mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-14 07:36:43 +07:00
ea5e9539ab
This patch exposes the jump_label reference count in preparation for the next patch. cpusets cares about both the jump_label being enabled and how many users of the cpusets there currently are. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jan Kara <jack@suse.cz> Cc: Michal Hocko <mhocko@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
207 lines
5.7 KiB
C
207 lines
5.7 KiB
C
#ifndef _LINUX_JUMP_LABEL_H
|
|
#define _LINUX_JUMP_LABEL_H
|
|
|
|
/*
|
|
* Jump label support
|
|
*
|
|
* Copyright (C) 2009-2012 Jason Baron <jbaron@redhat.com>
|
|
* Copyright (C) 2011-2012 Peter Zijlstra <pzijlstr@redhat.com>
|
|
*
|
|
* Jump labels provide an interface to generate dynamic branches using
|
|
* self-modifying code. Assuming toolchain and architecture support the result
|
|
* of a "if (static_key_false(&key))" statement is a unconditional branch (which
|
|
* defaults to false - and the true block is placed out of line).
|
|
*
|
|
* However at runtime we can change the branch target using
|
|
* static_key_slow_{inc,dec}(). These function as a 'reference' count on the key
|
|
* object and for as long as there are references all branches referring to
|
|
* that particular key will point to the (out of line) true block.
|
|
*
|
|
* Since this relies on modifying code the static_key_slow_{inc,dec}() functions
|
|
* must be considered absolute slow paths (machine wide synchronization etc.).
|
|
* OTOH, since the affected branches are unconditional their runtime overhead
|
|
* will be absolutely minimal, esp. in the default (off) case where the total
|
|
* effect is a single NOP of appropriate size. The on case will patch in a jump
|
|
* to the out-of-line block.
|
|
*
|
|
* When the control is directly exposed to userspace it is prudent to delay the
|
|
* decrement to avoid high frequency code modifications which can (and do)
|
|
* cause significant performance degradation. Struct static_key_deferred and
|
|
* static_key_slow_dec_deferred() provide for this.
|
|
*
|
|
* Lacking toolchain and or architecture support, it falls back to a simple
|
|
* conditional branch.
|
|
*
|
|
* struct static_key my_key = STATIC_KEY_INIT_TRUE;
|
|
*
|
|
* if (static_key_true(&my_key)) {
|
|
* }
|
|
*
|
|
* will result in the true case being in-line and starts the key with a single
|
|
* reference. Mixing static_key_true() and static_key_false() on the same key is not
|
|
* allowed.
|
|
*
|
|
* Not initializing the key (static data is initialized to 0s anyway) is the
|
|
* same as using STATIC_KEY_INIT_FALSE.
|
|
*
|
|
*/
|
|
|
|
#include <linux/types.h>
|
|
#include <linux/compiler.h>
|
|
#include <linux/bug.h>
|
|
|
|
extern bool static_key_initialized;
|
|
|
|
#define STATIC_KEY_CHECK_USE() WARN(!static_key_initialized, \
|
|
"%s used before call to jump_label_init", \
|
|
__func__)
|
|
|
|
#if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL)
|
|
|
|
struct static_key {
|
|
atomic_t enabled;
|
|
/* Set lsb bit to 1 if branch is default true, 0 ot */
|
|
struct jump_entry *entries;
|
|
#ifdef CONFIG_MODULES
|
|
struct static_key_mod *next;
|
|
#endif
|
|
};
|
|
|
|
# include <asm/jump_label.h>
|
|
# define HAVE_JUMP_LABEL
|
|
#else
|
|
struct static_key {
|
|
atomic_t enabled;
|
|
};
|
|
#endif /* CC_HAVE_ASM_GOTO && CONFIG_JUMP_LABEL */
|
|
|
|
enum jump_label_type {
|
|
JUMP_LABEL_DISABLE = 0,
|
|
JUMP_LABEL_ENABLE,
|
|
};
|
|
|
|
struct module;
|
|
|
|
#include <linux/atomic.h>
|
|
|
|
static inline int static_key_count(struct static_key *key)
|
|
{
|
|
return atomic_read(&key->enabled);
|
|
}
|
|
|
|
#ifdef HAVE_JUMP_LABEL
|
|
|
|
#define JUMP_LABEL_TYPE_FALSE_BRANCH 0UL
|
|
#define JUMP_LABEL_TYPE_TRUE_BRANCH 1UL
|
|
#define JUMP_LABEL_TYPE_MASK 1UL
|
|
|
|
static
|
|
inline struct jump_entry *jump_label_get_entries(struct static_key *key)
|
|
{
|
|
return (struct jump_entry *)((unsigned long)key->entries
|
|
& ~JUMP_LABEL_TYPE_MASK);
|
|
}
|
|
|
|
static inline bool jump_label_get_branch_default(struct static_key *key)
|
|
{
|
|
if (((unsigned long)key->entries & JUMP_LABEL_TYPE_MASK) ==
|
|
JUMP_LABEL_TYPE_TRUE_BRANCH)
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
static __always_inline bool static_key_false(struct static_key *key)
|
|
{
|
|
return arch_static_branch(key);
|
|
}
|
|
|
|
static __always_inline bool static_key_true(struct static_key *key)
|
|
{
|
|
return !static_key_false(key);
|
|
}
|
|
|
|
extern struct jump_entry __start___jump_table[];
|
|
extern struct jump_entry __stop___jump_table[];
|
|
|
|
extern void jump_label_init(void);
|
|
extern void jump_label_lock(void);
|
|
extern void jump_label_unlock(void);
|
|
extern void arch_jump_label_transform(struct jump_entry *entry,
|
|
enum jump_label_type type);
|
|
extern void arch_jump_label_transform_static(struct jump_entry *entry,
|
|
enum jump_label_type type);
|
|
extern int jump_label_text_reserved(void *start, void *end);
|
|
extern void static_key_slow_inc(struct static_key *key);
|
|
extern void static_key_slow_dec(struct static_key *key);
|
|
extern void jump_label_apply_nops(struct module *mod);
|
|
|
|
#define STATIC_KEY_INIT_TRUE ((struct static_key) \
|
|
{ .enabled = ATOMIC_INIT(1), \
|
|
.entries = (void *)JUMP_LABEL_TYPE_TRUE_BRANCH })
|
|
#define STATIC_KEY_INIT_FALSE ((struct static_key) \
|
|
{ .enabled = ATOMIC_INIT(0), \
|
|
.entries = (void *)JUMP_LABEL_TYPE_FALSE_BRANCH })
|
|
|
|
#else /* !HAVE_JUMP_LABEL */
|
|
|
|
static __always_inline void jump_label_init(void)
|
|
{
|
|
static_key_initialized = true;
|
|
}
|
|
|
|
static __always_inline bool static_key_false(struct static_key *key)
|
|
{
|
|
if (unlikely(static_key_count(key) > 0))
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
static __always_inline bool static_key_true(struct static_key *key)
|
|
{
|
|
if (likely(static_key_count(key) > 0))
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
static inline void static_key_slow_inc(struct static_key *key)
|
|
{
|
|
STATIC_KEY_CHECK_USE();
|
|
atomic_inc(&key->enabled);
|
|
}
|
|
|
|
static inline void static_key_slow_dec(struct static_key *key)
|
|
{
|
|
STATIC_KEY_CHECK_USE();
|
|
atomic_dec(&key->enabled);
|
|
}
|
|
|
|
static inline int jump_label_text_reserved(void *start, void *end)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
#define STATIC_KEY_INIT_TRUE ((struct static_key) \
|
|
{ .enabled = ATOMIC_INIT(1) })
|
|
#define STATIC_KEY_INIT_FALSE ((struct static_key) \
|
|
{ .enabled = ATOMIC_INIT(0) })
|
|
|
|
#endif /* HAVE_JUMP_LABEL */
|
|
|
|
#define STATIC_KEY_INIT STATIC_KEY_INIT_FALSE
|
|
#define jump_label_enabled static_key_enabled
|
|
|
|
static inline bool static_key_enabled(struct static_key *key)
|
|
{
|
|
return static_key_count(key) > 0;
|
|
}
|
|
|
|
#endif /* _LINUX_JUMP_LABEL_H */
|