x86, ds: fix buffer alignment in debug store selftest

The debug store selftest code uses a stack-allocated buffer, which is
not necessarily correctly aligned.

For tests using a buffer to hold a single entry, the buffer that is
passed to ds_request must already be suitably aligned.

Pass a suitably aligned portion of the bigger buffer.

[ Impact: fix hw-branch-tracer self-test failure ]

Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Cc: markus.t.metzger@gmail.com
LKML-Reference: <20090424094309.A30145@sedona.ch.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/x86/kernel/ds_selftest.c b/arch/x86/kernel/ds_selftest.c
index 5f104a0ace66..6bc7c199ab99 100644
--- a/arch/x86/kernel/ds_selftest.c
+++ b/arch/x86/kernel/ds_selftest.c
@@ -323,13 +323,15 @@ static int ds_selftest_bts_bad_request_task(void *buffer)
 int ds_selftest_bts(void)
 {
         struct ds_selftest_bts_conf conf;
-        unsigned char buffer[BUFFER_SIZE];
+        unsigned char buffer[BUFFER_SIZE], *small_buffer;
         unsigned long irq;
         int cpu;
 
         printk(KERN_INFO "[ds] bts selftest...");
         conf.error = 0;
 
+        small_buffer = (unsigned char *)ALIGN((unsigned long)buffer, 8) + 8;
+
         get_online_cpus();
         for_each_online_cpu(cpu) {
                 conf.suspend = ds_suspend_bts_wrap;
@@ -381,7 +383,7 @@ int ds_selftest_bts(void)
         conf.suspend = ds_suspend_bts_noirq;
         conf.resume = ds_resume_bts_noirq;
         conf.tracer =
-                ds_request_bts_task(current, buffer, SMALL_BUFFER_SIZE,
+                ds_request_bts_task(current, small_buffer, SMALL_BUFFER_SIZE,
                                    NULL, (size_t)-1, BTS_KERNEL);
         local_irq_save(irq);
         ds_selftest_bts_cpu(&conf);