[PATCH] drm/amd/amdgpu: add tracing of kernel DMA mappings and enable on init (v2)

[Tom St Denis]

This patch adds trace points to the amdgpu bo_kmap/bo/kunmap functions
which capture internal allocations.

(v2): Simply add a sleep to the init.  Users can use this script to
load with map debugging enabled:

   #!/bin/bash
   modprobe amdgpu map_debug=1 &
   sleep 1
   echo 1 > /sys/kernel/debug/tracing/events/amdgpu/amdgpu_ttm_tt_unpopulate/enable
   echo 1 > /sys/kernel/debug/tracing/events/amdgpu/amdgpu_ttm_tt_populate/enable

Signed-off-by: Tom St Denis <tom.stdenis at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu.h        |  1 +
 drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c    | 12 ++++++++++++
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 11 ++++++++++-
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c    |  4 ++--
 4 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index d2aaad77c353..2f5781df88c5 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -121,6 +121,7 @@ extern int amdgpu_cntl_sb_buf_per_se;
 extern int amdgpu_param_buf_per_se;
 extern int amdgpu_job_hang_limit;
 extern int amdgpu_lbpw;
+extern int amdgpu_enable_map_debugging;
 
 #ifdef CONFIG_DRM_AMDGPU_SI
 extern int amdgpu_si_support;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 2cdf8443e7d3..0ed777cc2f63 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -120,6 +120,7 @@ int amdgpu_cntl_sb_buf_per_se = 0;
 int amdgpu_param_buf_per_se = 0;
 int amdgpu_job_hang_limit = 0;
 int amdgpu_lbpw = -1;
+int amdgpu_enable_map_debugging = 0;
 
 MODULE_PARM_DESC(vramlimit, "Restrict VRAM for testing, in megabytes");
 module_param_named(vramlimit, amdgpu_vram_limit, int, 0600);
@@ -263,6 +264,9 @@ module_param_named(job_hang_limit, amdgpu_job_hang_limit, int ,0444);
 MODULE_PARM_DESC(lbpw, "Load Balancing Per Watt (LBPW) support (1 = enable, 0 = disable, -1 = auto)");
 module_param_named(lbpw, amdgpu_lbpw, int, 0444);
 
+MODULE_PARM_DESC(map_debug, "Enable map debugging in kernel (1 = on, 0 = off)");
+module_param_named(map_debug, amdgpu_enable_map_debugging, int, 0444);
+
 #ifdef CONFIG_DRM_AMDGPU_SI
 
 #if defined(CONFIG_DRM_RADEON) || defined(CONFIG_DRM_RADEON_MODULE)
@@ -865,11 +869,19 @@ static struct pci_driver amdgpu_kms_pci_driver = {
 };
 
 
+// enable trace events during init
+static void amdgpu_enable_dma_tracers(void)
+{
+	msleep(3000);
+}
 
 static int __init amdgpu_init(void)
 {
 	int r;
 
+	if (amdgpu_enable_map_debugging)
+		amdgpu_enable_dma_tracers();
+
 	r = amdgpu_sync_init();
 	if (r)
 		goto error_sync;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index e7e899190bef..a292e86fbaa7 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -37,6 +37,9 @@
 #include "amdgpu.h"
 #include "amdgpu_trace.h"
 
+void amdgpu_trace_dma_map(struct ttm_tt *ttm);
+void amdgpu_trace_dma_unmap(struct ttm_tt *ttm);
+
 static void amdgpu_ttm_bo_destroy(struct ttm_buffer_object *tbo)
 {
 	struct amdgpu_device *adev = amdgpu_ttm_adev(tbo->bdev);
@@ -625,6 +628,9 @@ int amdgpu_bo_kmap(struct amdgpu_bo *bo, void **ptr)
 	if (r)
 		return r;
 
+	if (unlikely(trace_amdgpu_ttm_tt_populate_enabled()) && bo->tbo.mem.mem_type != TTM_PL_VRAM)
+		amdgpu_trace_dma_map(bo->tbo.ttm);
+
 	if (ptr)
 		*ptr = amdgpu_bo_kptr(bo);
 
@@ -640,8 +646,11 @@ void *amdgpu_bo_kptr(struct amdgpu_bo *bo)
 
 void amdgpu_bo_kunmap(struct amdgpu_bo *bo)
 {
-	if (bo->kmap.bo)
+	if (bo->kmap.bo) {
+		if (unlikely(trace_amdgpu_ttm_tt_unpopulate_enabled()) && bo->tbo.mem.mem_type != TTM_PL_VRAM)
+			amdgpu_trace_dma_unmap(bo->tbo.ttm);
 		ttm_bo_kunmap(&bo->kmap);
+	}
 }
 
 struct amdgpu_bo *amdgpu_bo_ref(struct amdgpu_bo *bo)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 26665b4baf36..85727be3fbb7 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -663,7 +663,7 @@ int amdgpu_ttm_tt_get_user_pages(struct ttm_tt *ttm, struct page **pages)
 	return r;
 }
 
-static void amdgpu_trace_dma_map(struct ttm_tt *ttm)
+void amdgpu_trace_dma_map(struct ttm_tt *ttm)
 {
 	struct amdgpu_device *adev = amdgpu_ttm_adev(ttm->bdev);
 	struct amdgpu_ttm_tt *gtt = (void *)ttm;
@@ -679,7 +679,7 @@ static void amdgpu_trace_dma_map(struct ttm_tt *ttm)
 	}
 }
 
-static void amdgpu_trace_dma_unmap(struct ttm_tt *ttm)
+void amdgpu_trace_dma_unmap(struct ttm_tt *ttm)
 {
 	struct amdgpu_device *adev = amdgpu_ttm_adev(ttm->bdev);
 	struct amdgpu_ttm_tt *gtt = (void *)ttm;
-- 
2.12.0