From: kfraser <kfraser@localhost.localdomain>
Date: Thu, 7 Jun 2007 12:48:27 +0000 (+0100)
Subject: Add backtrace support to xenoprof.
X-Git-Tag: xen-3.2.0~219
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=6648568fc464daa971aa87c3f2b4186fc024c42c;p=legacy%2Flinux-2.6.18-xen.git

Add backtrace support to xenoprof.
Signed-off-by: Amitabha Roy <amitabha.roy@gmail.com>
Reviewed-by: Jose Renato G Santos <joserenato.santos@hp.com>
---

diff --git a/drivers/xen/xenoprof/xenoprofile.c b/drivers/xen/xenoprof/xenoprofile.c
index 382a50f6..37097f84 100644
--- a/drivers/xen/xenoprof/xenoprofile.c
+++ b/drivers/xen/xenoprof/xenoprofile.c
@@ -51,11 +51,13 @@ static int xenoprof_enabled = 0;
 static int xenoprof_is_primary = 0;
 static int active_defined;
 
+extern unsigned long backtrace_depth;
+
 /* Number of buffers in shared area (one per VCPU) */
 int nbuf;
 /* Mappings of VIRQ_XENOPROF to irq number (per cpu) */
 int ovf_irq[NR_CPUS];
-/* cpu model type string - copied from Xen memory space on XENOPROF_init command */
+/* cpu model type string - copied from Xen on XENOPROF_init command */
 char cpu_type[XENOPROF_CPU_TYPE_SIZE];
 
 #ifdef CONFIG_PM
@@ -115,38 +117,54 @@ unsigned long long p_oprofile_samples = 0;
 unsigned int pdomains;
 struct xenoprof_passive passive_domains[MAX_OPROF_DOMAINS];
 
+/* Check whether the given entry is an escape code */
+static int xenoprof_is_escape(xenoprof_buf_t * buf, int tail)
+{
+	return (buf->event_log[tail].eip == XENOPROF_ESCAPE_CODE);
+}
+
+/* Get the event at the given entry  */
+static uint8_t xenoprof_get_event(xenoprof_buf_t * buf, int tail)
+{
+	return (buf->event_log[tail].event);
+}
+
 static void xenoprof_add_pc(xenoprof_buf_t *buf, int is_passive)
 {
 	int head, tail, size;
+	int tracing = 0;
 
 	head = buf->event_head;
 	tail = buf->event_tail;
 	size = buf->event_size;
 
-	if (tail > head) {
-		while (tail < size) {
-			oprofile_add_pc(buf->event_log[tail].eip,
-					buf->event_log[tail].mode,
-					buf->event_log[tail].event);
+	while (tail != head) {
+		if (xenoprof_is_escape(buf, tail) &&
+		    xenoprof_get_event(buf, tail) == XENOPROF_TRACE_BEGIN) {
+			tracing=1;
+			oprofile_add_pc(ESCAPE_CODE, buf->event_log[tail].mode, 
+					CPU_TRACE_BEGIN); 
 			if (!is_passive)
 				oprofile_samples++;
 			else
 				p_oprofile_samples++;
-			tail++;
+			
+		} else {
+			oprofile_add_pc(buf->event_log[tail].eip,
+					buf->event_log[tail].mode,
+					buf->event_log[tail].event);
+			if (!tracing) {
+				if (!is_passive)
+					oprofile_samples++;
+				else
+					p_oprofile_samples++;
+			}
+       
 		}
-		tail = 0;
-	}
-	while (tail < head) {
-		oprofile_add_pc(buf->event_log[tail].eip,
-				buf->event_log[tail].mode,
-				buf->event_log[tail].event);
-		if (!is_passive)
-			oprofile_samples++;
-		else
-			p_oprofile_samples++;
 		tail++;
+		if(tail==size)
+		    tail=0;
 	}
-
 	buf->event_tail = tail;
 }
 
@@ -162,8 +180,8 @@ static void xenoprof_handle_passive(void)
 			if (buf->event_head == buf->event_tail)
 				continue;
 			if (!flag_domain) {
-				if (!oprofile_add_domain_switch(passive_domains[i].
-								domain_id))
+				if (!oprofile_add_domain_switch(
+					passive_domains[i].domain_id))
 					goto done;
 				flag_domain = 1;
 			}
@@ -284,22 +302,31 @@ static int xenoprof_setup(void)
 		/* Define dom0 as an active domain if not done yet */
 		if (!active_defined) {
 			domid_t domid;
-			ret = HYPERVISOR_xenoprof_op(XENOPROF_reset_active_list, NULL);
+			ret = HYPERVISOR_xenoprof_op(
+				XENOPROF_reset_active_list, NULL);
 			if (ret)
 				goto err;
 			domid = 0;
-			ret = HYPERVISOR_xenoprof_op(XENOPROF_set_active, &domid);
+			ret = HYPERVISOR_xenoprof_op(
+				XENOPROF_set_active, &domid);
 			if (ret)
 				goto err;
 			active_defined = 1;
 		}
 
+		if (backtrace_depth > 0) {
+			ret = HYPERVISOR_xenoprof_op(XENOPROF_set_backtrace, 
+						     &backtrace_depth);
+			if (ret)
+				backtrace_depth = 0;
+		}
+
 		ret = HYPERVISOR_xenoprof_op(XENOPROF_reserve_counters, NULL);
 		if (ret)
 			goto err;
+		
 		xenoprof_arch_counter();
 		ret = HYPERVISOR_xenoprof_op(XENOPROF_setup_events, NULL);
-
 		if (ret)
 			goto err;
 	}
@@ -425,7 +452,8 @@ static int xenoprof_set_passive(int * p_domains,
 			goto out;
 		for (j = 0; j < passive_domains[i].nbuf; j++) {
 			buf = (struct xenoprof_buf *)
-				&p_shared_buffer[i].buffer[j * passive_domains[i].bufsize];
+				&p_shared_buffer[i].buffer[
+				j * passive_domains[i].bufsize];
 			BUG_ON(buf->vcpu_id >= MAX_VIRT_CPUS);
 			p_xenoprof_buf[i][buf->vcpu_id] = buf;
 		}
@@ -438,9 +466,23 @@ out:
 	for (j = 0; j < i; j++)
 		xenoprof_arch_unmap_shared_buffer(&p_shared_buffer[i]);
 
- 	return ret;
+	return ret;
 }
 
+
+/* The dummy backtrace function to keep oprofile happy
+ * The real backtrace is done in xen
+ */
+static void xenoprof_dummy_backtrace(struct pt_regs * const regs, 
+				     unsigned int depth)
+{
+	/* this should never be called */
+	BUG();
+	return;
+}
+
+
+
 struct oprofile_operations xenoprof_ops = {
 #ifdef HAVE_XENOPROF_CREATE_FILES
 	.create_files 	= xenoprof_create_files,
@@ -450,7 +492,8 @@ struct oprofile_operations xenoprof_ops = {
 	.setup 		= xenoprof_setup,
 	.shutdown	= xenoprof_shutdown,
 	.start		= xenoprof_start,
-	.stop		= xenoprof_stop
+	.stop		= xenoprof_stop,
+	.backtrace	= xenoprof_dummy_backtrace
 };
 
 
@@ -481,6 +524,7 @@ int __init xenoprofile_init(struct oprofile_operations * ops)
 
 		active_defined = 0;
 	}
+
 	printk(KERN_INFO "%s: ret %d, events %d, xenoprof_is_primary %d\n",
 	       __func__, ret, init.num_events, xenoprof_is_primary);
 	return ret;