From 6520fe5564acf07ade7b18a1272db1184835c487 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Tue, 8 May 2012 21:22:24 +0300 Subject: [PATCH 1/3] x86, realmode: 16-bit real-mode code support for relocs tool A new option is added to the relocs tool called '--realmode'. This option causes the generation of 16-bit segment relocations and 32-bit linear relocations for the real-mode code. When the real-mode code is moved to the low-memory during kernel initialization, these relocation entries can be used to relocate the code properly. In the assembly code 16-bit segment relocations must be relative to the 'real_mode_seg' absolute symbol. Linear relocations must be relative to a symbol prefixed with 'pa_'. 16-bit segment relocation is used to load cs:ip in 16-bit code. Linear relocations are used in the 32-bit code for relocatable data references. They are declared in the linker script of the real-mode code. The relocs tool is moved to arch/x86/tools/relocs.c, and added new target archscripts that can be used to build scripts needed building an architecture. be compiled before building the arch/x86 tree. [ hpa: accelerating this because it detects invalid absolute relocations, a serious bug in binutils 2.22.52.0.x which currently produces bad kernels. ] Signed-off-by: H. Peter Anvin Link: http://lkml.kernel.org/r/1336501366-28617-2-git-send-email-jarkko.sakkinen@intel.com Signed-off-by: Jarkko Sakkinen Signed-off-by: H. Peter Anvin Cc: --- Makefile | 9 +- arch/x86/Makefile | 3 + arch/x86/boot/compressed/Makefile | 9 +- arch/x86/tools/.gitignore | 1 + arch/x86/tools/Makefile | 4 + arch/x86/{boot/compressed => tools}/relocs.c | 233 ++++++++++++++----- scripts/Makefile | 2 + 7 files changed, 196 insertions(+), 65 deletions(-) create mode 100644 arch/x86/tools/.gitignore rename arch/x86/{boot/compressed => tools}/relocs.c (77%) diff --git a/Makefile b/Makefile index 48bd1f50dcc39..db2bcf3d66b8d 100644 --- a/Makefile +++ b/Makefile @@ -442,7 +442,7 @@ asm-generic: no-dot-config-targets := clean mrproper distclean \ cscope gtags TAGS tags help %docs check% coccicheck \ - include/linux/version.h headers_% archheaders \ + include/linux/version.h headers_% archheaders archscripts \ kernelversion %src-pkg config-targets := 0 @@ -979,7 +979,7 @@ prepare1: prepare2 include/linux/version.h include/generated/utsrelease.h \ include/config/auto.conf $(cmd_crmodverdir) -archprepare: archheaders prepare1 scripts_basic +archprepare: archheaders archscripts prepare1 scripts_basic prepare0: archprepare FORCE $(Q)$(MAKE) $(build)=. @@ -1049,8 +1049,11 @@ hdr-dst = $(if $(KBUILD_HEADERS), dst=include/asm-$(hdr-arch), dst=include/asm) PHONY += archheaders archheaders: +PHONY += archscripts +archscripts: + PHONY += __headers -__headers: include/linux/version.h scripts_basic asm-generic archheaders FORCE +__headers: include/linux/version.h scripts_basic asm-generic archheaders archscripts FORCE $(Q)$(MAKE) $(build)=scripts build_unifdef PHONY += headers_install_all diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 41a7237606a3b..94e91e401da99 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -134,6 +134,9 @@ KBUILD_CFLAGS += $(call cc-option,-mno-avx,) KBUILD_CFLAGS += $(mflags-y) KBUILD_AFLAGS += $(mflags-y) +archscripts: + $(Q)$(MAKE) $(build)=arch/x86/tools relocs + ### # Syscall table generation diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index fd55a2ff3ad8e..e398bb5d63bb2 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -40,13 +40,12 @@ OBJCOPYFLAGS_vmlinux.bin := -R .comment -S $(obj)/vmlinux.bin: vmlinux FORCE $(call if_changed,objcopy) +targets += vmlinux.bin.all vmlinux.relocs -targets += vmlinux.bin.all vmlinux.relocs relocs -hostprogs-$(CONFIG_X86_NEED_RELOCS) += relocs - +CMD_RELOCS = arch/x86/tools/relocs quiet_cmd_relocs = RELOCS $@ - cmd_relocs = $(obj)/relocs $< > $@;$(obj)/relocs --abs-relocs $< -$(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE + cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $< +$(obj)/vmlinux.relocs: vmlinux FORCE $(call if_changed,relocs) vmlinux.bin.all-y := $(obj)/vmlinux.bin diff --git a/arch/x86/tools/.gitignore b/arch/x86/tools/.gitignore new file mode 100644 index 0000000000000..be0ed065249b7 --- /dev/null +++ b/arch/x86/tools/.gitignore @@ -0,0 +1 @@ +relocs diff --git a/arch/x86/tools/Makefile b/arch/x86/tools/Makefile index d511aa97533ab..733057b435b08 100644 --- a/arch/x86/tools/Makefile +++ b/arch/x86/tools/Makefile @@ -36,3 +36,7 @@ HOSTCFLAGS_insn_sanity.o := -Wall -I$(objtree)/arch/x86/lib/ -I$(srctree)/arch/x $(obj)/test_get_len.o: $(srctree)/arch/x86/lib/insn.c $(srctree)/arch/x86/lib/inat.c $(srctree)/arch/x86/include/asm/inat_types.h $(srctree)/arch/x86/include/asm/inat.h $(srctree)/arch/x86/include/asm/insn.h $(objtree)/arch/x86/lib/inat-tables.c $(obj)/insn_sanity.o: $(srctree)/arch/x86/lib/insn.c $(srctree)/arch/x86/lib/inat.c $(srctree)/arch/x86/include/asm/inat_types.h $(srctree)/arch/x86/include/asm/inat.h $(srctree)/arch/x86/include/asm/insn.h $(objtree)/arch/x86/lib/inat-tables.c + +HOST_EXTRACFLAGS += -I$(srctree)/tools/include +hostprogs-y += relocs +relocs: $(obj)/relocs diff --git a/arch/x86/boot/compressed/relocs.c b/arch/x86/tools/relocs.c similarity index 77% rename from arch/x86/boot/compressed/relocs.c rename to arch/x86/tools/relocs.c index fb7117a4ade1e..02914706e5b98 100644 --- a/arch/x86/boot/compressed/relocs.c +++ b/arch/x86/tools/relocs.c @@ -18,6 +18,8 @@ static void die(char *fmt, ...); static Elf32_Ehdr ehdr; static unsigned long reloc_count, reloc_idx; static unsigned long *relocs; +static unsigned long reloc16_count, reloc16_idx; +static unsigned long *relocs16; struct section { Elf32_Shdr shdr; @@ -28,52 +30,82 @@ struct section { }; static struct section *secs; +enum symtype { + S_ABS, + S_REL, + S_SEG, + S_LIN, + S_NSYMTYPES +}; + +static const char * const sym_regex_kernel[S_NSYMTYPES] = { /* * Following symbols have been audited. There values are constant and do * not change if bzImage is loaded at a different physical address than * the address for which it has been compiled. Don't warn user about * absolute relocations present w.r.t these symbols. */ -static const char abs_sym_regex[] = + [S_ABS] = "^(xen_irq_disable_direct_reloc$|" "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; } diff --git a/scripts/Makefile b/scripts/Makefile index df7678febf277..36266665dbcbb 100644 --- a/scripts/Makefile +++ b/scripts/Makefile @@ -8,6 +8,8 @@ # 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 From a3e854d95a76862cd37937e0b0438f540536771a Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Fri, 18 May 2012 00:24:09 -0700 Subject: [PATCH 2/3] x86, relocs: Workaround for binutils 2.22.52.0.1 section bug GNU ld 2.22.52.0.1 has a bug that it blindly changes symbols from section-relative to absolute if they are in a section of zero length. This turns the symbols __init_begin and __init_end into absolute symbols. Let the relocs program know that those should be treated as relative symbols. Reported-by: Ingo Molnar Signed-off-by: H. Peter Anvin Cc: H.J. Lu Cc: Cc: Jarkko Sakkinen --- arch/x86/tools/relocs.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c index 02914706e5b98..c3cfbb2d4a1d3 100644 --- a/arch/x86/tools/relocs.c +++ b/arch/x86/tools/relocs.c @@ -56,7 +56,11 @@ static const char * const sym_regex_kernel[S_NSYMTYPES] = { * as absolute (typically defined outside any section in the linker script.) */ [S_REL] = - "^_end$", + "^(__init_(begin|end)|" + "__x86_cpu_dev_(start|end)|" + "(__parainstructions|__alt_instructions)(|_end)|" + "(__iommu_table|__apicdrivers|__smp_locks)(|_end)|" + "_end)$" }; From 24ab82bd9bf18f3efc69a131d73577940941e1b7 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Fri, 18 May 2012 09:52:01 -0700 Subject: [PATCH 3/3] x86, relocs: When printing an error, say relative or absolute When the relocs tool throws an error, let the error message say if it is an absolute or relative symbol. This should make it a lot more clear what action the programmer needs to take and should help us find the reason if additional symbol bugs show up. Signed-off-by: H. Peter Anvin Cc: --- arch/x86/tools/relocs.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c index c3cfbb2d4a1d3..b43cfcd9bf40f 100644 --- a/arch/x86/tools/relocs.c +++ b/arch/x86/tools/relocs.c @@ -563,10 +563,14 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym), Elf32_Sym *sym; unsigned r_type; const char *symname; + int shn_abs; + rel = &sec->reltab[j]; sym = &sh_symtab[ELF32_R_SYM(rel->r_info)]; r_type = ELF32_R_TYPE(rel->r_info); + shn_abs = sym->st_shndx == SHN_ABS; + switch (r_type) { case R_386_NONE: case R_386_PC32: @@ -582,7 +586,7 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym), symname = sym_name(sym_strtab, sym); if (!use_real_mode) goto bad; - if (sym->st_shndx == SHN_ABS) { + if (shn_abs) { if (is_reloc(S_ABS, symname)) break; else if (!is_reloc(S_SEG, symname)) @@ -598,7 +602,7 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym), case R_386_32: symname = sym_name(sym_strtab, sym); - if (sym->st_shndx == SHN_ABS) { + if (shn_abs) { if (is_reloc(S_ABS, symname)) break; else if (!is_reloc(S_REL, symname)) @@ -616,7 +620,8 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym), break; bad: symname = sym_name(sym_strtab, sym); - die("Invalid %s relocation: %s\n", + die("Invalid %s %s relocation: %s\n", + shn_abs ? "absolute" : "relative", rel_type(r_type), symname); } }