powerpc: tracing: Add hypervisor call tracepoints
Add hcall_entry and hcall_exit tracepoints. This replaces the inline
assembly HCALL_STATS code and converts it to use the new tracepoints.
To keep the disabled case as quick as possible, we embed a status word
in the TOC so we can get at it with a single load. By doing so we
keep the overhead at a minimum. Time taken for a null hcall:
No tracepoint code: 135.79 cycles
Disabled tracepoints: 137.95 cycles
For reference, before this patch enabling HCALL_STATS resulted in a null
hcall of 201.44 cycles!
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/platforms/pseries/hvCall_inst.c b/arch/powerpc/platforms/pseries/hvCall_inst.c
index 3631a4f..e44e103 100644
--- a/arch/powerpc/platforms/pseries/hvCall_inst.c
+++ b/arch/powerpc/platforms/pseries/hvCall_inst.c
@@ -26,6 +26,7 @@
#include <asm/hvcall.h>
#include <asm/firmware.h>
#include <asm/cputable.h>
+#include <asm/trace.h>
DEFINE_PER_CPU(struct hcall_stats[HCALL_STAT_ARRAY_SIZE], hcall_stats);
@@ -100,6 +101,34 @@
#define HCALL_ROOT_DIR "hcall_inst"
#define CPU_NAME_BUF_SIZE 32
+
+static void probe_hcall_entry(unsigned long opcode)
+{
+ struct hcall_stats *h;
+
+ if (opcode > MAX_HCALL_OPCODE)
+ return;
+
+ h = &get_cpu_var(hcall_stats)[opcode / 4];
+ h->tb_start = mftb();
+ h->purr_start = mfspr(SPRN_PURR);
+}
+
+static void probe_hcall_exit(unsigned long opcode, unsigned long retval)
+{
+ struct hcall_stats *h;
+
+ if (opcode > MAX_HCALL_OPCODE)
+ return;
+
+ h = &__get_cpu_var(hcall_stats)[opcode / 4];
+ h->num_calls++;
+ h->tb_total = mftb() - h->tb_start;
+ h->purr_total = mfspr(SPRN_PURR) - h->purr_start;
+
+ put_cpu_var(hcall_stats);
+}
+
static int __init hcall_inst_init(void)
{
struct dentry *hcall_root;
@@ -110,6 +139,14 @@
if (!firmware_has_feature(FW_FEATURE_LPAR))
return 0;
+ if (register_trace_hcall_entry(probe_hcall_entry))
+ return -EINVAL;
+
+ if (register_trace_hcall_exit(probe_hcall_exit)) {
+ unregister_trace_hcall_entry(probe_hcall_entry);
+ return -EINVAL;
+ }
+
hcall_root = debugfs_create_dir(HCALL_ROOT_DIR, NULL);
if (!hcall_root)
return -ENOMEM;