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* kdb: call vkdb_printf() from vprintk_default() only when wantedPetr Mladek2016-12-141-7/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | kdb_trap_printk allows to pass normal printk() messages to kdb via vkdb_printk(). For example, it is used to get backtrace using the classic show_stack(), see kdb_show_stack(). vkdb_printf() tries to avoid a potential infinite loop by disabling the trap. But this approach is racy, for example: CPU1 CPU2 vkdb_printf() // assume that kdb_trap_printk == 0 saved_trap_printk = kdb_trap_printk; kdb_trap_printk = 0; kdb_show_stack() kdb_trap_printk++; Problem1: Now, a nested printk() on CPU0 calls vkdb_printf() even when it should have been disabled. It will not cause a deadlock but... // using the outdated saved value: 0 kdb_trap_printk = saved_trap_printk; kdb_trap_printk--; Problem2: Now, kdb_trap_printk == -1 and will stay like this. It means that all messages will get passed to kdb from now on. This patch removes the racy saved_trap_printk handling. Instead, the recursion is prevented by a check for the locked CPU. The solution is still kind of racy. A non-related printk(), from another process, might get trapped by vkdb_printf(). And the wanted printk() might not get trapped because kdb_printf_cpu is assigned. But this problem existed even with the original code. A proper solution would be to get_cpu() before setting kdb_trap_printk and trap messages only from this CPU. I am not sure if it is worth the effort, though. In fact, the race is very theoretical. When kdb is running any of the commands that use kdb_trap_printk there is a single active CPU and the other CPUs should be in a holding pen inside kgdb_cpu_enter(). The only time this is violated is when there is a timeout waiting for the other CPUs to report to the holding pen. Finally, note that the situation is a bit schizophrenic. vkdb_printf() explicitly allows recursion but only from KDB code that calls kdb_printf() directly. On the other hand, the generic printk() recursion is not allowed because it might cause an infinite loop. This is why we could not hide the decision inside vkdb_printf() easily. Link: http://lkml.kernel.org/r/1480412276-16690-4-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kdb: properly synchronize vkdb_printf() calls with other CPUsPetr Mladek2016-12-142-18/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | kdb_printf_lock does not prevent other CPUs from entering the critical section because it is ignored when KDB_STATE_PRINTF_LOCK is set. The problematic situation might look like: CPU0 CPU1 vkdb_printf() if (!KDB_STATE(PRINTF_LOCK)) KDB_STATE_SET(PRINTF_LOCK); spin_lock_irqsave(&kdb_printf_lock, flags); vkdb_printf() if (!KDB_STATE(PRINTF_LOCK)) BANG: The PRINTF_LOCK state is set and CPU1 is entering the critical section without spinning on the lock. The problem is that the code tries to implement locking using two state variables that are not handled atomically. Well, we need a custom locking because we want to allow reentering the critical section on the very same CPU. Let's use solution from Petr Zijlstra that was proposed for a similar scenario, see https://lkml.kernel.org/r/20161018171513.734367391@infradead.org This patch uses the same trick with cmpxchg(). The only difference is that we want to handle only recursion from the same context and therefore we disable interrupts. In addition, KDB_STATE_PRINTF_LOCK is removed. In fact, we are not able to set it a non-racy way. Link: http://lkml.kernel.org/r/1480412276-16690-3-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kdb: remove unused kdb_event handlingPetr Mladek2016-12-142-3/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | kdb_event state variable is only set but never checked in the kernel code. http://www.spinics.net/lists/kdb/msg01733.html suggests that this variable affected WARN_CONSOLE_UNLOCKED() in the original implementation. But this check never went upstream. The semantic is unclear and racy. The value is updated after the kdb_printf_lock is acquired and after it is released. It should be symmetric at minimum. The value should be manipulated either inside or outside the locked area. Fortunately, it seems that the original function is gone and we could simply remove the state variable. Link: http://lkml.kernel.org/r/1480412276-16690-2-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Suggested-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel/debug/debug_core.c: more properly delay for secondary CPUsDouglas Anderson2016-12-141-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | We've got a delay loop waiting for secondary CPUs. That loop uses loops_per_jiffy. However, loops_per_jiffy doesn't actually mean how many tight loops make up a jiffy on all architectures. It is quite common to see things like this in the boot log: Calibrating delay loop (skipped), value calculated using timer frequency.. 48.00 BogoMIPS (lpj=24000) In my case I was seeing lots of cases where other CPUs timed out entering the debugger only to print their stack crawls shortly after the kdb> prompt was written. Elsewhere in kgdb we already use udelay(), so that should be safe enough to use to implement our timeout. We'll delay 1 ms for 1000 times, which should give us a full second of delay (just like the old code wanted) but allow us to notice that we're done every 1 ms. [akpm@linux-foundation.org: simplifications, per Daniel] Link: http://lkml.kernel.org/r/1477091361-2039-1-git-send-email-dianders@chromium.org Signed-off-by: Douglas Anderson <dianders@chromium.org> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Brian Norris <briannorris@chromium.org> Cc: <stable@vger.kernel.org> [4.0+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* printk/kdb: handle more message headersPetr Mladek2016-12-121-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 4bcc595ccd80 ("printk: reinstate KERN_CONT for printing continuation lines") allows to define more message headers for a single message. The motivation is that continuous lines might get mixed. Therefore it make sense to define the right log level for every piece of a cont line. This patch introduces printk_skip_headers() that will skip all headers and uses it in the kdb code instead of printk_skip_level(). This approach helps to fix other printk_skip_level() users independently. Link: http://lkml.kernel.org/r/1478695291-12169-3-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Cc: Joe Perches <joe@perches.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Jaroslav Kysela <perex@perex.cz> Cc: Takashi Iwai <tiwai@suse.com> Cc: Chris Mason <clm@fb.com> Cc: Josef Bacik <jbacik@fb.com> Cc: David Sterba <dsterba@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/init: Add 'rodata=off' boot cmdline parameter to disable read-only kernel ↵Kees Cook2016-02-221-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | mappings It may be useful to debug writes to the readonly sections of memory, so provide a cmdline "rodata=off" to allow for this. This can be expanded in the future to support "log" and "write" modes, but that will need to be architecture-specific. This also makes KDB software breakpoints more usable, as read-only mappings can now be disabled on any kernel. Suggested-by: H. Peter Anvin <hpa@zytor.com> Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: David Brown <david.brown@linaro.org> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Emese Revfy <re.emese@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mathias Krause <minipli@googlemail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: PaX Team <pageexec@freemail.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: kernel-hardening@lists.openwall.com Cc: linux-arch <linux-arch@vger.kernel.org> Link: http://lkml.kernel.org/r/1455748879-21872-3-git-send-email-keescook@chromium.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* module: use a structure to encapsulate layout.Rusty Russell2015-12-041-2/+2
| | | | | | | | | | | | | | Makes it easier to handle init vs core cleanly, though the change is fairly invasive across random architectures. It simplifies the rbtree code immediately, however, while keeping the core data together in the same cachline (now iff the rbtree code is enabled). Acked-by: Peter Zijlstra <peterz@infradead.org> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
* debug: prevent entering debug mode on panic/exception.Colin Cross2015-02-191-0/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On non-developer devices, kgdb prevents the device from rebooting after a panic. Incase of panics and exceptions, to allow the device to reboot, prevent entering debug mode to avoid getting stuck waiting for the user to interact with debugger. To avoid entering the debugger on panic/exception without any extra configuration, panic_timeout is being used which can be set via /proc/sys/kernel/panic at run time and CONFIG_PANIC_TIMEOUT sets the default value. Setting panic_timeout indicates that the user requested machine to perform unattended reboot after panic. We dont want to get stuck waiting for the user input incase of panic. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: kgdb-bugreport@lists.sourceforge.net Cc: linux-kernel@vger.kernel.org Cc: Android Kernel Team <kernel-team@android.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Sumit Semwal <sumit.semwal@linaro.org> Signed-off-by: Colin Cross <ccross@android.com> [Kiran: Added context to commit message. panic_timeout is used instead of break_on_panic and break_on_exception to honor CONFIG_PANIC_TIMEOUT Modified the commit as per community feedback] Signed-off-by: Kiran Raparthy <kiran.kumar@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* kdb: Const qualifier for kdb_getstr's prompt argumentDaniel Thompson2015-02-192-2/+2
| | | | | | | | | All current callers of kdb_getstr() can pass constant pointers via the prompt argument. This patch adds a const qualification to make explicit the fact that this is safe. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* kdb: Provide forward search at more promptDaniel Thompson2015-02-193-5/+26
| | | | | | | | | | | | | | | Currently kdb allows the output of comamnds to be filtered using the | grep feature. This is useful but does not permit the output emitted shortly after a string match to be examined without wading through the entire unfiltered output of the command. Such a feature is particularly useful to navigate function traces because these traces often have a useful trigger string *before* the point of interest. This patch reuses the existing filtering logic to introduce a simple forward search to kdb that can be triggered from the more prompt. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* kdb: Fix a prompt management bug when using | grepDaniel Thompson2015-02-191-2/+2
| | | | | | | | | | | | | | | Currently when the "| grep" feature is used to filter the output of a command then the prompt is not displayed for the subsequent command. Likewise any characters typed by the user are also not echoed to the display. This rather disconcerting problem eventually corrects itself when the user presses Enter and the kdb_grepping_flag is cleared as kdb_parse() tries to make sense of whatever they typed. This patch resolves the problem by moving the clearing of this flag from the middle of command processing to the beginning. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* kdb: Remove stack dump when entering kgdb due to NMIDaniel Thompson2015-02-191-1/+0
| | | | | | | | | | | | | | | Issuing a stack dump feels ergonomically wrong when entering due to NMI. Entering due to NMI is normally a reaction to a user request, either the NMI button on a server or a "magic knock" on a UART. Therefore the backtrace behaviour on entry due to NMI should be like SysRq-g (no stack dump) rather than like oops. Note also that the stack dump does not offer any information that cannot be trivial retrieved using the 'bt' command. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* kdb: Avoid printing KERN_ levels to consolesDaniel Thompson2015-02-191-9/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently when kdb traps printk messages then the raw log level prefix (consisting of '\001' followed by a numeral) does not get stripped off before the message is issued to the various I/O handlers supported by kdb. This causes annoying visual noise as well as causing problems grepping for ^. It is also a change of behaviour compared to normal usage of printk() usage. For example <SysRq>-h ends up with different output to that of kdb's "sr h". This patch addresses the problem by stripping log levels from messages before they are issued to the I/O handlers. printk() which can also act as an i/o handler in some cases is special cased; if the caller provided a log level then the prefix will be preserved when sent to printk(). The addition of non-printable characters to the output of kdb commands is a regression, albeit and extremely elderly one, introduced by commit 04d2c8c83d0e ("printk: convert the format for KERN_<LEVEL> to a 2 byte pattern"). Note also that this patch does *not* restore the original behaviour from v3.5. Instead it makes printk() from within a kdb command display the message without any prefix (i.e. like printk() normally does). Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Joe Perches <joe@perches.com> Cc: stable@vger.kernel.org Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* kdb: Fix off by one error in kdb_cpu()Jason Wessel2015-02-192-2/+2
| | | | | | | | | | | | | | | | | | | There was a follow on replacement patch against the prior "kgdb: Timeout if secondary CPUs ignore the roundup". See: https://lkml.org/lkml/2015/1/7/442 This patch is the delta vs the patch that was committed upstream: * Fix an off-by-one error in kdb_cpu(). * Replace NR_CPUS with CONFIG_NR_CPUS to tell checkpatch that we really want a static limit. * Removed the "KGDB: " prefix from the pr_crit() in debug_core.c (kgdb-next contains a patch which introduced pr_fmt() to this file to the tag will now be applied automatically). Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: <stable@vger.kernel.org> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* kdb: fix incorrect counts in KDB summary command outputJay Lan2015-02-191-1/+1
| | | | | | | | | | | | | | | The output of KDB 'summary' command should report MemTotal, MemFree and Buffers output in kB. Current codes report in unit of pages. A define of K(x) as is defined in the code, but not used. This patch would apply the define to convert the values to kB. Please include me on Cc on replies. I do not subscribe to linux-kernel. Signed-off-by: Jay Lan <jlan@sgi.com> Cc: <stable@vger.kernel.org> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* Merge tag 'fixes-for-linus' of ↵Linus Torvalds2015-01-231-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux Pull module and param fixes from Rusty Russell: "Surprising number of fixes this merge window :( The first two are minor fallout from the param rework which went in this merge window. The next three are a series which fixes a longstanding (but never previously reported and unlikely , so no CC stable) race between kallsyms and freeing the init section. Finally, a minor cleanup as our module refcount will now be -1 during unload" * tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: module: make module_refcount() a signed integer. module: fix race in kallsyms resolution during module load success. module: remove mod arg from module_free, rename module_memfree(). module_arch_freeing_init(): new hook for archs before module->module_init freed. param: fix uninitialized read with CONFIG_DEBUG_LOCK_ALLOC param: initialize store function to NULL if not available.
| * module: make module_refcount() a signed integer.Rusty Russell2015-01-221-1/+1
| | | | | | | | | | | | | | | | | | | | | | James Bottomley points out that it will be -1 during unload. It's only used for diagnostics, so let's not hide that as it could be a clue as to what's gone wrong. Cc: Jason Wessel <jason.wessel@windriver.com> Acked-and-documention-added-by: James Bottomley <James.Bottomley@HansenPartnership.com> Reviewed-by: Masami Hiramatsu <maasami.hiramatsu.pt@hitachi.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
* | kernel/debug/debug_core.c: Logging clean-upFabian Frederick2014-11-111-22/+21
| | | | | | | | | | | | | | | | | | | | | | | | -Convert printk( to pr_foo() -Add pr_fmt -Coalesce formats Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Joe Perches <joe@perches.com> Signed-off-by: Fabian Frederick <fabf@skynet.be> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* | kgdb: timeout if secondary CPUs ignore the roundupDaniel Thompson2014-11-113-3/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently if an active CPU fails to respond to a roundup request the CPU that requested the roundup will become stuck. This needlessly reduces the robustness of the debugger. This patch introduces a timeout allowing the system state to be examined even when the system contains unresponsive processors. It also modifies kdb's cpu command to make it censor attempts to switch to unresponsive processors and to report their state as (D)ead. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* | kdb: Allow access to sensitive commands to be restricted by defaultDaniel Thompson2014-11-111-1/+1
| | | | | | | | | | | | | | | | | | | | Currently kiosk mode must be explicitly requested by the bootloader or userspace. It is convenient to be able to change the default value in a similar manner to CONFIG_MAGIC_SYSRQ_DEFAULT_MASK. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* | kdb: Add enable mask for groups of commandsAnton Vorontsov2014-11-111-1/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently all kdb commands are enabled whenever kdb is deployed. This makes it difficult to deploy kdb to help debug certain types of systems. Android phones provide one example; the FIQ debugger found on some Android devices has a deliberately weak set of commands to allow the debugger to enabled very late in the production cycle. Certain kiosk environments offer another interesting case where an engineer might wish to probe the system state using passive inspection commands without providing sufficient power for a passer by to root it. Without any restrictions, obtaining the root rights via KDB is a matter of a few commands, and works everywhere. For example, log in as a normal user: cbou:~$ id uid=1001(cbou) gid=1001(cbou) groups=1001(cbou) Now enter KDB (for example via sysrq): Entering kdb (current=0xffff8800065bc740, pid 920) due to Keyboard Entry kdb> ps 23 sleeping system daemon (state M) processes suppressed, use 'ps A' to see all. Task Addr Pid Parent [*] cpu State Thread Command 0xffff8800065bc740 920 919 1 0 R 0xffff8800065bca20 *bash 0xffff880007078000 1 0 0 0 S 0xffff8800070782e0 init [...snip...] 0xffff8800065be3c0 918 1 0 0 S 0xffff8800065be6a0 getty 0xffff8800065b9c80 919 1 0 0 S 0xffff8800065b9f60 login 0xffff8800065bc740 920 919 1 0 R 0xffff8800065bca20 *bash All we need is the offset of cred pointers. We can look up the offset in the distro's kernel source, but it is unnecessary. We can just start dumping init's task_struct, until we see the process name: kdb> md 0xffff880007078000 0xffff880007078000 0000000000000001 ffff88000703c000 ................ 0xffff880007078010 0040210000000002 0000000000000000 .....!@......... [...snip...] 0xffff8800070782b0 ffff8800073e0580 ffff8800073e0580 ..>.......>..... 0xffff8800070782c0 0000000074696e69 0000000000000000 init............ ^ Here, 'init'. Creds are just above it, so the offset is 0x02b0. Now we set up init's creds for our non-privileged shell: kdb> mm 0xffff8800065bc740+0x02b0 0xffff8800073e0580 0xffff8800065bc9f0 = 0xffff8800073e0580 kdb> mm 0xffff8800065bc740+0x02b8 0xffff8800073e0580 0xffff8800065bc9f8 = 0xffff8800073e0580 And thus gaining the root: kdb> go cbou:~$ id uid=0(root) gid=0(root) groups=0(root) cbou:~$ bash root:~# p.s. No distro enables kdb by default (although, with a nice KDB-over-KMS feature availability, I would expect at least some would enable it), so it's not actually some kind of a major issue. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* | kdb: Categorize kdb commands (similar to SysRq categorization)Daniel Thompson2014-11-112-40/+101
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch introduces several new flags to collect kdb commands into groups (later allowing them to be optionally disabled). This follows similar prior art to enable/disable magic sysrq commands. The commands have been categorized as follows: Always on: go (w/o args), env, set, help, ?, cpu (w/o args), sr, dmesg, disable_nmi, defcmd, summary, grephelp Mem read: md, mdr, mdp, mds, ef, bt (with args), per_cpu Mem write: mm Reg read: rd Reg write: go (with args), rm Inspect: bt (w/o args), btp, bta, btc, btt, ps, pid, lsmod Flow ctrl: bp, bl, bph, bc, be, bd, ss Signal: kill Reboot: reboot All: cpu, kgdb, (and all of the above), nmi_console Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* | kdb: Remove KDB_REPEAT_NONE flagAnton Vorontsov2014-11-112-33/+32
| | | | | | | | | | | | | | | | | | | | | | | | Since we now treat KDB_REPEAT_* as flags, there is no need to pass KDB_REPEAT_NONE. It's just the default behaviour when no flags are specified. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* | kdb: Use KDB_REPEAT_* values as flagsAnton Vorontsov2014-11-111-14/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The actual values of KDB_REPEAT_* enum values and overall logic stayed the same, but we now treat the values as flags. This makes it possible to add other flags and combine them, plus makes the code a lot simpler and shorter. But functionality-wise, there should be no changes. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* | kdb: Rename kdb_register_repeat() to kdb_register_flags()Anton Vorontsov2014-11-112-50/+50
| | | | | | | | | | | | | | | | | | | | | | | | | | We're about to add more options for commands behaviour, so let's give a more generic name to the low-level kdb command registration function. There are just various renames, no functional changes. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* | kdb: Rename kdb_repeat_t to kdb_cmdflags_t, cmd_repeat to cmd_flagsAnton Vorontsov2014-11-112-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | We're about to add more options for command behaviour, so let's expand the meaning of kdb_repeat_t. So far we just do various renames, there should be no functional changes. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* | kdb: Remove currently unused kdbtab_t->cmd_flagsAnton Vorontsov2014-11-112-2/+0
|/ | | | | | | | | | | | The struct member is never used in the code, so we can remove it. We will introduce real flags soon by renaming cmd_repeat to cmd_flags. Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Cc: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* kdb: replace strnicmp with strncasecmpRasmus Villemoes2014-10-141-3/+3
| | | | | | | | | | | | | | | | | The kernel used to contain two functions for length-delimited, case-insensitive string comparison, strnicmp with correct semantics and a slightly buggy strncasecmp. The latter is the POSIX name, so strnicmp was renamed to strncasecmp, and strnicmp made into a wrapper for the new strncasecmp to avoid breaking existing users. To allow the compat wrapper strnicmp to be removed at some point in the future, and to avoid the extra indirection cost, do s/strnicmp/strncasecmp/g. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kdb: Use ktime_get_ts()Thomas Gleixner2014-06-121-1/+1
| | | | | | | | | | | | do_posix_clock_monotonic_gettime() is a leftover from the initial posix timer implementation which maps to ktime_get_ts(). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jason Wessel <jason.wessel@windriver.com> Link: http://lkml.kernel.org/r/20140611234607.261629142@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* kernel/printk: use symbolic defines for console loglevelsBorislav Petkov2014-06-043-3/+3
| | | | | | | | | | | | | | | | | | | | ... instead of naked numbers. Stuff in sysrq.c used to set it to 8 which is supposed to mean above default level so set it to DEBUG instead as we're terminating/killing all tasks and we want to be verbose there. Also, correct the check in x86_64_start_kernel which should be >= as we're clearly issuing the string there for all debug levels, not only the magical 10. Signed-off-by: Borislav Petkov <bp@suse.de> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Randy Dunlap <rdunlap@infradead.org> Cc: Joe Perches <joe@perches.com> Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* arch: Mass conversion of smp_mb__*()Peter Zijlstra2014-04-181-2/+2
| | | | | | | | | | | Mostly scripted conversion of the smp_mb__* barriers. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Link: http://lkml.kernel.org/n/tip-55dhyhocezdw1dg7u19hmh1u@git.kernel.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: linux-arch@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* mm: per-thread vma cachingDavidlohr Bueso2014-04-071-3/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch is a continuation of efforts trying to optimize find_vma(), avoiding potentially expensive rbtree walks to locate a vma upon faults. The original approach (https://lkml.org/lkml/2013/11/1/410), where the largest vma was also cached, ended up being too specific and random, thus further comparison with other approaches were needed. There are two things to consider when dealing with this, the cache hit rate and the latency of find_vma(). Improving the hit-rate does not necessarily translate in finding the vma any faster, as the overhead of any fancy caching schemes can be too high to consider. We currently cache the last used vma for the whole address space, which provides a nice optimization, reducing the total cycles in find_vma() by up to 250%, for workloads with good locality. On the other hand, this simple scheme is pretty much useless for workloads with poor locality. Analyzing ebizzy runs shows that, no matter how many threads are running, the mmap_cache hit rate is less than 2%, and in many situations below 1%. The proposed approach is to replace this scheme with a small per-thread cache, maximizing hit rates at a very low maintenance cost. Invalidations are performed by simply bumping up a 32-bit sequence number. The only expensive operation is in the rare case of a seq number overflow, where all caches that share the same address space are flushed. Upon a miss, the proposed replacement policy is based on the page number that contains the virtual address in question. Concretely, the following results are seen on an 80 core, 8 socket x86-64 box: 1) System bootup: Most programs are single threaded, so the per-thread scheme does improve ~50% hit rate by just adding a few more slots to the cache. +----------------+----------+------------------+ | caching scheme | hit-rate | cycles (billion) | +----------------+----------+------------------+ | baseline | 50.61% | 19.90 | | patched | 73.45% | 13.58 | +----------------+----------+------------------+ 2) Kernel build: This one is already pretty good with the current approach as we're dealing with good locality. +----------------+----------+------------------+ | caching scheme | hit-rate | cycles (billion) | +----------------+----------+------------------+ | baseline | 75.28% | 11.03 | | patched | 88.09% | 9.31 | +----------------+----------+------------------+ 3) Oracle 11g Data Mining (4k pages): Similar to the kernel build workload. +----------------+----------+------------------+ | caching scheme | hit-rate | cycles (billion) | +----------------+----------+------------------+ | baseline | 70.66% | 17.14 | | patched | 91.15% | 12.57 | +----------------+----------+------------------+ 4) Ebizzy: There's a fair amount of variation from run to run, but this approach always shows nearly perfect hit rates, while baseline is just about non-existent. The amounts of cycles can fluctuate between anywhere from ~60 to ~116 for the baseline scheme, but this approach reduces it considerably. For instance, with 80 threads: +----------------+----------+------------------+ | caching scheme | hit-rate | cycles (billion) | +----------------+----------+------------------+ | baseline | 1.06% | 91.54 | | patched | 99.97% | 14.18 | +----------------+----------+------------------+ [akpm@linux-foundation.org: fix nommu build, per Davidlohr] [akpm@linux-foundation.org: document vmacache_valid() logic] [akpm@linux-foundation.org: attempt to untangle header files] [akpm@linux-foundation.org: add vmacache_find() BUG_ON] [hughd@google.com: add vmacache_valid_mm() (from Oleg)] [akpm@linux-foundation.org: coding-style fixes] [akpm@linux-foundation.org: adjust and enhance comments] Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Reviewed-by: Michel Lespinasse <walken@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Tested-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* KGDB: make kgdb_breakpoint() as noinlineVijaya Kumar K2014-02-261-1/+1
| | | | | | | | | | | | | | | | | | | | | | The function kgdb_breakpoint() sets up break point at compile time by calling arch_kgdb_breakpoint(); Though this call is surrounded by wmb() barrier, the compile can still re-order the break point, because this scheduling barrier is not a code motion barrier in gcc. Making kgdb_breakpoint() as noinline solves this problem of code reording around break point instruction and also avoids problem of being called as inline function from other places More details about discussion on this can be found here http://comments.gmane.org/gmane.linux.ports.arm.kernel/269732 Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@caviumnetworks.com> Acked-by: Will Deacon <will.deacon@arm.com> Acked-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* kgdb/kdb: Fix no KDB config problemMike Travis2014-01-252-4/+3
| | | | | | | | | | | | | | | | | | | Some code added to the debug_core module had KDB dependencies that it shouldn't have. Move the KDB dependent REASON back to the caller to remove the dependency in the debug core code. Update the call from the UV NMI handler to conform to the new interface. Signed-off-by: Mike Travis <travis@sgi.com> Reviewed-by: Hedi Berriche <hedi@sgi.com> Cc: Russ Anderson <rja@sgi.com> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Link: http://lkml.kernel.org/r/20140114162551.318251993@asylum.americas.sgi.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* kdb: Add support for external NMI handler to call KGDB/KDBMike Travis2013-10-034-3/+40
| | | | | | | | | | | | | | | | | | | | | | | | | | | This patch adds a kgdb_nmicallin() interface that can be used by external NMI handlers to call the KGDB/KDB handler. The primary need for this is for those types of NMI interrupts where all the CPUs have already received the NMI signal. Therefore no send_IPI(NMI) is required, and in fact it will cause a 2nd unhandled NMI to occur. This generates the "Dazed and Confuzed" messages. Since all the CPUs are getting the NMI at roughly the same time, it's not guaranteed that the first CPU that hits the NMI handler will manage to enter KGDB and set the dbg_master_lock before the slaves start entering. The new argument "send_ready" was added for KGDB to signal the NMI handler to release the slave CPUs for entry into KGDB. Signed-off-by: Mike Travis <travis@sgi.com> Acked-by: Jason Wessel <jason.wessel@windriver.com> Reviewed-by: Dimitri Sivanich <sivanich@sgi.com> Reviewed-by: Hedi Berriche <hedi@sgi.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Link: http://lkml.kernel.org/r/20131002151417.928886849@asylum.americas.sgi.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* kgdb/sysrq: fix inconstistent help message of sysrq keyzhangwei(Jovi)2013-04-301-1/+1
| | | | | | | | | | | | | | | | | | | | | Currently help message of /proc/sysrq-trigger highlight its upper-case characters, like below: SysRq : HELP : loglevel(0-9) reBoot Crash terminate-all-tasks(E) memory-full-oom-kill(F) kill-all-tasks(I) ... this would confuse user trigger sysrq by upper-case character, which is inconsistent with the real lower-case character registed key. This inconsistent help message will also lead more confused when 26 upper-case letters put into use in future. This patch fix kgdb sysrq key: "debug(g)" Signed-off-by: zhangwei(Jovi) <jovi.zhangwei@huawei.com> Cc: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge tag 'for_linux-3.9' of ↵Linus Torvalds2013-03-026-127/+62
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb Pull KGDB/KDB fixes and cleanups from Jason Wessel: "For a change we removed more code than we added. If people aren't using it we shouldn't be carrying it. :-) Cleanups: - Remove kdb ssb command - there is no in kernel disassembler to support it - Remove kdb ll command - Always caused a kernel oops and there were no bug reports so no one was using this command - Use kernel ARRAY_SIZE macro instead of array computations Fixes: - Stop oops in kdb if user executes kdb_defcmd with args - kdb help command truncated text - ppc64 support for kgdbts - Add missing kconfig option from original kdb port for dealing with catastrophic kernel crashes such that you can reboot automatically on continue from kdb" * tag 'for_linux-3.9' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb: kdb: Remove unhandled ssb command kdb: Prevent kernel oops with kdb_defcmd kdb: Remove the ll command kdb_main: fix help print kdb: Fix overlap in buffers with strcpy Fixed dead ifdef block by adding missing Kconfig option. kdb: Setup basic kdb state before invoking commands via kgdb kdb: use ARRAY_SIZE where possible kgdb/kgdbts: support ppc64 kdb: A fix for kdb command table expansion
| * kdb: Remove unhandled ssb commandVincent2013-03-024-39/+2
| | | | | | | | | | | | | | | | The 'ssb' command can only be handled when we have a disassembler, to check for branches, so remove the 'ssb' command for now. Signed-off-by: Vincent Stehlé <vincent.stehle@laposte.net> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
| * kdb: Prevent kernel oops with kdb_defcmdJason Wessel2013-03-021-2/+6
| | | | | | | | | | | | | | | | | | | | | | | | The kdb_defcmd can only be used to display the available command aliases while using the kernel debug shell. If you try to define a new macro while the kernel debugger is active it will oops. The debug shell macros must use pre-allocated memory set aside at the time kdb_init() is run, and the kdb_defcmd is restricted to only working at the time that the kdb_init sequence is being run, which only occurs if you actually activate the kernel debugger. Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
| * kdb: Remove the ll commandJason Wessel2013-03-021-65/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | Recently some code inspection was done after fixing a problem with kmalloc used while in the kernel debugger context (which is not legal), and it turned up the fact that kdb ll command will oops the kernel. Given that there have been zero bug reports on the command combined with the fact it will oops the kernel it is clearly not being used. Instead of fixing it, it will be removed. Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
| * kdb_main: fix help printJason Wessel2013-03-021-3/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The help command was chopping all the usage instructions such that they were not readable. Example: bta [D|R|S|T|C|Z|E|U|I| Backtrace all processes matching state flag per_cpu <sym> [<bytes>] [<c Display per_cpu variables Where as it should look like: bta [D|R|S|T|C|Z|E|U|I|M|A] Backtrace all processes matching state flag per_cpu <sym> [<bytes>] [<cpu>] Display per_cpu variables All that is needed is to check the how long the cmd_usage is and jump to the next line when appropriate. Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
| * kdb: Fix overlap in buffers with strcpyJason Wessel2013-03-021-9/+21
| | | | | | | | | | | | | | | | | | | | | | Maxime reported that strcpy(s->usage, s->usage+1) has no definitive guarantee that it will work on all archs the same way when you have overlapping memory. The fix is simple for the kdb code because we still have the original string memory in the function scope, so we just have to use that as the argument instead. Reported-by: Maxime Villard <rustyBSD@gmx.fr> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
| * kdb: Setup basic kdb state before invoking commands via kgdbMatt Klein2013-03-023-6/+23
| | | | | | | | | | | | | | | | | | | | Although invasive kdb commands are not supported via kgdb, some useful non-invasive commands like bt* require basic kdb state to be setup before calling into the kdb code. Factor out some of this code and call it before and after executing kdb commands via kgdb. Signed-off-by: Matt Klein <mklein@twitter.com> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
| * kdb: use ARRAY_SIZE where possibleSasha Levin2013-03-021-2/+2
| | | | | | | | | | Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
| * kdb: A fix for kdb command table expansionJohn Blackwood2013-03-021-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When locally adding in some additional kdb commands, I stumbled across an issue with the dynamic expansion of the kdb command table. When the number of kdb commands exceeds the size of the statically allocated kdb_base_commands[] array, additional space is allocated in the kdb_register_repeat() routine. The unused portion of the newly allocated array was not being initialized to zero properly and this would result in segfaults when help '?' was executed or when a search for a non-existing command would traverse the command table beyond the end of valid command entries and then attempt to use the non-zeroed area as actual command entries. Signed-off-by: John Blackwood <john.blackwood@ccur.com> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
* | kgdb: remove #include <linux/serial_8250.h> from kgdb.hGreg Kroah-Hartman2013-02-042-0/+2
|/ | | | | | | | | There's no reason kgdb.h itself needs to include the 8250 serial port header file. So push it down to the _very_ limited number of individual drivers that need the values in that file, and fix up the places where people really wanted serial_core.h and platform_device.h. Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* module: add new state MODULE_STATE_UNFORMED.Rusty Russell2013-01-121-0/+2
| | | | | | | | | You should never look at such a module, so it's excised from all paths which traverse the modules list. We add the state at the end, to avoid gratuitous ABI break (ksplice). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
* Merge tag 'for_linus-3.7' of ↵Linus Torvalds2012-10-134-5/+50
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb Pull KGDB/KDB fixes and cleanups from Jason Wessel: "Cleanups - Clean up compile warnings in kgdboc.c and x86/kernel/kgdb.c - Add module event hooks for simplified debugging with gdb Fixes - Fix kdb to stop paging with 'q' on bta and dmesg - Fix for data that scrolls off the vga console due to line wrapping when using the kdb pager New - The debug core registers for kernel module events which allows a kernel aware gdb to automatically load symbols and break on entry to a kernel module - Allow kgdboc=kdb to setup kdb on the vga console" * tag 'for_linus-3.7' of git://git.kernel.org/pub/scm/linux/kernel/git/jwessel/kgdb: tty/console: fix warnings in drivers/tty/serial/kgdboc.c kdb,vt_console: Fix missed data due to pager overruns kdb: Fix dmesg/bta scroll to quit with 'q' kgdboc: Accept either kbd or kdb to activate the vga + keyboard kdb shell kgdb,x86: fix warning about unused variable mips,kgdb: fix recursive page fault with CONFIG_KPROBES kgdb: Add module event hooks
| * kdb,vt_console: Fix missed data due to pager overrunsJason Wessel2012-10-121-5/+28
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It is possible to miss data when using the kdb pager. The kdb pager does not pay attention to the maximum column constraint of the screen or serial terminal. This result is not incrementing the shown lines correctly and the pager will print more lines that fit on the screen. Obviously that is less than useful when using a VGA console where you cannot scroll back. The pager will now look at the kdb_buffer string to see how many characters are printed. It might not be perfect considering you can output ASCII that might move the cursor position, but it is a substantially better approximation for viewing dmesg and trace logs. This also means that the vt screen needs to set the kdb COLUMNS variable. Cc: <stable@vger.kernel.org> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
| * kdb: Fix dmesg/bta scroll to quit with 'q'Jason Wessel2012-10-122-0/+4
| | | | | | | | | | | | | | | | | | If you press 'q' the pager should exit instead of printing everything from dmesg which can really bog down a 9600 baud serial link. The same is true for the bta command. Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
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