From be5bfc030892300b830d9ec66dedf914f18f7c56 Mon Sep 17 00:00:00 2001
From: fabient <fabient@FreeBSD.org>
Date: Wed, 23 May 2012 13:23:40 +0000
Subject: [PATCH] Soft PMC support for ARM. Callgraph is not captured, only
 current location.

Sample system wide profiling: "pmcstat -Sclock.hard -T"
---
 sys/arm/arm/machdep.c      |  6 +++---
 sys/arm/include/pmc_mdep.h |  6 ++++++
 sys/dev/hwpmc/hwpmc_arm.c  | 25 +++++++++++++++++--------
 3 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/sys/arm/arm/machdep.c b/sys/arm/arm/machdep.c
index abd04a7f6574..1ec4bc41bedf 100644
--- a/sys/arm/arm/machdep.c
+++ b/sys/arm/arm/machdep.c
@@ -674,9 +674,9 @@ fake_preload_metadata(void)
 	static uint32_t fake_preload[35];
 
 	fake_preload[i++] = MODINFO_NAME;
-	fake_preload[i++] = strlen("elf kernel") + 1;
-	strcpy((char*)&fake_preload[i++], "elf kernel");
-	i += 2;
+	fake_preload[i++] = strlen("kernel") + 1;
+	strcpy((char*)&fake_preload[i++], "kernel");
+	i += 1;
 	fake_preload[i++] = MODINFO_TYPE;
 	fake_preload[i++] = strlen("elf kernel") + 1;
 	strcpy((char*)&fake_preload[i++], "elf kernel");
diff --git a/sys/arm/include/pmc_mdep.h b/sys/arm/include/pmc_mdep.h
index 185fbd1744c0..ab08d3664486 100644
--- a/sys/arm/include/pmc_mdep.h
+++ b/sys/arm/include/pmc_mdep.h
@@ -54,6 +54,12 @@ union pmc_md_pmc {
 #define	PMC_TRAPFRAME_TO_FP(TF)	((TF)->tf_usr_lr)
 #define	PMC_TRAPFRAME_TO_SP(TF)	((TF)->tf_usr_sp)
 
+/* Build a fake kernel trapframe from current instruction pointer. */
+#define PMC_FAKE_TRAPFRAME(TF)						\
+	do {								\
+	__asm __volatile("mov %0, pc" : "=r" ((TF)->tf_pc));		\
+	} while (0)
+
 /*
  * Prototypes
  */
diff --git a/sys/dev/hwpmc/hwpmc_arm.c b/sys/dev/hwpmc/hwpmc_arm.c
index 86cfaf3cd93a..fc7616542185 100644
--- a/sys/dev/hwpmc/hwpmc_arm.c
+++ b/sys/dev/hwpmc/hwpmc_arm.c
@@ -38,38 +38,47 @@ __FBSDID("$FreeBSD$");
 struct pmc_mdep *
 pmc_md_initialize()
 {
+#ifdef CPU_XSCALE_IXP425
 	if (cpu_class == CPU_CLASS_XSCALE)
 		return pmc_xscale_initialize();
 	else
+#endif
 		return NULL;
 }
 
 void
 pmc_md_finalize(struct pmc_mdep *md)
 {
+#ifdef CPU_XSCALE_IXP425
 	if (cpu_class == CPU_CLASS_XSCALE)
 		pmc_xscale_finalize(md);
 	else
 		KASSERT(0, ("[arm,%d] Unknown CPU Class 0x%x", __LINE__,
 		    cpu_class));
+#endif
+}
+
+static int
+pmc_save_callchain(uintptr_t *cc, int maxsamples,
+    struct trapframe *tf)
+{
+
+	*cc = PMC_TRAPFRAME_TO_PC(tf);
+	return (1);
 }
 
 int
 pmc_save_kernel_callchain(uintptr_t *cc, int maxsamples,
     struct trapframe *tf)
 {
-	(void) cc;
-	(void) maxsamples;
-	(void) tf;
-	return (0);
+
+	return pmc_save_callchain(cc, maxsamples, tf);
 }
 
 int
 pmc_save_user_callchain(uintptr_t *cc, int maxsamples,
     struct trapframe *tf)
 {
-	(void) cc;
-	(void) maxsamples;
-	(void) tf;
-	return (0);
+
+	return pmc_save_callchain(cc, maxsamples, tf);
 }