From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A922044BC8E for ; Fri, 22 May 2026 14:35:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779460507; cv=none; b=rnVmzq4S7WVo8wkWJCa3h3KyCrpFdTm9NAuB5qkL71itWTx4K2AMq+MAruFeL8NFEQ1gxw3uBxOAxKxWFBggK+hP2rDvrKFBfYQr7sDO1dYW+IMvD+doFGJopXcvvNIXykUObzyf18ABqdEs0xWZcfT31pnSSGUiBneI30rNO0o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779460507; c=relaxed/simple; bh=vYWRFAjVeuVzDzRxjaGpHF17Ws0kCrh9LCXEzjYt6Hc=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=C/WGgGKxOg+meXPJvwylm/l1KPv5MaGX5Lu7EWvc+hDS87PqMx3JO4H2DI5CCc9gNHZsglZZz/Y8bHwFZqXMlnluN2E4+7YWZrsuMsDT4ACXeSrVKH7DFyPHv2J1H03+PSXT87OW1uXMfjYza/rxAJHlxYQetfZ3bj0uJctJmNM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lSfjyQDh; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lSfjyQDh" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0E1691F00ADE; Fri, 22 May 2026 14:35:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779460503; bh=KdaYUs9sUq5Agjn/nTlDwu47m8ybbTggHMIUaFT+UFo=; h=Date:From:To:Cc:Subject:References; b=lSfjyQDhJPqWv5HSxHsijXL2NDIhA6suXxZbcXTOnrocNPpMERp4GeQ2b0IJ+Cic9 pTof/OUIYz59lGwwd4WlXFlh/9rRbtEUDXvJ/7uFLe7LXqXLjCURuK5SWHZbswZ20V IxC0M99b00ecCicmh9RM3V6Z8Gy4uAo7mQtlZnZFtYUErdtu6uFm/T5G4GdUr4j8m1 GJwahNYYM1jp+qiES3c7LutlFX2HsGrpDLrH8v5DLxDrJYzDa/YRZDhCyKwLO/QpXn qr1FT7FKDCxLir9uSYLz8CrxXihmvR/r/XcHZsimL6tLksrZWfPc7vDoqwd+aqnnfq oaVENMwe4ezgQ== Received: from rostedt by gandalf with local (Exim 4.99.2) (envelope-from ) id 1wQQyE-000000066Ac-2lb3; Fri, 22 May 2026 10:35:26 -0400 Message-ID: <20260522143526.523134137@kernel.org> User-Agent: quilt/0.69 Date: Fri, 22 May 2026 10:35:18 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Arnaldo Carvalho de Melo , Jiri Olsa , Peter Zijlstra , Ian Rogers , Namhyung Kim Subject: [for-next][PATCH 10/15] tracing: Allow perf to read synthetic events References: <20260522143508.298439732@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 From: Steven Rostedt Currently, perf can not enable synthetic events. When it does, it either causes a warning in the kernel or errors with "no such device". Add the necessary code to allow perf to also attach to synthetic events. Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Peter Zijlstra Link: https://patch.msgid.link/20260513150007.3b280e87@gandalf.local.home Reported-by: Ian Rogers Acked-by: Namhyung Kim Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_synth.c | 121 +++++++++++++++++++++++------- 1 file changed, 94 insertions(+), 27 deletions(-) diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c index 39ac4eba0702..e6871230bde9 100644 --- a/kernel/trace/trace_events_synth.c +++ b/kernel/trace/trace_events_synth.c @@ -499,28 +499,19 @@ static unsigned int trace_stack(struct synth_trace_event *entry, return len; } -static void trace_event_raw_event_synth(void *__data, - u64 *var_ref_vals, - unsigned int *var_ref_idx) +static __always_inline int get_field_size(struct synth_event *event, + u64 *var_ref_vals, + unsigned int *var_ref_idx) { - unsigned int i, n_u64, val_idx, len, data_size = 0; - struct trace_event_file *trace_file = __data; - struct synth_trace_event *entry; - struct trace_event_buffer fbuffer; - struct trace_buffer *buffer; - struct synth_event *event; - int fields_size = 0; - - event = trace_file->event_call->data; - - if (trace_trigger_soft_disabled(trace_file)) - return; + int fields_size; fields_size = event->n_u64 * sizeof(u64); - for (i = 0; i < event->n_dynamic_fields; i++) { + for (int i = 0; i < event->n_dynamic_fields; i++) { unsigned int field_pos = event->dynamic_fields[i]->field_pos; char *str_val; + int val_idx; + int len; val_idx = var_ref_idx[field_pos]; str_val = (char *)(long)var_ref_vals[val_idx]; @@ -535,18 +526,18 @@ static void trace_event_raw_event_synth(void *__data, fields_size += len; } + return fields_size; +} - /* - * Avoid ring buffer recursion detection, as this event - * is being performed within another event. - */ - buffer = trace_file->tr->array_buffer.buffer; - guard(ring_buffer_nest)(buffer); - - entry = trace_event_buffer_reserve(&fbuffer, trace_file, - sizeof(*entry) + fields_size); - if (!entry) - return; +static __always_inline void write_synth_entry(struct synth_event *event, + struct synth_trace_event *entry, + u64 *var_ref_vals, + unsigned int *var_ref_idx) +{ + int data_size = 0; + int i, n_u64; + int val_idx; + int len; for (i = 0, n_u64 = 0; i < event->n_fields; i++) { val_idx = var_ref_idx[i]; @@ -587,10 +578,83 @@ static void trace_event_raw_event_synth(void *__data, n_u64++; } } +} + +static void trace_event_raw_event_synth(void *__data, + u64 *var_ref_vals, + unsigned int *var_ref_idx) +{ + struct trace_event_file *trace_file = __data; + struct synth_trace_event *entry; + struct trace_event_buffer fbuffer; + struct trace_buffer *buffer; + struct synth_event *event; + int fields_size; + + event = trace_file->event_call->data; + + if (trace_trigger_soft_disabled(trace_file)) + return; + + fields_size = get_field_size(event, var_ref_vals, var_ref_idx); + + /* + * Avoid ring buffer recursion detection, as this event + * is being performed within another event. + */ + buffer = trace_file->tr->array_buffer.buffer; + guard(ring_buffer_nest)(buffer); + + entry = trace_event_buffer_reserve(&fbuffer, trace_file, + sizeof(*entry) + fields_size); + if (!entry) + return; + + write_synth_entry(event, entry, var_ref_vals, var_ref_idx); trace_event_buffer_commit(&fbuffer); } +#ifdef CONFIG_PERF_EVENTS +static void perf_event_raw_event_synth(void *__data, + u64 *var_ref_vals, + unsigned int *var_ref_idx) +{ + struct trace_event_call *call = __data; + struct synth_trace_event *entry; + struct hlist_head *perf_head; + struct synth_event *event; + struct pt_regs *regs; + int fields_size; + size_t size; + int context; + + event = call->data; + + perf_head = this_cpu_ptr(call->perf_events); + + if (!perf_head || hlist_empty(perf_head)) + return; + + fields_size = get_field_size(event, var_ref_vals, var_ref_idx); + + size = ALIGN(sizeof(*entry) + fields_size, 8); + + entry = perf_trace_buf_alloc(size, ®s, &context); + + if (unlikely(!entry)) + return; + + write_synth_entry(event, entry, var_ref_vals, var_ref_idx); + + perf_fetch_caller_regs(regs); + + perf_trace_buf_submit(entry, size, context, + call->event.type, 1, regs, + perf_head, NULL); +} +#endif + static void free_synth_event_print_fmt(struct trace_event_call *call) { if (call) { @@ -917,6 +981,9 @@ static int register_synth_event(struct synth_event *event) call->flags = TRACE_EVENT_FL_TRACEPOINT; call->class->reg = synth_event_reg; call->class->probe = trace_event_raw_event_synth; +#ifdef CONFIG_PERF_EVENTS + call->class->perf_probe = perf_event_raw_event_synth; +#endif call->data = event; call->tp = event->tp; -- 2.53.0