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>

diff --git a/arch/x86/kernel/ds_selftest.c b/arch/x86/kernel/ds_selftest.c
index 5f104a0..6bc7c19 100644 (file)
--- 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);