diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2020-04-29 10:24:49 -0500 |
|---|---|---|
| committer | Jiri Kosina <jkosina@suse.cz> | 2020-05-08 00:12:43 +0200 |
| commit | 88fc078a7a8f67e47020d73d8d14ed11f03754ab (patch) | |
| tree | 6393c30749eebdede9ffe28893a0753544a9283d /arch/x86/kernel/module.c | |
| parent | be2422612a580e33b927d0cde7a5a3c7935b2849 (diff) | |
x86/module: Use text_poke() for late relocations
Because of late module patching, a livepatch module needs to be able to
apply some of its relocations well after it has been loaded. Instead of
playing games with module_{dis,en}able_ro(), use existing text poking
mechanisms to apply relocations after module loading.
So far only x86, s390 and Power have HAVE_LIVEPATCH but only the first
two also have STRICT_MODULE_RWX.
This will allow removal of the last module_disable_ro() usage in
livepatch. The ultimate goal is to completely disallow making
executable mappings writable.
[ jpoimboe: Split up patches. Use mod state to determine whether
memcpy() can be used. Implement text_poke() for UML. ]
Cc: x86@kernel.org
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'arch/x86/kernel/module.c')
| -rw-r--r-- | arch/x86/kernel/module.c | 38 |
1 files changed, 31 insertions, 7 deletions
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c index d5c72cb877b3..7614f478fd7a 100644 --- a/arch/x86/kernel/module.c +++ b/arch/x86/kernel/module.c @@ -126,11 +126,12 @@ int apply_relocate(Elf32_Shdr *sechdrs, return 0; } #else /*X86_64*/ -int apply_relocate_add(Elf64_Shdr *sechdrs, +static int __apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned int relsec, - struct module *me) + struct module *me, + void *(*write)(void *dest, const void *src, size_t len)) { unsigned int i; Elf64_Rela *rel = (void *)sechdrs[relsec].sh_addr; @@ -162,19 +163,19 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, case R_X86_64_64: if (*(u64 *)loc != 0) goto invalid_relocation; - *(u64 *)loc = val; + write(loc, &val, 8); break; case R_X86_64_32: if (*(u32 *)loc != 0) goto invalid_relocation; - *(u32 *)loc = val; + write(loc, &val, 4); if (val != *(u32 *)loc) goto overflow; break; case R_X86_64_32S: if (*(s32 *)loc != 0) goto invalid_relocation; - *(s32 *)loc = val; + write(loc, &val, 4); if ((s64)val != *(s32 *)loc) goto overflow; break; @@ -183,7 +184,7 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, if (*(u32 *)loc != 0) goto invalid_relocation; val -= (u64)loc; - *(u32 *)loc = val; + write(loc, &val, 4); #if 0 if ((s64)val != *(s32 *)loc) goto overflow; @@ -193,7 +194,7 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, if (*(u64 *)loc != 0) goto invalid_relocation; val -= (u64)loc; - *(u64 *)loc = val; + write(loc, &val, 8); break; default: pr_err("%s: Unknown rela relocation: %llu\n", @@ -215,6 +216,29 @@ overflow: me->name); return -ENOEXEC; } + +int apply_relocate_add(Elf64_Shdr *sechdrs, + const char *strtab, + unsigned int symindex, + unsigned int relsec, + struct module *me) +{ + int ret; + bool early = me->state == MODULE_STATE_UNFORMED; + void *(*write)(void *, const void *, size_t) = memcpy; + + if (!early) + write = text_poke; + + ret = __apply_relocate_add(sechdrs, strtab, symindex, relsec, me, + write); + + if (!early) + text_poke_sync(); + + return ret; +} + #endif int module_finalize(const Elf_Ehdr *hdr, |