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 <hpa@linux.intel.com> Link: http://lkml.kernel.org/r/1336501366-28617-2-git-send-email-jarkko.sakkinen@intel.com Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
H. Peter Anvin
Родитель
d48b97b403
Коммит
433de739bb
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@ -40,13 +40,12 @@ OBJCOPYFLAGS_vmlinux.bin := -R .comment -S
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$(obj)/vmlinux.bin: vmlinux FORCE
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$(call if_changed,objcopy)
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targets += vmlinux.bin.all vmlinux.relocs
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targets += vmlinux.bin.all vmlinux.relocs relocs
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hostprogs-$(CONFIG_X86_NEED_RELOCS) += relocs
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quiet_cmd_relocs = RELOCS $@
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cmd_relocs = $(obj)/relocs $< > $@;$(obj)/relocs --abs-relocs $<
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$(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE
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CMD_RELOCS = scripts/x86-relocs
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quiet_cmd_relocs = RELOCS $@
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cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $<
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$(obj)/vmlinux.relocs: vmlinux FORCE
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$(call if_changed,relocs)
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vmlinux.bin.all-y := $(obj)/vmlinux.bin
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@ -9,3 +9,4 @@ unifdef
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ihex2fw
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recordmcount
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docproc
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x86-relocs
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@ -8,11 +8,14 @@
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# conmakehash: Create arrays for initializing the kernel console tables
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# docproc: Used in Documentation/DocBook
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HOST_EXTRACFLAGS += -I$(srctree)/tools/include
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hostprogs-$(CONFIG_KALLSYMS) += kallsyms
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hostprogs-$(CONFIG_LOGO) += pnmtologo
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hostprogs-$(CONFIG_VT) += conmakehash
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hostprogs-$(CONFIG_IKCONFIG) += bin2c
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hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
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hostprogs-$(CONFIG_X86) += x86-relocs
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always := $(hostprogs-y) $(hostprogs-m)
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@ -18,6 +18,8 @@ static void die(char *fmt, ...);
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static Elf32_Ehdr ehdr;
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static unsigned long reloc_count, reloc_idx;
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static unsigned long *relocs;
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static unsigned long reloc16_count, reloc16_idx;
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static unsigned long *relocs16;
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struct section {
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Elf32_Shdr shdr;
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@ -28,52 +30,82 @@ struct section {
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};
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static struct section *secs;
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enum symtype {
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S_ABS,
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S_REL,
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S_SEG,
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S_LIN,
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S_NSYMTYPES
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};
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static const char * const sym_regex_kernel[S_NSYMTYPES] = {
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/*
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* Following symbols have been audited. There values are constant and do
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* not change if bzImage is loaded at a different physical address than
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* the address for which it has been compiled. Don't warn user about
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* absolute relocations present w.r.t these symbols.
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*/
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static const char abs_sym_regex[] =
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[S_ABS] =
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"^(xen_irq_disable_direct_reloc$|"
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"xen_save_fl_direct_reloc$|"
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"VDSO|"
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"__crc_)";
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static regex_t abs_sym_regex_c;
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static int is_abs_reloc(const char *sym_name)
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{
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return !regexec(&abs_sym_regex_c, sym_name, 0, NULL, 0);
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}
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"__crc_)",
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/*
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* These symbols are known to be relative, even if the linker marks them
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* as absolute (typically defined outside any section in the linker script.)
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*/
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static const char rel_sym_regex[] =
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"^_end$";
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static regex_t rel_sym_regex_c;
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static int is_rel_reloc(const char *sym_name)
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[S_REL] =
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"^_end$",
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};
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static const char * const sym_regex_realmode[S_NSYMTYPES] = {
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/*
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* These are 16-bit segment symbols when compiling 16-bit code.
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*/
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[S_SEG] =
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"^real_mode_seg$",
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/*
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* These are offsets belonging to segments, as opposed to linear addresses,
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* when compiling 16-bit code.
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*/
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[S_LIN] =
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"^pa_",
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};
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static const char * const *sym_regex;
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static regex_t sym_regex_c[S_NSYMTYPES];
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static int is_reloc(enum symtype type, const char *sym_name)
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{
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return !regexec(&rel_sym_regex_c, sym_name, 0, NULL, 0);
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return sym_regex[type] &&
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!regexec(&sym_regex_c[type], sym_name, 0, NULL, 0);
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}
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static void regex_init(void)
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static void regex_init(int use_real_mode)
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{
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char errbuf[128];
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int err;
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err = regcomp(&abs_sym_regex_c, abs_sym_regex,
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REG_EXTENDED|REG_NOSUB);
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if (err) {
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regerror(err, &abs_sym_regex_c, errbuf, sizeof errbuf);
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die("%s", errbuf);
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}
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int i;
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err = regcomp(&rel_sym_regex_c, rel_sym_regex,
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REG_EXTENDED|REG_NOSUB);
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if (err) {
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regerror(err, &rel_sym_regex_c, errbuf, sizeof errbuf);
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die("%s", errbuf);
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if (use_real_mode)
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sym_regex = sym_regex_realmode;
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else
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sym_regex = sym_regex_kernel;
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for (i = 0; i < S_NSYMTYPES; i++) {
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if (!sym_regex[i])
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continue;
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err = regcomp(&sym_regex_c[i], sym_regex[i],
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REG_EXTENDED|REG_NOSUB);
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if (err) {
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regerror(err, &sym_regex_c[i], errbuf, sizeof errbuf);
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die("%s", errbuf);
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}
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}
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}
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@ -154,6 +186,10 @@ static const char *rel_type(unsigned type)
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REL_TYPE(R_386_RELATIVE),
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REL_TYPE(R_386_GOTOFF),
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REL_TYPE(R_386_GOTPC),
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REL_TYPE(R_386_8),
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REL_TYPE(R_386_PC8),
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REL_TYPE(R_386_16),
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REL_TYPE(R_386_PC16),
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#undef REL_TYPE
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};
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const char *name = "unknown type rel type name";
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@ -189,7 +225,7 @@ static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
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name = sym_strtab + sym->st_name;
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}
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else {
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name = sec_name(secs[sym->st_shndx].shdr.sh_name);
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name = sec_name(sym->st_shndx);
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}
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return name;
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}
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@ -472,7 +508,7 @@ static void print_absolute_relocs(void)
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* Before warning check if this absolute symbol
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* relocation is harmless.
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*/
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if (is_abs_reloc(name) || is_rel_reloc(name))
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if (is_reloc(S_ABS, name) || is_reloc(S_REL, name))
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continue;
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if (!printed) {
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@ -496,7 +532,8 @@ static void print_absolute_relocs(void)
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printf("\n");
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}
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static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
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static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym),
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int use_real_mode)
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{
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int i;
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/* Walk through the relocations */
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@ -521,30 +558,62 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
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Elf32_Rel *rel;
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Elf32_Sym *sym;
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unsigned r_type;
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const char *symname;
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rel = &sec->reltab[j];
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sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
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r_type = ELF32_R_TYPE(rel->r_info);
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/* Don't visit relocations to absolute symbols */
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if (sym->st_shndx == SHN_ABS &&
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!is_rel_reloc(sym_name(sym_strtab, sym))) {
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continue;
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}
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switch (r_type) {
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case R_386_NONE:
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case R_386_PC32:
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case R_386_PC16:
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case R_386_PC8:
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/*
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* NONE can be ignored and and PC relative
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* relocations don't need to be adjusted.
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*/
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break;
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case R_386_16:
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symname = sym_name(sym_strtab, sym);
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if (!use_real_mode)
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goto bad;
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if (sym->st_shndx == SHN_ABS) {
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if (is_reloc(S_ABS, symname))
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break;
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else if (!is_reloc(S_SEG, symname))
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goto bad;
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} else {
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if (is_reloc(S_LIN, symname))
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goto bad;
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else
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break;
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}
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visit(rel, sym);
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break;
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case R_386_32:
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/* Visit relocations that need to be adjusted */
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symname = sym_name(sym_strtab, sym);
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if (sym->st_shndx == SHN_ABS) {
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if (is_reloc(S_ABS, symname))
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break;
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else if (!is_reloc(S_REL, symname))
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goto bad;
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} else {
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if (use_real_mode &&
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!is_reloc(S_LIN, symname))
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break;
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}
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visit(rel, sym);
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break;
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default:
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die("Unsupported relocation type: %s (%d)\n",
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rel_type(r_type), r_type);
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break;
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bad:
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symname = sym_name(sym_strtab, sym);
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die("Invalid %s relocation: %s\n",
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rel_type(r_type), symname);
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}
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}
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}
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@ -552,13 +621,19 @@ static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
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static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
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{
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reloc_count += 1;
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if (ELF32_R_TYPE(rel->r_info) == R_386_16)
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reloc16_count++;
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else
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reloc_count++;
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}
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static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
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{
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/* Remember the address that needs to be adjusted. */
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relocs[reloc_idx++] = rel->r_offset;
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if (ELF32_R_TYPE(rel->r_info) == R_386_16)
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relocs16[reloc16_idx++] = rel->r_offset;
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else
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relocs[reloc_idx++] = rel->r_offset;
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}
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static int cmp_relocs(const void *va, const void *vb)
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@ -568,23 +643,41 @@ static int cmp_relocs(const void *va, const void *vb)
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return (*a == *b)? 0 : (*a > *b)? 1 : -1;
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}
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static void emit_relocs(int as_text)
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static int write32(unsigned int v, FILE *f)
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{
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unsigned char buf[4];
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put_unaligned_le32(v, buf);
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return fwrite(buf, 1, 4, f) == 4 ? 0 : -1;
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}
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static void emit_relocs(int as_text, int use_real_mode)
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{
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int i;
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/* Count how many relocations I have and allocate space for them. */
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reloc_count = 0;
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walk_relocs(count_reloc);
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walk_relocs(count_reloc, use_real_mode);
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relocs = malloc(reloc_count * sizeof(relocs[0]));
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if (!relocs) {
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die("malloc of %d entries for relocs failed\n",
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reloc_count);
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}
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relocs16 = malloc(reloc16_count * sizeof(relocs[0]));
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if (!relocs16) {
|
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die("malloc of %d entries for relocs16 failed\n",
|
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reloc16_count);
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}
|
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/* Collect up the relocations */
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reloc_idx = 0;
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walk_relocs(collect_reloc);
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walk_relocs(collect_reloc, use_real_mode);
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|
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if (reloc16_count && !use_real_mode)
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die("Segment relocations found but --realmode not specified\n");
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|
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/* Order the relocations for more efficient processing */
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qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
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qsort(relocs16, reloc16_count, sizeof(relocs16[0]), cmp_relocs);
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|
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/* Print the relocations */
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if (as_text) {
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@ -593,58 +686,83 @@ static void emit_relocs(int as_text)
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*/
|
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printf(".section \".data.reloc\",\"a\"\n");
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printf(".balign 4\n");
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for (i = 0; i < reloc_count; i++) {
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printf("\t .long 0x%08lx\n", relocs[i]);
|
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if (use_real_mode) {
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printf("\t.long %lu\n", reloc16_count);
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for (i = 0; i < reloc16_count; i++)
|
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printf("\t.long 0x%08lx\n", relocs16[i]);
|
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printf("\t.long %lu\n", reloc_count);
|
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for (i = 0; i < reloc_count; i++) {
|
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printf("\t.long 0x%08lx\n", relocs[i]);
|
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}
|
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} else {
|
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/* Print a stop */
|
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printf("\t.long 0x%08lx\n", (unsigned long)0);
|
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for (i = 0; i < reloc_count; i++) {
|
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printf("\t.long 0x%08lx\n", relocs[i]);
|
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}
|
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}
|
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|
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printf("\n");
|
||||
}
|
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else {
|
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unsigned char buf[4];
|
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/* Print a stop */
|
||||
fwrite("\0\0\0\0", 4, 1, stdout);
|
||||
/* Now print each relocation */
|
||||
for (i = 0; i < reloc_count; i++) {
|
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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;
|
||||
}
|
||||
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Ссылка в новой задаче