[POWERPC] powerpc: Instrument Hypervisor Calls

Add instrumentation for hypervisor calls on pseries.  Call statistics
include number of calls, wall time and cpu cycles (if available) and
are made available via debugfs.  Instrumentation code is behind the
HCALL_STATS config option and has no impact if not enabled.

Signed-off-by: Mike Kravetz <kravetz@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

5 files changed, 223 insertions, 0 deletions

diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index e29ef77d3b00..d7b2aedd89aa 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -18,6 +18,20 @@ config DEBUG_STACK_USAGE
 
           This option will slow down process creation somewhat.
 
+config HCALL_STATS
+        bool "Hypervisor call instrumentation"
+        depends on PPC_PSERIES && DEBUG_FS
+        help
+          Adds code to keep track of the number of hypervisor calls made and
+          the amount of time spent in hypervisor callsr.  Wall time spent in
+          each call is always calculated, and if available CPU cycles spent
+          are also calculated.  A directory named hcall_inst is added at the
+          root of the debugfs filesystem.  Within the hcall_inst directory
+          are files that contain CPU specific call statistics.
+
+          This option will add a small amount of overhead to all hypervisor
+          calls.
+
 config DEBUGGER
         bool "Enable debugger hooks"
         depends on DEBUG_KERNEL
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index c53acd2a6dfc..c578e7ab8173 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -137,6 +137,7 @@ int main(void)
         DEFINE(PACA_USER_TIME, offsetof(struct paca_struct, user_time));
         DEFINE(PACA_SYSTEM_TIME, offsetof(struct paca_struct, system_time));
         DEFINE(PACA_SLBSHADOWPTR, offsetof(struct paca_struct, slb_shadow_ptr));
+        DEFINE(PACA_DATA_OFFSET, offsetof(struct paca_struct, data_offset));
 
         DEFINE(SLBSHADOW_STACKVSID,
                offsetof(struct slb_shadow, save_area[SLB_NUM_BOLTED - 1].vsid));
@@ -165,6 +166,12 @@ int main(void)
         /* Create extra stack space for SRR0 and SRR1 when calling prom/rtas. */
         DEFINE(PROM_FRAME_SIZE, STACK_FRAME_OVERHEAD + sizeof(struct pt_regs) + 16);
         DEFINE(RTAS_FRAME_SIZE, STACK_FRAME_OVERHEAD + sizeof(struct pt_regs) + 16);
+
+        /* hcall statistics */
+        DEFINE(HCALL_STAT_SIZE, sizeof(struct hcall_stats));
+        DEFINE(HCALL_STAT_CALLS, offsetof(struct hcall_stats, num_calls));
+        DEFINE(HCALL_STAT_TB, offsetof(struct hcall_stats, tb_total));
+        DEFINE(HCALL_STAT_PURR, offsetof(struct hcall_stats, purr_total));
 #endif /* CONFIG_PPC64 */
         DEFINE(GPR0, STACK_FRAME_OVERHEAD+offsetof(struct pt_regs, gpr[0]));
         DEFINE(GPR1, STACK_FRAME_OVERHEAD+offsetof(struct pt_regs, gpr[1]));
diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index e5e0ff466904..997243a91be8 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -12,3 +12,4 @@ obj-$(CONFIG_EEH)	+= eeh.o eeh_cache.o eeh_driver.o eeh_event.o
 
 obj-$(CONFIG_HVC_CONSOLE)       += hvconsole.o
 obj-$(CONFIG_HVCS)              += hvcserver.o
+obj-$(CONFIG_HCALL_STATS)       += hvCall_inst.o
diff --git a/arch/powerpc/platforms/pseries/hvCall.S b/arch/powerpc/platforms/pseries/hvCall.S
index 9a99b056bd27..c00cfed7af2c 100644
--- a/arch/powerpc/platforms/pseries/hvCall.S
+++ b/arch/powerpc/platforms/pseries/hvCall.S
@@ -10,9 +10,69 @@
 #include <asm/hvcall.h>
 #include <asm/processor.h>
 #include <asm/ppc_asm.h>
+#include <asm/asm-offsets.h>
         
 #define STK_PARM(i)     (48 + ((i)-3)*8)
 
+#ifdef CONFIG_HCALL_STATS
+/*
+ * precall must preserve all registers.  use unused STK_PARM()
+ * areas to save snapshots and opcode.
+ */
+#define HCALL_INST_PRECALL                                      \
+        std     r3,STK_PARM(r3)(r1);    /* save opcode */       \
+        mftb    r0;                     /* get timebase and */  \
+        std     r0,STK_PARM(r5)(r1);    /* save for later */    \
+BEGIN_FTR_SECTION;                                              \
+        mfspr   r0,SPRN_PURR;           /* get PURR and */      \
+        std     r0,STK_PARM(r6)(r1);    /* save for later */    \
+END_FTR_SECTION_IFCLR(CPU_FTR_PURR);
+        
+/*
+ * postcall is performed immediately before function return which
+ * allows liberal use of volatile registers.
+ */
+#define HCALL_INST_POSTCALL                                     \
+        ld      r4,STK_PARM(r3)(r1);    /* validate opcode */   \
+        cmpldi  cr7,r4,MAX_HCALL_OPCODE;                        \
+        bgt-    cr7,1f;                                         \
+                                                                \
+        /* get time and PURR snapshots after hcall */           \
+        mftb    r7;                     /* timebase after */    \
+BEGIN_FTR_SECTION;                                              \
+        mfspr   r8,SPRN_PURR;           /* PURR after */        \
+        ld      r6,STK_PARM(r6)(r1);    /* PURR before */       \
+        subf    r6,r6,r8;               /* delta */             \
+END_FTR_SECTION_IFCLR(CPU_FTR_PURR);                            \
+        ld      r5,STK_PARM(r5)(r1);    /* timebase before */   \
+        subf    r5,r5,r7;               /* time delta */        \
+                                                                \
+        /* calculate address of stat structure r4 = opcode */   \
+        srdi    r4,r4,2;                /* index into array */  \
+        mulli   r4,r4,HCALL_STAT_SIZE;                          \
+        LOAD_REG_ADDR(r7, per_cpu__hcall_stats);                \
+        add     r4,r4,r7;                                       \
+        ld      r7,PACA_DATA_OFFSET(r13); /* per cpu offset */  \
+        add     r4,r4,r7;                                       \
+                                                                \
+        /* update stats */                                      \
+        ld      r7,HCALL_STAT_CALLS(r4); /* count */            \
+        addi    r7,r7,1;                                        \
+        std     r7,HCALL_STAT_CALLS(r4);                        \
+        ld      r7,HCALL_STAT_TB(r4);   /* timebase */          \
+        add     r7,r7,r5;                                       \
+        std     r7,HCALL_STAT_TB(r4);                           \
+BEGIN_FTR_SECTION;                                              \
+        ld      r7,HCALL_STAT_PURR(r4); /* PURR */              \
+        add     r7,r7,r6;                                       \
+        std     r7,HCALL_STAT_PURR(r4);                         \
+END_FTR_SECTION_IFCLR(CPU_FTR_PURR);                            \
+1:
+#else
+#define HCALL_INST_PRECALL
+#define HCALL_INST_POSTCALL
+#endif
+
         .text
 
 _GLOBAL(plpar_hcall_norets)
@@ -21,8 +81,12 @@ _GLOBAL(plpar_hcall_norets)
         mfcr    r0
         stw     r0,8(r1)
 
+        HCALL_INST_PRECALL
+
         HVSC                            /* invoke the hypervisor */
 
+        HCALL_INST_POSTCALL
+
         lwz     r0,8(r1)
         mtcrf   0xff,r0
         blr                             /* return r3 = status */
@@ -33,6 +97,8 @@ _GLOBAL(plpar_hcall)
         mfcr    r0
         stw     r0,8(r1)
 
+        HCALL_INST_PRECALL
+
         std     r4,STK_PARM(r4)(r1)     /* Save ret buffer */
 
         mr      r4,r5
@@ -50,6 +116,8 @@ _GLOBAL(plpar_hcall)
         std     r6, 16(r12)
         std     r7, 24(r12)
 
+        HCALL_INST_POSTCALL
+
         lwz     r0,8(r1)
         mtcrf   0xff,r0
 
@@ -61,6 +129,8 @@ _GLOBAL(plpar_hcall9)
         mfcr    r0
         stw     r0,8(r1)
 
+        HCALL_INST_PRECALL
+
         std     r4,STK_PARM(r4)(r1)     /* Save ret buffer */
 
         mr      r4,r5
@@ -86,6 +156,8 @@ _GLOBAL(plpar_hcall9)
         std     r11,56(r12)
         std     r12,64(r12)
 
+        HCALL_INST_POSTCALL
+
         lwz     r0,8(r1)
         mtcrf   0xff,r0
 
diff --git a/arch/powerpc/platforms/pseries/hvCall_inst.c b/arch/powerpc/platforms/pseries/hvCall_inst.c
new file mode 100644
index 000000000000..641e6511cf06
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/hvCall_inst.c
@@ -0,0 +1,129 @@
+/*
+ * Copyright (C) 2006 Mike Kravetz IBM Corporation
+ *
+ * Hypervisor Call Instrumentation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/percpu.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/cpumask.h>
+#include <asm/hvcall.h>
+#include <asm/firmware.h>
+#include <asm/cputable.h>
+
+DEFINE_PER_CPU(struct hcall_stats[HCALL_STAT_ARRAY_SIZE], hcall_stats);
+
+/*
+ * Routines for displaying the statistics in debugfs
+ */
+static void *hc_start(struct seq_file *m, loff_t *pos)
+{
+        if ((int)*pos < HCALL_STAT_ARRAY_SIZE)
+                return (void *)(unsigned long)(*pos + 1);
+
+        return NULL;
+}
+
+static void *hc_next(struct seq_file *m, void *p, loff_t * pos)
+{
+        ++*pos;
+
+        return hc_start(m, pos);
+}
+
+static void hc_stop(struct seq_file *m, void *p)
+{
+}
+
+static int hc_show(struct seq_file *m, void *p)
+{
+        unsigned long h_num = (unsigned long)p;
+        struct hcall_stats *hs = (struct hcall_stats *)m->private;
+
+        if (hs[h_num].num_calls) {
+                if (!cpu_has_feature(CPU_FTR_PURR))
+                        seq_printf(m, "%lu %lu %lu %lu\n", h_num<<2,
+                                   hs[h_num].num_calls,
+                                   hs[h_num].tb_total,
+                                   hs[h_num].purr_total);
+                else
+                        seq_printf(m, "%lu %lu %lu\n", h_num<<2,
+                                   hs[h_num].num_calls,
+                                   hs[h_num].tb_total);
+        }
+
+        return 0;
+}
+
+static struct seq_operations hcall_inst_seq_ops = {
+        .start = hc_start,
+        .next  = hc_next,
+        .stop  = hc_stop,
+        .show  = hc_show
+};
+
+static int hcall_inst_seq_open(struct inode *inode, struct file *file)
+{
+        int rc;
+        struct seq_file *seq;
+
+        rc = seq_open(file, &hcall_inst_seq_ops);
+        seq = file->private_data;
+        seq->private = file->f_dentry->d_inode->u.generic_ip;
+
+        return rc;
+}
+
+static struct file_operations hcall_inst_seq_fops = {
+        .open = hcall_inst_seq_open,
+        .read = seq_read,
+        .llseek = seq_lseek,
+        .release = seq_release,
+};
+
+#define HCALL_ROOT_DIR          "hcall_inst"
+#define CPU_NAME_BUF_SIZE       32
+
+static int __init hcall_inst_init(void)
+{
+        struct dentry *hcall_root;
+        struct dentry *hcall_file;
+        char cpu_name_buf[CPU_NAME_BUF_SIZE];
+        int cpu;
+
+        if (!firmware_has_feature(FW_FEATURE_LPAR))
+                return 0;
+
+        hcall_root = debugfs_create_dir(HCALL_ROOT_DIR, NULL);
+        if (!hcall_root)
+                return -ENOMEM;
+
+        for_each_possible_cpu(cpu) {
+                snprintf(cpu_name_buf, CPU_NAME_BUF_SIZE, "cpu%d", cpu);
+                hcall_file = debugfs_create_file(cpu_name_buf, S_IRUGO,
+                                                 hcall_root,
+                                                 per_cpu(hcall_stats, cpu),
+                                                 &hcall_inst_seq_fops);
+                if (!hcall_file)
+                        return -ENOMEM;
+        }
+
+        return 0;
+}
+__initcall(hcall_inst_init);