kallsyms: store type information in its own array
When a module is loaded, its symbols' Elf_Sym information is stored in a symtab. Further, type information is also captured. Since Elf_Sym has no type field, historically the st_info field has been hijacked for storing type: st_info was overwritten. commit5439c985c5
("module: Overwrite st_size instead of st_info") changes that practice, as its one-liner indicates. Unfortunately, this change overwrites symbol size, information that a tool like DTrace expects to find. Allocate a typetab array to store type information so that no Elf_Sym field needs to be overwritten. Fixes:5439c985c5
("module: Overwrite st_size instead of st_info") Signed-off-by: Eugene Loh <eugene.loh@oracle.com> Reviewed-by: Nick Alcock <nick.alcock@oracle.com> [jeyu: renamed typeoff -> typeoffs ] Signed-off-by: Jessica Yu <jeyu@kernel.org>
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@ -331,6 +331,7 @@ struct mod_kallsyms {
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Elf_Sym *symtab;
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unsigned int num_symtab;
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char *strtab;
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char *typetab;
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};
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#ifdef CONFIG_LIVEPATCH
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@ -20,7 +20,7 @@ struct load_info {
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unsigned long len;
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Elf_Shdr *sechdrs;
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char *secstrings, *strtab;
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unsigned long symoffs, stroffs;
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unsigned long symoffs, stroffs, init_typeoffs, core_typeoffs;
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struct _ddebug *debug;
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unsigned int num_debug;
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bool sig_ok;
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@ -2647,6 +2647,8 @@ static void layout_symtab(struct module *mod, struct load_info *info)
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info->symoffs = ALIGN(mod->core_layout.size, symsect->sh_addralign ?: 1);
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info->stroffs = mod->core_layout.size = info->symoffs + ndst * sizeof(Elf_Sym);
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mod->core_layout.size += strtab_size;
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info->core_typeoffs = mod->core_layout.size;
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mod->core_layout.size += ndst * sizeof(char);
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mod->core_layout.size = debug_align(mod->core_layout.size);
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/* Put string table section at end of init part of module. */
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@ -2660,6 +2662,8 @@ static void layout_symtab(struct module *mod, struct load_info *info)
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__alignof__(struct mod_kallsyms));
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info->mod_kallsyms_init_off = mod->init_layout.size;
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mod->init_layout.size += sizeof(struct mod_kallsyms);
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info->init_typeoffs = mod->init_layout.size;
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mod->init_layout.size += nsrc * sizeof(char);
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mod->init_layout.size = debug_align(mod->init_layout.size);
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}
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@ -2683,20 +2687,23 @@ static void add_kallsyms(struct module *mod, const struct load_info *info)
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mod->kallsyms->num_symtab = symsec->sh_size / sizeof(Elf_Sym);
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/* Make sure we get permanent strtab: don't use info->strtab. */
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mod->kallsyms->strtab = (void *)info->sechdrs[info->index.str].sh_addr;
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mod->kallsyms->typetab = mod->init_layout.base + info->init_typeoffs;
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/* Set types up while we still have access to sections. */
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for (i = 0; i < mod->kallsyms->num_symtab; i++)
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mod->kallsyms->symtab[i].st_size
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= elf_type(&mod->kallsyms->symtab[i], info);
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/* Now populate the cut down core kallsyms for after init. */
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/*
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* Now populate the cut down core kallsyms for after init
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* and set types up while we still have access to sections.
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*/
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mod->core_kallsyms.symtab = dst = mod->core_layout.base + info->symoffs;
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mod->core_kallsyms.strtab = s = mod->core_layout.base + info->stroffs;
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mod->core_kallsyms.typetab = mod->core_layout.base + info->core_typeoffs;
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src = mod->kallsyms->symtab;
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for (ndst = i = 0; i < mod->kallsyms->num_symtab; i++) {
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mod->kallsyms->typetab[i] = elf_type(src + i, info);
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if (i == 0 || is_livepatch_module(mod) ||
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is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum,
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info->index.pcpu)) {
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mod->core_kallsyms.typetab[ndst] =
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mod->kallsyms->typetab[i];
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dst[ndst] = src[i];
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dst[ndst++].st_name = s - mod->core_kallsyms.strtab;
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s += strlcpy(s, &mod->kallsyms->strtab[src[i].st_name],
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@ -4080,7 +4087,7 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
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const Elf_Sym *sym = &kallsyms->symtab[symnum];
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*value = kallsyms_symbol_value(sym);
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*type = sym->st_size;
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*type = kallsyms->typetab[symnum];
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strlcpy(name, kallsyms_symbol_name(kallsyms, symnum), KSYM_NAME_LEN);
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strlcpy(module_name, mod->name, MODULE_NAME_LEN);
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*exported = is_exported(name, *value, mod);
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