[PATCH v4 10/11] x86/module: Use text_mutex in apply_relocate_add()

Josh Poimboeuf
2020-04-29T15:25:45Z

Now that the livepatch code no longer needs the text_mutex for changing
module permissions, move its usage down to apply_relocate_add().

Note the s390 version of apply_relocate_add() doesn't need to use the
text_mutex because it already uses s390_kernel_write_lock, which
accomplishes the same task.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
Acked-by: Miroslav Benes <mbenes@suse.cz>
---
arch/x86/kernel/module.c | 9 +++++++--
kernel/livepatch/core.c | 6 ------
2 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index 7614f478fd7a..23c95a53d20e 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -18,6 +18,7 @@
#include <linux/gfp.h>
#include <linux/jump_label.h>
#include <linux/random.h>
+#include <linux/memory.h>

#include <asm/text-patching.h>
#include <asm/page.h>
@@ -227,14 +228,18 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
bool early = me->state == MODULE_STATE_UNFORMED;
void *(*write)(void *, const void *, size_t) = memcpy;

- if (!early)
+ if (!early) {
write = text_poke;
+ mutex_lock(&text_mutex);
+ }

ret = __apply_relocate_add(sechdrs, strtab, symindex, relsec, me,
write);

- if (!early)
+ if (!early) {
text_poke_sync();
+ mutex_unlock(&text_mutex);
+ }

return ret;
}
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 6b8b3c067be0..96d2da14eb0d 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -775,9 +775,6 @@ static int klp_init_object_loaded(struct klp_patch *patch,
int ret;

if (klp_is_module(obj)) {
-
- mutex_lock(&text_mutex);
-
/*
* Only write module-specific relocations here
* (.klp.rela.{module}.*). vmlinux-specific relocations were
@@ -785,9 +782,6 @@ static int klp_init_object_loaded(struct klp_patch *patch,
* itself.
*/
ret = klp_apply_object_relocs(patch, obj);
-
- mutex_unlock(&text_mutex);
-
if (ret)
return ret;
}
--
2.21.1