diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/debugfs-kmemtrace | 71 | ||||
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-pci | 27 | ||||
| -rw-r--r-- | Documentation/DocBook/device-drivers.tmpl | 1 | ||||
| -rw-r--r-- | Documentation/feature-removal-schedule.txt | 33 | ||||
| -rw-r--r-- | Documentation/filesystems/sysfs-pci.txt | 7 | ||||
| -rw-r--r-- | Documentation/filesystems/sysfs.txt | 46 | ||||
| -rw-r--r-- | Documentation/firmware_class/hotplug-script | 17 | ||||
| -rw-r--r-- | Documentation/hwmon/pkgtemp | 36 | ||||
| -rw-r--r-- | Documentation/kernel-parameters.txt | 7 | ||||
| -rw-r--r-- | Documentation/pcmcia/driver-changes.txt | 12 | ||||
| -rw-r--r-- | Documentation/timers/timers-howto.txt | 105 | ||||
| -rw-r--r-- | Documentation/trace/ftrace-design.txt | 153 | ||||
| -rw-r--r-- | Documentation/trace/kmemtrace.txt | 126 | ||||
| -rw-r--r-- | Documentation/trace/kprobetrace.txt | 2 |
14 files changed, 375 insertions, 268 deletions
diff --git a/Documentation/ABI/testing/debugfs-kmemtrace b/Documentation/ABI/testing/debugfs-kmemtrace deleted file mode 100644 index 5e6a92a02d85..000000000000 --- a/Documentation/ABI/testing/debugfs-kmemtrace +++ /dev/null @@ -1,71 +0,0 @@ -What: /sys/kernel/debug/kmemtrace/ -Date: July 2008 -Contact: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro> -Description: - -In kmemtrace-enabled kernels, the following files are created: - -/sys/kernel/debug/kmemtrace/ - cpu<n> (0400) Per-CPU tracing data, see below. (binary) - total_overruns (0400) Total number of bytes which were dropped from - cpu<n> files because of full buffer condition, - non-binary. (text) - abi_version (0400) Kernel's kmemtrace ABI version. (text) - -Each per-CPU file should be read according to the relay interface. That is, -the reader should set affinity to that specific CPU and, as currently done by -the userspace application (though there are other methods), use poll() with -an infinite timeout before every read(). Otherwise, erroneous data may be -read. The binary data has the following _core_ format: - - Event ID (1 byte) Unsigned integer, one of: - 0 - represents an allocation (KMEMTRACE_EVENT_ALLOC) - 1 - represents a freeing of previously allocated memory - (KMEMTRACE_EVENT_FREE) - Type ID (1 byte) Unsigned integer, one of: - 0 - this is a kmalloc() / kfree() - 1 - this is a kmem_cache_alloc() / kmem_cache_free() - 2 - this is a __get_free_pages() et al. - Event size (2 bytes) Unsigned integer representing the - size of this event. Used to extend - kmemtrace. Discard the bytes you - don't know about. - Sequence number (4 bytes) Signed integer used to reorder data - logged on SMP machines. Wraparound - must be taken into account, although - it is unlikely. - Caller address (8 bytes) Return address to the caller. - Pointer to mem (8 bytes) Pointer to target memory area. Can be - NULL, but not all such calls might be - recorded. - -In case of KMEMTRACE_EVENT_ALLOC events, the next fields follow: - - Requested bytes (8 bytes) Total number of requested bytes, - unsigned, must not be zero. - Allocated bytes (8 bytes) Total number of actually allocated - bytes, unsigned, must not be lower - than requested bytes. - Requested flags (4 bytes) GFP flags supplied by the caller. - Target CPU (4 bytes) Signed integer, valid for event id 1. - If equal to -1, target CPU is the same - as origin CPU, but the reverse might - not be true. - -The data is made available in the same endianness the machine has. - -Other event ids and type ids may be defined and added. Other fields may be -added by increasing event size, but see below for details. -Every modification to the ABI, including new id definitions, are followed -by bumping the ABI version by one. - -Adding new data to the packet (features) is done at the end of the mandatory -data: - Feature size (2 byte) - Feature ID (1 byte) - Feature data (Feature size - 3 bytes) - - -Users: - kmemtrace-user - git://repo.or.cz/kmemtrace-user.git - diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci index 25be3250f7d6..f979d825d112 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci +++ b/Documentation/ABI/testing/sysfs-bus-pci @@ -139,3 +139,30 @@ Contact: linux-pci@vger.kernel.org Description: This symbolic link points to the PCI hotplug controller driver module that manages the hotplug slot. + +What: /sys/bus/pci/devices/.../label +Date: July 2010 +Contact: Narendra K <narendra_k@dell.com>, linux-bugs@dell.com +Description: + Reading this attribute will provide the firmware + given name(SMBIOS type 41 string) of the PCI device. + The attribute will be created only if the firmware + has given a name to the PCI device. +Users: + Userspace applications interested in knowing the + firmware assigned name of the PCI device. + +What: /sys/bus/pci/devices/.../index +Date: July 2010 +Contact: Narendra K <narendra_k@dell.com>, linux-bugs@dell.com +Description: + Reading this attribute will provide the firmware + given instance(SMBIOS type 41 device type instance) + of the PCI device. The attribute will be created + only if the firmware has given a device type instance + to the PCI device. +Users: + Userspace applications interested in knowing the + firmware assigned device type instance of the PCI + device that can help in understanding the firmware + intended order of the PCI device. diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl index 1b2dd4fc3db2..ecd35e9d4410 100644 --- a/Documentation/DocBook/device-drivers.tmpl +++ b/Documentation/DocBook/device-drivers.tmpl @@ -111,6 +111,7 @@ X!Edrivers/base/attribute_container.c <!-- X!Edrivers/base/interface.c --> +!Iinclude/linux/platform_device.h !Edrivers/base/platform.c !Edrivers/base/bus.c </sect1> diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index be7030e4dd73..71f0fea1058f 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -116,29 +116,6 @@ Who: Mauro Carvalho Chehab <mchehab@infradead.org> --------------------------- -What: PCMCIA control ioctl (needed for pcmcia-cs [cardmgr, cardctl]) -When: 2.6.35/2.6.36 -Files: drivers/pcmcia/: pcmcia_ioctl.c -Why: With the 16-bit PCMCIA subsystem now behaving (almost) like a - normal hotpluggable bus, and with it using the default kernel - infrastructure (hotplug, driver core, sysfs) keeping the PCMCIA - control ioctl needed by cardmgr and cardctl from pcmcia-cs is - unnecessary and potentially harmful (it does not provide for - proper locking), and makes further cleanups and integration of the - PCMCIA subsystem into the Linux kernel device driver model more - difficult. The features provided by cardmgr and cardctl are either - handled by the kernel itself now or are available in the new - pcmciautils package available at - http://kernel.org/pub/linux/utils/kernel/pcmcia/ - - For all architectures except ARM, the associated config symbol - has been removed from kernel 2.6.34; for ARM, it will be likely - be removed from kernel 2.6.35. The actual code will then likely - be removed from kernel 2.6.36. -Who: Dominik Brodowski <linux@dominikbrodowski.net> - ---------------------------- - What: sys_sysctl When: September 2010 Option: CONFIG_SYSCTL_SYSCALL @@ -468,16 +445,6 @@ Who: Jan Kiszka <jan.kiszka@web.de> ---------------------------- -What: xtime, wall_to_monotonic -When: 2.6.36+ -Files: kernel/time/timekeeping.c include/linux/time.h -Why: Cleaning up timekeeping internal values. Please use - existing timekeeping accessor functions to access - the equivalent functionality. -Who: John Stultz <johnstul@us.ibm.com> - ----------------------------- - What: KVM paravirt mmu host support When: January 2011 Why: The paravirt mmu host support is slower than non-paravirt mmu, both diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt index 85354b32d731..74eaac26f8b8 100644 --- a/Documentation/filesystems/sysfs-pci.txt +++ b/Documentation/filesystems/sysfs-pci.txt @@ -39,7 +39,7 @@ files, each with their own function. local_cpus nearby CPU mask (cpumask, ro) remove remove device from kernel's list (ascii, wo) resource PCI resource host addresses (ascii, ro) - resource0..N PCI resource N, if present (binary, mmap) + resource0..N PCI resource N, if present (binary, mmap, rw[1]) resource0_wc..N_wc PCI WC map resource N, if prefetchable (binary, mmap) rom PCI ROM resource, if present (binary, ro) subsystem_device PCI subsystem device (ascii, ro) @@ -54,13 +54,16 @@ files, each with their own function. binary - file contains binary data cpumask - file contains a cpumask type +[1] rw for RESOURCE_IO (I/O port) regions only + The read only files are informational, writes to them will be ignored, with the exception of the 'rom' file. Writable files can be used to perform actions on the device (e.g. changing config space, detaching a device). mmapable files are available via an mmap of the file at offset 0 and can be used to do actual device programming from userspace. Note that some platforms don't support mmapping of certain resources, so be sure to check the return -value from any attempted mmap. +value from any attempted mmap. The most notable of these are I/O port +resources, which also provide read/write access. The 'enable' file provides a counter that indicates how many times the device has been enabled. If the 'enable' file currently returns '4', and a '1' is diff --git a/Documentation/filesystems/sysfs.txt b/Documentation/filesystems/sysfs.txt index 931c806642c5..5d1335faec2d 100644 --- a/Documentation/filesystems/sysfs.txt +++ b/Documentation/filesystems/sysfs.txt @@ -4,7 +4,7 @@ sysfs - _The_ filesystem for exporting kernel objects. Patrick Mochel <mochel@osdl.org> Mike Murphy <mamurph@cs.clemson.edu> -Revised: 22 February 2009 +Revised: 15 July 2010 Original: 10 January 2003 @@ -124,7 +124,7 @@ show and store methods of the attribute owners. struct sysfs_ops { ssize_t (*show)(struct kobject *, struct attribute *, char *); - ssize_t (*store)(struct kobject *, struct attribute *, const char *); + ssize_t (*store)(struct kobject *, struct attribute *, const char *, size_t); }; [ Subsystems should have already defined a struct kobj_type as a @@ -139,18 +139,22 @@ calls the associated methods. To illustrate: +#define to_dev(obj) container_of(obj, struct device, kobj) #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr) -#define to_dev(d) container_of(d, struct device, kobj) -static ssize_t -dev_attr_show(struct kobject * kobj, struct attribute * attr, char * buf) +static ssize_t dev_attr_show(struct kobject *kobj, struct attribute *attr, + char *buf) { - struct device_attribute * dev_attr = to_dev_attr(attr); - struct device * dev = to_dev(kobj); - ssize_t ret = 0; + struct device_attribute *dev_attr = to_dev_attr(attr); + struct device *dev = to_dev(kobj); + ssize_t ret = -EIO; if (dev_attr->show) - ret = dev_attr->show(dev, buf); + ret = dev_attr->show(dev, dev_attr, buf); + if (ret >= (ssize_t)PAGE_SIZE) { + print_symbol("dev_attr_show: %s returned bad count\n", + (unsigned long)dev_attr->show); + } return ret; } @@ -163,10 +167,9 @@ To read or write attributes, show() or store() methods must be specified when declaring the attribute. The method types should be as simple as those defined for device attributes: -ssize_t (*show)(struct device * dev, struct device_attribute * attr, - char * buf); -ssize_t (*store)(struct device * dev, struct device_attribute * attr, - const char * buf); +ssize_t (*show)(struct device *dev, struct device_attribute *attr, char *buf); +ssize_t (*store)(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count); IOW, they should take only an object, an attribute, and a buffer as parameters. @@ -209,8 +212,8 @@ Other notes: - show() should always use snprintf(). -- store() should return the number of bytes used from the buffer. This - can be done using strlen(). +- store() should return the number of bytes used from the buffer. If the + entire buffer has been used, just return the count argument. - show() or store() can always return errors. If a bad value comes through, be sure to return an error. @@ -223,15 +226,18 @@ Other notes: A very simple (and naive) implementation of a device attribute is: -static ssize_t show_name(struct device *dev, struct device_attribute *attr, char *buf) +static ssize_t show_name(struct device *dev, struct device_attribute *attr, + char *buf) { return snprintf(buf, PAGE_SIZE, "%s\n", dev->name); } -static ssize_t store_name(struct device * dev, const char * buf) +static ssize_t store_name(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) { - sscanf(buf, "%20s", dev->name); - return strnlen(buf, PAGE_SIZE); + snprintf(dev->name, sizeof(dev->name), "%.*s", + (int)min(count, sizeof(dev->name) - 1), buf); + return count; } static DEVICE_ATTR(name, S_IRUGO, show_name, store_name); @@ -327,7 +333,7 @@ Structure: struct bus_attribute { struct attribute attr; ssize_t (*show)(struct bus_type *, char * buf); - ssize_t (*store)(struct bus_type *, const char * buf); + ssize_t (*store)(struct bus_type *, const char * buf, size_t count); }; Declaring: diff --git a/Documentation/firmware_class/hotplug-script b/Documentation/firmware_class/hotplug-script index 1990130f2ab1..8143a950b607 100644 --- a/Documentation/firmware_class/hotplug-script +++ b/Documentation/firmware_class/hotplug-script @@ -6,11 +6,12 @@ HOTPLUG_FW_DIR=/usr/lib/hotplug/firmware/ -echo 1 > /sys/$DEVPATH/loading -cat $HOTPLUG_FW_DIR/$FIRMWARE > /sys/$DEVPATH/data -echo 0 > /sys/$DEVPATH/loading - -# To cancel the load in case of error: -# -# echo -1 > /sys/$DEVPATH/loading -# +if [ "$SUBSYSTEM" == "firmware" -a "$ACTION" == "add" ]; then + if [ -f $HOTPLUG_FW_DIR/$FIRMWARE ]; then + echo 1 > /sys/$DEVPATH/loading + cat $HOTPLUG_FW_DIR/$FIRMWARE > /sys/$DEVPATH/data + echo 0 > /sys/$DEVPATH/loading + else + echo -1 > /sys/$DEVPATH/loading + fi +fi diff --git a/Documentation/hwmon/pkgtemp b/Documentation/hwmon/pkgtemp new file mode 100644 index 000000000000..c8e1fb0fadd3 --- /dev/null +++ b/Documentation/hwmon/pkgtemp @@ -0,0 +1,36 @@ +Kernel driver pkgtemp +====================== + +Supported chips: + * Intel family + Prefix: 'pkgtemp' + CPUID: + Datasheet: Intel 64 and IA-32 Architectures Software Developer's Manual + Volume 3A: System Programming Guide + +Author: Fenghua Yu + +Description +----------- + +This driver permits reading package level temperature sensor embedded inside +Intel CPU package. The sensors can be in core, uncore, memory controller, or +other components in a package. The feature is first implemented in Intel Sandy +Bridge platform. + +Temperature is measured in degrees Celsius and measurement resolution is +1 degree C. Valid temperatures are from 0 to TjMax degrees C, because the actual +value of temperature register is in fact a delta from TjMax. + +Temperature known as TjMax is the maximum junction temperature of package. +We get this from MSR_IA32_TEMPERATURE_TARGET. If the MSR is not accessible, +we define TjMax as 100 degrees Celsius. At this temperature, protection +mechanism will perform actions to forcibly cool down the package. Alarm +may be raised, if the temperature grows enough (more than TjMax) to trigger +the Out-Of-Spec bit. Following table summarizes the exported sysfs files: + +temp1_input - Package temperature (in millidegrees Celsius). +temp1_max - All cooling devices should be turned on. +temp1_crit - Maximum junction temperature (in millidegrees Celsius). +temp1_crit_alarm - Set when Out-of-spec bit is set, never clears. + Correct CPU operation is no longer guaranteed. diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index f72ba727441f..71d286307cae 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -73,7 +73,6 @@ parameter is applicable: MTD MTD (Memory Technology Device) support is enabled. NET Appropriate network support is enabled. NUMA NUMA support is enabled. - GENERIC_TIME The generic timeofday code is enabled. NFS Appropriate NFS support is enabled. OSS OSS sound support is enabled. PV_OPS A paravirtualized kernel is enabled. @@ -470,7 +469,7 @@ and is between 256 and 4096 characters. It is defined in the file clocksource is not available, it defaults to PIT. Format: { pit | tsc | cyclone | pmtmr } - clocksource= [GENERIC_TIME] Override the default clocksource + clocksource= Override the default clocksource Format: <string> Override the default clocksource and use the clocksource with the name specified. @@ -1816,6 +1815,8 @@ and is between 256 and 4096 characters. It is defined in the file nousb [USB] Disable the USB subsystem + nowatchdog [KNL] Disable the lockup detector. + nowb [ARM] nox2apic [X86-64,APIC] Do not enable x2APIC mode. @@ -1974,6 +1975,8 @@ and is between 256 and 4096 characters. It is defined in the file norom [X86] Do not assign address space to expansion ROMs that do not already have BIOS assigned address ranges. + nobar [X86] Do not assign address space to the + BARs that weren't assigned by the BIOS. irqmask=0xMMMM [X86] Set a bit mask of IRQs allowed to be assigned automatically to PCI devices. You can make the kernel exclude IRQs of your ISA cards diff --git a/Documentation/pcmcia/driver-changes.txt b/Documentation/pcmcia/driver-changes.txt index 61bc4e943116..26c0f9c00545 100644 --- a/Documentation/pcmcia/driver-changes.txt +++ b/Documentation/pcmcia/driver-changes.txt @@ -1,4 +1,16 @@ This file details changes in 2.6 which affect PCMCIA card driver authors: +* pcmcia_request_io changes (as of 2.6.36) + Instead of io_req_t, drivers are now requested to fill out + struct pcmcia_device *p_dev->resource[0,1] for up to two ioport + ranges. After a call to pcmcia_request_io(), the ports found there + are reserved, after calling pcmcia_request_configuration(), they may + be used. + +* No dev_info_t, no cs_types.h (as of 2.6.36) + dev_info_t and a few other typedefs are removed. No longer use them + in PCMCIA device drivers. Also, do not include pcmcia/cs_types.h, as + this file is gone. + * No dev_node_t (as of 2.6.35) There is no more need to fill out a "dev_node_t" structure. diff --git a/Documentation/timers/timers-howto.txt b/Documentation/timers/timers-howto.txt new file mode 100644 index 000000000000..c9ef29d2ede3 --- /dev/null +++ b/Documentation/timers/timers-howto.txt @@ -0,0 +1,105 @@ +delays - Information on the various kernel delay / sleep mechanisms +------------------------------------------------------------------- + +This document seeks to answer the common question: "What is the +RightWay (TM) to insert a delay?" + +This question is most often faced by driver writers who have to +deal with hardware delays and who may not be the most intimately +familiar with the inner workings of the Linux Kernel. + + +Inserting Delays +---------------- + +The first, and most important, question you need to ask is "Is my +code in an atomic context?" This should be followed closely by "Does +it really need to delay in atomic context?" If so... + +ATOMIC CONTEXT: + You must use the *delay family of functions. These + functions use the jiffie estimation of clock speed + and will busy wait for enough loop cycles to achieve + the desired delay: + + ndelay(unsigned long nsecs) + udelay(unsigned long usecs) + mdelay(unsgined long msecs) + + udelay is the generally preferred API; ndelay-level + precision may not actually exist on many non-PC devices. + + mdelay is macro wrapper around udelay, to account for + possible overflow when passing large arguments to udelay. + In general, use of mdelay is discouraged and code should + be refactored to allow for the use of msleep. + +NON-ATOMIC CONTEXT: + You should use the *sleep[_range] family of functions. + There are a few more options here, while any of them may + work correctly, using the "right" sleep function will + help the scheduler, power management, and just make your + driver better :) + + -- Backed by busy-wait loop: + udelay(unsigned long usecs) + -- Backed by hrtimers: + usleep_range(unsigned long min, unsigned long max) + -- Backed by jiffies / legacy_timers + msleep(unsigned long msecs) + msleep_interruptible(unsigned long msecs) + + Unlike the *delay family, the underlying mechanism + driving each of these calls varies, thus there are + quirks you should be aware of. + + + SLEEPING FOR "A FEW" USECS ( < ~10us? ): + * Use udelay + + - Why not usleep? + On slower systems, (embedded, OR perhaps a speed- + stepped PC!) the overhead of setting up the hrtimers + for usleep *may* not be worth it. Such an evaluation + will obviously depend on your specific situation, but + it is something to be aware of. + + SLEEPING FOR ~USECS OR SMALL MSECS ( 10us - 20ms): + * Use usleep_range + + - Why not msleep for (1ms - 20ms)? + Explained originally here: + http://lkml.org/lkml/2007/8/3/250 + msleep(1~20) may not do what the caller intends, and + will often sleep longer (~20 ms actual sleep for any + value given in the 1~20ms range). In many cases this + is not the desired behavior. + + - Why is there no "usleep" / What is a good range? + Since usleep_range is built on top of hrtimers, the + wakeup will be very precise (ish), thus a simple + usleep function would likely introduce a large number + of undesired interrupts. + + With the introduction of a range, the scheduler is + free to coalesce your wakeup with any other wakeup + that may have happened for other reasons, or at the + worst case, fire an interrupt for your upper bound. + + The larger a range you supply, the greater a chance + that you will not trigger an interrupt; this should + be balanced with what is an acceptable upper bound on + delay / performance for your specific code path. Exact + tolerances here are very situation specific, thus it + is left to the caller to determine a reasonable range. + + SLEEPING FOR LARGER MSECS ( 10ms+ ) + * Use msleep or possibly msleep_interruptible + + - What's the difference? + msleep sets the current task to TASK_UNINTERRUPTIBLE + whereas msleep_interruptible sets the current task to + TASK_INTERRUPTIBLE before scheduling the sleep. In + short, the difference is whether the sleep can be ended + early by a signal. In general, just use msleep unless + you know you have a need for the interruptible variant. diff --git a/Documentation/trace/ftrace-design.txt b/Documentation/trace/ftrace-design.txt index f1f81afee8a0..dc52bd442c92 100644 --- a/Documentation/trace/ftrace-design.txt +++ b/Documentation/trace/ftrace-design.txt @@ -13,6 +13,9 @@ Note that this focuses on architecture implementation details only. If you want more explanation of a feature in terms of common code, review the common ftrace.txt file. +Ideally, everyone who wishes to retain performance while supporting tracing in +their kernel should make it all the way to dynamic ftrace support. + Prerequisites ------------- @@ -215,7 +218,7 @@ An arch may pass in a unique value (frame pointer) to both the entering and exiting of a function. On exit, the value is compared and if it does not match, then it will panic the kernel. This is largely a sanity check for bad code generation with gcc. If gcc for your port sanely updates the frame -pointer under different opitmization levels, then ignore this option. +pointer under different optimization levels, then ignore this option. However, adding support for it isn't terribly difficult. In your assembly code that calls prepare_ftrace_return(), pass the frame pointer as the 3rd argument. @@ -234,7 +237,7 @@ If you can't trace NMI functions, then skip this option. HAVE_SYSCALL_TRACEPOINTS ---------------------- +------------------------ You need very few things to get the syscalls tracing in an arch. @@ -250,12 +253,152 @@ You need very few things to get the syscalls tracing in an arch. HAVE_FTRACE_MCOUNT_RECORD ------------------------- -See scripts/recordmcount.pl for more info. +See scripts/recordmcount.pl for more info. Just fill in the arch-specific +details for how to locate the addresses of mcount call sites via objdump. +This option doesn't make much sense without also implementing dynamic ftrace. + +HAVE_DYNAMIC_FTRACE +------------------- + +You will first need HAVE_FTRACE_MCOUNT_RECORD and HAVE_FUNCTION_TRACER, so +scroll your reader back up if you got over eager. + +Once those are out of the way, you will need to implement: + - asm/ftrace.h: + - MCOUNT_ADDR + - ftrace_call_adjust() + - struct dyn_arch_ftrace{} + - asm code: + - mcount() (new stub) + - ftrace_caller() + - ftrace_call() + - ftrace_stub() + - C code: + - ftrace_dyn_arch_init() + - ftrace_make_nop() + - ftrace_make_call() + - ftrace_update_ftrace_func() + +First you will need to fill out some arch details in your asm/ftrace.h. + +Define MCOUNT_ADDR as the address of your mcount symbol similar to: + #define MCOUNT_ADDR ((unsigned long)mcount) +Since no one else will have a decl for that function, you will need to: + extern void mcount(void); + +You will also need the helper function ftrace_call_adjust(). Most people +will be able to stub it out like so: + static inline unsigned long ftrace_call_adjust(unsigned long addr) + { + return addr; + } <details to be filled> +Lastly you will need the custom dyn_arch_ftrace structure. If you need +some extra state when runtime patching arbitrary call sites, this is the +place. For now though, create an empty struct: + struct dyn_arch_ftrace { + /* No extra data needed */ + }; + +With the header out of the way, we can fill out the assembly code. While we +did already create a mcount() function earlier, dynamic ftrace only wants a +stub function. This is because the mcount() will only be used during boot +and then all references to it will be patched out never to return. Instead, +the guts of the old mcount() will be used to create a new ftrace_caller() +function. Because the two are hard to merge, it will most likely be a lot +easier to have two separate definitions split up by #ifdefs. Same goes for +the ftrace_stub() as that will now be inlined in ftrace_caller(). + +Before we get confused anymore, let's check out some pseudo code so you can +implement your own stuff in assembly: -HAVE_DYNAMIC_FTRACE ---------------------- +void mcount(void) +{ + return; +} + +void ftrace_caller(void) +{ + /* implement HAVE_FUNCTION_TRACE_MCOUNT_TEST if you desire */ + + /* save all state needed by the ABI (see paragraph above) */ + + unsigned long frompc = ...; + unsigned long selfpc = <return address> - MCOUNT_INSN_SIZE; + +ftrace_call: + ftrace_stub(frompc, selfpc); + + /* restore all state needed by the ABI */ + +ftrace_stub: + return; +} + +This might look a little odd at first, but keep in mind that we will be runtime +patching multiple things. First, only functions that we actually want to trace +will be patched to call ftrace_caller(). Second, since we only have one tracer +active at a time, we will patch the ftrace_caller() function itself to call the +specific tracer in question. That is the point of the ftrace_call label. + +With that in mind, let's move on to the C code that will actually be doing the +runtime patching. You'll need a little knowledge of your arch's opcodes in +order to make it through the next section. + +Every arch has an init callback function. If you need to do something early on +to initialize some state, this is the time to do that. Otherwise, this simple +function below should be sufficient for most people: + +int __init ftrace_dyn_arch_init(void *data) +{ + /* return value is done indirectly via data */ + *(unsigned long *)data = 0; + + return 0; +} + +There are two functions that are used to do runtime patching of arbitrary +functions. The first is used to turn the mcount call site into a nop (which +is what helps us retain runtime performance when not tracing). The second is +used to turn the mcount call site into a call to an arbitrary location (but +typically that is ftracer_caller()). See the general function definition in +linux/ftrace.h for the functions: + ftrace_make_nop() + ftrace_make_call() +The rec->ip value is the address of the mcount call site that was collected +by the scripts/recordmcount.pl during build time. + +The last function is used to do runtime patching of the active tracer. This +will be modifying the assembly code at the location of the ftrace_call symbol +inside of the ftrace_caller() function. So you should have sufficient padding +at that location to support the new function calls you'll be inserting. Some +people will be using a "call" type instruction while others will be using a +"branch" type instruction. Specifically, the function is: + ftrace_update_ftrace_func() + + +HAVE_DYNAMIC_FTRACE + HAVE_FUNCTION_GRAPH_TRACER +------------------------------------------------ + +The function grapher needs a few tweaks in order to work with dynamic ftrace. +Basically, you will need to: + - update: + - ftrace_caller() + - ftrace_graph_call() + - ftrace_graph_caller() + - implement: + - ftrace_enable_ftrace_graph_caller() + - ftrace_disable_ftrace_graph_caller() <details to be filled> +Quick notes: + - add a nop stub after the ftrace_call location named ftrace_graph_call; + stub needs to be large enough to support a call to ftrace_graph_caller() + - update ftrace_graph_caller() to work with being called by the new + ftrace_caller() since some semantics may have changed + - ftrace_enable_ftrace_graph_caller() will runtime patch the + ftrace_graph_call location with a call to ftrace_graph_caller() + - ftrace_disable_ftrace_graph_caller() will runtime patch the + ftrace_graph_call location with nops diff --git a/Documentation/trace/kmemtrace.txt b/Documentation/trace/kmemtrace.txt deleted file mode 100644 index 6308735e58ca..000000000000 --- a/Documentation/trace/kmemtrace.txt +++ /dev/null @@ -1,126 +0,0 @@ - kmemtrace - Kernel Memory Tracer - - by Eduard - Gabriel Munteanu - <eduard.munteanu@linux360.ro> - -I. Introduction -=============== - -kmemtrace helps kernel developers figure out two things: -1) how different allocators (SLAB, SLUB etc.) perform -2) how kernel code allocates memory and how much - -To do this, we trace every allocation and export information to the userspace -through the relay interface. We export things such as the number of requested -bytes, the number of bytes actually allocated (i.e. including internal -fragmentation), whether this is a slab allocation or a plain kmalloc() and so -on. - -The actual analysis is performed by a userspace tool (see section III for -details on where to get it from). It logs the data exported by the kernel, -processes it and (as of writing this) can provide the following information: -- the total amount of memory allocated and fragmentation per call-site -- the amount of memory allocated and fragmentation per allocation -- total memory allocated and fragmentation in the collected dataset -- number of cross-CPU allocation and frees (makes sense in NUMA environments) - -Moreover, it can potentially find inconsistent and erroneous behavior in -kernel code, such as using slab free functions on kmalloc'ed memory or -allocating less memory than requested (but not truly failed allocations). - -kmemtrace also makes provisions for tracing on some arch and analysing the -data on another. - -II. Design and goals -==================== - -kmemtrace was designed to handle rather large amounts of data. Thus, it uses -the relay interface to export whatever is logged to userspace, which then -stores it. Analysis and reporting is done asynchronously, that is, after the -data is collected and stored. By design, it allows one to log and analyse -on different machines and different arches. - -As of writing this, the ABI is not considered stable, though it might not -change much. However, no guarantees are made about compatibility yet. When -deemed stable, the ABI should still allow easy extension while maintaining -backward compatibility. This is described further in Documentation/ABI. - -Summary of design goals: - - allow logging and analysis to be done across different machines - - be fast and anticipate usage in high-load environments (*) - - be reasonably extensible - - make it possible for GNU/Linux distributions to have kmemtrace - included in their repositories - -(*) - one of the reasons Pekka Enberg's original userspace data analysis - tool's code was rewritten from Perl to C (although this is more than a - simple conversion) - - -III. Quick usage guide -====================== - -1) Get a kernel that supports kmemtrace and build it accordingly (i.e. enable -CONFIG_KMEMTRACE). - -2) Get the userspace tool and build it: -$ git clone git://repo.or.cz/kmemtrace-user.git # current repository -$ cd kmemtrace-user/ -$ ./autogen.sh -$ ./configure -$ make - -3) Boot the kmemtrace-enabled kernel if you haven't, preferably in the -'single' runlevel (so that relay buffers don't fill up easily), and run -kmemtrace: -# '$' does not mean user, but root here. -$ mount -t debugfs none /sys/kernel/debug -$ mount -t proc none /proc -$ cd path/to/kmemtrace-user/ -$ ./kmemtraced -Wait a bit, then stop it with CTRL+C. -$ cat /sys/kernel/debug/kmemtrace/total_overruns # Check if we didn't - # overrun, should - # be zero. -$ (Optionally) [Run kmemtrace_check separately on each cpu[0-9]*.out file to - check its correctness] -$ ./kmemtrace-report - -Now you should have a nice and short summary of how the allocator performs. - -IV. FAQ and known issues -======================== - -Q: 'cat /sys/kernel/debug/kmemtrace/total_overruns' is non-zero, how do I fix -this? Should I worry? -A: If it's non-zero, this affects kmemtrace's accuracy, depending on how -large the number is. You can fix it by supplying a higher -'kmemtrace.subbufs=N' kernel parameter. ---- - -Q: kmemtrace_check reports errors, how do I fix this? Should I worry? -A: This is a bug and should be reported. It can occur for a variety of -reasons: - - possible bugs in relay code - - possible misuse of relay by kmemtrace - - timestamps being collected unorderly -Or you may fix it yourself and send us a patch. ---- - -Q: kmemtrace_report shows many errors, how do I fix this? Should I worry? -A: This is a known issue and I'm working on it. These might be true errors -in kernel code, which may have inconsistent behavior (e.g. allocating memory -with kmem_cache_alloc() and freeing it with kfree()). Pekka Enberg pointed -out this behavior may work with SLAB, but may fail with other allocators. - -It may also be due to lack of tracing in some unusual allocator functions. - -We don't want bug reports regarding this issue yet. ---- - -V. See also -=========== - -Documentation/kernel-parameters.txt -Documentation/ABI/testing/debugfs-kmemtrace - diff --git a/Documentation/trace/kprobetrace.txt b/Documentation/trace/kprobetrace.txt index ec94748ae65b..5f77d94598dd 100644 --- a/Documentation/trace/kprobetrace.txt +++ b/Documentation/trace/kprobetrace.txt @@ -42,7 +42,7 @@ Synopsis of kprobe_events +|-offs(FETCHARG) : Fetch memory at FETCHARG +|- offs address.(**) NAME=FETCHARG : Set NAME as the argument name of FETCHARG. FETCHARG:TYPE : Set TYPE as the type of FETCHARG. Currently, basic types - (u8/u16/u32/u64/s8/s16/s32/s64) are supported. + (u8/u16/u32/u64/s8/s16/s32/s64) and string are supported. (*) only for return probe. (**) this is useful for fetching a field of data structures. |