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Commit 150f5164 authored by Markus Metzger's avatar Markus Metzger Committed by Ingo Molnar
Browse files

x86, ds: allow small debug store buffers 



Check the buffer size more precisely to allow buffers for exactly
one element provided the base address is already properly aligned.

Add a debug store selftest.

Reported-by: default avatarStephane Eranian <eranian@googlemail.com>
Signed-off-by: default avatarMarkus Metzger <markus.t.metzger@intel.com>
Cc: roland@redhat.com
Cc: eranian@googlemail.com
Cc: oleg@redhat.com
Cc: juan.villacis@intel.com
Cc: ak@linux.jf.intel.com
LKML-Reference: <20090403144606.139137000@intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 608780a9

arch/x86/kernel/ds.c

+7 −2
Original line number Diff line number Diff line
@@ -656,6 +656,7 @@ static int ds_request(struct ds_tracer *tracer, struct ds_trace *trace, 
{

	struct ds_context *context;

	int error;

	size_t req_size;



	error = -EOPNOTSUPP;

	if (!ds_cfg.sizeof_rec[qual])
@@ -665,9 +666,13 @@ static int ds_request(struct ds_tracer *tracer, struct ds_trace *trace, 
	if (!base)

		goto out;



	/* We need space for alignment adjustments in ds_init_ds_trace(). */

	req_size = ds_cfg.sizeof_rec[qual];

	/* We might need space for alignment adjustments. */

	if (!IS_ALIGNED((unsigned long)base, DS_ALIGNMENT))

		req_size += DS_ALIGNMENT;



	error = -EINVAL;

	if (size < (DS_ALIGNMENT + ds_cfg.sizeof_rec[qual]))

	if (size < req_size)

		goto out;



	if (th != (size_t)-1) {

arch/x86/kernel/ds_selftest.c

+3 −3
Original line number Diff line number Diff line
@@ -17,7 +17,7 @@ 




#define BUFFER_SIZE		521	/* Intentionally chose an odd size. */



#define SMALL_BUFFER_SIZE	24	/* A single bts entry. */



struct ds_selftest_bts_conf {

	struct bts_tracer *tracer;
@@ -381,7 +381,7 @@ 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, BUFFER_SIZE,

		ds_request_bts_task(current, buffer, SMALL_BUFFER_SIZE,

				   NULL, (size_t)-1, BTS_KERNEL);

	local_irq_save(irq);

	ds_selftest_bts_cpu(&conf);