From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755402AbdEALgO (ORCPT ); Mon, 1 May 2017 07:36:14 -0400 Received: from mail-wm0-f68.google.com ([74.125.82.68]:34378 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S3000580AbdEALfk (ORCPT ); Mon, 1 May 2017 07:35:40 -0400 Date: Mon, 1 May 2017 13:35:34 +0200 From: Ingo Molnar To: Linus Torvalds Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Thomas Gleixner , "H. Peter Anvin" , Peter Zijlstra , Andrew Morton Subject: [GIT PULL] x86/debug changes for v4.12 Message-ID: <20170501113534.qzshgaq5fep7ane7@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus, Please pull the latest x86-debug-for-linus git tree from: git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86-debug-for-linus # HEAD: 1b326277798aa820c1043617786609b9bb4bee78 usb/doc: Add document for USB3 debug port usage The biggest update is the addition of USB3 debug port based early-console. Greg was fine with the USB changes and with the routing of these patches: https://www.spinics.net/lists/linux-usb/msg155093.html out-of-topic modifications in x86-debug-for-linus: ---------------------------------------------------- drivers/usb/Makefile # aeb9dd1de98c: usb/early: Add driver for xh drivers/usb/early/Makefile # aeb9dd1de98c: usb/early: Add driver for xh drivers/usb/early/xhci-dbc.c # aeb9dd1de98c: usb/early: Add driver for xh drivers/usb/early/xhci-dbc.h # aeb9dd1de98c: usb/early: Add driver for xh drivers/usb/serial/usb_debug.c # 57fb47279a04: usb/serial: Add DBC debug de include/linux/usb/xhci-dbgp.h # aeb9dd1de98c: usb/early: Add driver for xh Thanks, Ingo ------------------> Lu Baolu (5): x86/timers: Add simple udelay calibration usb/early: Add driver for xhci debug capability x86/earlyprintk: Add support for earlyprintk via USB3 debug port usb/serial: Add DBC debug device support to usb_debug usb/doc: Add document for USB3 debug port usage Documentation/admin-guide/kernel-parameters.txt | 1 + Documentation/usb/usb3-debug-port.rst | 100 +++ arch/x86/Kconfig.debug | 27 +- arch/x86/kernel/early_printk.c | 5 + arch/x86/kernel/setup.c | 26 + drivers/usb/Makefile | 2 +- drivers/usb/early/Makefile | 1 + drivers/usb/early/xhci-dbc.c | 1014 +++++++++++++++++++++++ drivers/usb/early/xhci-dbc.h | 211 +++++ drivers/usb/serial/usb_debug.c | 28 +- include/linux/usb/xhci-dbgp.h | 29 + 11 files changed, 1438 insertions(+), 6 deletions(-) create mode 100644 Documentation/usb/usb3-debug-port.rst create mode 100644 drivers/usb/early/xhci-dbc.c create mode 100644 drivers/usb/early/xhci-dbc.h create mode 100644 include/linux/usb/xhci-dbgp.h diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 2ba45caabada..ea1293d60f17 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -989,6 +989,7 @@ earlyprintk=ttySn[,baudrate] earlyprintk=dbgp[debugController#] earlyprintk=pciserial,bus:device.function[,baudrate] + earlyprintk=xdbc[xhciController#] earlyprintk is useful when the kernel crashes before the normal console is initialized. It is not enabled by diff --git a/Documentation/usb/usb3-debug-port.rst b/Documentation/usb/usb3-debug-port.rst new file mode 100644 index 000000000000..feb1a36a65b7 --- /dev/null +++ b/Documentation/usb/usb3-debug-port.rst @@ -0,0 +1,100 @@ +=============== +USB3 debug port +=============== + +:Author: Lu Baolu +:Date: March 2017 + +GENERAL +======= + +This is a HOWTO for using the USB3 debug port on x86 systems. + +Before using any kernel debugging functionality based on USB3 +debug port, you need to:: + + 1) check whether any USB3 debug port is available in + your system; + 2) check which port is used for debugging purposes; + 3) have a USB 3.0 super-speed A-to-A debugging cable. + +INTRODUCTION +============ + +The xHCI debug capability (DbC) is an optional but standalone +functionality provided by the xHCI host controller. The xHCI +specification describes DbC in the section 7.6. + +When DbC is initialized and enabled, it will present a debug +device through the debug port (normally the first USB3 +super-speed port). The debug device is fully compliant with +the USB framework and provides the equivalent of a very high +performance full-duplex serial link between the debug target +(the system under debugging) and a debug host. + +EARLY PRINTK +============ + +DbC has been designed to log early printk messages. One use for +this feature is kernel debugging. For example, when your machine +crashes very early before the regular console code is initialized. +Other uses include simpler, lockless logging instead of a full- +blown printk console driver and klogd. + +On the debug target system, you need to customize a debugging +kernel with CONFIG_EARLY_PRINTK_USB_XDBC enabled. And, add below +kernel boot parameter:: + + "earlyprintk=xdbc" + +If there are multiple xHCI controllers in your system, you can +append a host contoller index to this kernel parameter. This +index starts from 0. + +Current design doesn't support DbC runtime suspend/resume. As +the result, you'd better disable runtime power management for +USB subsystem by adding below kernel boot parameter:: + + "usbcore.autosuspend=-1" + +Before starting the debug target, you should connect the debug +port to a USB port (root port or port of any external hub) on +the debug host. The cable used to connect these two ports +should be a USB 3.0 super-speed A-to-A debugging cable. + +During early boot of the debug target, DbC will be detected and +initialized. After initialization, the debug host should be able +to enumerate the debug device in debug target. The debug host +will then bind the debug device with the usb_debug driver module +and create the /dev/ttyUSB device. + +If the debug device enumeration goes smoothly, you should be able +to see below kernel messages on the debug host:: + + # tail -f /var/log/kern.log + [ 1815.983374] usb 4-3: new SuperSpeed USB device number 4 using xhci_hcd + [ 1815.999595] usb 4-3: LPM exit latency is zeroed, disabling LPM. + [ 1815.999899] usb 4-3: New USB device found, idVendor=1d6b, idProduct=0004 + [ 1815.999902] usb 4-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3 + [ 1815.999903] usb 4-3: Product: Remote GDB + [ 1815.999904] usb 4-3: Manufacturer: Linux + [ 1815.999905] usb 4-3: SerialNumber: 0001 + [ 1816.000240] usb_debug 4-3:1.0: xhci_dbc converter detected + [ 1816.000360] usb 4-3: xhci_dbc converter now attached to ttyUSB0 + +You can use any communication program, for example minicom, to +read and view the messages. Below simple bash scripts can help +you to check the sanity of the setup. + +.. code-block:: sh + + ===== start of bash scripts ============= + #!/bin/bash + + while true ; do + while [ ! -d /sys/class/tty/ttyUSB0 ] ; do + : + done + cat /dev/ttyUSB0 + done + ===== end of bash scripts =============== diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug index 63c1d13aaf9f..fcb7604172ce 100644 --- a/arch/x86/Kconfig.debug +++ b/arch/x86/Kconfig.debug @@ -5,6 +5,9 @@ config TRACE_IRQFLAGS_SUPPORT source "lib/Kconfig.debug" +config EARLY_PRINTK_USB + bool + config X86_VERBOSE_BOOTUP bool "Enable verbose x86 bootup info messages" default y @@ -23,19 +26,20 @@ config EARLY_PRINTK This is useful for kernel debugging when your machine crashes very early before the console code is initialized. For normal operation it is not recommended because it looks ugly and doesn't cooperate - with klogd/syslogd or the X server. You should normally N here, + with klogd/syslogd or the X server. You should normally say N here, unless you want to debug such a crash. config EARLY_PRINTK_DBGP bool "Early printk via EHCI debug port" depends on EARLY_PRINTK && PCI + select EARLY_PRINTK_USB ---help--- Write kernel log output directly into the EHCI debug port. This is useful for kernel debugging when your machine crashes very early before the console code is initialized. For normal operation it is not recommended because it looks ugly and doesn't cooperate - with klogd/syslogd or the X server. You should normally N here, + with klogd/syslogd or the X server. You should normally say N here, unless you want to debug such a crash. You need usb debug device. config EARLY_PRINTK_EFI @@ -48,6 +52,25 @@ config EARLY_PRINTK_EFI This is useful for kernel debugging when your machine crashes very early before the console code is initialized. +config EARLY_PRINTK_USB_XDBC + bool "Early printk via the xHCI debug port" + depends on EARLY_PRINTK && PCI + select EARLY_PRINTK_USB + ---help--- + Write kernel log output directly into the xHCI debug port. + + One use for this feature is kernel debugging, for example when your + machine crashes very early before the regular console code is + initialized. Other uses include simpler, lockless logging instead of + a full-blown printk console driver + klogd. + + For normal production environments this is normally not recommended, + because it doesn't feed events into klogd/syslogd and doesn't try to + print anything on the screen. + + You should normally say N here, unless you want to debug early + crashes or need a very simple printk logging facility. + config X86_PTDUMP_CORE def_bool n diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c index 8a121991e5ba..0f0840304452 100644 --- a/arch/x86/kernel/early_printk.c +++ b/arch/x86/kernel/early_printk.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include @@ -381,6 +382,10 @@ static int __init setup_early_printk(char *buf) if (!strncmp(buf, "efi", 3)) early_console_register(&early_efi_console, keep); #endif +#ifdef CONFIG_EARLY_PRINTK_USB_XDBC + if (!strncmp(buf, "xdbc", 4)) + early_xdbc_parse_parameter(buf + 4); +#endif buf++; } diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 4bf0c8926a1c..2600b1d0043b 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -70,6 +70,7 @@ #include #include +#include #include