Adding perf_msr_probe function to provide interface for
checking up on MSR register and add its related event
attributes if it passes the check.
User defines following struct for each MSR register:
struct perf_msr {
u64 msr;
struct attribute **attrs;
bool (*test)(int idx, void *data);
bool no_check;
};
Where:
msr - is the MSR address
attrs - is attributes array to add if the check passed
test - is test function pointer
no_check - is bool that bypass the check and adds the
attribute without any test
The array of struct perf_msr is passed into:
perf_msr_probe(struct perf_msr *msr, int cnt,
struct attribute **attrs, void *data)
Together with:
cnt - which is the number of struct msr array elements
attrs - which is an array placeholder for added attributes
and needs to be big enough
data -which is user pointer passed to the test function
The perf_msr_probe will executed test code, read the MSR and
check the value is != 0. If all these tests pass, related
attributes are added into attrs array.
Also adding MSR_ATTR macro helper to define attribute array
from single attribute. It will be used in following patches.
Signed-off-by: Jiri Olsa <[email protected]>
---
arch/x86/events/Makefile | 2 +-
arch/x86/events/probe.c | 36 ++++++++++++++++++++++++++++++++++++
arch/x86/events/probe.h | 22 ++++++++++++++++++++++
3 files changed, 59 insertions(+), 1 deletion(-)
create mode 100644 arch/x86/events/probe.c
create mode 100644 arch/x86/events/probe.h
diff --git a/arch/x86/events/Makefile b/arch/x86/events/Makefile
index b8ccdb5c9244..ec29a466444a 100644
--- a/arch/x86/events/Makefile
+++ b/arch/x86/events/Makefile
@@ -1,4 +1,4 @@
-obj-y += core.o
+obj-y += core.o probe.o
obj-y += amd/
obj-$(CONFIG_X86_LOCAL_APIC) += msr.o
obj-$(CONFIG_CPU_SUP_INTEL) += intel/
diff --git a/arch/x86/events/probe.c b/arch/x86/events/probe.c
new file mode 100644
index 000000000000..0052b730c55e
--- /dev/null
+++ b/arch/x86/events/probe.c
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/export.h>
+#include <linux/bits.h>
+#include "probe.h"
+
+unsigned long
+perf_msr_probe(struct perf_msr *msr, int cnt,
+ struct attribute **attrs, void *data)
+{
+ unsigned long avail = 0;
+ unsigned int bit;
+ u64 val;
+
+ if (cnt >= BITS_PER_LONG)
+ return 0;
+
+ for (bit = 0; bit < cnt; bit++) {
+ struct attribute **a = msr[bit].attrs;
+
+ if (!msr[bit].no_check) {
+ if (msr[bit].test && !msr[bit].test(bit, data))
+ continue;
+ if (rdmsrl_safe(msr[bit].msr, &val) || !val)
+ continue;
+ }
+
+ while (*a)
+ *attrs++ = *a++;
+
+ avail |= bit;
+ }
+
+ *attrs = NULL;
+ return avail;
+}
+EXPORT_SYMBOL_GPL(perf_msr_probe);
diff --git a/arch/x86/events/probe.h b/arch/x86/events/probe.h
new file mode 100644
index 000000000000..42dd666533c3
--- /dev/null
+++ b/arch/x86/events/probe.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ARCH_X86_EVENTS_PROBE_H__
+#define __ARCH_X86_EVENTS_PROBE_H__
+#include <linux/sysfs.h>
+
+#define MSR_ATTR(__n) \
+static struct attribute *msr_##__n[] = { \
+ &__n.attr.attr, \
+ NULL, \
+}
+
+struct perf_msr {
+ u64 msr;
+ struct attribute **attrs;
+ bool (*test)(int idx, void *data);
+ bool no_check;
+};
+
+unsigned long
+perf_msr_probe(struct perf_msr *msr, int cnt,
+ struct attribute **attrs, void *data);
+#endif /* __ARCH_X86_EVENTS_PROBE_H__ */
--
2.17.2
