[PATCH v3 23/24] drm/amdkfd: set debug trap bit when enabling PC Sampling

James Zhu James.Zhu at amd.com
Fri Dec 15 15:59:50 UTC 2023


From: David Yat Sin <David.YatSin at amd.com>

We need the SPI_GDBG_PER_VMID_CNTL.TRAP_EN bit to be set during PC
Sampling so that the TTMP registers are valid inside the sampling data.
runtime_info.ttmp_setup will be cleared when the user application
does the AMDKFD_IOC_RUNTIME_ENABLE ioctl without
KFD_RUNTIME_ENABLE_MODE_ENABLE_MASK flag on exit.

It is also not valid to have the debugger attached to a process while PC
sampling is enabled so adding some checks to prevent this.

Signed-off-by: David Yat Sin <David.YatSin at amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_chardev.c     | 31 ++++----------
 drivers/gpu/drm/amd/amdkfd/kfd_debug.c       | 22 ++++++++++
 drivers/gpu/drm/amd/amdkfd/kfd_debug.h       |  3 ++
 drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c | 43 +++++++++++++++++---
 drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.h |  4 +-
 5 files changed, 75 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index 1a3a8ded9c93..f7a8794c2bde 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -1775,7 +1775,7 @@ static int kfd_ioctl_pc_sample(struct file *filep,
 			pr_debug("failed to bind process %p with gpu id 0x%x", p, args->gpu_id);
 			ret = -ESRCH;
 		} else {
-			ret = kfd_pc_sample(pdd, args);
+			ret = kfd_pc_sample(p, pdd, args);
 		}
 	}
 	mutex_unlock(&p->mutex);
@@ -2808,26 +2808,9 @@ static int runtime_enable(struct kfd_process *p, uint64_t r_debug,
 
 	p->runtime_info.runtime_state = DEBUG_RUNTIME_STATE_ENABLED;
 	p->runtime_info.r_debug = r_debug;
-	p->runtime_info.ttmp_setup = enable_ttmp_setup;
 
-	if (p->runtime_info.ttmp_setup) {
-		for (i = 0; i < p->n_pdds; i++) {
-			struct kfd_process_device *pdd = p->pdds[i];
-
-			if (!kfd_dbg_is_rlc_restore_supported(pdd->dev)) {
-				amdgpu_gfx_off_ctrl(pdd->dev->adev, false);
-				pdd->dev->kfd2kgd->enable_debug_trap(
-						pdd->dev->adev,
-						true,
-						pdd->dev->vm_info.last_vmid_kfd);
-			} else if (kfd_dbg_is_per_vmid_supported(pdd->dev)) {
-				pdd->spi_dbg_override = pdd->dev->kfd2kgd->enable_debug_trap(
-						pdd->dev->adev,
-						false,
-						0);
-			}
-		}
-	}
+	if (enable_ttmp_setup)
+		kfd_dbg_enable_ttmp_setup(p);
 
 retry:
 	if (p->debug_trap_enabled) {
@@ -2976,9 +2959,13 @@ static int kfd_ioctl_set_debug_trap(struct file *filep, struct kfd_process *p, v
 		goto out;
 	}
 
-	/* Check if target is still PTRACED. */
 	rcu_read_lock();
-	if (target != p && args->op != KFD_IOC_DBG_TRAP_DISABLE
+
+	if (kfd_pc_sampling_enabled(target)) {
+		pr_debug("Cannot enable debug trap on PID:%d because PC Sampling active\n", args->pid);
+		r = -EBUSY;
+	/* Check if target is still PTRACED. */
+	} else if (target != p && args->op != KFD_IOC_DBG_TRAP_DISABLE
 				&& ptrace_parent(target->lead_thread) != current) {
 		pr_err("PID %i is not PTRACED and cannot be debugged\n", args->pid);
 		r = -EPERM;
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_debug.c b/drivers/gpu/drm/amd/amdkfd/kfd_debug.c
index 9ec750666382..092c2dc84d24 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_debug.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_debug.c
@@ -1118,3 +1118,25 @@ void kfd_dbg_set_enabled_debug_exception_mask(struct kfd_process *target,
 
 	mutex_unlock(&target->event_mutex);
 }
+
+void kfd_dbg_enable_ttmp_setup(struct kfd_process *p)
+{
+	int i;
+	p->runtime_info.ttmp_setup = true;
+	for (i = 0; i < p->n_pdds; i++) {
+		struct kfd_process_device *pdd = p->pdds[i];
+
+		if (!kfd_dbg_is_rlc_restore_supported(pdd->dev)) {
+			amdgpu_gfx_off_ctrl(pdd->dev->adev, false);
+			pdd->dev->kfd2kgd->enable_debug_trap(
+					pdd->dev->adev,
+					true,
+					pdd->dev->vm_info.last_vmid_kfd);
+		} else if (kfd_dbg_is_per_vmid_supported(pdd->dev)) {
+			pdd->spi_dbg_override = pdd->dev->kfd2kgd->enable_debug_trap(
+					pdd->dev->adev,
+					false,
+					0);
+		}
+	}
+}
\ No newline at end of file
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_debug.h b/drivers/gpu/drm/amd/amdkfd/kfd_debug.h
index fd0ff64d4184..d7ce0b119dd0 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_debug.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_debug.h
@@ -90,6 +90,9 @@ int kfd_dbg_trap_device_snapshot(struct kfd_process *target,
 
 void kfd_dbg_set_enabled_debug_exception_mask(struct kfd_process *target,
 					uint64_t exception_set_mask);
+
+void kfd_dbg_enable_ttmp_setup(struct kfd_process *p);
+
 /*
  * If GFX off is enabled, chips that do not support RLC restore for the debug
  * registers will disable GFX off temporarily for the entire debug session.
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c b/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c
index d8286aabd5a7..6870548fc42c 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.c
@@ -24,6 +24,7 @@
 #include "kfd_priv.h"
 #include "amdgpu_amdkfd.h"
 #include "kfd_pc_sampling.h"
+#include "kfd_debug.h"
 #include "kfd_device_queue_manager.h"
 
 struct supported_pc_sample_info {
@@ -39,6 +40,19 @@ struct supported_pc_sample_info supported_formats[] = {
 	{ IP_VERSION(9, 4, 2), &sample_info_hosttrap_9_0_0 },
 };
 
+/* Checks whether PC Sampling is enabled on any devices in use by this process */
+bool kfd_pc_sampling_enabled(struct kfd_process *p) {
+	int i;
+
+	for (i = 0; i < p->n_pdds; i++) {
+		struct kfd_process_device *pdd = p->pdds[i];
+
+		if (pdd->dev->pcs_data.hosttrap_entry.base.pc_sample_info.method)
+			return true;
+	}
+	return false;
+}
+
 static int kfd_pc_sample_thread(void *param)
 {
 	struct amdgpu_device *adev;
@@ -99,13 +113,19 @@ static int kfd_pc_sample_thread_start(struct kfd_node *node)
 	return ret;
 }
 
-static int kfd_pc_sample_query_cap(struct kfd_process_device *pdd,
+static int kfd_pc_sample_query_cap(struct kfd_process *p, struct kfd_process_device *pdd,
 					struct kfd_ioctl_pc_sample_args __user *user_args)
 {
 	uint64_t sample_offset;
 	int num_method = 0;
 	int i;
 
+	if (p->debug_trap_enabled) {
+		pr_debug("Cannot have PC Sampling and debug trap simultaneously");
+		user_args->num_sample_info = 0;
+		return 0;
+	}
+
 	for (i = 0; i < ARRAY_SIZE(supported_formats); i++)
 		if (KFD_GC_VERSION(pdd->dev) == supported_formats[i].ip_version)
 			num_method++;
@@ -205,7 +225,7 @@ static int kfd_pc_sample_stop(struct kfd_process_device *pdd,
 	return 0;
 }
 
-static int kfd_pc_sample_create(struct kfd_process_device *pdd,
+static int kfd_pc_sample_create(struct kfd_process *p, struct kfd_process_device *pdd,
 					struct kfd_ioctl_pc_sample_args __user *user_args)
 {
 	struct kfd_pc_sample_info *supported_format = NULL;
@@ -217,6 +237,11 @@ static int kfd_pc_sample_create(struct kfd_process_device *pdd,
 	if (user_args->num_sample_info != 1)
 		return -EINVAL;
 
+	if (p->debug_trap_enabled) {
+		pr_debug("Cannot have PC Sampling and debug trap simultaneously");
+		return -EBUSY;
+	}
+
 	ret = copy_from_user(&user_info, (void __user *) user_args->sample_info_ptr,
 				sizeof(struct kfd_pc_sample_info));
 	if (ret) {
@@ -275,6 +300,14 @@ static int kfd_pc_sample_create(struct kfd_process_device *pdd,
 	pcs_entry->pdd = pdd;
 	user_args->trace_id = (uint32_t)i;
 
+	/*
+	 * Set SPI_GDBG_PER_VMID_CNTL.TRAP_EN so that TTMP registers are valid in the sampling data
+	 * p->runtime_info.ttmp_setup will be cleared when user application calls runtime_disable
+	 * on exit.
+	 */
+	if (!p->runtime_info.ttmp_setup)
+		kfd_dbg_enable_ttmp_setup(p);
+
 	pr_debug("alloc pcs_entry = %p, trace_id = 0x%x on gpu 0x%x", pcs_entry, i, pdd->dev->id);
 
 	return 0;
@@ -321,7 +354,7 @@ void kfd_pc_sample_release(struct kfd_process_device *pdd)
 	mutex_unlock(&pdd->dev->pcs_data.mutex);
 }
 
-int kfd_pc_sample(struct kfd_process_device *pdd,
+int kfd_pc_sample(struct kfd_process *p, struct kfd_process_device *pdd,
 					struct kfd_ioctl_pc_sample_args __user *args)
 {
 	struct pc_sampling_entry *pcs_entry;
@@ -344,10 +377,10 @@ int kfd_pc_sample(struct kfd_process_device *pdd,
 
 	switch (args->op) {
 	case KFD_IOCTL_PCS_OP_QUERY_CAPABILITIES:
-		return kfd_pc_sample_query_cap(pdd, args);
+		return kfd_pc_sample_query_cap(p, pdd, args);
 
 	case KFD_IOCTL_PCS_OP_CREATE:
-		return kfd_pc_sample_create(pdd, args);
+		return kfd_pc_sample_create(p, pdd, args);
 
 	case KFD_IOCTL_PCS_OP_DESTROY:
 		if (pcs_entry->enabled)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.h b/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.h
index 6175563ca9be..42525feefb85 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_pc_sampling.h
@@ -28,8 +28,10 @@
 #include "amdgpu.h"
 #include "kfd_priv.h"
 
-int kfd_pc_sample(struct kfd_process_device *pdd,
+int kfd_pc_sample(struct kfd_process *p, struct kfd_process_device *pdd,
 					struct kfd_ioctl_pc_sample_args __user *args);
 void kfd_pc_sample_release(struct kfd_process_device *pdd);
 
+bool kfd_pc_sampling_enabled(struct kfd_process *p);
+
 #endif /* KFD_PC_SAMPLING_H_ */
-- 
2.25.1



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