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Date: Thu, 23 Jul 2015 16:49:30 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Jason Baron <jasonbaron0@...il.com>
Cc: Borislav Petkov <bp@...en8.de>,
Andy Lutomirski <luto@...capital.net>,
Thomas Gleixner <tglx@...utronix.de>,
Mikulas Patocka <mpatocka@...hat.com>,
Paul Mackerras <paulus@...ba.org>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Kees Cook <keescook@...omium.org>,
Andrea Arcangeli <aarcange@...hat.com>,
Vince Weaver <vince@...ter.net>,
"hillf.zj" <hillf.zj@...baba-inc.com>,
Valdis Kletnieks <Valdis.Kletnieks@...edu>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Steven Rostedt <rostedt@...dmis.org>
Subject: Re: Kernel broken on processors without performance counters
On Thu, Jul 23, 2015 at 04:33:08PM +0200, Peter Zijlstra wrote:
> Lemme finish this and I'll post it.
Compile tested on x86_64 only..
Please have a look, I think you said I got some of the logic wrong, I've
not double checked that.
I'll go write comments and double check things.
---
arch/arm/include/asm/jump_label.h | 22 +++++++-
arch/arm64/include/asm/jump_label.h | 22 +++++++-
arch/mips/include/asm/jump_label.h | 23 +++++++-
arch/powerpc/include/asm/jump_label.h | 23 +++++++-
arch/s390/include/asm/jump_label.h | 23 +++++++-
arch/sparc/include/asm/jump_label.h | 38 ++++++++++---
arch/x86/include/asm/jump_label.h | 24 +++++++-
include/linux/jump_label.h | 101 +++++++++++++++++++++++++++++++++-
kernel/jump_label.c | 89 +++++++++++++++---------------
9 files changed, 297 insertions(+), 68 deletions(-)
diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h
index 5f337dc5c108..6c9789b33497 100644
--- a/arch/arm/include/asm/jump_label.h
+++ b/arch/arm/include/asm/jump_label.h
@@ -13,14 +13,32 @@
#define JUMP_LABEL_NOP "nop"
#endif
-static __always_inline bool arch_static_branch(struct static_key *key)
+static __always_inline bool arch_static_branch(struct static_key *key, bool inv)
{
+ unsigned long kval = (unsigned long)key + inv;
+
asm_volatile_goto("1:\n\t"
JUMP_LABEL_NOP "\n\t"
".pushsection __jump_table, \"aw\"\n\t"
".word 1b, %l[l_yes], %c0\n\t"
".popsection\n\t"
- : : "i" (key) : : l_yes);
+ : : "i" (kval) : : l_yes);
+
+ return false;
+l_yes:
+ return true;
+}
+
+static __always_inline bool arch_static_branch_jump(struct static_key *key, bool inv)
+{
+ unsigned long kval = (unsigned long)key + inv;
+
+ asm_volatile_goto("1:\n\t"
+ "b %l[l_yes]\n\t"
+ ".pushsection __jump_table, \"aw\"\n\t"
+ ".word 1b, %l[l_yes], %c0\n\t"
+ ".popsection\n\t"
+ : : "i" (kval) : : l_yes);
return false;
l_yes:
diff --git a/arch/arm64/include/asm/jump_label.h b/arch/arm64/include/asm/jump_label.h
index c0e5165c2f76..e5cda5d75c62 100644
--- a/arch/arm64/include/asm/jump_label.h
+++ b/arch/arm64/include/asm/jump_label.h
@@ -26,14 +26,32 @@
#define JUMP_LABEL_NOP_SIZE AARCH64_INSN_SIZE
-static __always_inline bool arch_static_branch(struct static_key *key)
+static __always_inline bool arch_static_branch(struct static_key *key, bool inv)
{
+ unsigned long kval = (unsigned long)key + inv;
+
asm goto("1: nop\n\t"
".pushsection __jump_table, \"aw\"\n\t"
".align 3\n\t"
".quad 1b, %l[l_yes], %c0\n\t"
".popsection\n\t"
- : : "i"(key) : : l_yes);
+ : : "i"(kval) : : l_yes);
+
+ return false;
+l_yes:
+ return true;
+}
+
+static __always_inline bool arch_static_branch_jump(struct static_key *key, bool inv)
+{
+ unsigned long kval = (unsigned long)key + inv;
+
+ asm goto("1: b %l[l_yes]\n\t"
+ ".pushsection __jump_table, \"aw\"\n\t"
+ ".align 3\n\t"
+ ".quad 1b, %l[l_yes], %c0\n\t"
+ ".popsection\n\t"
+ : : "i"(kval) : : l_yes);
return false;
l_yes:
diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h
index 608aa57799c8..d9fca6f52a93 100644
--- a/arch/mips/include/asm/jump_label.h
+++ b/arch/mips/include/asm/jump_label.h
@@ -26,14 +26,33 @@
#define NOP_INSN "nop"
#endif
-static __always_inline bool arch_static_branch(struct static_key *key)
+static __always_inline bool arch_static_branch(struct static_key *key, bool inv)
{
+ unsigned long kval = (unsigned long)key + inv;
+
asm_volatile_goto("1:\t" NOP_INSN "\n\t"
"nop\n\t"
".pushsection __jump_table, \"aw\"\n\t"
WORD_INSN " 1b, %l[l_yes], %0\n\t"
".popsection\n\t"
- : : "i" (key) : : l_yes);
+ : : "i" (kval) : : l_yes);
+
+ return false;
+l_yes:
+ return true;
+}
+
+static __always_inline bool arch_static_branch_jump(struct static_key *key, bool inv)
+{
+ unsigned long kval = (unsigned long)key + inv;
+
+ asm_volatile_goto("1:\tj %l[l_yes]\n\t"
+ "nop\n\t"
+ ".pushsection __jump_table, \"aw\"\n\t"
+ WORD_INSN " 1b, %l[l_yes], %0\n\t"
+ ".popsection\n\t"
+ : : "i" (kval) : : l_yes);
+
return false;
l_yes:
return true;
diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
index efbf9a322a23..c7cffedb1801 100644
--- a/arch/powerpc/include/asm/jump_label.h
+++ b/arch/powerpc/include/asm/jump_label.h
@@ -18,14 +18,33 @@
#define JUMP_ENTRY_TYPE stringify_in_c(FTR_ENTRY_LONG)
#define JUMP_LABEL_NOP_SIZE 4
-static __always_inline bool arch_static_branch(struct static_key *key)
+static __always_inline bool arch_static_branch(struct static_key *key, bool inv)
{
+ unsigned long kval = (unsigned long)key + inv;
+
asm_volatile_goto("1:\n\t"
"nop\n\t"
".pushsection __jump_table, \"aw\"\n\t"
JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"
".popsection \n\t"
- : : "i" (key) : : l_yes);
+ : : "i" (kval) : : l_yes);
+
+ return false;
+l_yes:
+ return true;
+}
+
+static __always_inline bool arch_static_branch_jump(struct static_key *key, bool inv)
+{
+ unsigned long kval = (unsigned long)key + inv;
+
+ asm_volatile_goto("1:\n\t"
+ "b %l[l_yes]\n\t"
+ ".pushsection __jump_table, \"aw\"\n\t"
+ JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"
+ ".popsection \n\t"
+ : : "i" (kval) : : l_yes);
+
return false;
l_yes:
return true;
diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h
index 69972b7957ee..4734b09b9fce 100644
--- a/arch/s390/include/asm/jump_label.h
+++ b/arch/s390/include/asm/jump_label.h
@@ -12,14 +12,33 @@
* We use a brcl 0,2 instruction for jump labels at compile time so it
* can be easily distinguished from a hotpatch generated instruction.
*/
-static __always_inline bool arch_static_branch(struct static_key *key)
+static __always_inline bool arch_static_branch(struct static_key *key, bool inv)
{
+ unsigned long kval = (unsigned long)key + inv;
+
asm_volatile_goto("0: brcl 0,"__stringify(JUMP_LABEL_NOP_OFFSET)"\n"
".pushsection __jump_table, \"aw\"\n"
".balign 8\n"
".quad 0b, %l[label], %0\n"
".popsection\n"
- : : "X" (key) : : label);
+ : : "X" (kval) : : label);
+
+ return false;
+label:
+ return true;
+}
+
+static __always_inline bool arch_static_branch_jump(struct static_key *key, bool inv)
+{
+ unsigned long kval = (unsigned long)key + inv;
+
+ asm_volatile_goto("0: j %l[l_yes]\n"
+ ".pushsection __jump_table, \"aw\"\n"
+ ".balign 8\n"
+ ".quad 0b, %l[label], %0\n"
+ ".popsection\n"
+ : : "X" (kval) : : label);
+
return false;
label:
return true;
diff --git a/arch/sparc/include/asm/jump_label.h b/arch/sparc/include/asm/jump_label.h
index cc9b04a2b11b..764f3c21da21 100644
--- a/arch/sparc/include/asm/jump_label.h
+++ b/arch/sparc/include/asm/jump_label.h
@@ -7,16 +7,36 @@
#define JUMP_LABEL_NOP_SIZE 4
-static __always_inline bool arch_static_branch(struct static_key *key)
+static __always_inline bool arch_static_branch(struct static_key *key, bool inv)
{
- asm_volatile_goto("1:\n\t"
- "nop\n\t"
- "nop\n\t"
- ".pushsection __jump_table, \"aw\"\n\t"
- ".align 4\n\t"
- ".word 1b, %l[l_yes], %c0\n\t"
- ".popsection \n\t"
- : : "i" (key) : : l_yes);
+ unsigned long kval = (unsigned long)key + inv;
+
+ asm_volatile_goto("1:\n\t"
+ "nop\n\t"
+ "nop\n\t"
+ ".pushsection __jump_table, \"aw\"\n\t"
+ ".align 4\n\t"
+ ".word 1b, %l[l_yes], %c0\n\t"
+ ".popsection \n\t"
+ : : "i" (kval) : : l_yes);
+
+ return false;
+l_yes:
+ return true;
+}
+
+static __always_inline bool arch_static_branch_jump(struct static_key *key, bool inv)
+{
+ unsigned long kval = (unsigned long)key + inv;
+
+ asm_volatile_goto("1:\n\t"
+ "b %l[l_yes]\n\t"
+ ".pushsection __jump_table, \"aw\"\n\t"
+ ".align 4\n\t"
+ ".word 1b, %l[l_yes], %c0\n\t"
+ ".popsection \n\t"
+ : : "i" (kval) : : l_yes);
+
return false;
l_yes:
return true;
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index a4c1cf7e93f8..43531baaee38 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -16,15 +16,35 @@
# define STATIC_KEY_INIT_NOP GENERIC_NOP5_ATOMIC
#endif
-static __always_inline bool arch_static_branch(struct static_key *key)
+static __always_inline bool arch_static_branch(struct static_key *key, bool inv)
{
+ unsigned long kval = (unsigned long)key + inv;
+
asm_volatile_goto("1:"
".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t"
".pushsection __jump_table, \"aw\" \n\t"
_ASM_ALIGN "\n\t"
_ASM_PTR "1b, %l[l_yes], %c0 \n\t"
".popsection \n\t"
- : : "i" (key) : : l_yes);
+ : : "i" (kval) : : l_yes);
+
+ return false;
+l_yes:
+ return true;
+}
+
+static __always_inline bool arch_static_branch_jump(struct static_key *key, bool inv)
+{
+ unsigned long kval = (unsigned long)key + inv;
+
+ asm_volatile_goto("1:"
+ "jmp %l[l_yes]\n\t"
+ ".pushsection __jump_table, \"aw\" \n\t"
+ _ASM_ALIGN "\n\t"
+ _ASM_PTR "1b, %l[l_yes], %c0 \n\t"
+ ".popsection \n\t"
+ : : "i" (kval) : : l_yes);
+
return false;
l_yes:
return true;
diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index f4de473f226b..4c97fed7acea 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -122,7 +122,7 @@ static inline bool jump_label_get_branch_default(struct static_key *key)
static __always_inline bool static_key_false(struct static_key *key)
{
- return arch_static_branch(key);
+ return arch_static_branch(key, false);
}
static __always_inline bool static_key_true(struct static_key *key)
@@ -213,6 +213,105 @@ static inline bool static_key_enabled(struct static_key *key)
return static_key_count(key) > 0;
}
+static inline void static_key_enable(struct static_key *key)
+{
+ int count = static_key_count(key);
+
+ WARN_ON_ONCE(count < 0 || count > 1);
+
+ if (!count)
+ static_key_slow_inc(key);
+}
+
+static inline void static_key_disable(struct static_key *key)
+{
+ int count = static_key_count(key);
+
+ WARN_ON_ONCE(count < 0 || count > 1);
+
+ if (count)
+ static_key_slow_dec(key);
+}
+
+
+/* -------------------------------------------------------------------------- */
+
+/*
+ * Two type wrappers around static_key, such that we can use compile time
+ * type differentiation to emit the right code.
+ *
+ * All the below code is macros in order to play type games.
+ */
+
+struct static_key_true {
+ struct static_key key;
+};
+
+struct static_key_false {
+ struct static_key key;
+};
+
+#define STATIC_KEY_TRUE_INIT (struct static_key_true) { .key = STATIC_KEY_INIT_TRUE, }
+#define STATIC_KEY_FALSE_INIT (struct static_key_false){ .key = STATIC_KEY_INIT_FALSE, }
+
+#define DEFINE_STATIC_KEY_TRUE(name) \
+ struct static_key_true name = STATIC_KEY_TRUE_INIT
+
+#define DEFINE_STATIC_KEY_FALSE(name) \
+ struct static_key_false name = STATIC_KEY_FALSE_INIT
+
+#ifdef HAVE_JUMP_LABEL
+
+/*
+ * Combine the right initial value (type) with the right branch order and section
+ * to generate the desired result.
+ */
+
+#define static_branch_likely(x) \
+({ \
+ bool branch; \
+ if (__builtin_types_compatible_p(typeof(x), struct static_key_true)) \
+ branch = !arch_static_branch(&(x)->key, false); \
+ else if (__builtin_types_compatible_p(typeof(x), struct static_key_false)) \
+ branch = !arch_static_branch_jump(&(x)->key, true); \
+ else \
+ branch = ____wrong_branch_error(); \
+ branch; \
+})
+
+#define static_branch_unlikely(x) \
+({ \
+ bool branch; \
+ if (__builtin_types_compatible_p(typeof(x), struct static_key_true)) \
+ branch = arch_static_branch(&(x)->key, true); \
+ else if (__builtin_types_compatible_p(typeof(x), struct static_key_false)) \
+ branch = arch_static_branch_jump(&(x)->key, false); \
+ else \
+ branch = ____wrong_branch_error(); \
+ branch; \
+})
+
+#else /* !HAVE_JUMP_LABEL */
+
+#define static_branch_likely(x) static_key_true(&(x)->key)
+#define static_branch_unlikely(x) static_key_false(&(x)->key)
+
+#endif /* HAVE_JUMP_LABEL */
+
+/*
+ * Advanced usage; refcount, branch is enabled when: count != 0
+ */
+
+#define static_branch_inc(x) static_key_slow_inc(&(x)->key)
+#define static_branch_dec(x) static_key_slow_dec(&(x)->key)
+
+/*
+ * Normal usage; boolean enable/disable.
+ */
+
+#define static_branch_enable(x) static_key_enable(&(x)->key)
+#define static_branch_disable(x) static_key_disable(&(x)->key)
+
#endif /* _LINUX_JUMP_LABEL_H */
#endif /* __ASSEMBLY__ */
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 52ebaca1b9fc..8d0cb621c5bc 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -54,7 +54,7 @@ jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
}
-static void jump_label_update(struct static_key *key, int enable);
+static void jump_label_update(struct static_key *key);
void static_key_slow_inc(struct static_key *key)
{
@@ -63,13 +63,8 @@ void static_key_slow_inc(struct static_key *key)
return;
jump_label_lock();
- if (atomic_read(&key->enabled) == 0) {
- if (!jump_label_get_branch_default(key))
- jump_label_update(key, JUMP_LABEL_ENABLE);
- else
- jump_label_update(key, JUMP_LABEL_DISABLE);
- }
- atomic_inc(&key->enabled);
+ if (atomic_inc_and_test(&key->enabled))
+ jump_label_update(key);
jump_label_unlock();
}
EXPORT_SYMBOL_GPL(static_key_slow_inc);
@@ -87,10 +82,7 @@ static void __static_key_slow_dec(struct static_key *key,
atomic_inc(&key->enabled);
schedule_delayed_work(work, rate_limit);
} else {
- if (!jump_label_get_branch_default(key))
- jump_label_update(key, JUMP_LABEL_DISABLE);
- else
- jump_label_update(key, JUMP_LABEL_ENABLE);
+ jump_label_update(key);
}
jump_label_unlock();
}
@@ -149,7 +141,7 @@ static int __jump_label_text_reserved(struct jump_entry *iter_start,
return 0;
}
-/*
+/*
* Update code which is definitely not currently executing.
* Architectures which need heavyweight synchronization to modify
* running code can override this to make the non-live update case
@@ -158,37 +150,44 @@ static int __jump_label_text_reserved(struct jump_entry *iter_start,
void __weak __init_or_module arch_jump_label_transform_static(struct jump_entry *entry,
enum jump_label_type type)
{
- arch_jump_label_transform(entry, type);
+ arch_jump_label_transform(entry, type);
+}
+
+static struct static_key *static_key_cast(jump_label_t key_addr)
+{
+ return (struct static_key *)(key_addr & ~1UL);
+}
+
+static bool static_key_inv(jump_label_t key_addr)
+{
+ return key_addr & 1UL;
+}
+
+static enum jump_label_type jump_label_type(struct jump_entry *entry)
+{
+ struct static_key *key = static_key_cast(iter->key);
+ bool true_branch = jump_label_get_branch_default(key);
+ bool state = static_key_enabled(key);
+ bool inv = static_key_inv(iter->key);
+
+ return (true_branch ^ state) ^ inv;
}
static void __jump_label_update(struct static_key *key,
struct jump_entry *entry,
- struct jump_entry *stop, int enable)
+ struct jump_entry *stop)
{
- for (; (entry < stop) &&
- (entry->key == (jump_label_t)(unsigned long)key);
- entry++) {
+ for (; (entry < stop) && (static_key_cast(entry->key) == key); entry++) {
/*
* entry->code set to 0 invalidates module init text sections
* kernel_text_address() verifies we are not in core kernel
* init code, see jump_label_invalidate_module_init().
*/
if (entry->code && kernel_text_address(entry->code))
- arch_jump_label_transform(entry, enable);
+ arch_jump_label_transform(entry, jump_label_type(entry));
}
}
-static enum jump_label_type jump_label_type(struct static_key *key)
-{
- bool true_branch = jump_label_get_branch_default(key);
- bool state = static_key_enabled(key);
-
- if ((!true_branch && state) || (true_branch && !state))
- return JUMP_LABEL_ENABLE;
-
- return JUMP_LABEL_DISABLE;
-}
-
void __init jump_label_init(void)
{
struct jump_entry *iter_start = __start___jump_table;
@@ -202,8 +201,8 @@ void __init jump_label_init(void)
for (iter = iter_start; iter < iter_stop; iter++) {
struct static_key *iterk;
- iterk = (struct static_key *)(unsigned long)iter->key;
- arch_jump_label_transform_static(iter, jump_label_type(iterk));
+ arch_jump_label_transform_static(iter, jump_label_type(iter));
+ iterk = static_key_cast(iter->key);
if (iterk == key)
continue;
@@ -243,17 +242,15 @@ static int __jump_label_mod_text_reserved(void *start, void *end)
start, end);
}
-static void __jump_label_mod_update(struct static_key *key, int enable)
+static void __jump_label_mod_update(struct static_key *key)
{
- struct static_key_mod *mod = key->next;
+ struct static_key_mod *mod;
- while (mod) {
+ for (mod = key->next; mod; mod = mod->next) {
struct module *m = mod->mod;
__jump_label_update(key, mod->entries,
- m->jump_entries + m->num_jump_entries,
- enable);
- mod = mod->next;
+ m->jump_entries + m->num_jump_entries)
}
}
@@ -276,7 +273,8 @@ void jump_label_apply_nops(struct module *mod)
return;
for (iter = iter_start; iter < iter_stop; iter++) {
- arch_jump_label_transform_static(iter, JUMP_LABEL_DISABLE);
+ if (jump_label_type(iter) == JUMP_LABEL_DISABLE)
+ arch_jump_label_transform_static(iter, JUMP_LABEL_DISABLE);
}
}
@@ -297,7 +295,7 @@ static int jump_label_add_module(struct module *mod)
for (iter = iter_start; iter < iter_stop; iter++) {
struct static_key *iterk;
- iterk = (struct static_key *)(unsigned long)iter->key;
+ iterk = static_key_cast(iter->key);
if (iterk == key)
continue;
@@ -318,8 +316,7 @@ static int jump_label_add_module(struct module *mod)
jlm->next = key->next;
key->next = jlm;
- if (jump_label_type(key) == JUMP_LABEL_ENABLE)
- __jump_label_update(key, iter, iter_stop, JUMP_LABEL_ENABLE);
+ __jump_label_update(key, iter, iter_stop);
}
return 0;
@@ -334,10 +331,10 @@ static void jump_label_del_module(struct module *mod)
struct static_key_mod *jlm, **prev;
for (iter = iter_start; iter < iter_stop; iter++) {
- if (iter->key == (jump_label_t)(unsigned long)key)
+ if (static_key_cast(iter->key) == key)
continue;
- key = (struct static_key *)(unsigned long)iter->key;
+ key = static_key_cast(iter->key);
if (within_module(iter->key, mod))
continue;
@@ -439,7 +436,7 @@ int jump_label_text_reserved(void *start, void *end)
return ret;
}
-static void jump_label_update(struct static_key *key, int enable)
+static void jump_label_update(struct static_key *key)
{
struct jump_entry *stop = __stop___jump_table;
struct jump_entry *entry = jump_label_get_entries(key);
@@ -456,7 +453,7 @@ static void jump_label_update(struct static_key *key, int enable)
#endif
/* if there are no users, entry can be NULL */
if (entry)
- __jump_label_update(key, entry, stop, enable);
+ __jump_label_update(key, entry, stop);
}
#endif
--
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