Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753796Ab2FMCDk (ORCPT ); Tue, 12 Jun 2012 22:03:40 -0400 Received: from e31.co.us.ibm.com ([32.97.110.149]:58361 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752913Ab2FMCDi (ORCPT ); Tue, 12 Jun 2012 22:03:38 -0400 From: John Stultz To: LKML Cc: =?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?= , Russell King , Paul Gortmaker , Alexander Shishkin , Mathieu Poirier , John Stultz Subject: [PATCH 03/15] ARM: etm: Don't try to clear the buffer full status after reading the buffer Date: Tue, 12 Jun 2012 19:01:21 -0700 Message-Id: <1339552887-17204-4-git-send-email-john.stultz@linaro.org> X-Mailer: git-send-email 1.7.3.2.146.gca209 In-Reply-To: <1339552887-17204-1-git-send-email-john.stultz@linaro.org> References: <1339552887-17204-1-git-send-email-john.stultz@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 12061302-7282-0000-0000-000009DBDF1B Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4279 Lines: 148 From: Arve Hjønnevåg If the write address was at the end of the buffer, toggling the trace capture bit would set the RAM-full status instead of clearing it, and if any of the stop bits in the formatter is set toggling the trace capture bit may not do anything. Instead use the read position to find out if the data has already been returned. This also fixes the read function so it works when the trace buffer is larger than the buffer passed in from user space. The old version would reset the trace buffer pointers after every read, so the second call to read would always return 0. CC: Russell King CC: Paul Gortmaker CC: Alexander Shishkin CC: Mathieu Poirier Acked-by: Alexander Shishkin Signed-off-by: Arve Hjønnevåg Signed-off-by: John Stultz --- arch/arm/kernel/etm.c | 58 ++++++++++++++++++++++--------------------------- 1 files changed, 26 insertions(+), 32 deletions(-) diff --git a/arch/arm/kernel/etm.c b/arch/arm/kernel/etm.c index d7622f9..a51bccc 100644 --- a/arch/arm/kernel/etm.c +++ b/arch/arm/kernel/etm.c @@ -92,6 +92,7 @@ static int trace_start(struct tracectx *t) etb_unlock(t); + etb_writel(t, 0, ETBR_WRITEADDR); etb_writel(t, 0, ETBR_FORMATTERCTRL); etb_writel(t, 1, ETBR_CTRL); @@ -185,24 +186,15 @@ static int trace_stop(struct tracectx *t) static int etb_getdatalen(struct tracectx *t) { u32 v; - int rp, wp; + int wp; v = etb_readl(t, ETBR_STATUS); if (v & 1) return t->etb_bufsz; - rp = etb_readl(t, ETBR_READADDR); wp = etb_readl(t, ETBR_WRITEADDR); - - if (rp > wp) { - etb_writel(t, 0, ETBR_READADDR); - etb_writel(t, 0, ETBR_WRITEADDR); - - return 0; - } - - return wp - rp; + return wp; } /* sysrq+v will always stop the running trace and leave it at that */ @@ -235,14 +227,6 @@ static void etm_dump(void) printk("%08x", cpu_to_be32(etb_readl(t, ETBR_READMEM))); printk(KERN_INFO "\n--- ETB buffer end ---\n"); - /* deassert the overflow bit */ - etb_writel(t, 1, ETBR_CTRL); - etb_writel(t, 0, ETBR_CTRL); - - etb_writel(t, 0, ETBR_TRIGGERCOUNT); - etb_writel(t, 0, ETBR_READADDR); - etb_writel(t, 0, ETBR_WRITEADDR); - etb_lock(t); } @@ -276,6 +260,10 @@ static ssize_t etb_read(struct file *file, char __user *data, struct tracectx *t = file->private_data; u32 first = 0; u32 *buf; + int wpos; + int skip; + long wlength; + loff_t pos = *ppos; mutex_lock(&t->mutex); @@ -290,28 +278,34 @@ static ssize_t etb_read(struct file *file, char __user *data, if (total == t->etb_bufsz) first = etb_readl(t, ETBR_WRITEADDR); + if (pos > total * 4) { + skip = 0; + wpos = total; + } else { + skip = (int)pos % 4; + wpos = (int)pos / 4; + } + total -= wpos; + first = (first + wpos) % t->etb_bufsz; + etb_writel(t, first, ETBR_READADDR); - length = min(total * 4, (int)len); - buf = vmalloc(length); + wlength = min(total, DIV_ROUND_UP(skip + (int)len, 4)); + length = min(total * 4 - skip, (int)len); + buf = vmalloc(wlength * 4); - dev_dbg(t->dev, "ETB buffer length: %d\n", total); + dev_dbg(t->dev, "ETB read %ld bytes to %lld from %ld words at %d\n", + length, pos, wlength, first); + dev_dbg(t->dev, "ETB buffer length: %d\n", total + wpos); dev_dbg(t->dev, "ETB status reg: %x\n", etb_readl(t, ETBR_STATUS)); - for (i = 0; i < length / 4; i++) + for (i = 0; i < wlength; i++) buf[i] = etb_readl(t, ETBR_READMEM); - /* the only way to deassert overflow bit in ETB status is this */ - etb_writel(t, 1, ETBR_CTRL); - etb_writel(t, 0, ETBR_CTRL); - - etb_writel(t, 0, ETBR_WRITEADDR); - etb_writel(t, 0, ETBR_READADDR); - etb_writel(t, 0, ETBR_TRIGGERCOUNT); - etb_lock(t); - length -= copy_to_user(data, buf, length); + length -= copy_to_user(data, (u8 *)buf + skip, length); vfree(buf); + *ppos = pos + length; out: mutex_unlock(&t->mutex); -- 1.7.3.2.146.gca209 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/