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Date: Fri, 13 Mar 2009 11:00:39 GMT
From: Markus Metzger <markus.t.metzger@...el.com>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
markus.t.metzger@...el.com, tglx@...utronix.de, mingo@...e.hu
Subject: [tip:tracing/hw-branch-tracing] x86, bts: add selftest for BTS
Commit-ID: 8a327f6d1b05f5ce16572b4413a5df1d0e872283
Gitweb: http://git.kernel.org/tip/8a327f6d1b05f5ce16572b4413a5df1d0e872283
Author: Markus Metzger <markus.t.metzger@...el.com>
AuthorDate: Fri, 13 Mar 2009 10:45:07 +0100
Commit: Ingo Molnar <mingo@...e.hu>
CommitDate: Fri, 13 Mar 2009 11:57:20 +0100
x86, bts: add selftest for BTS
Perform a selftest of branch trace store when a cpu is initialized.
WARN and disable branch trace store support if the selftest fails.
Signed-off-by: Markus Metzger <markus.t.metzger@...el.com>
LKML-Reference: <20090313104507.A30125@...ona.ch.intel.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
arch/x86/Kconfig.debug | 9 ++
arch/x86/kernel/Makefile | 1 +
arch/x86/kernel/ds.c | 21 ++++
arch/x86/kernel/ds_selftest.c | 241 +++++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/ds_selftest.h | 15 +++
5 files changed, 287 insertions(+), 0 deletions(-)
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index fdb45df..dfd74ab 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -175,6 +175,15 @@ config IOMMU_LEAK
Add a simple leak tracer to the IOMMU code. This is useful when you
are debugging a buggy device driver that leaks IOMMU mappings.
+config X86_DS_SELFTEST
+ bool "DS selftest"
+ default y
+ depends on DEBUG_KERNEL
+ depends on X86_DS
+ ---help---
+ Perform Debug Store selftests at boot time.
+ If in doubt, say "N".
+
config HAVE_MMIOTRACE_SUPPORT
def_bool y
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 339ce35..a0c9e13 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -44,6 +44,7 @@ obj-y += process.o
obj-y += i387.o xsave.o
obj-y += ptrace.o
obj-$(CONFIG_X86_DS) += ds.o
+obj-$(CONFIG_X86_DS_SELFTEST) += ds_selftest.o
obj-$(CONFIG_X86_32) += tls.o
obj-$(CONFIG_IA32_EMULATION) += tls.o
obj-y += step.o
diff --git a/arch/x86/kernel/ds.c b/arch/x86/kernel/ds.c
index 6e5ec67..51c936c 100644
--- a/arch/x86/kernel/ds.c
+++ b/arch/x86/kernel/ds.c
@@ -29,6 +29,7 @@
#include <linux/mm.h>
#include <linux/kernel.h>
+#include "ds_selftest.h"
/*
* The configuration for a particular DS hardware implementation.
@@ -940,6 +941,26 @@ ds_configure(const struct ds_configuration *cfg,
printk(KERN_INFO "[ds] pebs not available\n");
}
+ if (ds_cfg.sizeof_rec[ds_bts]) {
+ int error;
+
+ error = ds_selftest_bts();
+ if (error) {
+ WARN(1, "[ds] selftest failed. disabling bts.\n");
+ ds_cfg.sizeof_rec[ds_bts] = 0;
+ }
+ }
+
+ if (ds_cfg.sizeof_rec[ds_pebs]) {
+ int error;
+
+ error = ds_selftest_pebs();
+ if (error) {
+ WARN(1, "[ds] selftest failed. disabling pebs.\n");
+ ds_cfg.sizeof_rec[ds_pebs] = 0;
+ }
+ }
+
printk(KERN_INFO "[ds] sizes: address: %u bit, ",
8 * ds_cfg.sizeof_ptr_field);
printk("bts/pebs record: %u/%u bytes\n",
diff --git a/arch/x86/kernel/ds_selftest.c b/arch/x86/kernel/ds_selftest.c
new file mode 100644
index 0000000..8c46fbf
--- /dev/null
+++ b/arch/x86/kernel/ds_selftest.c
@@ -0,0 +1,241 @@
+/*
+ * Debug Store support - selftest
+ *
+ *
+ * Copyright (C) 2009 Intel Corporation.
+ * Markus Metzger <markus.t.metzger@...el.com>, 2009
+ */
+
+#include "ds_selftest.h"
+
+#include <linux/kernel.h>
+#include <linux/string.h>
+
+#include <asm/ds.h>
+
+
+#define DS_SELFTEST_BUFFER_SIZE 1021 /* Intentionally chose an odd size. */
+
+
+static int ds_selftest_bts_consistency(const struct bts_trace *trace)
+{
+ int error = 0;
+
+ if (!trace) {
+ printk(KERN_CONT "failed to access trace...");
+ /* Bail out. Other tests are pointless. */
+ return -1;
+ }
+
+ if (!trace->read) {
+ printk(KERN_CONT "bts read not available...");
+ error = -1;
+ }
+
+ /* Do some sanity checks on the trace configuration. */
+ if (!trace->ds.n) {
+ printk(KERN_CONT "empty bts buffer...");
+ error = -1;
+ }
+ if (!trace->ds.size) {
+ printk(KERN_CONT "bad bts trace setup...");
+ error = -1;
+ }
+ if (trace->ds.end !=
+ (char *)trace->ds.begin + (trace->ds.n * trace->ds.size)) {
+ printk(KERN_CONT "bad bts buffer setup...");
+ error = -1;
+ }
+ if ((trace->ds.top < trace->ds.begin) ||
+ (trace->ds.end <= trace->ds.top)) {
+ printk(KERN_CONT "bts top out of bounds...");
+ error = -1;
+ }
+
+ return error;
+}
+
+static int ds_selftest_bts_read(struct bts_tracer *tracer,
+ const struct bts_trace *trace,
+ const void *from, const void *to)
+{
+ const unsigned char *at;
+
+ /*
+ * Check a few things which do not belong to this test.
+ * They should be covered by other tests.
+ */
+ if (!trace)
+ return -1;
+
+ if (!trace->read)
+ return -1;
+
+ if (to < from)
+ return -1;
+
+ if (from < trace->ds.begin)
+ return -1;
+
+ if (trace->ds.end < to)
+ return -1;
+
+ if (!trace->ds.size)
+ return -1;
+
+ /* Now to the test itself. */
+ for (at = from; (void *)at < to; at += trace->ds.size) {
+ struct bts_struct bts;
+ size_t index;
+ int error;
+
+ if (((void *)at - trace->ds.begin) % trace->ds.size) {
+ printk(KERN_CONT
+ "read from non-integer index...");
+ return -1;
+ }
+ index = ((void *)at - trace->ds.begin) / trace->ds.size;
+
+ memset(&bts, 0, sizeof(bts));
+ error = trace->read(tracer, at, &bts);
+ if (error < 0) {
+ printk(KERN_CONT
+ "error reading bts trace at [%lu] (0x%p)...",
+ index, at);
+ return error;
+ }
+
+ switch (bts.qualifier) {
+ case BTS_BRANCH:
+ break;
+ default:
+ printk(KERN_CONT
+ "unexpected bts entry %llu at [%lu] (0x%p)...",
+ bts.qualifier, index, at);
+ return -1;
+ }
+ }
+
+ return 0;
+}
+
+int ds_selftest_bts(void)
+{
+ const struct bts_trace *trace;
+ struct bts_tracer *tracer;
+ int error = 0;
+ void *top;
+ unsigned char buffer[DS_SELFTEST_BUFFER_SIZE];
+
+ printk(KERN_INFO "[ds] bts selftest...");
+
+ tracer = ds_request_bts(NULL, buffer, DS_SELFTEST_BUFFER_SIZE,
+ NULL, (size_t)-1, BTS_KERNEL);
+ if (IS_ERR(tracer)) {
+ error = PTR_ERR(tracer);
+ tracer = NULL;
+
+ printk(KERN_CONT
+ "initialization failed (err: %d)...", error);
+ goto out;
+ }
+
+ /* The return should already give us enough trace. */
+ ds_suspend_bts(tracer);
+
+ /* Let's see if we can access the trace. */
+ trace = ds_read_bts(tracer);
+
+ error = ds_selftest_bts_consistency(trace);
+ if (error < 0)
+ goto out;
+
+ /* If everything went well, we should have a few trace entries. */
+ if (trace->ds.top == trace->ds.begin) {
+ /*
+ * It is possible but highly unlikely that we got a
+ * buffer overflow and end up at exactly the same
+ * position we started from.
+ * Let's issue a warning, but continue.
+ */
+ printk(KERN_CONT "no trace/overflow...");
+ }
+
+ /* Let's try to read the trace we collected. */
+ error = ds_selftest_bts_read(tracer, trace,
+ trace->ds.begin, trace->ds.top);
+ if (error < 0)
+ goto out;
+
+ /*
+ * Let's read the trace again.
+ * Since we suspended tracing, we should get the same result.
+ */
+ top = trace->ds.top;
+
+ trace = ds_read_bts(tracer);
+ error = ds_selftest_bts_consistency(trace);
+ if (error < 0)
+ goto out;
+
+ if (top != trace->ds.top) {
+ printk(KERN_CONT "suspend not working...");
+ error = -1;
+ goto out;
+ }
+
+ /* Let's collect some more trace - see if resume is working. */
+ ds_resume_bts(tracer);
+ ds_suspend_bts(tracer);
+
+ trace = ds_read_bts(tracer);
+
+ error = ds_selftest_bts_consistency(trace);
+ if (error < 0)
+ goto out;
+
+ if (trace->ds.top == top) {
+ /*
+ * It is possible but highly unlikely that we got a
+ * buffer overflow and end up at exactly the same
+ * position we started from.
+ * Let's issue a warning and check the full trace.
+ */
+ printk(KERN_CONT
+ "no resume progress/overflow...");
+
+ error = ds_selftest_bts_read(tracer, trace,
+ trace->ds.begin, trace->ds.end);
+ } else if (trace->ds.top < top) {
+ /*
+ * We had a buffer overflow - the entire buffer should
+ * contain trace records.
+ */
+ error = ds_selftest_bts_read(tracer, trace,
+ trace->ds.begin, trace->ds.end);
+ } else {
+ /*
+ * It is quite likely that the buffer did not overflow.
+ * Let's just check the delta trace.
+ */
+ error = ds_selftest_bts_read(tracer, trace,
+ top, trace->ds.top);
+ }
+ if (error < 0)
+ goto out;
+
+ error = 0;
+
+ /* The final test: release the tracer while tracing is suspended. */
+ out:
+ ds_release_bts(tracer);
+
+ printk(KERN_CONT "%s.\n", (error ? "failed" : "passed"));
+
+ return error;
+}
+
+int ds_selftest_pebs(void)
+{
+ return 0;
+}
diff --git a/arch/x86/kernel/ds_selftest.h b/arch/x86/kernel/ds_selftest.h
new file mode 100644
index 0000000..0e6e19d
--- /dev/null
+++ b/arch/x86/kernel/ds_selftest.h
@@ -0,0 +1,15 @@
+/*
+ * Debug Store support - selftest
+ *
+ *
+ * Copyright (C) 2009 Intel Corporation.
+ * Markus Metzger <markus.t.metzger@...el.com>, 2009
+ */
+
+#ifdef CONFIG_X86_DS_SELFTEST
+extern int ds_selftest_bts(void);
+extern int ds_selftest_pebs(void);
+#else
+static inline int ds_selftest_bts(void) { return 0; }
+static inline int ds_selftest_pebs(void) { return 0; }
+#endif /* CONFIG_X86_DS_SELFTEST */
--
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