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Merge tag 'livepatching-for-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching

Browse Source 
Pull livepatching updates from Petr Mladek:

 - Allow reloading a livepatched module by clearing livepatch-specific
   relocations in the livepatch module.

   Otherwise, the repeated load would fail on consistency checks.

* tag 'livepatching-for-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching:
  livepatch,x86: Clear relocation targets on a module removal
  x86/module: remove unused code in __apply_relocate_add
This commit is contained in:
Linus Torvalds
2023-02-23 14:00:10 -08:00
parent d876315445 0c05e7bd2d
commit 7dd86cf801
3 changed files with 126 additions and 50 deletions
Download Patch File Download Diff File Expand all files Collapse all files

62
kernel/livepatch/core.c
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@@ -260,6 +260,14 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab,
return 0;
}
void __weak clear_relocate_add(Elf_Shdr *sechdrs,
const char *strtab,
unsigned int symindex,
unsigned int relsec,
struct module *me)
{
}
/*
* At a high-level, there are two types of klp relocation sections: those which
* reference symbols which live in vmlinux; and those which reference symbols
@@ -283,10 +291,10 @@ static int klp_resolve_symbols(Elf_Shdr *sechdrs, const char *strtab,
* the to-be-patched module to be loaded and patched sometime *after* the
* klp module is loaded.
*/
int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
const char *shstrtab, const char *strtab,
unsigned int symndx, unsigned int secndx,
const char *objname)
static int klp_write_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
const char *shstrtab, const char *strtab,
unsigned int symndx, unsigned int secndx,
const char *objname, bool apply)
{
int cnt, ret;
char sec_objname[MODULE_NAME_LEN];
@@ -308,11 +316,26 @@ int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
if (strcmp(objname ? objname : "vmlinux", sec_objname))
return 0;
ret = klp_resolve_symbols(sechdrs, strtab, symndx, sec, sec_objname);
if (ret)
return ret;
if (apply) {
ret = klp_resolve_symbols(sechdrs, strtab, symndx,
sec, sec_objname);
if (ret)
return ret;
return apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod);
return apply_relocate_add(sechdrs, strtab, symndx, secndx, pmod);
}
clear_relocate_add(sechdrs, strtab, symndx, secndx, pmod);
return 0;
}
int klp_apply_section_relocs(struct module *pmod, Elf_Shdr *sechdrs,
const char *shstrtab, const char *strtab,
unsigned int symndx, unsigned int secndx,
const char *objname)
{
return klp_write_section_relocs(pmod, sechdrs, shstrtab, strtab, symndx,
secndx, objname, true);
}
/*
@@ -761,8 +784,9 @@ static int klp_init_func(struct klp_object *obj, struct klp_func *func)
func->old_sympos ? func->old_sympos : 1);
}
static int klp_apply_object_relocs(struct klp_patch *patch,
struct klp_object *obj)
static int klp_write_object_relocs(struct klp_patch *patch,
struct klp_object *obj,
bool apply)
{
int i, ret;
struct klp_modinfo *info = patch->mod->klp_info;
@@ -773,10 +797,10 @@ static int klp_apply_object_relocs(struct klp_patch *patch,
if (!(sec->sh_flags & SHF_RELA_LIVEPATCH))
continue;
ret = klp_apply_section_relocs(patch->mod, info->sechdrs,
ret = klp_write_section_relocs(patch->mod, info->sechdrs,
info->secstrings,
patch->mod->core_kallsyms.strtab,
info->symndx, i, obj->name);
info->symndx, i, obj->name, apply);
if (ret)
return ret;
}
@@ -784,6 +808,18 @@ static int klp_apply_object_relocs(struct klp_patch *patch,
return 0;
}
static int klp_apply_object_relocs(struct klp_patch *patch,
struct klp_object *obj)
{
return klp_write_object_relocs(patch, obj, true);
}
static void klp_clear_object_relocs(struct klp_patch *patch,
struct klp_object *obj)
{
klp_write_object_relocs(patch, obj, false);
}
/* parts of the initialization that is done only when the object is loaded */
static int klp_init_object_loaded(struct klp_patch *patch,
struct klp_object *obj)
@@ -1171,7 +1207,7 @@ static void klp_cleanup_module_patches_limited(struct module *mod,
klp_unpatch_object(obj);
klp_post_unpatch_callback(obj);
klp_clear_object_relocs(patch, obj);
klp_free_object_loaded(obj);
break;
}