gpu: host1x: trace: fix string fields in host1x traces

[PATCH] gpu: host1x: trace: fix string fields in host1x traces

Posted by Artur Kowalski 3 weeks, 1 day ago

Use __assign_str and __get_str as required by tracing subsystem. Fixes
string fields being rejected by the verifier and unreadable from
userspace.

Tested on v6.18.21.

Signed-off-by: Artur Kowalski <arturkow2000@gmail.com>
---
 include/trace/events/host1x.h | 50 ++++++++++++++++++++++---------------------
 1 file changed, 26 insertions(+), 24 deletions(-)

diff --git a/include/trace/events/host1x.h b/include/trace/events/host1x.h
index 1ba84b738e46..1b6aeb7b177b 100644
--- a/include/trace/events/host1x.h
+++ b/include/trace/events/host1x.h
@@ -21,9 +21,11 @@ struct host1x_bo;
 DECLARE_EVENT_CLASS(host1x,
 	TP_PROTO(const char *name),
 	TP_ARGS(name),
-	TP_STRUCT__entry(__field(const char *, name)),
-	TP_fast_assign(__entry->name = name;),
-	TP_printk("name=%s", __entry->name)
+	TP_STRUCT__entry(__string(name, name)),
+	TP_fast_assign(
+		__assign_str(name);
+	),
+	TP_printk("name=%s", __get_str(name))
 );
 
 DEFINE_EVENT(host1x, host1x_channel_open,
@@ -52,19 +54,19 @@ TRACE_EVENT(host1x_cdma_push,
 	TP_ARGS(name, op1, op2),
 
 	TP_STRUCT__entry(
-		__field(const char *, name)
+		__string(name, name)
 		__field(u32, op1)
 		__field(u32, op2)
 	),
 
 	TP_fast_assign(
-		__entry->name = name;
+		__assign_str(name);
 		__entry->op1 = op1;
 		__entry->op2 = op2;
 	),
 
 	TP_printk("name=%s, op1=%08x, op2=%08x",
-		__entry->name, __entry->op1, __entry->op2)
+		__get_str(name), __entry->op1, __entry->op2)
 );
 
 TRACE_EVENT(host1x_cdma_push_wide,
@@ -73,7 +75,7 @@ TRACE_EVENT(host1x_cdma_push_wide,
 	TP_ARGS(name, op1, op2, op3, op4),
 
 	TP_STRUCT__entry(
-		__field(const char *, name)
+		__string(name, name)
 		__field(u32, op1)
 		__field(u32, op2)
 		__field(u32, op3)
@@ -81,7 +83,7 @@ TRACE_EVENT(host1x_cdma_push_wide,
 	),
 
 	TP_fast_assign(
-		__entry->name = name;
+		__assign_str(name);
 		__entry->op1 = op1;
 		__entry->op2 = op2;
 		__entry->op3 = op3;
@@ -89,7 +91,7 @@ TRACE_EVENT(host1x_cdma_push_wide,
 	),
 
 	TP_printk("name=%s, op1=%08x, op2=%08x, op3=%08x op4=%08x",
-		__entry->name, __entry->op1, __entry->op2, __entry->op3,
+		__get_str(name), __entry->op1, __entry->op2, __entry->op3,
 		__entry->op4)
 );
 
@@ -100,7 +102,7 @@ TRACE_EVENT(host1x_cdma_push_gather,
 	TP_ARGS(name, bo, words, offset, cmdbuf),
 
 	TP_STRUCT__entry(
-		__field(const char *, name)
+		__string(name, name)
 		__field(struct host1x_bo *, bo)
 		__field(u32, words)
 		__field(u32, offset)
@@ -114,14 +116,14 @@ TRACE_EVENT(host1x_cdma_push_gather,
 					words * sizeof(u32));
 		}
 		__entry->cmdbuf = cmdbuf;
-		__entry->name = name;
+		__assign_str(name);
 		__entry->bo = bo;
 		__entry->words = words;
 		__entry->offset = offset;
 	),
 
 	TP_printk("name=%s, bo=%p, words=%u, offset=%d, contents=[%s]",
-	  __entry->name, __entry->bo,
+	  __get_str(name), __entry->bo,
 	  __entry->words, __entry->offset,
 	  __print_hex(__get_dynamic_array(cmdbuf),
 		  __entry->cmdbuf ? __entry->words * 4 : 0))
@@ -134,7 +136,7 @@ TRACE_EVENT(host1x_channel_submit,
 	TP_ARGS(name, cmdbufs, relocs, syncpt_id, syncpt_incrs),
 
 	TP_STRUCT__entry(
-		__field(const char *, name)
+		__string(name, name)
 		__field(u32, cmdbufs)
 		__field(u32, relocs)
 		__field(u32, syncpt_id)
@@ -142,7 +144,7 @@ TRACE_EVENT(host1x_channel_submit,
 	),
 
 	TP_fast_assign(
-		__entry->name = name;
+		__assign_str(name);
 		__entry->cmdbufs = cmdbufs;
 		__entry->relocs = relocs;
 		__entry->syncpt_id = syncpt_id;
@@ -151,7 +153,7 @@ TRACE_EVENT(host1x_channel_submit,
 
 	TP_printk("name=%s, cmdbufs=%u, relocs=%u, syncpt_id=%u, "
 		  "syncpt_incrs=%u",
-		  __entry->name, __entry->cmdbufs, __entry->relocs,
+		  __get_str(name), __entry->cmdbufs, __entry->relocs,
 		  __entry->syncpt_id, __entry->syncpt_incrs)
 );
 
@@ -161,19 +163,19 @@ TRACE_EVENT(host1x_channel_submitted,
 	TP_ARGS(name, syncpt_base, syncpt_max),
 
 	TP_STRUCT__entry(
-		__field(const char *, name)
+		__string(name, name)
 		__field(u32, syncpt_base)
 		__field(u32, syncpt_max)
 	),
 
 	TP_fast_assign(
-		__entry->name = name;
+		__assign_str(name);
 		__entry->syncpt_base = syncpt_base;
 		__entry->syncpt_max = syncpt_max;
 	),
 
 	TP_printk("name=%s, syncpt_base=%d, syncpt_max=%d",
-		__entry->name, __entry->syncpt_base, __entry->syncpt_max)
+		__get_str(name), __entry->syncpt_base, __entry->syncpt_max)
 );
 
 TRACE_EVENT(host1x_channel_submit_complete,
@@ -182,19 +184,19 @@ TRACE_EVENT(host1x_channel_submit_complete,
 	TP_ARGS(name, count, thresh),
 
 	TP_STRUCT__entry(
-		__field(const char *, name)
+		__string(name, name)
 		__field(int, count)
 		__field(u32, thresh)
 	),
 
 	TP_fast_assign(
-		__entry->name = name;
+		__assign_str(name);
 		__entry->count = count;
 		__entry->thresh = thresh;
 	),
 
 	TP_printk("name=%s, count=%d, thresh=%d",
-		__entry->name, __entry->count, __entry->thresh)
+		__get_str(name), __entry->count, __entry->thresh)
 );
 
 TRACE_EVENT(host1x_wait_cdma,
@@ -203,16 +205,16 @@ TRACE_EVENT(host1x_wait_cdma,
 	TP_ARGS(name, eventid),
 
 	TP_STRUCT__entry(
-		__field(const char *, name)
+		__string(name, name)
 		__field(u32, eventid)
 	),
 
 	TP_fast_assign(
-		__entry->name = name;
+		__assign_str(name);
 		__entry->eventid = eventid;
 	),
 
-	TP_printk("name=%s, event=%d", __entry->name, __entry->eventid)
+	TP_printk("name=%s, event=%d", __get_str(name), __entry->eventid)
 );
 
 TRACE_EVENT(host1x_syncpt_load_min,

---
base-commit: ab5fce87a778cb780a05984a2ca448f2b41aafbf
change-id: 20260519-host1x-tracing-e2d608ec5e37

Best regards,
--  
Artur Kowalski <arturkow2000@gmail.com>

Re: [PATCH] gpu: host1x: trace: fix string fields in host1x traces

Posted by Thierry Reding 1 week, 6 days ago

On Tue, May 19, 2026 at 12:16:43PM +0200, Artur Kowalski wrote:
> Use __assign_str and __get_str as required by tracing subsystem. Fixes
> string fields being rejected by the verifier and unreadable from
> userspace.
> 
> Tested on v6.18.21.
> 
> Signed-off-by: Artur Kowalski <arturkow2000@gmail.com>
> ---
>  include/trace/events/host1x.h | 50 ++++++++++++++++++++++---------------------
>  1 file changed, 26 insertions(+), 24 deletions(-)

Applied, thanks.

Thierry

Re: [PATCH] gpu: host1x: trace: fix string fields in host1x traces

Posted by Steven Rostedt 3 weeks ago

On Tue, 19 May 2026 12:16:43 +0200
Artur Kowalski <arturkow2000@gmail.com> wrote:

> Use __assign_str and __get_str as required by tracing subsystem. Fixes
> string fields being rejected by the verifier and unreadable from
> userspace.

Does anyone use these tracepoints? The fact that they have been broken
for 5 years and nobody noticed makes me think they are useless.

I rather remove them than fix them, but if someone thinks that these
are still useful then by all means apply this patch.

Acked-by: Steven Rostedt <rostedt@goodmis.org>

-- Steve


> 
> Tested on v6.18.21.
> 
> Signed-off-by: Artur Kowalski <arturkow2000@gmail.com>
> ---
>  include/trace/events/host1x.h | 50 ++++++++++++++++++++++---------------------
>  1 file changed, 26 insertions(+), 24 deletions(-)
> 
> diff --git a/include/trace/events/host1x.h b/include/trace/events/host1x.h
> index 1ba84b738e46..1b6aeb7b177b 100644
> --- a/include/trace/events/host1x.h
> +++ b/include/trace/events/host1x.h
> @@ -21,9 +21,11 @@ struct host1x_bo;
>  DECLARE_EVENT_CLASS(host1x,
>  	TP_PROTO(const char *name),
>  	TP_ARGS(name),
> -	TP_STRUCT__entry(__field(const char *, name)),
> -	TP_fast_assign(__entry->name = name;),
> -	TP_printk("name=%s", __entry->name)
> +	TP_STRUCT__entry(__string(name, name)),
> +	TP_fast_assign(
> +		__assign_str(name);
> +	),
> +	TP_printk("name=%s", __get_str(name))
>  );
>  
>  DEFINE_EVENT(host1x, host1x_channel_open,
> @@ -52,19 +54,19 @@ TRACE_EVENT(host1x_cdma_push,
>  	TP_ARGS(name, op1, op2),
>  
>  	TP_STRUCT__entry(
> -		__field(const char *, name)
> +		__string(name, name)
>  		__field(u32, op1)
>  		__field(u32, op2)
>  	),
>  
>  	TP_fast_assign(
> -		__entry->name = name;
> +		__assign_str(name);
>  		__entry->op1 = op1;
>  		__entry->op2 = op2;
>  	),
>  
>  	TP_printk("name=%s, op1=%08x, op2=%08x",
> -		__entry->name, __entry->op1, __entry->op2)
> +		__get_str(name), __entry->op1, __entry->op2)
>  );
>  
>  TRACE_EVENT(host1x_cdma_push_wide,
> @@ -73,7 +75,7 @@ TRACE_EVENT(host1x_cdma_push_wide,
>  	TP_ARGS(name, op1, op2, op3, op4),
>  
>  	TP_STRUCT__entry(
> -		__field(const char *, name)
> +		__string(name, name)
>  		__field(u32, op1)
>  		__field(u32, op2)
>  		__field(u32, op3)
> @@ -81,7 +83,7 @@ TRACE_EVENT(host1x_cdma_push_wide,
>  	),
>  
>  	TP_fast_assign(
> -		__entry->name = name;
> +		__assign_str(name);
>  		__entry->op1 = op1;
>  		__entry->op2 = op2;
>  		__entry->op3 = op3;
> @@ -89,7 +91,7 @@ TRACE_EVENT(host1x_cdma_push_wide,
>  	),
>  
>  	TP_printk("name=%s, op1=%08x, op2=%08x, op3=%08x op4=%08x",
> -		__entry->name, __entry->op1, __entry->op2, __entry->op3,
> +		__get_str(name), __entry->op1, __entry->op2, __entry->op3,
>  		__entry->op4)
>  );
>  
> @@ -100,7 +102,7 @@ TRACE_EVENT(host1x_cdma_push_gather,
>  	TP_ARGS(name, bo, words, offset, cmdbuf),
>  
>  	TP_STRUCT__entry(
> -		__field(const char *, name)
> +		__string(name, name)
>  		__field(struct host1x_bo *, bo)
>  		__field(u32, words)
>  		__field(u32, offset)
> @@ -114,14 +116,14 @@ TRACE_EVENT(host1x_cdma_push_gather,
>  					words * sizeof(u32));
>  		}
>  		__entry->cmdbuf = cmdbuf;
> -		__entry->name = name;
> +		__assign_str(name);
>  		__entry->bo = bo;
>  		__entry->words = words;
>  		__entry->offset = offset;
>  	),
>  
>  	TP_printk("name=%s, bo=%p, words=%u, offset=%d, contents=[%s]",
> -	  __entry->name, __entry->bo,
> +	  __get_str(name), __entry->bo,
>  	  __entry->words, __entry->offset,
>  	  __print_hex(__get_dynamic_array(cmdbuf),
>  		  __entry->cmdbuf ? __entry->words * 4 : 0))
> @@ -134,7 +136,7 @@ TRACE_EVENT(host1x_channel_submit,
>  	TP_ARGS(name, cmdbufs, relocs, syncpt_id, syncpt_incrs),
>  
>  	TP_STRUCT__entry(
> -		__field(const char *, name)
> +		__string(name, name)
>  		__field(u32, cmdbufs)
>  		__field(u32, relocs)
>  		__field(u32, syncpt_id)
> @@ -142,7 +144,7 @@ TRACE_EVENT(host1x_channel_submit,
>  	),
>  
>  	TP_fast_assign(
> -		__entry->name = name;
> +		__assign_str(name);
>  		__entry->cmdbufs = cmdbufs;
>  		__entry->relocs = relocs;
>  		__entry->syncpt_id = syncpt_id;
> @@ -151,7 +153,7 @@ TRACE_EVENT(host1x_channel_submit,
>  
>  	TP_printk("name=%s, cmdbufs=%u, relocs=%u, syncpt_id=%u, "
>  		  "syncpt_incrs=%u",
> -		  __entry->name, __entry->cmdbufs, __entry->relocs,
> +		  __get_str(name), __entry->cmdbufs, __entry->relocs,
>  		  __entry->syncpt_id, __entry->syncpt_incrs)
>  );
>  
> @@ -161,19 +163,19 @@ TRACE_EVENT(host1x_channel_submitted,
>  	TP_ARGS(name, syncpt_base, syncpt_max),
>  
>  	TP_STRUCT__entry(
> -		__field(const char *, name)
> +		__string(name, name)
>  		__field(u32, syncpt_base)
>  		__field(u32, syncpt_max)
>  	),
>  
>  	TP_fast_assign(
> -		__entry->name = name;
> +		__assign_str(name);
>  		__entry->syncpt_base = syncpt_base;
>  		__entry->syncpt_max = syncpt_max;
>  	),
>  
>  	TP_printk("name=%s, syncpt_base=%d, syncpt_max=%d",
> -		__entry->name, __entry->syncpt_base, __entry->syncpt_max)
> +		__get_str(name), __entry->syncpt_base, __entry->syncpt_max)
>  );
>  
>  TRACE_EVENT(host1x_channel_submit_complete,
> @@ -182,19 +184,19 @@ TRACE_EVENT(host1x_channel_submit_complete,
>  	TP_ARGS(name, count, thresh),
>  
>  	TP_STRUCT__entry(
> -		__field(const char *, name)
> +		__string(name, name)
>  		__field(int, count)
>  		__field(u32, thresh)
>  	),
>  
>  	TP_fast_assign(
> -		__entry->name = name;
> +		__assign_str(name);
>  		__entry->count = count;
>  		__entry->thresh = thresh;
>  	),
>  
>  	TP_printk("name=%s, count=%d, thresh=%d",
> -		__entry->name, __entry->count, __entry->thresh)
> +		__get_str(name), __entry->count, __entry->thresh)
>  );
>  
>  TRACE_EVENT(host1x_wait_cdma,
> @@ -203,16 +205,16 @@ TRACE_EVENT(host1x_wait_cdma,
>  	TP_ARGS(name, eventid),
>  
>  	TP_STRUCT__entry(
> -		__field(const char *, name)
> +		__string(name, name)
>  		__field(u32, eventid)
>  	),
>  
>  	TP_fast_assign(
> -		__entry->name = name;
> +		__assign_str(name);
>  		__entry->eventid = eventid;
>  	),
>  
> -	TP_printk("name=%s, event=%d", __entry->name, __entry->eventid)
> +	TP_printk("name=%s, event=%d", __get_str(name), __entry->eventid)
>  );
>  
>  TRACE_EVENT(host1x_syncpt_load_min,
> 
> ---
> base-commit: ab5fce87a778cb780a05984a2ca448f2b41aafbf
> change-id: 20260519-host1x-tracing-e2d608ec5e37
> 
> Best regards,
> --  
> Artur Kowalski <arturkow2000@gmail.com>

Re: [PATCH] gpu: host1x: trace: fix string fields in host1x traces

Posted by Thierry Reding 3 weeks ago

On Tue, May 19, 2026 at 02:10:59PM -0400, Steven Rostedt wrote:
> On Tue, 19 May 2026 12:16:43 +0200
> Artur Kowalski <arturkow2000@gmail.com> wrote:
> 
> > Use __assign_str and __get_str as required by tracing subsystem. Fixes
> > string fields being rejected by the verifier and unreadable from
> > userspace.
> 
> Does anyone use these tracepoints? The fact that they have been broken
> for 5 years and nobody noticed makes me think they are useless.
> 
> I rather remove them than fix them, but if someone thinks that these
> are still useful then by all means apply this patch.
> 
> Acked-by: Steven Rostedt <rostedt@goodmis.org>

I know that Mikko used them a lot early on, but this driver is pretty
mature now, so we rarely need this low level of tracing. I'll defer to
Mikko on whether we still need these.

Thierry

Re: [PATCH] gpu: host1x: trace: fix string fields in host1x traces

Posted by Mikko Perttunen 2 weeks, 6 days ago

On Wednesday, May 20, 2026 9:03 PM Thierry Reding wrote:
> On Tue, May 19, 2026 at 02:10:59PM -0400, Steven Rostedt wrote:
> > On Tue, 19 May 2026 12:16:43 +0200
> > Artur Kowalski <arturkow2000@gmail.com> wrote:
> > 
> > > Use __assign_str and __get_str as required by tracing subsystem. Fixes
> > > string fields being rejected by the verifier and unreadable from
> > > userspace.
> > 
> > Does anyone use these tracepoints? The fact that they have been broken
> > for 5 years and nobody noticed makes me think they are useless.
> > 
> > I rather remove them than fix them, but if someone thinks that these
> > are still useful then by all means apply this patch.
> > 
> > Acked-by: Steven Rostedt <rostedt@goodmis.org>
> 
> I know that Mikko used them a lot early on, but this driver is pretty
> mature now, so we rarely need this low level of tracing. I'll defer to
> Mikko on whether we still need these.
> 
> Thierry

Yeah, these have been quite useful in the past when debugging why a job
is failing. Without the cdma traces it can be cumbersome to find out
exactly what is being sent to the hardware in some cases.

My preference is for keeping them for now.

Mikko

Re: [PATCH] gpu: host1x: trace: fix string fields in host1x traces

Posted by Thierry Reding 2 weeks, 6 days ago

On Thu, May 21, 2026 at 01:33:24PM +0900, Mikko Perttunen wrote:
> On Wednesday, May 20, 2026 9:03 PM Thierry Reding wrote:
> > On Tue, May 19, 2026 at 02:10:59PM -0400, Steven Rostedt wrote:
> > > On Tue, 19 May 2026 12:16:43 +0200
> > > Artur Kowalski <arturkow2000@gmail.com> wrote:
> > > 
> > > > Use __assign_str and __get_str as required by tracing subsystem. Fixes
> > > > string fields being rejected by the verifier and unreadable from
> > > > userspace.
> > > 
> > > Does anyone use these tracepoints? The fact that they have been broken
> > > for 5 years and nobody noticed makes me think they are useless.
> > > 
> > > I rather remove them than fix them, but if someone thinks that these
> > > are still useful then by all means apply this patch.
> > > 
> > > Acked-by: Steven Rostedt <rostedt@goodmis.org>
> > 
> > I know that Mikko used them a lot early on, but this driver is pretty
> > mature now, so we rarely need this low level of tracing. I'll defer to
> > Mikko on whether we still need these.
> > 
> > Thierry
> 
> Yeah, these have been quite useful in the past when debugging why a job
> is failing. Without the cdma traces it can be cumbersome to find out
> exactly what is being sent to the hardware in some cases.
> 
> My preference is for keeping them for now.

Thanks, I'll pick this up then.

Thierry