mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-27 12:57:53 +00:00
c550f0055c
[ Upstream commit8f8cd6c0a4] The synchronization here is to ensure the ordering of freeing of a module init so that it happens before W+X checking. It is worth noting it is not that the freeing was not happening, it is just that our sanity checkers raced against the permission checkers which assume init memory is already gone. Commit1a7b7d9220("modules: Use vmalloc special flag") moved calling do_free_init() into a global workqueue instead of relying on it being called through call_rcu(..., do_free_init), which used to allowed us call do_free_init() asynchronously after the end of a subsequent grace period. The move to a global workqueue broke the gaurantees for code which needed to be sure the do_free_init() would complete with rcu_barrier(). To fix this callers which used to rely on rcu_barrier() must now instead use flush_work(&init_free_wq). Without this fix, we still could encounter false positive reports in W+X checking since the rcu_barrier() here can not ensure the ordering now. Even worse, the rcu_barrier() can introduce significant delay. Eric Chanudet reported that the rcu_barrier introduces ~0.1s delay on a PREEMPT_RT kernel. [ 0.291444] Freeing unused kernel memory: 5568K [ 0.402442] Run /sbin/init as init process With this fix, the above delay can be eliminated. Link: https://lkml.kernel.org/r/20240227023546.2490667-1-changbin.du@huawei.com Fixes:1a7b7d9220("modules: Use vmalloc special flag") Signed-off-by: Changbin Du <changbin.du@huawei.com> Tested-by: Eric Chanudet <echanude@redhat.com> Acked-by: Luis Chamberlain <mcgrof@kernel.org> Cc: Xiaoyi Su <suxiaoyi@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
120 lines
3.4 KiB
C
120 lines
3.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef _LINUX_MODULELOADER_H
|
|
#define _LINUX_MODULELOADER_H
|
|
/* The stuff needed for archs to support modules. */
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/elf.h>
|
|
|
|
/* These may be implemented by architectures that need to hook into the
|
|
* module loader code. Architectures that don't need to do anything special
|
|
* can just rely on the 'weak' default hooks defined in kernel/module.c.
|
|
* Note, however, that at least one of apply_relocate or apply_relocate_add
|
|
* must be implemented by each architecture.
|
|
*/
|
|
|
|
/* Adjust arch-specific sections. Return 0 on success. */
|
|
int module_frob_arch_sections(Elf_Ehdr *hdr,
|
|
Elf_Shdr *sechdrs,
|
|
char *secstrings,
|
|
struct module *mod);
|
|
|
|
/* Additional bytes needed by arch in front of individual sections */
|
|
unsigned int arch_mod_section_prepend(struct module *mod, unsigned int section);
|
|
|
|
/* Allocator used for allocating struct module, core sections and init
|
|
sections. Returns NULL on failure. */
|
|
void *module_alloc(unsigned long size);
|
|
|
|
/* Free memory returned from module_alloc. */
|
|
void module_memfree(void *module_region);
|
|
|
|
/* Determines if the section name is an init section (that is only used during
|
|
* module loading).
|
|
*/
|
|
bool module_init_section(const char *name);
|
|
|
|
/* Determines if the section name is an exit section (that is only used during
|
|
* module unloading)
|
|
*/
|
|
bool module_exit_section(const char *name);
|
|
|
|
/* Describes whether within_module_init() will consider this an init section
|
|
* or not. This behaviour changes with CONFIG_MODULE_UNLOAD.
|
|
*/
|
|
bool module_init_layout_section(const char *sname);
|
|
|
|
/*
|
|
* Apply the given relocation to the (simplified) ELF. Return -error
|
|
* or 0.
|
|
*/
|
|
#ifdef CONFIG_MODULES_USE_ELF_REL
|
|
int apply_relocate(Elf_Shdr *sechdrs,
|
|
const char *strtab,
|
|
unsigned int symindex,
|
|
unsigned int relsec,
|
|
struct module *mod);
|
|
#else
|
|
static inline int apply_relocate(Elf_Shdr *sechdrs,
|
|
const char *strtab,
|
|
unsigned int symindex,
|
|
unsigned int relsec,
|
|
struct module *me)
|
|
{
|
|
printk(KERN_ERR "module %s: REL relocation unsupported\n",
|
|
module_name(me));
|
|
return -ENOEXEC;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Apply the given add relocation to the (simplified) ELF. Return
|
|
* -error or 0
|
|
*/
|
|
#ifdef CONFIG_MODULES_USE_ELF_RELA
|
|
int apply_relocate_add(Elf_Shdr *sechdrs,
|
|
const char *strtab,
|
|
unsigned int symindex,
|
|
unsigned int relsec,
|
|
struct module *mod);
|
|
#else
|
|
static inline int apply_relocate_add(Elf_Shdr *sechdrs,
|
|
const char *strtab,
|
|
unsigned int symindex,
|
|
unsigned int relsec,
|
|
struct module *me)
|
|
{
|
|
printk(KERN_ERR "module %s: REL relocation unsupported\n",
|
|
module_name(me));
|
|
return -ENOEXEC;
|
|
}
|
|
#endif
|
|
|
|
/* Any final processing of module before access. Return -error or 0. */
|
|
int module_finalize(const Elf_Ehdr *hdr,
|
|
const Elf_Shdr *sechdrs,
|
|
struct module *mod);
|
|
|
|
#ifdef CONFIG_MODULES
|
|
void flush_module_init_free_work(void);
|
|
#else
|
|
static inline void flush_module_init_free_work(void)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
/* Any cleanup needed when module leaves. */
|
|
void module_arch_cleanup(struct module *mod);
|
|
|
|
/* Any cleanup before freeing mod->module_init */
|
|
void module_arch_freeing_init(struct module *mod);
|
|
|
|
#if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \
|
|
!defined(CONFIG_KASAN_VMALLOC)
|
|
#include <linux/kasan.h>
|
|
#define MODULE_ALIGN (PAGE_SIZE << KASAN_SHADOW_SCALE_SHIFT)
|
|
#else
|
|
#define MODULE_ALIGN PAGE_SIZE
|
|
#endif
|
|
|
|
#endif
|