[PATCH 2/3] jump_label: mips: move module NOP patching into arch code

Ard Biesheuvel
2022-06-08T10:45:39Z

MIPS is the only remaining architecture that needs to patch jump label
NOP encodings to initialize them at load time. So let's move the module
patching part of that from generic code into arch/mips, and drop it from
the others.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/mips/kernel/jump_label.c | 17 ++++++++++++
arch/mips/kernel/module.c | 5 ++--
arch/s390/kernel/module.c | 1 -
arch/sparc/kernel/module.c | 3 ---
arch/x86/kernel/module.c | 3 ---
include/linux/jump_label.h | 7 +----
kernel/jump_label.c | 27 +-------------------
7 files changed, 22 insertions(+), 41 deletions(-)

diff --git a/arch/mips/kernel/jump_label.c b/arch/mips/kernel/jump_label.c
index 662c8db9f45b..0f98e7f1461f 100644
--- a/arch/mips/kernel/jump_label.c
+++ b/arch/mips/kernel/jump_label.c
@@ -88,3 +88,20 @@ void arch_jump_label_transform(struct jump_entry *e,

mutex_unlock(&text_mutex);
}
+
+void jump_label_apply_nops(struct module *mod)
+{
+ struct jump_entry *iter_start = mod->jump_entries;
+ struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
+ struct jump_entry *iter;
+
+ /* if the module doesn't have jump label entries, just return */
+ if (iter_start == iter_stop)
+ return;
+
+ for (iter = iter_start; iter < iter_stop; iter++) {
+ /* Only write NOPs for arch_branch_static(). */
+ if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
+ arch_jump_label_transform(iter, JUMP_LABEL_NOP);
+ }
+}
diff --git a/arch/mips/kernel/module.c b/arch/mips/kernel/module.c
index 14f46d17500a..0c936cbf20c5 100644
--- a/arch/mips/kernel/module.c
+++ b/arch/mips/kernel/module.c
@@ -21,6 +21,7 @@
#include <linux/spinlock.h>
#include <linux/jump_label.h>

+extern void jump_label_apply_nops(struct module *mod);

struct mips_hi16 {
struct mips_hi16 *next;
@@ -428,8 +429,8 @@ int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *s;
char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;

- /* Make jump label nops. */
- jump_label_apply_nops(me);
+ if (IS_ENABLED(CONFIG_JUMP_LABEL))
+ jump_label_apply_nops(me);

INIT_LIST_HEAD(&me->arch.dbe_list);
for (s = sechdrs; s < sechdrs + hdr->e_shnum; s++) {
diff --git a/arch/s390/kernel/module.c b/arch/s390/kernel/module.c
index 26125a9c436d..2d159b32885b 100644
--- a/arch/s390/kernel/module.c
+++ b/arch/s390/kernel/module.c
@@ -548,6 +548,5 @@ int module_finalize(const Elf_Ehdr *hdr,
#endif /* CONFIG_FUNCTION_TRACER */
}

- jump_label_apply_nops(me);
return 0;
}
diff --git a/arch/sparc/kernel/module.c b/arch/sparc/kernel/module.c
index df39580f398d..66c45a2764bc 100644
--- a/arch/sparc/kernel/module.c
+++ b/arch/sparc/kernel/module.c
@@ -208,9 +208,6 @@ int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *me)
{
- /* make jump label nops */
- jump_label_apply_nops(me);
-
do_patch_sections(hdr, sechdrs);

/* Cheetah's I-cache is fully coherent. */
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index b98ffcf4d250..95b9cf25d4bd 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -304,9 +304,6 @@ int module_finalize(const Elf_Ehdr *hdr,
tseg, tseg + text->sh_size);
}

- /* make jump label nops */
- jump_label_apply_nops(me);
-
if (orc && orc_ip)
unwind_module_init(me, (void *)orc_ip->sh_addr, orc_ip->sh_size,
(void *)orc->sh_addr, orc->sh_size);
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index bf1eef337a07..2003a0935478 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -230,12 +230,12 @@ extern void static_key_slow_inc(struct static_key *key);
extern void static_key_slow_dec(struct static_key *key);
extern void static_key_slow_inc_cpuslocked(struct static_key *key);
extern void static_key_slow_dec_cpuslocked(struct static_key *key);
-extern void jump_label_apply_nops(struct module *mod);
extern int static_key_count(struct static_key *key);
extern void static_key_enable(struct static_key *key);
extern void static_key_disable(struct static_key *key);
extern void static_key_enable_cpuslocked(struct static_key *key);
extern void static_key_disable_cpuslocked(struct static_key *key);
+extern enum jump_label_type jump_label_init_type(struct jump_entry *entry);

/*
* We should be using ATOMIC_INIT() for initializing .enabled, but
@@ -303,11 +303,6 @@ static inline int jump_label_text_reserved(void *start, void *end)
static inline void jump_label_lock(void) {}
static inline void jump_label_unlock(void) {}

-static inline int jump_label_apply_nops(struct module *mod)
-{
- return 0;
-}
-
static inline void static_key_enable(struct static_key *key)
{
STATIC_KEY_CHECK_USE(key);
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index b156e152d6b4..b1ac2948be79 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -508,7 +508,7 @@ void __init jump_label_init(void)

#ifdef CONFIG_MODULES

-static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
+enum jump_label_type jump_label_init_type(struct jump_entry *entry)
{
struct static_key *key = jump_entry_key(entry);
bool type = static_key_type(key);
@@ -596,31 +596,6 @@ static void __jump_label_mod_update(struct static_key *key)
}
}

-/***
- * apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
- * @mod: module to patch
- *
- * Allow for run-time selection of the optimal nops. Before the module
- * loads patch these with arch_get_jump_label_nop(), which is specified by
- * the arch specific jump label code.
- */
-void jump_label_apply_nops(struct module *mod)
-{
- struct jump_entry *iter_start = mod->jump_entries;
- struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
- struct jump_entry *iter;
-
- /* if the module doesn't have jump label entries, just return */
- if (iter_start == iter_stop)
- return;
-
- for (iter = iter_start; iter < iter_stop; iter++) {
- /* Only write NOPs for arch_branch_static(). */
- if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
- arch_jump_label_transform_static(iter, JUMP_LABEL_NOP);
- }
-}
-
static int jump_label_add_module(struct module *mod)
{
struct jump_entry *iter_start = mod->jump_entries;
--
2.30.2