From 9672e2cb0fbdcb11d64ac43bcb4ee86a76b4221f Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Sun, 30 Dec 2018 13:40:04 +0100 Subject: [PATCH 1/3] vmlinux.lds.h: drop unused __vermagic The reference to '__vermagic' is a relict from v2.5 times. And even there it had a very short life time, from v2.5.59 (commit 1d411b80ee18 ("Module Sanity Check") in the historic tree) to v2.5.69 (commit 67ac5b866bda ("[PATCH] complete modinfo section")). Neither current kernels nor modules contain a '__vermagic' section any more, so get rid of it. Signed-off-by: Mathias Krause Cc: Rusty Russell Cc: Jessica Yu Signed-off-by: Jessica Yu --- include/asm-generic/vmlinux.lds.h | 1 - 1 file changed, 1 deletion(-) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index f8f6f04c445379..42844931b8513f 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -332,7 +332,6 @@ __start_rodata = .; \ *(.rodata) *(.rodata.*) \ RO_AFTER_INIT_DATA /* Read only after init */ \ - KEEP(*(__vermagic)) /* Kernel version magic */ \ . = ALIGN(8); \ __start___tracepoints_ptrs = .; \ KEEP(*(__tracepoints_ptrs)) /* Tracepoints: pointer array */ \ From 1c7651f43777cdd59c1aaa82c87324d3e7438c7b Mon Sep 17 00:00:00 2001 From: Eugene Loh Date: Mon, 25 Feb 2019 11:59:58 -0800 Subject: [PATCH 2/3] 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. commit 5439c985c5a83a8419f762115afdf560ab72a452 ("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: 5439c985c5a8 ("module: Overwrite st_size instead of st_info") Signed-off-by: Eugene Loh Reviewed-by: Nick Alcock [jeyu: renamed typeoff -> typeoffs ] Signed-off-by: Jessica Yu --- include/linux/module.h | 1 + kernel/module-internal.h | 2 +- kernel/module.c | 21 ++++++++++++++------- 3 files changed, 16 insertions(+), 8 deletions(-) diff --git a/include/linux/module.h b/include/linux/module.h index 5bf5dcd91009ee..3abe8176df984d 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -331,6 +331,7 @@ struct mod_kallsyms { Elf_Sym *symtab; unsigned int num_symtab; char *strtab; + char *typetab; }; #ifdef CONFIG_LIVEPATCH diff --git a/kernel/module-internal.h b/kernel/module-internal.h index 79c9be2dbbe987..d354341f8cc0c3 100644 --- a/kernel/module-internal.h +++ b/kernel/module-internal.h @@ -20,7 +20,7 @@ struct load_info { unsigned long len; Elf_Shdr *sechdrs; char *secstrings, *strtab; - unsigned long symoffs, stroffs; + unsigned long symoffs, stroffs, init_typeoffs, core_typeoffs; struct _ddebug *debug; unsigned int num_debug; bool sig_ok; diff --git a/kernel/module.c b/kernel/module.c index 0b9aa8ab89f08a..69e52e82242a2f 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2647,6 +2647,8 @@ static void layout_symtab(struct module *mod, struct load_info *info) info->symoffs = ALIGN(mod->core_layout.size, symsect->sh_addralign ?: 1); info->stroffs = mod->core_layout.size = info->symoffs + ndst * sizeof(Elf_Sym); mod->core_layout.size += strtab_size; + info->core_typeoffs = mod->core_layout.size; + mod->core_layout.size += ndst * sizeof(char); mod->core_layout.size = debug_align(mod->core_layout.size); /* Put string table section at end of init part of module. */ @@ -2660,6 +2662,8 @@ static void layout_symtab(struct module *mod, struct load_info *info) __alignof__(struct mod_kallsyms)); info->mod_kallsyms_init_off = mod->init_layout.size; mod->init_layout.size += sizeof(struct mod_kallsyms); + info->init_typeoffs = mod->init_layout.size; + mod->init_layout.size += nsrc * sizeof(char); mod->init_layout.size = debug_align(mod->init_layout.size); } @@ -2683,20 +2687,23 @@ static void add_kallsyms(struct module *mod, const struct load_info *info) mod->kallsyms->num_symtab = symsec->sh_size / sizeof(Elf_Sym); /* Make sure we get permanent strtab: don't use info->strtab. */ mod->kallsyms->strtab = (void *)info->sechdrs[info->index.str].sh_addr; + mod->kallsyms->typetab = mod->init_layout.base + info->init_typeoffs; - /* Set types up while we still have access to sections. */ - for (i = 0; i < mod->kallsyms->num_symtab; i++) - mod->kallsyms->symtab[i].st_size - = elf_type(&mod->kallsyms->symtab[i], info); - - /* Now populate the cut down core kallsyms for after init. */ + /* + * Now populate the cut down core kallsyms for after init + * and set types up while we still have access to sections. + */ mod->core_kallsyms.symtab = dst = mod->core_layout.base + info->symoffs; mod->core_kallsyms.strtab = s = mod->core_layout.base + info->stroffs; + mod->core_kallsyms.typetab = mod->core_layout.base + info->core_typeoffs; src = mod->kallsyms->symtab; for (ndst = i = 0; i < mod->kallsyms->num_symtab; i++) { + mod->kallsyms->typetab[i] = elf_type(src + i, info); if (i == 0 || is_livepatch_module(mod) || is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum, info->index.pcpu)) { + mod->core_kallsyms.typetab[ndst] = + mod->kallsyms->typetab[i]; dst[ndst] = src[i]; dst[ndst++].st_name = s - mod->core_kallsyms.strtab; s += strlcpy(s, &mod->kallsyms->strtab[src[i].st_name], @@ -4080,7 +4087,7 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type, const Elf_Sym *sym = &kallsyms->symtab[symnum]; *value = kallsyms_symbol_value(sym); - *type = sym->st_size; + *type = kallsyms->typetab[symnum]; strlcpy(name, kallsyms_symbol_name(kallsyms, symnum), KSYM_NAME_LEN); strlcpy(module_name, mod->name, MODULE_NAME_LEN); *exported = is_exported(name, *value, mod); From dadec066d8fa7da227f623f632ea114690fecaf8 Mon Sep 17 00:00:00 2001 From: Tri Vo Date: Mon, 15 Apr 2019 11:18:33 -0700 Subject: [PATCH 3/3] module: add stubs for within_module functions Provide stubs for within_module_core(), within_module_init(), and within_module() to prevent build errors when !CONFIG_MODULES. Suggested-by: Matthew Wilcox Reported-by: Randy Dunlap Reported-by: kbuild test robot Link: https://marc.info/?l=linux-mm&m=155384681109231&w=2 Signed-off-by: Tri Vo Signed-off-by: Jessica Yu --- include/linux/module.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/include/linux/module.h b/include/linux/module.h index 3abe8176df984d..7e63c340a8bfc1 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -710,6 +710,23 @@ static inline bool is_module_text_address(unsigned long addr) return false; } +static inline bool within_module_core(unsigned long addr, + const struct module *mod) +{ + return false; +} + +static inline bool within_module_init(unsigned long addr, + const struct module *mod) +{ + return false; +} + +static inline bool within_module(unsigned long addr, const struct module *mod) +{ + return false; +} + /* Get/put a kernel symbol (calls should be symmetric) */ #define symbol_get(x) ({ extern typeof(x) x __attribute__((weak)); &(x); }) #define symbol_put(x) do { } while (0)