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module: refactor load_module part 2 

Here's a second one. It's slightly less trivial - since we now have error
cases - and equally untested so it may well be totally broken. But it also
cleans up a bit more, and avoids one of the goto targets, because the
"move_module()" helper now does both allocations or none.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Linus Torvalds 2010-08-05 12:59:02 -06:00 committed by Rusty Russell
parent f91a13bb99
commit 65b8a9b4d5
1 changed files with 72 additions and 57 deletions
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129
kernel/module.c
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@ -2082,7 +2082,8 @@ static void *module_alloc_update_bounds(unsigned long size)
#ifdef CONFIG_DEBUG_KMEMLEAK
static void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,
Elf_Shdr *sechdrs, char *secstrings)
const Elf_Shdr *sechdrs,
const char *secstrings)
{
unsigned int i;
@ -2102,7 +2103,8 @@ static void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,
}
#else
static inline void kmemleak_load_module(struct module *mod, Elf_Ehdr *hdr,
Elf_Shdr *sechdrs, char *secstrings)
Elf_Shdr *sechdrs,
const char *secstrings)
{
}
#endif
@ -2172,6 +2174,70 @@ static void find_module_sections(struct module *mod, Elf_Ehdr *hdr,
#endif
}
static struct module *move_module(struct module *mod,
Elf_Ehdr *hdr, Elf_Shdr *sechdrs,
const char *secstrings, unsigned modindex)
{
int i;
void *ptr;
/* Do the allocs. */
ptr = module_alloc_update_bounds(mod->core_size);
/*
* The pointer to this block is stored in the module structure
* which is inside the block. Just mark it as not being a
* leak.
*/
kmemleak_not_leak(ptr);
if (!ptr)
return ERR_PTR(-ENOMEM);
memset(ptr, 0, mod->core_size);
mod->module_core = ptr;
ptr = module_alloc_update_bounds(mod->init_size);
/*
* The pointer to this block is stored in the module structure
* which is inside the block. This block doesn't need to be
* scanned as it contains data and code that will be freed
* after the module is initialized.
*/
kmemleak_ignore(ptr);
if (!ptr && mod->init_size) {
module_free(mod, mod->module_core);
return ERR_PTR(-ENOMEM);
}
memset(ptr, 0, mod->init_size);
mod->module_init = ptr;
/* Transfer each section which specifies SHF_ALLOC */
DEBUGP("final section addresses:\n");
for (i = 0; i < hdr->e_shnum; i++) {
void *dest;
if (!(sechdrs[i].sh_flags & SHF_ALLOC))
continue;
if (sechdrs[i].sh_entsize & INIT_OFFSET_MASK)
dest = mod->module_init
+ (sechdrs[i].sh_entsize & ~INIT_OFFSET_MASK);
else
dest = mod->module_core + sechdrs[i].sh_entsize;
if (sechdrs[i].sh_type != SHT_NOBITS)
memcpy(dest, (void *)sechdrs[i].sh_addr,
sechdrs[i].sh_size);
/* Update sh_addr to point to copy in image. */
sechdrs[i].sh_addr = (unsigned long)dest;
DEBUGP("\t0x%lx %s\n",
sechdrs[i].sh_addr, secstrings + sechdrs[i].sh_name);
}
/* Module has been moved. */
mod = (void *)sechdrs[modindex].sh_addr;
kmemleak_load_module(mod, hdr, sechdrs, secstrings);
return mod;
}
/* Allocate and load the module: note that size of section 0 is always
zero, and we rely on this for optional sections. */
static noinline struct module *load_module(void __user *umod,
@ -2188,7 +2254,6 @@ static noinline struct module *load_module(void __user *umod,
unsigned int modindex, versindex, infoindex, pcpuindex;
struct module *mod;
long err = 0;
void *ptr = NULL; /* Stops spurious gcc warning */
unsigned long symoffs, stroffs, *strmap;
void __percpu *percpu;
struct _ddebug *debug = NULL;
@ -2342,61 +2407,12 @@ static noinline struct module *load_module(void __user *umod,
symoffs = layout_symtab(mod, sechdrs, symindex, strindex, hdr,
secstrings, &stroffs, strmap);
/* Do the allocs. */
ptr = module_alloc_update_bounds(mod->core_size);
/*
* The pointer to this block is stored in the module structure
* which is inside the block. Just mark it as not being a
* leak.
*/
kmemleak_not_leak(ptr);
if (!ptr) {
err = -ENOMEM;
/* Allocate and move to the final place */
mod = move_module(mod, hdr, sechdrs, secstrings, modindex);
if (IS_ERR(mod)) {
err = PTR_ERR(mod);
goto free_percpu;
}
memset(ptr, 0, mod->core_size);
mod->module_core = ptr;
ptr = module_alloc_update_bounds(mod->init_size);
/*
* The pointer to this block is stored in the module structure
* which is inside the block. This block doesn't need to be
* scanned as it contains data and code that will be freed
* after the module is initialized.
*/
kmemleak_ignore(ptr);
if (!ptr && mod->init_size) {
err = -ENOMEM;
goto free_core;
}
memset(ptr, 0, mod->init_size);
mod->module_init = ptr;
/* Transfer each section which specifies SHF_ALLOC */
DEBUGP("final section addresses:\n");
for (i = 0; i < hdr->e_shnum; i++) {
void *dest;
if (!(sechdrs[i].sh_flags & SHF_ALLOC))
continue;
if (sechdrs[i].sh_entsize & INIT_OFFSET_MASK)
dest = mod->module_init
+ (sechdrs[i].sh_entsize & ~INIT_OFFSET_MASK);
else
dest = mod->module_core + sechdrs[i].sh_entsize;
if (sechdrs[i].sh_type != SHT_NOBITS)
memcpy(dest, (void *)sechdrs[i].sh_addr,
sechdrs[i].sh_size);
/* Update sh_addr to point to copy in image. */
sechdrs[i].sh_addr = (unsigned long)dest;
DEBUGP("\t0x%lx %s\n",
sechdrs[i].sh_addr, secstrings + sechdrs[i].sh_name);
}
/* Module has been moved. */
mod = (void *)sechdrs[modindex].sh_addr;
kmemleak_load_module(mod, hdr, sechdrs, secstrings);
#if defined(CONFIG_MODULE_UNLOAD)
mod->refptr = alloc_percpu(struct module_ref);
@ -2580,7 +2596,6 @@ static noinline struct module *load_module(void __user *umod,
free_init:
#endif
module_free(mod, mod->module_init);
free_core:
module_free(mod, mod->module_core);
/* mod will be freed with core. Don't access it beyond this line! */
free_percpu: