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linux_dsm_epyc7002/arch/avr32/kernel/module.c
Linus Torvalds 5336377d62 modules: Fix module_bug_list list corruption race 
With all the recent module loading cleanups, we've minimized the code
that sits under module_mutex, fixing various deadlocks and making it
possible to do most of the module loading in parallel.

However, that whole conversion totally missed the rather obscure code
that adds a new module to the list for BUG() handling.  That code was
doubly obscure because (a) the code itself lives in lib/bugs.c (for
dubious reasons) and (b) it gets called from the architecture-specific
"module_finalize()" rather than from generic code.

Calling it from arch-specific code makes no sense what-so-ever to begin
with, and is now actively wrong since that code isn't protected by the
module loading lock any more.

So this commit moves the "module_bug_{finalize,cleanup}()" calls away
from the arch-specific code, and into the generic code - and in the
process protects it with the module_mutex so that the list operations
are now safe.

Future fixups:
 - move the module list handling code into kernel/module.c where it
   belongs.
 - get rid of 'module_bug_list' and just use the regular list of modules
   (called 'modules' - imagine that) that we already create and maintain
   for other reasons.

Reported-and-tested-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Adrian Bunk <bunk@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-10-05 11:29:27 -07:00

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/*
* AVR32-specific kernel module loader
*
* Copyright (C) 2005-2006 Atmel Corporation
*
* GOT initialization parts are based on the s390 version
* Copyright (C) 2002, 2003 IBM Deutschland Entwicklung GmbH,
* IBM Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/bug.h>
#include <linux/elf.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleloader.h>
#include <linux/vmalloc.h>
void *module_alloc(unsigned long size)
{
if (size == 0)
return NULL;
return vmalloc(size);
}
void module_free(struct module *mod, void *module_region)
{
vfree(mod->arch.syminfo);
mod->arch.syminfo = NULL;
vfree(module_region);
}
static inline int check_rela(Elf32_Rela *rela, struct module *module,
char *strings, Elf32_Sym *symbols)
{
struct mod_arch_syminfo *info;
info = module->arch.syminfo + ELF32_R_SYM(rela->r_info);
switch (ELF32_R_TYPE(rela->r_info)) {
case R_AVR32_GOT32:
case R_AVR32_GOT16:
case R_AVR32_GOT8:
case R_AVR32_GOT21S:
case R_AVR32_GOT18SW: /* mcall */
case R_AVR32_GOT16S: /* ld.w */
if (rela->r_addend != 0) {
printk(KERN_ERR
"GOT relocation against %s at offset %u with addend\n",
strings + symbols[ELF32_R_SYM(rela->r_info)].st_name,
rela->r_offset);
return -ENOEXEC;
}
if (info->got_offset == -1UL) {
info->got_offset = module->arch.got_size;
module->arch.got_size += sizeof(void *);
}
pr_debug("GOT[%3lu] %s\n", info->got_offset,
strings + symbols[ELF32_R_SYM(rela->r_info)].st_name);
break;
}
return 0;
}
int module_frob_arch_sections(Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
char *secstrings, struct module *module)
{
Elf32_Shdr *symtab;
Elf32_Sym *symbols;
Elf32_Rela *rela;
char *strings;
int nrela, i, j;
int ret;
/* Find the symbol table */
symtab = NULL;
for (i = 0; i < hdr->e_shnum; i++)
switch (sechdrs[i].sh_type) {
case SHT_SYMTAB:
symtab = &sechdrs[i];
break;
}
if (!symtab) {
printk(KERN_ERR "module %s: no symbol table\n", module->name);
return -ENOEXEC;
}
/* Allocate room for one syminfo structure per symbol. */
module->arch.nsyms = symtab->sh_size / sizeof(Elf_Sym);
module->arch.syminfo = vmalloc(module->arch.nsyms
* sizeof(struct mod_arch_syminfo));
if (!module->arch.syminfo)
return -ENOMEM;
symbols = (void *)hdr + symtab->sh_offset;
strings = (void *)hdr + sechdrs[symtab->sh_link].sh_offset;
for (i = 0; i < module->arch.nsyms; i++) {
if (symbols[i].st_shndx == SHN_UNDEF &&
strcmp(strings + symbols[i].st_name,
"_GLOBAL_OFFSET_TABLE_") == 0)
/* "Define" it as absolute. */
symbols[i].st_shndx = SHN_ABS;
module->arch.syminfo[i].got_offset = -1UL;
module->arch.syminfo[i].got_initialized = 0;
}
/* Allocate GOT entries for symbols that need it. */
module->arch.got_size = 0;
for (i = 0; i < hdr->e_shnum; i++) {
if (sechdrs[i].sh_type != SHT_RELA)
continue;
nrela = sechdrs[i].sh_size / sizeof(Elf32_Rela);
rela = (void *)hdr + sechdrs[i].sh_offset;
for (j = 0; j < nrela; j++) {
ret = check_rela(rela + j, module,
strings, symbols);
if (ret)
goto out_free_syminfo;
}
}
/*
* Increase core size to make room for GOT and set start
* offset for GOT.
*/
module->core_size = ALIGN(module->core_size, 4);
module->arch.got_offset = module->core_size;
module->core_size += module->arch.got_size;
return 0;
out_free_syminfo:
vfree(module->arch.syminfo);
module->arch.syminfo = NULL;
return ret;
}
static inline int reloc_overflow(struct module *module, const char *reloc_name,
Elf32_Addr relocation)
{
printk(KERN_ERR "module %s: Value %lx does not fit relocation %s\n",
module->name, (unsigned long)relocation, reloc_name);
return -ENOEXEC;
}
#define get_u16(loc) (*((uint16_t *)loc))
#define put_u16(loc, val) (*((uint16_t *)loc) = (val))
int apply_relocate_add(Elf32_Shdr *sechdrs, const char *strtab,
unsigned int symindex, unsigned int relindex,
struct module *module)
{
Elf32_Shdr *symsec = sechdrs + symindex;
Elf32_Shdr *relsec = sechdrs + relindex;
Elf32_Shdr *dstsec = sechdrs + relsec->sh_info;
Elf32_Rela *rel = (void *)relsec->sh_addr;
unsigned int i;
int ret = 0;
for (i = 0; i < relsec->sh_size / sizeof(Elf32_Rela); i++, rel++) {
struct mod_arch_syminfo *info;
Elf32_Sym *sym;
Elf32_Addr relocation;
uint32_t *location;
uint32_t value;
location = (void *)dstsec->sh_addr + rel->r_offset;
sym = (Elf32_Sym *)symsec->sh_addr + ELF32_R_SYM(rel->r_info);
relocation = sym->st_value + rel->r_addend;
info = module->arch.syminfo + ELF32_R_SYM(rel->r_info);
/* Initialize GOT entry if necessary */
switch (ELF32_R_TYPE(rel->r_info)) {
case R_AVR32_GOT32:
case R_AVR32_GOT16:
case R_AVR32_GOT8:
case R_AVR32_GOT21S:
case R_AVR32_GOT18SW:
case R_AVR32_GOT16S:
if (!info->got_initialized) {
Elf32_Addr *gotent;
gotent = (module->module_core
+ module->arch.got_offset
+ info->got_offset);
*gotent = relocation;
info->got_initialized = 1;
}
relocation = info->got_offset;
break;
}
switch (ELF32_R_TYPE(rel->r_info)) {
case R_AVR32_32:
case R_AVR32_32_CPENT:
*location = relocation;
break;
case R_AVR32_22H_PCREL:
relocation -= (Elf32_Addr)location;
if ((relocation & 0xffe00001) != 0
&& (relocation & 0xffc00001) != 0xffc00000)
return reloc_overflow(module,
"R_AVR32_22H_PCREL",
relocation);
relocation >>= 1;
value = *location;
value = ((value & 0xe1ef0000)
| (relocation & 0xffff)
| ((relocation & 0x10000) << 4)
| ((relocation & 0x1e0000) << 8));
*location = value;
break;
case R_AVR32_11H_PCREL:
relocation -= (Elf32_Addr)location;
if ((relocation & 0xfffffc01) != 0
&& (relocation & 0xfffff801) != 0xfffff800)
return reloc_overflow(module,
"R_AVR32_11H_PCREL",
relocation);
value = get_u16(location);
value = ((value & 0xf00c)
| ((relocation & 0x1fe) << 3)
| ((relocation & 0x600) >> 9));
put_u16(location, value);
break;
case R_AVR32_9H_PCREL:
relocation -= (Elf32_Addr)location;
if ((relocation & 0xffffff01) != 0
&& (relocation & 0xfffffe01) != 0xfffffe00)
return reloc_overflow(module,
"R_AVR32_9H_PCREL",
relocation);
value = get_u16(location);
value = ((value & 0xf00f)
| ((relocation & 0x1fe) << 3));
put_u16(location, value);
break;
case R_AVR32_9UW_PCREL:
relocation -= ((Elf32_Addr)location) & 0xfffffffc;
if ((relocation & 0xfffffc03) != 0)
return reloc_overflow(module,
"R_AVR32_9UW_PCREL",
relocation);
value = get_u16(location);
value = ((value & 0xf80f)
| ((relocation & 0x1fc) << 2));
put_u16(location, value);
break;
case R_AVR32_GOTPC:
/*
* R6 = PC - (PC - GOT)
*
* At this point, relocation contains the
* value of PC. Just subtract the value of
* GOT, and we're done.
*/
pr_debug("GOTPC: PC=0x%x, got_offset=0x%lx, core=0x%p\n",
relocation, module->arch.got_offset,
module->module_core);
relocation -= ((unsigned long)module->module_core
+ module->arch.got_offset);
*location = relocation;
break;
case R_AVR32_GOT18SW:
if ((relocation & 0xfffe0003) != 0
&& (relocation & 0xfffc0003) != 0xffff0000)
return reloc_overflow(module, "R_AVR32_GOT18SW",
relocation);
relocation >>= 2;
/* fall through */
case R_AVR32_GOT16S:
if ((relocation & 0xffff8000) != 0
&& (relocation & 0xffff0000) != 0xffff0000)
return reloc_overflow(module, "R_AVR32_GOT16S",
relocation);
pr_debug("GOT reloc @ 0x%x -> %u\n",
rel->r_offset, relocation);
value = *location;
value = ((value & 0xffff0000)
| (relocation & 0xffff));
*location = value;
break;
default:
printk(KERN_ERR "module %s: Unknown relocation: %u\n",
module->name, ELF32_R_TYPE(rel->r_info));
return -ENOEXEC;
}
}
return ret;
}
int apply_relocate(Elf32_Shdr *sechdrs, const char *strtab,
unsigned int symindex, unsigned int relindex,
struct module *module)
{
printk(KERN_ERR "module %s: REL relocations are not supported\n",
module->name);
return -ENOEXEC;
}
int module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
struct module *module)
{
vfree(module->arch.syminfo);
module->arch.syminfo = NULL;
return 0;
}
void module_arch_cleanup(struct module *module)
{
}
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