } + if (fread(sec->strtab, 1, sec->shdr.sh_size, fp) + != sec->shdr.sh_size) { + die("Cannot read symbol table: %s\n", + strerror(errno)); + } + } +} + +static void read_symtabs(FILE *fp) +{ + int i,j; + for (i = 0; i < ehdr.e_shnum; i++) { + struct section *sec = &secs[i]; + if (sec->shdr.sh_type != SHT_SYMTAB) { + continue; + } + sec->symtab = malloc(sec->shdr.sh_size); + if (!sec->symtab) { + die("malloc of %d bytes for symtab failed\n", + sec->shdr.sh_size); + } + if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) { + die("Seek to %d failed: %s\n", + sec->shdr.sh_offset, strerror(errno)); + } + if (fread(sec->symtab, 1, sec->shdr.sh_size, fp) + != sec->shdr.sh_size) { + die("Cannot read symbol table: %s\n", + strerror(errno)); + } + for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) { + Elf32_Sym *sym = &sec->symtab[j]; + sym->st_name = elf32_to_cpu(sym->st_name); + sym->st_value = elf32_to_cpu(sym->st_value); + sym->st_size = elf32_to_cpu(sym->st_size); + sym->st_shndx = elf16_to_cpu(sym->st_shndx); + } + } +} + + +static void read_relocs(FILE *fp) +{ + int i,j; + for (i = 0; i < ehdr.e_shnum; i++) { + struct section *sec = &secs[i]; + if (sec->shdr.sh_type != SHT_REL) { + continue; + } + sec->reltab = malloc(sec->shdr.sh_size); + if (!sec->reltab) { + die("malloc of %d bytes for relocs failed\n", + sec->shdr.sh_size); + } + if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) { + die("Seek to %d failed: %s\n", + sec->shdr.sh_offset, strerror(errno)); + } + if (fread(sec->reltab, 1, sec->shdr.sh_size, fp) + != sec->shdr.sh_size) { + die("Cannot read symbol table: %s\n", + strerror(errno)); + } + for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) { + Elf32_Rel *rel = &sec->reltab[j]; + rel->r_offset = elf32_to_cpu(rel->r_offset); + rel->r_info = elf32_to_cpu(rel->r_info); + } + } +} + + +static void print_absolute_symbols(void) +{ + int i; + printf("Absolute symbols\n"); + printf(" Num: Value Size Type Bind Visibility Name\n"); + for (i = 0; i < ehdr.e_shnum; i++) { + struct section *sec = &secs[i]; + char *sym_strtab; + int j; + + if (sec->shdr.sh_type != SHT_SYMTAB) { + continue; + } + sym_strtab = sec->link->strtab; + for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Sym); j++) { + Elf32_Sym *sym; + const char *name; + sym = &sec->symtab[j]; + name = sym_name(sym_strtab, sym); + if (sym->st_shndx != SHN_ABS) { + continue; + } + printf("%5d %08x %5d %10s %10s %12s %s\n", + j, sym->st_value, sym->st_size, + sym_type(ELF32_ST_TYPE(sym->st_info)), + sym_bind(ELF32_ST_BIND(sym->st_info)), + sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)), + name); + } + } + printf("\n"); +} + +static void print_absolute_relocs(void) +{ + int i, printed = 0; + + for (i = 0; i < ehdr.e_shnum; i++) { + struct section *sec = &secs[i]; + struct section *sec_applies, *sec_symtab; + char *sym_strtab; + Elf32_Sym *sh_symtab; + int j; + if (sec->shdr.sh_type != SHT_REL) { + continue; + } + sec_symtab = sec->link; + sec_applies = &secs[sec->shdr.sh_info]; + if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) { + continue; + } + sh_symtab = sec_symtab->symtab; + sym_strtab = sec_symtab->link->strtab; + for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) { + Elf32_Rel *rel; + Elf32_Sym *sym; + const char *name; + rel = &sec->reltab[j]; + sym = &sh_symtab[ELF32_R_SYM(rel->r_info)]; + name = sym_name(sym_strtab, sym); + if (sym->st_shndx != SHN_ABS) { + continue; + } + + /* Absolute symbols are not relocated if bzImage is + * loaded at a non-compiled address. Display a warning + * to user at compile time about the absolute + * relocations present. + * + * User need to audit the code to make sure + * some symbols which should have been section + * relative have not become absolute because of some + * linker optimization or wrong programming usage. + * + * Before warning check if this absolute symbol + * relocation is harmless. + */ + if (is_reloc(S_ABS, name) || is_reloc(S_REL, name)) + continue; + + if (!printed) { + printf("WARNING: Absolute relocations" + " present\n"); + printf("Offset Info Type Sym.Value " + "Sym.Name\n"); + printed = 1; + } + + printf("%08x %08x %10s %08x %s\n", + rel->r_offset, + rel->r_info, + rel_type(ELF32_R_TYPE(rel->r_info)), + sym->st_value, + name); + } + } + + if (printed) + printf("\n"); +} + +static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym), + int use_real_mode) +{ + int i; + /* Walk through the relocations */ + for (i = 0; i < ehdr.e_shnum; i++) { + char *sym_strtab; + Elf32_Sym *sh_symtab; + struct section *sec_applies, *sec_symtab; + int j; + struct section *sec = &secs[i]; + + if (sec->shdr.sh_type != SHT_REL) { + continue; + } + sec_symtab = sec->link; + sec_applies = &secs[sec->shdr.sh_info]; + if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) { + continue; + } + sh_symtab = sec_symtab->symtab; + sym_strtab = sec_symtab->link->strtab; + for (j = 0; j < sec->shdr.sh_size/sizeof(Elf32_Rel); j++) { + Elf32_Rel *rel; + Elf32_Sym *sym; + unsigned r_type; + const char *symname; + rel = &sec->reltab[j]; + sym = &sh_symtab[ELF32_R_SYM(rel->r_info)]; + r_type = ELF32_R_TYPE(rel->r_info); + + switch (r_type) { + case R_386_NONE: + case R_386_PC32: + case R_386_PC16: + case R_386_PC8: + /* + * NONE can be ignored and and PC relative + * relocations don't need to be adjusted. + */ + break; + + case R_386_16: + symname = sym_name(sym_strtab, sym); + if (!use_real_mode) + goto bad; + if (sym->st_shndx == SHN_ABS) { + if (is_reloc(S_ABS, symname)) + break; + else if (!is_reloc(S_SEG, symname)) + goto bad; + } else { + if (is_reloc(S_LIN, symname)) + goto bad; + else + break; + } + visit(rel, sym); + break; + + case R_386_32: + symname = sym_name(sym_strtab, sym); + if (sym->st_shndx == SHN_ABS) { + if (is_reloc(S_ABS, symname)) + break; + else if (!is_reloc(S_REL, symname)) + goto bad; + } else { + if (use_real_mode && + !is_reloc(S_LIN, symname)) + break; + } + visit(rel, sym); + break; + default: + die("Unsupported relocation type: %s (%d)\n", + rel_type(r_type), r_type); + break; + bad: + symname = sym_name(sym_strtab, sym); + die("Invalid %s relocation: %s\n", + rel_type(r_type), symname); + } + } + } +} + +static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym) +{ + if (ELF32_R_TYPE(rel->r_info) == R_386_16) + reloc16_count++; + else + reloc_count++; +} + +static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym) +{ + /* Remember the address that needs to be adjusted. */ + if (ELF32_R_TYPE(rel->r_info) == R_386_16) + relocs16[reloc16_idx++] = rel->r_offset; + else + relocs[reloc_idx++] = rel->r_offset; +} + +static int cmp_relocs(const void *va, const void *vb) +{ + const unsigned long *a, *b; + a = va; b = vb; + return (*a == *b)? 0 : (*a > *b)? 1 : -1; +} + +static int write32(unsigned int v, FILE *f) +{ + unsigned char buf[4]; + + put_unaligned_le32(v, buf); + return fwrite(buf, 1, 4, f) == 4 ? 0 : -1; +} + +static void emit_relocs(int as_text, int use_real_mode) +{ + int i; + /* Count how many relocations I have and allocate space for them. */ + reloc_count = 0; + walk_relocs(count_reloc, use_real_mode); + relocs = malloc(reloc_count * sizeof(relocs[0])); + if (!relocs) { + die("malloc of %d entries for relocs failed\n", + reloc_count); + } + + relocs16 = malloc(reloc16_count * sizeof(relocs[0])); + if (!relocs16) { + die("malloc of %d entries for relocs16 failed\n", + reloc16_count); + } + /* Collect up the relocations */ + reloc_idx = 0; + walk_relocs(collect_reloc, use_real_mode); + + if (reloc16_count && !use_real_mode) + die("Segment relocations found but --realmode not specified\n"); + + /* Order the relocations for more efficient processing */ + qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs); + qsort(relocs16, reloc16_count, sizeof(relocs16[0]), cmp_relocs); + + /* Print the relocations */ + if (as_text) { + /* Print the relocations in a form suitable that + * gas will like. + */ + printf(".section \".data.reloc\",\"a\"\n"); + printf(".balign 4\n"); + if (use_real_mode) { + printf("\t.long %lu\n", reloc16_count); + for (i = 0; i < reloc16_count; i++) + printf("\t.long 0x%08lx\n", relocs16[i]); + printf("\t.long %lu\n", reloc_count); + for (i = 0; i < reloc_count; i++) { + printf("\t.long 0x%08lx\n", relocs[i]); + } + } else { + /* Print a stop */ + printf("\t.long 0x%08lx\n", (unsigned long)0); + for (i = 0; i < reloc_count; i++) { + printf("\t.long 0x%08lx\n", relocs[i]); + } + } + + printf("\n"); + } + else { + if (use_real_mode) { + write32(reloc16_count, stdout); + for (i = 0; i < reloc16_count; i++) + write32(relocs16[i], stdout); + write32(reloc_count, stdout); + + /* Now print each relocation */ + for (i = 0; i < reloc_count; i++) + write32(relocs[i], stdout); + } else { + /* Print a stop */ + write32(0, stdout); + + /* Now print each relocation */ + for (i = 0; i < reloc_count; i++) { + write32(relocs[i], stdout); + } + } + } +} + +static void usage(void) +{ + die("relocs [--abs-syms|--abs-relocs|--text|--realmode] vmlinux\n"); +} + +int main(int argc, char **argv) +{ + int show_absolute_syms, show_absolute_relocs; + int as_text, use_real_mode; + const char *fname; + FILE *fp; + int i; + + show_absolute_syms = 0; + show_absolute_relocs = 0; + as_text = 0; + use_real_mode = 0; + fname = NULL; + for (i = 1; i < argc; i++) { + char *arg = argv[i]; + if (*arg == '-') { + if (strcmp(arg, "--abs-syms") == 0) { + show_absolute_syms = 1; + continue; + } + if (strcmp(arg, "--abs-relocs") == 0) { + show_absolute_relocs = 1; + continue; + } + if (strcmp(arg, "--text") == 0) { + as_text = 1; + continue; + } + if (strcmp(arg, "--realmode") == 0) { + use_real_mode = 1; + continue; + } + } + else if (!fname) { + fname = arg; + continue; + } + usage(); + } + if (!fname) { + usage(); + } + regex_init(use_real_mode); + fp = fopen(fname, "r"); + if (!fp) { + die("Cannot open %s: %s\n", + fname, strerror(errno)); + } + read_ehdr(fp); + read_shdrs(fp); + read_strtabs(fp); + read_symtabs(fp); + read_relocs(fp); + if (show_absolute_syms) { + print_absolute_symbols(); + return 0; + } + if (show_absolute_relocs) { + print_absolute_relocs(); + return 0; + } + emit_relocs(as_text, use_real_mode); + return 0; +} |