From 433de739bbc22a5b2c87602116566ce27e3b4cab Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Tue, 8 May 2012 21:22:24 +0300 Subject: [PATCH] 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 scripts/x86-relocs.c so it will be compiled before building the arch/x86 tree. 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 --- arch/x86/boot/compressed/Makefile | 11 +- scripts/.gitignore | 1 + scripts/Makefile | 3 + .../relocs.c => scripts/x86-relocs.c | 233 +++++++++++++----- 4 files changed, 185 insertions(+), 63 deletions(-) rename arch/x86/boot/compressed/relocs.c => scripts/x86-relocs.c (77%) diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index fd55a2ff3ad8..0435e8a2d20e 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 := $(obj)/vmlinux.bin diff --git a/scripts/.gitignore b/scripts/.gitignore index 105b21f08185..68c0f32fdc9b 100644 --- a/scripts/.gitignore +++ b/scripts/.gitignore @@ -9,3 +9,4 @@ unifdef ihex2fw recordmcount docproc +x86-relocs diff --git a/scripts/Makefile b/scripts/Makefile index df7678febf27..a241359d2c82 100644 --- a/scripts/Makefile +++ b/scripts/Makefile @@ -8,11 +8,14 @@ # conmakehash: Create arrays for initializing the kernel console tables # docproc: Used in Documentation/DocBook +HOST_EXTRACFLAGS += -I$(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) $(hostprogs-m) diff --git a/arch/x86/boot/compressed/relocs.c b/scripts/x86-relocs.c similarity index 77% rename from arch/x86/boot/compressed/relocs.c rename to scripts/x86-relocs.c index fb7117a4ade1..02914706e5b9 100644 --- a/arch/x86/boot/compressed/relocs.c +++ b/scripts/x86-relocs.c @@ -18,6 +18,8 @@ static void die(char *fmt, ...); static Elf32_Ehdr ehdr; static unsigned long reloc_count, reloc_idx; static unsigned long *relocs; +static unsigned long reloc16_count, reloc16_idx; +static unsigned long *relocs16; struct section { Elf32_Shdr shdr; @@ -28,52 +30,82 @@ struct section { }; static struct section *secs; +enum symtype { + S_ABS, + S_REL, + S_SEG, + S_LIN, + S_NSYMTYPES +}; + +static const char * const sym_regex_kernel[S_NSYMTYPES] = { /* * Following symbols have been audited. There values are constant and do * not change if bzImage is loaded at a different physical address than * the address for which it has been compiled. Don't warn user about * absolute relocations present w.r.t these symbols. */ -static const char abs_sym_regex[] = + [S_ABS] = "^(xen_irq_disable_direct_reloc$|" "xen_save_fl_direct_reloc$|" "VDSO|" - "__crc_)"; -static regex_t abs_sym_regex_c; -static int is_abs_reloc(const char *sym_name) -{ - return !regexec(&abs_sym_regex_c, sym_name, 0, NULL, 0); -} + "__crc_)", /* * These symbols are known to be relative, even if the linker marks them * as absolute (typically defined outside any section in the linker script.) */ -static const char rel_sym_regex[] = - "^_end$"; -static regex_t rel_sym_regex_c; -static int is_rel_reloc(const char *sym_name) + [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 !regexec(&rel_sym_regex_c, sym_name, 0, NULL, 0); + return sym_regex[type] && + !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0); } -static void regex_init(void) +static void regex_init(int use_real_mode) { 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); - } + int i; - 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); + 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); + } } } @@ -154,6 +186,10 @@ static const char *rel_type(unsigned type) 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"; @@ -189,7 +225,7 @@ static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym) name = sym_strtab + sym->st_name; } else { - name = sec_name(secs[sym->st_shndx].shdr.sh_name); + name = sec_name(sym->st_shndx); } return name; } @@ -472,7 +508,7 @@ static void print_absolute_relocs(void) * Before warning check if this absolute symbol * relocation is harmless. */ - if (is_abs_reloc(name) || is_rel_reloc(name)) + if (is_reloc(S_ABS, name) || is_reloc(S_REL, name)) continue; if (!printed) { @@ -496,7 +532,8 @@ static void print_absolute_relocs(void) printf("\n"); } -static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym)) +static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym), + int use_real_mode) { int i; /* Walk through the relocations */ @@ -521,30 +558,62 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym)) 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); - /* 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: + 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: - /* Visit relocations that need to be adjusted */ + 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); } } } @@ -552,13 +621,19 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym)) static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym) { - reloc_count += 1; + 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. */ - relocs[reloc_idx++] = rel->r_offset; + 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) @@ -568,23 +643,41 @@ static int cmp_relocs(const void *va, const void *vb) return (*a == *b)? 0 : (*a > *b)? 1 : -1; } -static void emit_relocs(int as_text) +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); + 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); + 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) { @@ -593,58 +686,83 @@ static void emit_relocs(int as_text) */ 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]); + 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 { - 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); + 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] vmlinux\n"); + 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; + int as_text, use_real_mode; const char *fname; FILE *fp; int i; - regex_init(); - 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(argv[1], "--abs-syms") == 0) { + if (strcmp(arg, "--abs-syms") == 0) { show_absolute_syms = 1; continue; } - - if (strcmp(argv[1], "--abs-relocs") == 0) { + if (strcmp(arg, "--abs-relocs") == 0) { show_absolute_relocs = 1; continue; } - else if (strcmp(argv[1], "--text") == 0) { + if (strcmp(arg, "--text") == 0) { as_text = 1; continue; } + if (strcmp(arg, "--realmode") == 0) { + use_real_mode = 1; + continue; + } } else if (!fname) { fname = arg; @@ -655,6 +773,7 @@ int main(int argc, char **argv) if (!fname) { usage(); } + regex_init(use_real_mode); fp = fopen(fname, "r"); if (!fp) { die("Cannot open %s: %s\n", @@ -673,6 +792,6 @@ int main(int argc, char **argv) print_absolute_relocs(); return 0; } - emit_relocs(as_text); + emit_relocs(as_text, use_real_mode); return 0; } -- 2.34.1