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jump_label: Do not profile branch annotations 

While running my branch profiler that checks for incorrect "likely" and
"unlikely"s around the kernel, there's a large number of them that are
incorrect due to being "static_branches".

As static_branches are rather special, as they are likely or unlikely for
other reasons than normal annotations are used for, there's no reason to
have them be profiled.

Expose the "unlikely_notrace" and "likely_notrace" so that the
static_branch can use them, and have them be ignored by the branch
profilers.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201211163754.585174b9@gandalf.local.home
master
Steven Rostedt (VMware) 2020-12-11 16:37:54 -05:00 committed by Peter Zijlstra
parent c753925814
commit 2f0df49c89
2 changed files with 8 additions and 6 deletions
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2
include/linux/compiler.h
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@ -76,6 +76,8 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
#else
# define likely(x) __builtin_expect(!!(x), 1)
# define unlikely(x) __builtin_expect(!!(x), 0)
# define likely_notrace(x) likely(x)
# define unlikely_notrace(x) unlikely(x)
#endif
/* Optimization barrier */

12
include/linux/jump_label.h
View File

@ -261,14 +261,14 @@ static __always_inline void jump_label_init(void)
static __always_inline bool static_key_false(struct static_key *key)
{
if (unlikely(static_key_count(key) > 0))
if (unlikely_notrace(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))
if (likely_notrace(static_key_count(key) > 0))
return true;
return false;
}
@ -460,7 +460,7 @@ extern bool ____wrong_branch_error(void);
branch = !arch_static_branch_jump(&(x)->key, true); \
else \
branch = ____wrong_branch_error(); \
likely(branch); \
likely_notrace(branch); \
})
#define static_branch_unlikely(x) \
@ -472,13 +472,13 @@ extern bool ____wrong_branch_error(void);
branch = arch_static_branch(&(x)->key, false); \
else \
branch = ____wrong_branch_error(); \
unlikely(branch); \
unlikely_notrace(branch); \
})
#else /* !CONFIG_JUMP_LABEL */
#define static_branch_likely(x) likely(static_key_enabled(&(x)->key))
#define static_branch_unlikely(x) unlikely(static_key_enabled(&(x)->key))
#define static_branch_likely(x) likely_notrace(static_key_enabled(&(x)->key))
#define static_branch_unlikely(x) unlikely_notrace(static_key_enabled(&(x)->key))
#endif /* CONFIG_JUMP_LABEL */