* [PATCH 00/23] x86, realmode: new infrastructure for realmode code @ 2012-05-08 18:20 Jarkko Sakkinen 2012-05-08 18:20 ` [PATCH 01/23] x86, realmode: 16-bit real-mode code support for relocs tool Jarkko Sakkinen 2012-05-08 18:20 ` [PATCH 02/23] x86, realmode: realmode.bin infrastructure Jarkko Sakkinen 0 siblings, 2 replies; 4+ messages in thread From: Jarkko Sakkinen @ 2012-05-08 18:20 UTC (permalink / raw) To: linux-kernel Cc: linux-kbuild, Michal Marek, Sam Ravnborg, Shane Wang, H. Peter Anvin, Jarkko Sakkinen I've been working together with H. Peter Anvin in order replace the ad-hoc real-mode code inside .x86_trampoline section with an encapsulated binary that is fully relocatable to any memory location under 1MB. Everything that is needs to be relocated is relocated during initialization. Benefits: - Simplifies things. Real-mode code does not have to find its own location any more. This makes maintaining and extending this code much nicer experience. - Cleans up code base a lot. Now real-mode code is encapsulated from kernel both in source tree and in vmlinux. - We can set proper permissions to pages of text, data/bss and rodata. Before, .x86_trampoline had just rwx permissions. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 01/23] x86, realmode: 16-bit real-mode code support for relocs tool 2012-05-08 18:20 [PATCH 00/23] x86, realmode: new infrastructure for realmode code Jarkko Sakkinen @ 2012-05-08 18:20 ` Jarkko Sakkinen 2012-05-08 18:20 ` [PATCH 02/23] x86, realmode: realmode.bin infrastructure Jarkko Sakkinen 1 sibling, 0 replies; 4+ messages in thread From: Jarkko Sakkinen @ 2012-05-08 18:20 UTC (permalink / raw) To: linux-kernel Cc: linux-kbuild, Michal Marek, Sam Ravnborg, Shane Wang, H. Peter Anvin, Jarkko Sakkinen From: "H. Peter Anvin" <hpa@linux.intel.com> 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 scripts/x86-relocs.c so it will be compiled before building the arch/x86 tree. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com> --- arch/x86/boot/compressed/Makefile | 11 +- arch/x86/boot/compressed/relocs.c | 680 ------------------------------- scripts/.gitignore | 1 + scripts/Makefile | 3 + scripts/x86-relocs.c | 797 +++++++++++++++++++++++++++++++++++++ 5 files changed, 806 insertions(+), 686 deletions(-) delete mode 100644 arch/x86/boot/compressed/relocs.c create mode 100644 scripts/x86-relocs.c diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index fd55a2f..0435e8a 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 - -quiet_cmd_relocs = RELOCS $@ - cmd_relocs = $(obj)/relocs $< > $@;$(obj)/relocs --abs-relocs $< -$(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE +CMD_RELOCS = scripts/x86-relocs +quiet_cmd_relocs = RELOCS $@ + cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $< +$(obj)/vmlinux.relocs: vmlinux FORCE $(call if_changed,relocs) vmlinux.bin.all-y := $(obj)/vmlinux.bin diff --git a/arch/x86/boot/compressed/relocs.c b/arch/x86/boot/compressed/relocs.c deleted file mode 100644 index d3c0b02..0000000 --- a/arch/x86/boot/compressed/relocs.c +++ /dev/null @@ -1,680 +0,0 @@ -#include <stdio.h> -#include <stdarg.h> -#include <stdlib.h> -#include <stdint.h> -#include <string.h> -#include <errno.h> -#include <unistd.h> -#include <elf.h> -#include <byteswap.h> -#define USE_BSD -#include <endian.h> -#include <regex.h> -#include <tools/le_byteshift.h> - -static void die(char *fmt, ...); - -#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) -static Elf32_Ehdr ehdr; -static unsigned long reloc_count, reloc_idx; -static unsigned long *relocs; - -struct section { - Elf32_Shdr shdr; - struct section *link; - Elf32_Sym *symtab; - Elf32_Rel *reltab; - char *strtab; -}; -static struct section *secs; - -/* - * Following symbols have been audited. There values are constant and do - * not change if bzImage is loaded at a different physical address than - * the address for which it has been compiled. Don't warn user about - * absolute relocations present w.r.t these symbols. - */ -static const char abs_sym_regex[] = - "^(xen_irq_disable_direct_reloc$|" - "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 = "<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(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; - Elf32_Sym *sh_symtab; - int j; - - if (sec->shdr.sh_type != SHT_SYMTAB) { - continue; - } - sh_symtab = sec->symtab; - 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; -} diff --git a/scripts/.gitignore b/scripts/.gitignore index 105b21f..68c0f32 100644 --- a/scripts/.gitignore +++ b/scripts/.gitignore @@ -9,3 +9,4 @@ unifdef ihex2fw recordmcount docproc +x86-relocs diff --git a/scripts/Makefile b/scripts/Makefile index df7678f..a241359d 100644 --- a/scripts/Makefile +++ b/scripts/Makefile @@ -8,11 +8,14 @@ # conmakehash: Create arrays for initializing the kernel console tables # docproc: Used in Documentation/DocBook +HOST_EXTRACFLAGS += -I$(srctree)/tools/include + hostprogs-$(CONFIG_KALLSYMS) += kallsyms hostprogs-$(CONFIG_LOGO) += pnmtologo hostprogs-$(CONFIG_VT) += conmakehash hostprogs-$(CONFIG_IKCONFIG) += bin2c hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount +hostprogs-$(CONFIG_X86) += x86-relocs always := $(hostprogs-y) $(hostprogs-m) diff --git a/scripts/x86-relocs.c b/scripts/x86-relocs.c new file mode 100644 index 0000000..0291470 --- /dev/null +++ b/scripts/x86-relocs.c @@ -0,0 +1,797 @@ +#include <stdio.h> +#include <stdarg.h> +#include <stdlib.h> +#include <stdint.h> +#include <string.h> +#include <errno.h> +#include <unistd.h> +#include <elf.h> +#include <byteswap.h> +#define USE_BSD +#include <endian.h> +#include <regex.h> +#include <tools/le_byteshift.h> + +static void die(char *fmt, ...); + +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) +static Elf32_Ehdr ehdr; +static unsigned long reloc_count, reloc_idx; +static unsigned long *relocs; +static unsigned long reloc16_count, reloc16_idx; +static unsigned long *relocs16; + +struct section { + Elf32_Shdr shdr; + struct section *link; + Elf32_Sym *symtab; + Elf32_Rel *reltab; + char *strtab; +}; +static struct section *secs; + +enum symtype { + S_ABS, + S_REL, + S_SEG, + S_LIN, + S_NSYMTYPES +}; + +static const char * const sym_regex_kernel[S_NSYMTYPES] = { +/* + * Following symbols have been audited. There values are constant and do + * not change if bzImage is loaded at a different physical address than + * the address for which it has been compiled. Don't warn user about + * absolute relocations present w.r.t these symbols. + */ + [S_ABS] = + "^(xen_irq_disable_direct_reloc$|" + "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; +} -- 1.7.9.5 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 02/23] x86, realmode: realmode.bin infrastructure 2012-05-08 18:20 [PATCH 00/23] x86, realmode: new infrastructure for realmode code Jarkko Sakkinen 2012-05-08 18:20 ` [PATCH 01/23] x86, realmode: 16-bit real-mode code support for relocs tool Jarkko Sakkinen @ 2012-05-08 18:20 ` Jarkko Sakkinen 1 sibling, 0 replies; 4+ messages in thread From: Jarkko Sakkinen @ 2012-05-08 18:20 UTC (permalink / raw) To: linux-kernel Cc: linux-kbuild, Michal Marek, Sam Ravnborg, Shane Wang, H. Peter Anvin, Jarkko Sakkinen Create realmode.bin and realmode.relocs files. Piggy pack them into relocatable object that will be included into .init.data section of the main kernel image. The first file includes binary image of the real-mode code. The latter file includes all relocations. The layout of the binary image is specified in realmode.lds.S. The makefile generates pa_ prefixed symbols for each exported global. These are used in 32-bit code and in realmode header to define symbols that need to be relocated. Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com> Originally-by: H. Peter Anvin <hpa@linux.intel.com> --- arch/x86/Kbuild | 2 +- arch/x86/realmode/Makefile | 20 +++++++++++ arch/x86/realmode/rm/.gitignore | 3 ++ arch/x86/realmode/rm/Makefile | 63 ++++++++++++++++++++++++++++++++ arch/x86/realmode/rm/header.S | 16 +++++++++ arch/x86/realmode/rm/realmode.lds.S | 68 +++++++++++++++++++++++++++++++++++ arch/x86/realmode/rmpiggy.S | 18 ++++++++++ 7 files changed, 189 insertions(+), 1 deletion(-) create mode 100644 arch/x86/realmode/Makefile create mode 100644 arch/x86/realmode/rm/.gitignore create mode 100644 arch/x86/realmode/rm/Makefile create mode 100644 arch/x86/realmode/rm/header.S create mode 100644 arch/x86/realmode/rm/realmode.lds.S create mode 100644 arch/x86/realmode/rmpiggy.S diff --git a/arch/x86/Kbuild b/arch/x86/Kbuild index 0e9dec6..e5287d8 100644 --- a/arch/x86/Kbuild +++ b/arch/x86/Kbuild @@ -1,4 +1,3 @@ - obj-$(CONFIG_KVM) += kvm/ # Xen paravirtualization support @@ -7,6 +6,7 @@ obj-$(CONFIG_XEN) += xen/ # lguest paravirtualization support obj-$(CONFIG_LGUEST_GUEST) += lguest/ +obj-y += realmode/ obj-y += kernel/ obj-y += mm/ diff --git a/arch/x86/realmode/Makefile b/arch/x86/realmode/Makefile new file mode 100644 index 0000000..f22a4f8 --- /dev/null +++ b/arch/x86/realmode/Makefile @@ -0,0 +1,20 @@ +# +# arch/x86/realmode/Makefile +# +# This file is subject to the terms and conditions of the GNU General Public +# License. See the file "COPYING" in the main directory of this archive +# for more details. +# +# + +subdir- := rm + +obj-y += rmpiggy.o + +$(obj)/rmpiggy.o: $(obj)/rm/realmode.relocs $(obj)/rm/realmode.bin + +$(obj)/rm/realmode.bin: FORCE + $(Q)$(MAKE) $(build)=$(obj)/rm $@ + +$(obj)/rm/realmode.relocs: FORCE + $(Q)$(MAKE) $(build)=$(obj)/rm $@ diff --git a/arch/x86/realmode/rm/.gitignore b/arch/x86/realmode/rm/.gitignore new file mode 100644 index 0000000..b6ed3a2 --- /dev/null +++ b/arch/x86/realmode/rm/.gitignore @@ -0,0 +1,3 @@ +pasyms.h +realmode.lds +realmode.relocs diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile new file mode 100644 index 0000000..7c3f202 --- /dev/null +++ b/arch/x86/realmode/rm/Makefile @@ -0,0 +1,63 @@ +# +# arch/x86/realmode/Makefile +# +# This file is subject to the terms and conditions of the GNU General Public +# License. See the file "COPYING" in the main directory of this archive +# for more details. +# +# + +subdir- := wakeup + +always := realmode.bin + +realmode-y += header.o + +targets += $(realmode-y) + +REALMODE_OBJS = $(addprefix $(obj)/,$(realmode-y)) + +sed-pasyms := -n -r -e 's/^([0-9a-fA-F]+) [ABCDGRSTVW] (.+)$$/pa_\2 = \2;/p' + +quiet_cmd_pasyms = PASYMS $@ + cmd_pasyms = $(NM) $(filter-out FORCE,$^) | \ + sed $(sed-pasyms) | sort | uniq > $@ + +$(obj)/pasyms.h: $(REALMODE_OBJS) FORCE + $(call if_changed,pasyms) + +$(obj)/realmode.lds: $(obj)/pasyms.h + +LDFLAGS_realmode.elf := --emit-relocs -T +CPPFLAGS_realmode.lds += -P -C -I$(obj) + +$(obj)/realmode.elf: $(obj)/realmode.lds $(REALMODE_OBJS) FORCE + $(call if_changed,ld) + +OBJCOPYFLAGS_realmode.bin := -O binary + +$(obj)/realmode.bin: $(obj)/realmode.elf + $(call if_changed,objcopy) + +quiet_cmd_relocs = RELOCS $@ + cmd_relocs = scripts/x86-relocs --realmode $< > $@ +$(obj)/realmode.relocs: $(obj)/realmode.elf FORCE + $(call if_changed,relocs) + +# --------------------------------------------------------------------------- + +# How to compile the 16-bit code. Note we always compile for -march=i386, +# that way we can complain to the user if the CPU is insufficient. +KBUILD_CFLAGS := $(LINUXINCLUDE) -m32 -g -Os -D_SETUP -D__KERNEL__ \ + -DDISABLE_BRANCH_PROFILING \ + -Wall -Wstrict-prototypes \ + -march=i386 -mregparm=3 \ + -include $(srctree)/$(src)/../../boot/code16gcc.h \ + -fno-strict-aliasing -fomit-frame-pointer \ + $(call cc-option, -ffreestanding) \ + $(call cc-option, -fno-toplevel-reorder,\ + $(call cc-option, -fno-unit-at-a-time)) \ + $(call cc-option, -fno-stack-protector) \ + $(call cc-option, -mpreferred-stack-boundary=2) +KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__ +GCOV_PROFILE := n diff --git a/arch/x86/realmode/rm/header.S b/arch/x86/realmode/rm/header.S new file mode 100644 index 0000000..7be17f2 --- /dev/null +++ b/arch/x86/realmode/rm/header.S @@ -0,0 +1,16 @@ +/* + * Real-mode blob header; this should match realmode.h and be + * readonly; for mutable data instead add pointers into the .data + * or .bss sections as appropriate. + */ + +#include <linux/linkage.h> +#include <asm/page_types.h> + + .section ".header", "a" + +ENTRY(real_mode_header) + .long pa_text_start + .long pa_ro_end + .long pa_end +END(real_mode_header) diff --git a/arch/x86/realmode/rm/realmode.lds.S b/arch/x86/realmode/rm/realmode.lds.S new file mode 100644 index 0000000..c5b8a4f --- /dev/null +++ b/arch/x86/realmode/rm/realmode.lds.S @@ -0,0 +1,68 @@ +/* + * realmode.lds.S + * + * Linker script for the real-mode code + */ + +#include <asm/page_types.h> + +#undef i386 + +OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386") +OUTPUT_ARCH(i386) + +SECTIONS +{ + real_mode_seg = 0; + + . = 0; + .header : { + pa_real_mode_base = .; + *(.header) + } + + . = ALIGN(4); + .rodata : { + *(.rodata) + *(.rodata.*) + } + + . = ALIGN(PAGE_SIZE); + .text : { + pa_text_start = .; + *(.text) + *(.text.*) + } + + .text32 : { + *(.text32) + *(.text32.*) + pa_ro_end = .; + } + + . = ALIGN(PAGE_SIZE); + .data : { + *(.data) + *(.data.*) + } + + . = ALIGN(128); + .bss : { + *(.bss*) + } + + /* End signature for integrity checking */ + . = ALIGN(4); + .signature : { + *(.signature) + pa_end = .; + } + + /DISCARD/ : { + *(.note*) + *(.debug*) + *(.eh_frame*) + } + +#include "pasyms.h" +} diff --git a/arch/x86/realmode/rmpiggy.S b/arch/x86/realmode/rmpiggy.S new file mode 100644 index 0000000..6047d7f --- /dev/null +++ b/arch/x86/realmode/rmpiggy.S @@ -0,0 +1,18 @@ +/* + * Wrapper script for the realmode binary as a transport object + * before copying to low memory. + */ +#include <linux/linkage.h> +#include <asm/page_types.h> + + .section ".init.data","aw" + + .balign PAGE_SIZE + +ENTRY(real_mode_blob) + .incbin "arch/x86/realmode/rm/realmode.bin" +END(real_mode_blob) + +ENTRY(real_mode_relocs) + .incbin "arch/x86/realmode/rm/realmode.relocs" +END(real_mode_relocs) -- 1.7.9.5 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH 00/23] x86, realmode: new infrastructure for realmode code @ 2012-05-08 18:22 Jarkko Sakkinen 2012-05-08 18:22 ` [PATCH 01/23] x86, realmode: 16-bit real-mode code support for relocs tool Jarkko Sakkinen 0 siblings, 1 reply; 4+ messages in thread From: Jarkko Sakkinen @ 2012-05-08 18:22 UTC (permalink / raw) To: linux-kernel Cc: linux-kbuild, Michal Marek, Sam Ravnborg, Joseph Cihula, Shane Wang, hpa, Jarkko Sakkinen I've been working together with H. Peter Anvin in order replace the ad-hoc real-mode code inside .x86_trampoline section with an encapsulated binary that is fully relocatable to any memory location under 1MB. Everything that is needs to be relocated is relocated during initialization. Benefits: - Simplifies things. Real-mode code does not have to find its own location any more. This makes maintaining and extending this code much nicer experience. - Cleans up code base a lot. Now real-mode code is encapsulated from kernel both in source tree and in vmlinux. - We can set proper permissions to pages of text, data/bss and rodata. Before, .x86_trampoline had just rwx permissions. ^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH 01/23] x86, realmode: 16-bit real-mode code support for relocs tool 2012-05-08 18:22 [PATCH 00/23] x86, realmode: new infrastructure for realmode code Jarkko Sakkinen @ 2012-05-08 18:22 ` Jarkko Sakkinen 0 siblings, 0 replies; 4+ messages in thread From: Jarkko Sakkinen @ 2012-05-08 18:22 UTC (permalink / raw) To: linux-kernel Cc: linux-kbuild, Michal Marek, Sam Ravnborg, Joseph Cihula, Shane Wang, hpa, Jarkko Sakkinen From: "H. Peter Anvin" <hpa@linux.intel.com> 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 scripts/x86-relocs.c so it will be compiled before building the arch/x86 tree. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com> --- arch/x86/boot/compressed/Makefile | 11 +- arch/x86/boot/compressed/relocs.c | 680 ------------------------------- scripts/.gitignore | 1 + scripts/Makefile | 3 + scripts/x86-relocs.c | 797 +++++++++++++++++++++++++++++++++++++ 5 files changed, 806 insertions(+), 686 deletions(-) delete mode 100644 arch/x86/boot/compressed/relocs.c create mode 100644 scripts/x86-relocs.c diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index fd55a2f..0435e8a 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 - -quiet_cmd_relocs = RELOCS $@ - cmd_relocs = $(obj)/relocs $< > $@;$(obj)/relocs --abs-relocs $< -$(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE +CMD_RELOCS = scripts/x86-relocs +quiet_cmd_relocs = RELOCS $@ + cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $< +$(obj)/vmlinux.relocs: vmlinux FORCE $(call if_changed,relocs) vmlinux.bin.all-y := $(obj)/vmlinux.bin diff --git a/arch/x86/boot/compressed/relocs.c b/arch/x86/boot/compressed/relocs.c deleted file mode 100644 index d3c0b02..0000000 --- a/arch/x86/boot/compressed/relocs.c +++ /dev/null @@ -1,680 +0,0 @@ -#include <stdio.h> -#include <stdarg.h> -#include <stdlib.h> -#include <stdint.h> -#include <string.h> -#include <errno.h> -#include <unistd.h> -#include <elf.h> -#include <byteswap.h> -#define USE_BSD -#include <endian.h> -#include <regex.h> -#include <tools/le_byteshift.h> - -static void die(char *fmt, ...); - -#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) -static Elf32_Ehdr ehdr; -static unsigned long reloc_count, reloc_idx; -static unsigned long *relocs; - -struct section { - Elf32_Shdr shdr; - struct section *link; - Elf32_Sym *symtab; - Elf32_Rel *reltab; - char *strtab; -}; -static struct section *secs; - -/* - * Following symbols have been audited. There values are constant and do - * not change if bzImage is loaded at a different physical address than - * the address for which it has been compiled. Don't warn user about - * absolute relocations present w.r.t these symbols. - */ -static const char abs_sym_regex[] = - "^(xen_irq_disable_direct_reloc$|" - "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 = "<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(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; - Elf32_Sym *sh_symtab; - int j; - - if (sec->shdr.sh_type != SHT_SYMTAB) { - continue; - } - sh_symtab = sec->symtab; - 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; -} diff --git a/scripts/.gitignore b/scripts/.gitignore index 105b21f..68c0f32 100644 --- a/scripts/.gitignore +++ b/scripts/.gitignore @@ -9,3 +9,4 @@ unifdef ihex2fw recordmcount docproc +x86-relocs diff --git a/scripts/Makefile b/scripts/Makefile index df7678f..a241359d 100644 --- a/scripts/Makefile +++ b/scripts/Makefile @@ -8,11 +8,14 @@ # conmakehash: Create arrays for initializing the kernel console tables # docproc: Used in Documentation/DocBook +HOST_EXTRACFLAGS += -I$(srctree)/tools/include + hostprogs-$(CONFIG_KALLSYMS) += kallsyms hostprogs-$(CONFIG_LOGO) += pnmtologo hostprogs-$(CONFIG_VT) += conmakehash hostprogs-$(CONFIG_IKCONFIG) += bin2c hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount +hostprogs-$(CONFIG_X86) += x86-relocs always := $(hostprogs-y) $(hostprogs-m) diff --git a/scripts/x86-relocs.c b/scripts/x86-relocs.c new file mode 100644 index 0000000..0291470 --- /dev/null +++ b/scripts/x86-relocs.c @@ -0,0 +1,797 @@ +#include <stdio.h> +#include <stdarg.h> +#include <stdlib.h> +#include <stdint.h> +#include <string.h> +#include <errno.h> +#include <unistd.h> +#include <elf.h> +#include <byteswap.h> +#define USE_BSD +#include <endian.h> +#include <regex.h> +#include <tools/le_byteshift.h> + +static void die(char *fmt, ...); + +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) +static Elf32_Ehdr ehdr; +static unsigned long reloc_count, reloc_idx; +static unsigned long *relocs; +static unsigned long reloc16_count, reloc16_idx; +static unsigned long *relocs16; + +struct section { + Elf32_Shdr shdr; + struct section *link; + Elf32_Sym *symtab; + Elf32_Rel *reltab; + char *strtab; +}; +static struct section *secs; + +enum symtype { + S_ABS, + S_REL, + S_SEG, + S_LIN, + S_NSYMTYPES +}; + +static const char * const sym_regex_kernel[S_NSYMTYPES] = { +/* + * Following symbols have been audited. There values are constant and do + * not change if bzImage is loaded at a different physical address than + * the address for which it has been compiled. Don't warn user about + * absolute relocations present w.r.t these symbols. + */ + [S_ABS] = + "^(xen_irq_disable_direct_reloc$|" + "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; +} -- 1.7.9.5 ^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-05-08 18:23 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2012-05-08 18:20 [PATCH 00/23] x86, realmode: new infrastructure for realmode code Jarkko Sakkinen 2012-05-08 18:20 ` [PATCH 01/23] x86, realmode: 16-bit real-mode code support for relocs tool Jarkko Sakkinen 2012-05-08 18:20 ` [PATCH 02/23] x86, realmode: realmode.bin infrastructure Jarkko Sakkinen 2012-05-08 18:22 [PATCH 00/23] x86, realmode: new infrastructure for realmode code Jarkko Sakkinen 2012-05-08 18:22 ` [PATCH 01/23] x86, realmode: 16-bit real-mode code support for relocs tool Jarkko Sakkinen
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).