From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id BFC621773A; Thu, 5 Dec 2024 17:01:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733418117; cv=none; b=uvcW6H9dCXagGvWZvKoDajSmTDpjo2CUW0IuO7tadpsq6hbRMYo86DvwOMX4vn0iMrrSa5MY22U8IUq1ueq3OX9qmS7ONbaX4TGRaNLj7vqOV7qtNkq59sUEPx6bNAjt5+j5hwpL2ruxbwvKrXnjzedoV7WBIvtQNXg9/ee6+a4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733418117; c=relaxed/simple; bh=Whapanp2F9YUEI+YugJVd+euaX5xRY4YjBBljMVWfcg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=nFgcYouD1Ourd2CTZrXIr1/SXqIN4On2Tgmlr2rpGK2LSiPO/+FePLNVgUva3RiVyuPcxnv96VXsRKELv/cWtm0alLcdaW1mSl47jyz5fKfRKD/QD/LdcUDFqNE2oVUXVi2WY4E4wSDwLq6nYzlD4WlVuGDZFFaAPtZeZ9Sk79E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 569091063; Thu, 5 Dec 2024 09:02:23 -0800 (PST) Received: from [10.1.197.1] (ewhatever.cambridge.arm.com [10.1.197.1]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 682513F71E; Thu, 5 Dec 2024 09:01:53 -0800 (PST) Message-ID: Date: Thu, 5 Dec 2024 17:01:51 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v12 5/8] coresight: tmc: Add support for reading crash data To: Linu Cherian , mike.leach@linaro.org, james.clark@arm.com Cc: linux-arm-kernel@lists.infradead.org, coresight@lists.linaro.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, corbet@lwn.net, devicetree@vger.kernel.org, sgoutham@marvell.com, gcherian@marvell.com, Anil Kumar Reddy , Tanmay Jagdale References: <20241129084714.3057080-1-lcherian@marvell.com> <20241129084714.3057080-6-lcherian@marvell.com> Content-Language: en-US From: Suzuki K Poulose In-Reply-To: <20241129084714.3057080-6-lcherian@marvell.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Linu, On 29/11/2024 08:47, Linu Cherian wrote: > * Add support for reading crashdata using special device files. > The special device files /dev/crash_tmc_xxx would be available > for read file operation only when the crash data is valid. > > * User can read the crash data as below > > For example, for reading crash data from tmc_etf sink > > #dd if=/dev/crash_tmc_etfXX of=~/cstrace.bin > Unfortunately there is still a bug that I picked up, see below for the barrier_packet insertion. > Signed-off-by: Anil Kumar Reddy > Signed-off-by: Tanmay Jagdale > Signed-off-by: Linu Cherian > --- > .../hwtracing/coresight/coresight-tmc-core.c | 231 +++++++++++++++++- > .../hwtracing/coresight/coresight-tmc-etr.c | 19 +- > drivers/hwtracing/coresight/coresight-tmc.h | 13 +- > 3 files changed, 260 insertions(+), 3 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c > index 1e3938ec12cb..5f3789314c4d 100644 > --- a/drivers/hwtracing/coresight/coresight-tmc-core.c > +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c > @@ -105,6 +105,151 @@ u32 tmc_get_memwidth_mask(struct tmc_drvdata *drvdata) > return mask; > } > > +bool is_tmc_crashdata_valid(struct tmc_drvdata *drvdata) > +{ > + struct tmc_crash_metadata *mdata; > + > + if (!tmc_has_reserved_buffer(drvdata) || > + !tmc_has_crash_mdata_buffer(drvdata)) > + return false; > + > + mdata = drvdata->crash_mdata.vaddr; > + > + /* Check version match */ > + if (mdata->version != CS_CRASHDATA_VERSION) > + return false; > + > + /* Check for valid metadata */ > + if (!mdata->valid) { > + dev_dbg(&drvdata->csdev->dev, > + "Data invalid in tmc crash metadata\n"); > + return false; > + } > + > + /* > + * Buffer address given by metadata for retrieval of trace data > + * from previous boot is expected to be same as the reserved > + * trace buffer memory region provided through DTS > + */ > + if (drvdata->resrv_buf.paddr != mdata->trace_paddr) { > + dev_dbg(&drvdata->csdev->dev, > + "Trace buffer address of previous boot invalid\n"); > + return false; > + } > + > + /* Check data integrity of metadata */ > + if (mdata->crc32_mdata != find_crash_metadata_crc(mdata)) { > + dev_dbg(&drvdata->csdev->dev, > + "CRC mismatch in tmc crash metadata\n"); > + return false; > + } > + /* Check data integrity of tracedata */ > + if (mdata->crc32_tdata != find_crash_tracedata_crc(drvdata, mdata)) { > + dev_dbg(&drvdata->csdev->dev, > + "CRC mismatch in tmc crash tracedata\n"); > + return false; > + } > + > + return true; > +} > + > +int tmc_read_prepare_crashdata(struct tmc_drvdata *drvdata) > +{ > + int ret = 0; > + u32 status, size; > + u64 rrp, rwp, dba; > + unsigned long flags; > + struct tmc_resrv_buf *rbuf; > + struct tmc_crash_metadata *mdata; > + > + spin_lock_irqsave(&drvdata->spinlock, flags); > + > + if (drvdata->reading) { > + ret = -EBUSY; > + goto out; > + } > + > + if (!is_tmc_crashdata_valid(drvdata)) { > + ret = -ENXIO; > + goto out; > + } > + > + mdata = drvdata->crash_mdata.vaddr; > + rbuf = &drvdata->resrv_buf; > + > + rrp = mdata->tmc_rrp; > + rwp = mdata->tmc_rwp; > + dba = mdata->tmc_dba; > + status = mdata->tmc_sts; > + size = mdata->tmc_ram_size << 2; > + > + /* Sync the buffer pointers */ > + rbuf->offset = rrp - dba; > + if (status & TMC_STS_FULL) > + rbuf->len = size; > + else > + rbuf->len = rwp - rrp; > + I believe all of the above can be done one time probe and don't need to be repeated every time we do a read_prepare() ? > + /* Additional sanity checks for validating metadata */ > + if ((rbuf->offset > size) || > + (rbuf->len > size)) { > + dev_dbg(&drvdata->csdev->dev, > + "Offset and length invalid in tmc crash metadata\n"); > + return -EINVAL; > + } Ideally this should also be done once and "don't expose" crash_tmc device if the above is invalid in metada. > + > + if (status & 0x1) minor nit: s/0x1/TMC_STS_FULL ? > + coresight_insert_barrier_packet(drvdata->buf); And this looks completely out of nowhere and corrupting the drvdata->buf ? drvdata->buf is for active sessions, which we haven't set here ? > + > + drvdata->reading = true; Also, we agreed to not overload "drvdata->reading" ? See https://lkml.kernel.org/r/20241017114054.GC896339@hyd1403.caveonetworks.com We are allowed to the ETR (which drvdata->reading prevents from btw) while crash data is being read. You could instead move it to drvdata->resrv_buf->reading ? Suzuki > +out: > + spin_unlock_irqrestore(&drvdata->spinlock, flags); > + return ret; > +} > + > +int tmc_read_unprepare_crashdata(struct tmc_drvdata *drvdata) > +{ > + unsigned long flags; > + struct tmc_resrv_buf *rbuf; > + > + spin_lock_irqsave(&drvdata->spinlock, flags); > + > + rbuf = &drvdata->resrv_buf; > + /* Reset valid length */ > + rbuf->len = 0; > + > + drvdata->reading = false; > + spin_unlock_irqrestore(&drvdata->spinlock, flags); > + > + return 0; > +} > + > +static inline ssize_t tmc_get_resvbuf_trace(struct tmc_drvdata *drvdata, > + loff_t pos, size_t len, char **bufpp) > +{ > + s64 offset; > + ssize_t actual = len; > + struct tmc_resrv_buf *rbuf = &drvdata->resrv_buf; > + > + if (pos + actual > rbuf->len) > + actual = rbuf->len - pos; > + if (actual <= 0) > + return 0; > + > + /* Compute the offset from which we read the data */ > + offset = rbuf->offset + pos; > + if (offset >= rbuf->size) > + offset -= rbuf->size; > + > + /* Adjust the length to limit this transaction to end of buffer */ > + actual = (actual < (rbuf->size - offset)) ? > + actual : rbuf->size - offset; > + > + *bufpp = (char *)rbuf->vaddr + offset; > + > + return actual; > +} > + > static int tmc_read_prepare(struct tmc_drvdata *drvdata) > { > int ret = 0; > @@ -223,6 +368,69 @@ static const struct file_operations tmc_fops = { > .release = tmc_release, > }; > > +static int tmc_crashdata_open(struct inode *inode, struct file *file) > +{ > + int ret; > + struct tmc_drvdata *drvdata = container_of(file->private_data, > + struct tmc_drvdata, > + crashdev); > + > + ret = tmc_read_prepare_crashdata(drvdata); > + if (ret) > + return ret; > + > + nonseekable_open(inode, file); > + > + dev_dbg(&drvdata->csdev->dev, "%s: successfully opened\n", __func__); > + return 0; > +} > + > +static ssize_t tmc_crashdata_read(struct file *file, char __user *data, > + size_t len, loff_t *ppos) > +{ > + char *bufp; > + ssize_t actual; > + struct tmc_drvdata *drvdata = container_of(file->private_data, > + struct tmc_drvdata, > + crashdev); > + > + actual = tmc_get_resvbuf_trace(drvdata, *ppos, len, &bufp); > + if (actual <= 0) > + return 0; > + > + if (copy_to_user(data, bufp, actual)) { > + dev_dbg(&drvdata->csdev->dev, > + "%s: copy_to_user failed\n", __func__); > + return -EFAULT; > + } > + > + *ppos += actual; > + dev_dbg(&drvdata->csdev->dev, "%zu bytes copied\n", actual); > + > + return actual; > + > +} > + > +static int tmc_crashdata_release(struct inode *inode, struct file *file) > +{ > + int ret = 0; > + struct tmc_drvdata *drvdata = container_of(file->private_data, > + struct tmc_drvdata, > + crashdev); > + > + ret = tmc_read_unprepare_crashdata(drvdata); > + > + dev_dbg(&drvdata->csdev->dev, "%s: released\n", __func__); > + return ret; > +} > + > +static const struct file_operations tmc_crashdata_fops = { > + .owner = THIS_MODULE, > + .open = tmc_crashdata_open, > + .read = tmc_crashdata_read, > + .release = tmc_crashdata_release, > +}; > + > static enum tmc_mem_intf_width tmc_get_memwidth(u32 devid) > { > enum tmc_mem_intf_width memwidth; > @@ -532,6 +740,20 @@ static u32 tmc_etr_get_max_burst_size(struct device *dev) > return burst_size; > } > > +static void register_crash_dev_interface(struct tmc_drvdata *drvdata, > + const char *name) > +{ > + drvdata->crashdev.name = > + devm_kasprintf(&drvdata->csdev->dev, GFP_KERNEL, "%s_%s", "crash", name); > + drvdata->crashdev.minor = MISC_DYNAMIC_MINOR; > + drvdata->crashdev.fops = &tmc_crashdata_fops; > + if (misc_register(&drvdata->crashdev)) { > + dev_dbg(&drvdata->csdev->dev, > + "Failed to setup user interface for crashdata\n"); > + drvdata->crashdev.fops = NULL; > + } > +} > + > static int __tmc_probe(struct device *dev, struct resource *res) > { > int ret = 0; > @@ -632,8 +854,13 @@ static int __tmc_probe(struct device *dev, struct resource *res) > drvdata->miscdev.minor = MISC_DYNAMIC_MINOR; > drvdata->miscdev.fops = &tmc_fops; > ret = misc_register(&drvdata->miscdev); > - if (ret) > + if (ret) { > coresight_unregister(drvdata->csdev); > + goto out; > + } > + > + if (is_tmc_crashdata_valid(drvdata)) > + register_crash_dev_interface(drvdata, desc.name); > out: > return ret; > } > @@ -687,6 +914,8 @@ static void __tmc_remove(struct device *dev) > * handler to this device is closed. > */ > misc_deregister(&drvdata->miscdev); > + if (drvdata->crashdev.fops) > + misc_deregister(&drvdata->crashdev); > coresight_unregister(drvdata->csdev); > } > > diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c > index fb944a68a11c..18752f58dfa6 100644 > --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c > +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c > @@ -2012,6 +2012,23 @@ static ssize_t buf_mode_preferred_show(struct device *dev, > return sysfs_emit(buf, "%s\n", buf_modes_str[drvdata->etr_mode]); > } > > +static int buf_mode_set_resrv(struct tmc_drvdata *drvdata) > +{ > + unsigned long flags; > + int err = 0; > + > + /* Ensure there are no active crashdata read sessions */ > + spin_lock_irqsave(&drvdata->spinlock, flags); > + if (!drvdata->reading) { > + tmc_crashdata_set_invalid(drvdata); > + drvdata->etr_mode = ETR_MODE_RESRV; > + > + } else > + err = -1; > + spin_unlock_irqrestore(&drvdata->spinlock, flags); > + return err; > +} > + > static ssize_t buf_mode_preferred_store(struct device *dev, > struct device_attribute *attr, > const char *buf, size_t size) > @@ -2027,7 +2044,7 @@ static ssize_t buf_mode_preferred_store(struct device *dev, > else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_CATU]) && buf_hw.has_catu) > drvdata->etr_mode = ETR_MODE_CATU; > else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_RESRV]) && buf_hw.has_resrv) > - drvdata->etr_mode = ETR_MODE_RESRV; > + return buf_mode_set_resrv(drvdata) ? -EBUSY : size; > else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_AUTO])) > drvdata->etr_mode = ETR_MODE_AUTO; > else > diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h > index d76e83fc840b..2ece44e09911 100644 > --- a/drivers/hwtracing/coresight/coresight-tmc.h > +++ b/drivers/hwtracing/coresight/coresight-tmc.h > @@ -195,11 +195,15 @@ struct etr_buf { > * @paddr : Start address of reserved memory region. > * @vaddr : Corresponding CPU virtual address. > * @size : Size of reserved memory region. > + * @offset : Offset of the trace data in the buffer for consumption. > + * @len : Available trace data @buf (may round up to the beginning). > */ > struct tmc_resrv_buf { > phys_addr_t paddr; > void *vaddr; > size_t size; > + unsigned long offset; > + s64 len; > }; > > /** > @@ -208,6 +212,8 @@ struct tmc_resrv_buf { > * @base: memory mapped base address for this component. > * @csdev: component vitals needed by the framework. > * @miscdev: specifics to handle "/dev/xyz.tmc" entry. > + * @crashdev: specifics to handle "/dev/crash_tmc_xyz" entry for reading > + * crash tracedata. > * @spinlock: only one at a time pls. > * @pid: Process ID of the process that owns the session that is using > * this component. For example this would be the pid of the Perf > @@ -227,7 +233,7 @@ struct tmc_resrv_buf { > * @idr_mutex: Access serialisation for idr. > * @sysfs_buf: SYSFS buffer for ETR. > * @perf_buf: PERF buffer for ETR. > - * @resrv_buf: Used by ETR as hardware trace buffer and for trace data > + * @resrv_buf: Used by ETR as hardware trace buffer and for trace data > * retention (after crash) only when ETR_MODE_RESRV buffer > * mode is enabled. Used by ETF for trace data retention > * (after crash) by default. > @@ -239,6 +245,7 @@ struct tmc_drvdata { > void __iomem *base; > struct coresight_device *csdev; > struct miscdevice miscdev; > + struct miscdevice crashdev; > spinlock_t spinlock; > pid_t pid; > bool reading; > @@ -309,6 +316,8 @@ void tmc_flush_and_stop(struct tmc_drvdata *drvdata); > void tmc_enable_hw(struct tmc_drvdata *drvdata); > void tmc_disable_hw(struct tmc_drvdata *drvdata); > u32 tmc_get_memwidth_mask(struct tmc_drvdata *drvdata); > +int tmc_read_prepare_crashdata(struct tmc_drvdata *drvdata); > +int tmc_read_unprepare_crashdata(struct tmc_drvdata *drvdata); > > /* ETB/ETF functions */ > int tmc_read_prepare_etb(struct tmc_drvdata *drvdata); > @@ -371,6 +380,8 @@ void tmc_sg_table_sync_data_range(struct tmc_sg_table *table, > u64 offset, u64 size); > ssize_t tmc_sg_table_get_data(struct tmc_sg_table *sg_table, > u64 offset, size_t len, char **bufpp); > + > +bool is_tmc_crashdata_valid(struct tmc_drvdata *drvdata); > static inline unsigned long > tmc_sg_table_buf_size(struct tmc_sg_table *sg_table) > {