module: kallsyms: Fix suspicious rcu usage
No functional change. The purpose of this patch is to address the various Sparse warnings due to the incorrect dereference/or access of an __rcu pointer. Signed-off-by: Aaron Tomlin <atomlin@redhat.com> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
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@ -171,14 +171,17 @@ void add_kallsyms(struct module *mod, const struct load_info *info)
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Elf_Shdr *symsec = &info->sechdrs[info->index.sym];
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/* Set up to point into init section. */
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mod->kallsyms = mod->init_layout.base + info->mod_kallsyms_init_off;
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mod->kallsyms = (void __rcu *)mod->init_layout.base +
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info->mod_kallsyms_init_off;
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preempt_disable();
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/* The following is safe since this pointer cannot change */
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mod->kallsyms->symtab = (void *)symsec->sh_addr;
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mod->kallsyms->num_symtab = symsec->sh_size / sizeof(Elf_Sym);
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rcu_dereference_sched(mod->kallsyms)->symtab = (void *)symsec->sh_addr;
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rcu_dereference_sched(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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rcu_dereference_sched(mod->kallsyms)->strtab =
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(void *)info->sechdrs[info->index.str].sh_addr;
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rcu_dereference_sched(mod->kallsyms)->typetab = mod->init_layout.base + info->init_typeoffs;
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/*
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* Now populate the cut down core kallsyms for after init
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@ -187,20 +190,22 @@ void add_kallsyms(struct module *mod, const struct load_info *info)
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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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src = rcu_dereference_sched(mod->kallsyms)->symtab;
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for (ndst = i = 0; i < rcu_dereference_sched(mod->kallsyms)->num_symtab; i++) {
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rcu_dereference_sched(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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rcu_dereference_sched(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 += strscpy(s, &mod->kallsyms->strtab[src[i].st_name],
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s += strscpy(s,
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&rcu_dereference_sched(mod->kallsyms)->strtab[src[i].st_name],
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KSYM_NAME_LEN) + 1;
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}
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}
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preempt_enable();
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mod->core_kallsyms.num_symtab = ndst;
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}
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@ -478,11 +483,16 @@ int module_kallsyms_on_each_symbol(int (*fn)(void *, const char *,
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mutex_lock(&module_mutex);
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list_for_each_entry(mod, &modules, list) {
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/* We hold module_mutex: no need for rcu_dereference_sched */
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struct mod_kallsyms *kallsyms = mod->kallsyms;
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struct mod_kallsyms *kallsyms;
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if (mod->state == MODULE_STATE_UNFORMED)
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continue;
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/* Use rcu_dereference_sched() to remain compliant with the sparse tool */
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preempt_disable();
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kallsyms = rcu_dereference_sched(mod->kallsyms);
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preempt_enable();
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for (i = 0; i < kallsyms->num_symtab; i++) {
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const Elf_Sym *sym = &kallsyms->symtab[i];
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