[PATCH 3/3 v2] x86: Use tracepoint_enabled() for msr tracepoints instead of open coding it

Steven Rostedt
2020-09-25T21:18:24Z

From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>

7f47d8cc039f ("x86, tracing, perf: Add trace point for MSR accesses") added
tracing of msr read and write, but because of complexity in having
tracepoints in headers, and even more so for a core header like msr.h, not
to mention the bloat a tracepoint adds to inline functions, a helper
function is needed to be called from the header.

Use the new tracepoint_enabled() macro in tracepoint-defs.h to test if the
tracepoint is active before calling the helper function, instead of open
coding the same logic, which requires knowing the internals of a tracepoint.

Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
arch/x86/include/asm/msr.h | 18 ++++++++----------
1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/arch/x86/include/asm/msr.h b/arch/x86/include/asm/msr.h
index 86f20d520a07..fd4a32f0947b 100644
--- a/arch/x86/include/asm/msr.h
+++ b/arch/x86/include/asm/msr.h
@@ -67,15 +67,13 @@ struct saved_msrs {
#include <asm/atomic.h>
#include <linux/tracepoint-defs.h>

-extern struct tracepoint __tracepoint_read_msr;
-extern struct tracepoint __tracepoint_write_msr;
-extern struct tracepoint __tracepoint_rdpmc;
-#define msr_tracepoint_active(t) static_key_false(&(t).key)
+DECLARE_TRACEPOINT(read_msr);
+DECLARE_TRACEPOINT(write_msr);
+DECLARE_TRACEPOINT(rdpmc);
extern void do_trace_write_msr(unsigned int msr, u64 val, int failed);
extern void do_trace_read_msr(unsigned int msr, u64 val, int failed);
extern void do_trace_rdpmc(unsigned int msr, u64 val, int failed);
#else
-#define msr_tracepoint_active(t) false
static inline void do_trace_write_msr(unsigned int msr, u64 val, int failed) {}
static inline void do_trace_read_msr(unsigned int msr, u64 val, int failed) {}
static inline void do_trace_rdpmc(unsigned int msr, u64 val, int failed) {}
@@ -128,7 +126,7 @@ static inline unsigned long long native_read_msr(unsigned int msr)

val = __rdmsr(msr);

- if (msr_tracepoint_active(__tracepoint_read_msr))
+ if (tracepoint_enabled(read_msr))
do_trace_read_msr(msr, val, 0);

return val;
@@ -150,7 +148,7 @@ static inline unsigned long long native_read_msr_safe(unsigned int msr,
_ASM_EXTABLE(2b, 3b)
: [err] "=r" (*err), EAX_EDX_RET(val, low, high)
: "c" (msr), [fault] "i" (-EIO));
- if (msr_tracepoint_active(__tracepoint_read_msr))
+ if (tracepoint_enabled(read_msr))
do_trace_read_msr(msr, EAX_EDX_VAL(val, low, high), *err);
return EAX_EDX_VAL(val, low, high);
}
@@ -161,7 +159,7 @@ native_write_msr(unsigned int msr, u32 low, u32 high)
{
__wrmsr(msr, low, high);

- if (msr_tracepoint_active(__tracepoint_write_msr))
+ if (tracepoint_enabled(write_msr))
do_trace_write_msr(msr, ((u64)high << 32 | low), 0);
}

@@ -181,7 +179,7 @@ native_write_msr_safe(unsigned int msr, u32 low, u32 high)
: "c" (msr), "0" (low), "d" (high),
[fault] "i" (-EIO)
: "memory");
- if (msr_tracepoint_active(__tracepoint_write_msr))
+ if (tracepoint_enabled(write_msr))
do_trace_write_msr(msr, ((u64)high << 32 | low), err);
return err;
}
@@ -248,7 +246,7 @@ static inline unsigned long long native_read_pmc(int counter)
DECLARE_ARGS(val, low, high);

asm volatile("rdpmc" : EAX_EDX_RET(val, low, high) : "c" (counter));
- if (msr_tracepoint_active(__tracepoint_rdpmc))
+ if (tracepoint_enabled(rdpmc))
do_trace_rdpmc(counter, EAX_EDX_VAL(val, low, high), 0);
return EAX_EDX_VAL(val, low, high);
}
--
2.28.0