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AJvYcCVIhq8aWrICSWJRaw6R6HTyPqwqTQWmqzkt/ckwddAWBJM1nBZFHurgBImwh+Dgjil1+vFoq1JGvzugw/yv7ykXp5I=@vger.kernel.org X-Gm-Message-State: AOJu0YwY6ElTZ04S/MFdnoirAnTAfdv2B2gVqHJuuC7NX8zrQDdR+xp9 o0sI/NSc57PN7jaGsz5VDo4o/Ly6vFCZY5pdco/JVjvdwjYwQdkzkxLIcFuK5GguZ4tXQ6GoRFm nCIHPBxYJSbdg0PHPDg== X-Google-Smtp-Source: AGHT+IHQGpayqqEkTmw/Zvqr6LdF1E/ueJfO1lglmZUQzjDwUDQWHOMK/KK1dg4emFnGMwfhnTYT5JRRxbk4ic04 X-Received: from wmbhc15.prod.google.com ([2002:a05:600c:870f:b0:439:858e:8ce6]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:1e23:b0:439:987c:2309 with SMTP id 5b1f17b1804b1-439ae221d7dmr101374675e9.27.1740399340381; Mon, 24 Feb 2025 04:15:40 -0800 (PST) Date: Mon, 24 Feb 2025 12:13:50 +0000 In-Reply-To: <20250224121353.98697-1-vdonnefort@google.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250224121353.98697-1-vdonnefort@google.com> X-Mailer: git-send-email 2.48.1.601.g30ceb7b040-goog Message-ID: <20250224121353.98697-9-vdonnefort@google.com> Subject: [PATCH 08/11] KVM: arm64: Add raw interface for hyp tracefs From: Vincent Donnefort To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, linux-trace-kernel@vger.kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, jstultz@google.com, qperret@google.com, will@kernel.org, kernel-team@android.com, linux-kernel@vger.kernel.org, Vincent Donnefort The raw interface enables userspace tools such as trace-cmd to directly read the ring-buffer without any decoding by the kernel. Signed-off-by: Vincent Donnefort diff --git a/arch/arm64/kvm/hyp_trace.c b/arch/arm64/kvm/hyp_trace.c index 3f91ad69c25b..38d97e34eada 100644 --- a/arch/arm64/kvm/hyp_trace.c +++ b/arch/arm64/kvm/hyp_trace.c @@ -746,6 +746,85 @@ static const struct file_operations hyp_trace_pipe_fops = { .release = hyp_trace_pipe_release, }; +static ssize_t +hyp_trace_raw_read(struct file *file, char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + struct ht_iterator *iter = (struct ht_iterator *)file->private_data; + size_t size; + int ret; + + if (iter->copy_leftover) + goto read; + +again: + ret = ring_buffer_read_page(iter->trace_buffer, + (struct buffer_data_read_page *)iter->spare, + cnt, iter->cpu, 0); + if (ret < 0) { + if (!ring_buffer_empty_cpu(iter->trace_buffer, iter->cpu)) + return 0; + + ret = ring_buffer_wait(iter->trace_buffer, iter->cpu, 0, NULL, + NULL); + if (ret < 0) + return ret; + + goto again; + } + + iter->copy_leftover = 0; + +read: + size = PAGE_SIZE - iter->copy_leftover; + if (size > cnt) + size = cnt; + + ret = copy_to_user(ubuf, iter->spare + PAGE_SIZE - size, size); + if (ret == size) + return -EFAULT; + + size -= ret; + *ppos += size; + iter->copy_leftover = ret; + + return size; +} + +static int hyp_trace_raw_open(struct inode *inode, struct file *file) +{ + int ret = hyp_trace_pipe_open(inode, file); + struct ht_iterator *iter; + + if (ret) + return ret; + + iter = file->private_data; + iter->spare = ring_buffer_alloc_read_page(iter->trace_buffer, iter->cpu); + if (IS_ERR(iter->spare)) { + ret = PTR_ERR(iter->spare); + iter->spare = NULL; + return ret; + } + + return 0; +} + +static int hyp_trace_raw_release(struct inode *inode, struct file *file) +{ + struct ht_iterator *iter = file->private_data; + + ring_buffer_free_read_page(iter->trace_buffer, iter->cpu, iter->spare); + + return hyp_trace_pipe_release(inode, file); +} + +static const struct file_operations hyp_trace_raw_fops = { + .open = hyp_trace_raw_open, + .read = hyp_trace_raw_read, + .release = hyp_trace_raw_release, +}; + static int hyp_trace_clock_show(struct seq_file *m, void *v) { seq_puts(m, "[boot]\n"); @@ -800,6 +879,9 @@ int hyp_trace_init_tracefs(void) tracefs_create_file("trace_pipe", TRACEFS_MODE_READ, per_cpu_dir, (void *)cpu, &hyp_trace_pipe_fops); + + tracefs_create_file("trace_pipe_raw", TRACEFS_MODE_READ, per_cpu_dir, + (void *)cpu, &hyp_trace_pipe_fops); } return 0;