From 6520fe5564acf07ade7b18a1272db1184835c487 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Tue, 8 May 2012 21:22:24 +0300 Subject: x86, realmode: 16-bit real-mode code support for relocs tool A new option is added to the relocs tool called '--realmode'. This option causes the generation of 16-bit segment relocations and 32-bit linear relocations for the real-mode code. When the real-mode code is moved to the low-memory during kernel initialization, these relocation entries can be used to relocate the code properly. In the assembly code 16-bit segment relocations must be relative to the 'real_mode_seg' absolute symbol. Linear relocations must be relative to a symbol prefixed with 'pa_'. 16-bit segment relocation is used to load cs:ip in 16-bit code. Linear relocations are used in the 32-bit code for relocatable data references. They are declared in the linker script of the real-mode code. The relocs tool is moved to arch/x86/tools/relocs.c, and added new target archscripts that can be used to build scripts needed building an architecture. be compiled before building the arch/x86 tree. [ hpa: accelerating this because it detects invalid absolute relocations, a serious bug in binutils 2.22.52.0.x which currently produces bad kernels. ] Signed-off-by: H. Peter Anvin Link: http://lkml.kernel.org/r/1336501366-28617-2-git-send-email-jarkko.sakkinen@intel.com Signed-off-by: Jarkko Sakkinen Signed-off-by: H. Peter Anvin Cc: --- arch/x86/boot/compressed/Makefile | 9 +- arch/x86/boot/compressed/relocs.c | 678 -------------------------------------- 2 files changed, 4 insertions(+), 683 deletions(-) delete mode 100644 arch/x86/boot/compressed/relocs.c (limited to 'arch/x86/boot') diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index fd55a2ff3ad8..e398bb5d63bb 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -40,13 +40,12 @@ OBJCOPYFLAGS_vmlinux.bin := -R .comment -S $(obj)/vmlinux.bin: vmlinux FORCE $(call if_changed,objcopy) +targets += vmlinux.bin.all vmlinux.relocs -targets += vmlinux.bin.all vmlinux.relocs relocs -hostprogs-$(CONFIG_X86_NEED_RELOCS) += relocs - +CMD_RELOCS = arch/x86/tools/relocs quiet_cmd_relocs = RELOCS $@ - cmd_relocs = $(obj)/relocs $< > $@;$(obj)/relocs --abs-relocs $< -$(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE + cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $< +$(obj)/vmlinux.relocs: vmlinux FORCE $(call if_changed,relocs) vmlinux.bin.all-y := $(obj)/vmlinux.bin diff --git a/arch/x86/boot/compressed/relocs.c b/arch/x86/boot/compressed/relocs.c deleted file mode 100644 index fb7117a4ade1..000000000000 --- a/arch/x86/boot/compressed/relocs.c +++ /dev/null @@ -1,678 +0,0 @@ -#include -#include -#include -#include -#include -#include -#include -#include -#include -#define USE_BSD -#include -#include -#include - -static void die(char *fmt, ...); - -#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) -static Elf32_Ehdr ehdr; -static unsigned long reloc_count, reloc_idx; -static unsigned long *relocs; - -struct section { - Elf32_Shdr shdr; - struct section *link; - Elf32_Sym *symtab; - Elf32_Rel *reltab; - char *strtab; -}; -static struct section *secs; - -/* - * Following symbols have been audited. There values are constant and do - * not change if bzImage is loaded at a different physical address than - * the address for which it has been compiled. Don't warn user about - * absolute relocations present w.r.t these symbols. - */ -static const char abs_sym_regex[] = - "^(xen_irq_disable_direct_reloc$|" - "xen_save_fl_direct_reloc$|" - "VDSO|" - "__crc_)"; -static regex_t abs_sym_regex_c; -static int is_abs_reloc(const char *sym_name) -{ - return !regexec(&abs_sym_regex_c, sym_name, 0, NULL, 0); -} - -/* - * These symbols are known to be relative, even if the linker marks them - * as absolute (typically defined outside any section in the linker script.) - */ -static const char rel_sym_regex[] = - "^_end$"; -static regex_t rel_sym_regex_c; -static int is_rel_reloc(const char *sym_name) -{ - return !regexec(&rel_sym_regex_c, sym_name, 0, NULL, 0); -} - -static void regex_init(void) -{ - char errbuf[128]; - int err; - - err = regcomp(&abs_sym_regex_c, abs_sym_regex, - REG_EXTENDED|REG_NOSUB); - if (err) { - regerror(err, &abs_sym_regex_c, errbuf, sizeof errbuf); - die("%s", errbuf); - } - - err = regcomp(&rel_sym_regex_c, rel_sym_regex, - REG_EXTENDED|REG_NOSUB); - if (err) { - regerror(err, &rel_sym_regex_c, 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), -#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 = ""; - 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 = ""; - if (sym->st_name) { - name = sym_strtab + sym->st_name; - } - else { - name = sec_name(secs[sym->st_shndx].shdr.sh_name); - } - 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_abs_reloc(name) || is_rel_reloc(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 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; - rel = &sec->reltab[j]; - sym = &sh_symtab[ELF32_R_SYM(rel->r_info)]; - r_type = ELF32_R_TYPE(rel->r_info); - /* Don't visit relocations to absolute symbols */ - if (sym->st_shndx == SHN_ABS && - !is_rel_reloc(sym_name(sym_strtab, sym))) { - continue; - } - switch (r_type) { - case R_386_NONE: - case R_386_PC32: - /* - * NONE can be ignored and and PC relative - * relocations don't need to be adjusted. - */ - break; - case R_386_32: - /* Visit relocations that need to be adjusted */ - visit(rel, sym); - break; - default: - die("Unsupported relocation type: %s (%d)\n", - rel_type(r_type), r_type); - break; - } - } - } -} - -static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym) -{ - reloc_count += 1; -} - -static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym) -{ - /* Remember the address that needs to be adjusted. */ - 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 void emit_relocs(int as_text) -{ - int i; - /* Count how many relocations I have and allocate space for them. */ - reloc_count = 0; - walk_relocs(count_reloc); - relocs = malloc(reloc_count * sizeof(relocs[0])); - if (!relocs) { - die("malloc of %d entries for relocs failed\n", - reloc_count); - } - /* Collect up the relocations */ - reloc_idx = 0; - walk_relocs(collect_reloc); - - /* Order the relocations for more efficient processing */ - qsort(relocs, reloc_count, sizeof(relocs[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"); - for (i = 0; i < reloc_count; i++) { - printf("\t .long 0x%08lx\n", relocs[i]); - } - printf("\n"); - } - else { - unsigned char buf[4]; - /* Print a stop */ - fwrite("\0\0\0\0", 4, 1, stdout); - /* Now print each relocation */ - for (i = 0; i < reloc_count; i++) { - put_unaligned_le32(relocs[i], buf); - fwrite(buf, 4, 1, stdout); - } - } -} - -static void usage(void) -{ - die("relocs [--abs-syms |--abs-relocs | --text] vmlinux\n"); -} - -int main(int argc, char **argv) -{ - int show_absolute_syms, show_absolute_relocs; - int as_text; - const char *fname; - FILE *fp; - int i; - - regex_init(); - - show_absolute_syms = 0; - show_absolute_relocs = 0; - as_text = 0; - fname = NULL; - for (i = 1; i < argc; i++) { - char *arg = argv[i]; - if (*arg == '-') { - if (strcmp(argv[1], "--abs-syms") == 0) { - show_absolute_syms = 1; - continue; - } - - if (strcmp(argv[1], "--abs-relocs") == 0) { - show_absolute_relocs = 1; - continue; - } - else if (strcmp(argv[1], "--text") == 0) { - as_text = 1; - continue; - } - } - else if (!fname) { - fname = arg; - continue; - } - usage(); - } - if (!fname) { - usage(); - } - 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); - return 0; -} -- cgit v1.2.3