summaryrefslogtreecommitdiff
path: root/arch/x86_64/kernel/traps.c
AgeCommit message (Collapse)Author
2007-01-03[PATCH] x86_64: Fix dump_trace()OGAWA Hirofumi
If caller passed the tsk, we should use it to validate a stack ptr. Otherwise, sysrq-t and other debugging stuff doesn't work. Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-15Remove stack unwinder for nowLinus Torvalds
It has caused more problems than it ever really solved, and is apparently not getting cleaned up and fixed. We can put it back when it's stable and isn't likely to make warning or bug events worse. In the meantime, enable frame pointers for more readable stack traces. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08[PATCH] Generic BUG for x86-64Jeremy Fitzhardinge
This makes x86-64 use the generic BUG machinery. The main advantage in using the generic BUG machinery for x86-64 is that the inlined overhead of BUG is just the ud2a instruction; the file+line information are no longer inlined into the instruction stream. This reduces cache pollution. Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Andi Kleen <ak@muc.de> Cc: Hugh Dickens <hugh@veritas.com> Cc: Michael Ellerman <michael@ellerman.id.au> Cc: Paul Mackerras <paulus@samba.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07[PATCH] x86-64: Remove unwind stack pointer alignment forcing againAndi Kleen
This was added as a workaround for the fallback unwinder not supporting unaligned stack pointers properly. But now it was fixed to do that, so it's not needed anymore Cc: mingo@elte.hu Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07[PATCH] unwinder: more sanity checks in Dwarf2 unwinderJan Beulich
Tighten the requirements on both input to and output from the Dwarf2 unwinder. Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07[PATCH] unwinder: always use unlocked module list access in unwinder fallbackAndi Kleen
We're already well protected against module unloads because module unload uses stop_machine(). The only exception is NMIs, but other users already risk lockless accesses here. This avoids some hackery in lockdep and also a potential deadlock This matches what i386 does. Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07[PATCH] x86: add sysctl for kstack_depth_to_printChuck Ebbert
Add sysctl for kstack_depth_to_print. This lets users change the amount of raw stack data printed in dump_stack() without having to reboot. Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07[PATCH] x86-64: Use probe_kernel_address in arch/x86_64/*Andi Kleen
Instead of open coded __get_user Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07[PATCH] x86: Mention PCI instead of RAM in NMI parity error messageAndi Kleen
On modern systems RAM errors don't cause NMIs, but it's usually caused by PCI SERR. Mention PCI instead of RAM in the printk. Reported by r_hayashi@ctc-g.co.jp (Ryutaro Hayashi) Cc: r_hayashi@ctc-g.co.jp Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07[PATCH] x86-64: dump_trace() atomicity fixAndrew Morton
Fix BUG: using smp_processor_id() in preemptible [00000001] code: in backtracer on preemptible debug kernels. Cc: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07[PATCH] x86: Compress stack unwinder outputAndi Kleen
The unwinder has some extra newlines, which eat up loads of screen space when it spews. (See https://bugzilla.redhat.com/bugzilla/attachment.cgi?id=137900 for a nasty example). warning_symbol-> and warning-> already printk a newline, so don't add one in the strings passed to them. [AK: redone for new code] Signed-off-by: Dave Jones <davej@redhat.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-12-07[PATCH] x86: shorten lines in unwinder to be <= 80 charactersAndi Kleen
Andrew complained about > 80 character lines in the new unwinder. Fix that. Signed-off-by: Andi Kleen <ak@suse.de>
2006-11-28[PATCH] x86-64: Use stricter in process stack check for unwinderAndi Kleen
Previously it would check for alignment only, which could break if the stack pointer was unaligned. Now explicitely check if the stack pointer is in the stack page of the current process. Ported from i386. Signed-off-by: Andi Kleen <ak@suse.de>
2006-11-17[PATCH] x86_64: stack unwinder crash fixIngo Molnar
the new dwarf2 unwinder crashes while trying to dump the stack: Leftover inexact backtrace: Unable to handle kernel paging request at ffffffff82800000 RIP: [<ffffffff8026cf26>] dump_trace+0x35b/0x3d2 PGD 203027 PUD 205027 PMD 0 Oops: 0000 [2] PREEMPT SMP CPU 0 Modules linked in: Pid: 30, comm: khelper Not tainted 2.6.19-rc6-rt1 #11 RIP: 0010:[<ffffffff8026cf26>] [<ffffffff8026cf26>] dump_trace+0x35b/0x3d2 RSP: 0000:ffff81003fb9d848 EFLAGS: 00010006 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff805b3520 RDI: 0000000000000000 RBP: ffffffff827ffff9 R08: ffffffff80aad000 R09: 0000000000000005 R10: ffffffff80aae000 R11: ffffffff8037961b R12: ffff81003fb9d858 R13: 0000000000000000 R14: ffffffff80598460 R15: ffffffff80ab1fc0 FS: 0000000000000000(0000) GS:ffffffff806c4200(0000) knlGS:0000000000000000 CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b CR2: ffffffff82800000 CR3: 0000000000201000 CR4: 00000000000006e0 this crash happened because it did not sanitize the dwarf2 data it got, and got an unaligned stack pointer - which happily walked past the process stack (and eventually reached the end of kernel memory and pagefaulted there) due to this naive iteration condition: HANDLE_STACK (((long) stack & (THREAD_SIZE-1)) != 0); note that i386 is alot more conservative when it comes to trusting stack pointers: static inline int valid_stack_ptr(struct thread_info *tinfo, void *p) { return p > (void *)tinfo && p < (void *)tinfo + THREAD_SIZE - 3; } but the x86_64 code did not take this bit of i386 code. The fix is to align the stack pointer. Signed-off-by: Ingo Molnar <mingo@elte.hu> Cc: Andi Kleen <ak@suse.de> Cc: Jan Beulich <jbeulich@novell.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-05[PATCH] x86-64: Fix compilation without CONFIG_KALLSYMSRandy Dunlap
Include linux/kallsyms.h unconditionally for print_symbol(). Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-26[PATCH] Don't use kernel_text_address in oops contextAndi Kleen
Because it can take spinlocks. Suggested by Mathieu Desnoyers Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org> Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26[PATCH] Remove most of the special cases for the debug IST stackKeith Owens
Remove most of the special cases for the debug IST stack. This is a follow on clean up patch, it requires the bug fix patch that adds orig_ist. Signed-off-by: Keith Owens <kaos@ocs.com.au> Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26[PATCH] Remove safe_smp_processor_id()Andi Kleen
And replace all users with ordinary smp_processor_id. The function was originally added to get some basic oops information out even if the GS register was corrupted. However that didn't work for some anymore because printk is needed to print the oops and it uses smp_processor_id() already. Also GS register corruptions are not particularly common anymore. This also helps the Xen port which would otherwise need to do this in a special way because it can't access the local APIC. Cc: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26[PATCH] wire up oops_enter()/oops_exit()Andrew Morton
Implement pause_on_oops() on x86_64. AK: I redid the patch to do the oops_enter/exit in the existing oops_begin()/end(). This makes it much shorter. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26[PATCH] non lazy "sleazy" fpu implementationArjan van de Ven
Right now the kernel on x86-64 has a 100% lazy fpu behavior: after *every* context switch a trap is taken for the first FPU use to restore the FPU context lazily. This is of course great for applications that have very sporadic or no FPU use (since then you avoid doing the expensive save/restore all the time). However for very frequent FPU users... you take an extra trap every context switch. The patch below adds a simple heuristic to this code: After 5 consecutive context switches of FPU use, the lazy behavior is disabled and the context gets restored every context switch. If the app indeed uses the FPU, the trap is avoided. (the chance of the 6th time slice using FPU after the previous 5 having done so are quite high obviously). After 256 switches, this is reset and lazy behavior is returned (until there are 5 consecutive ones again). The reason for this is to give apps that do longer bursts of FPU use still the lazy behavior back after some time. [akpm@osdl.org: place new task_struct field next to jit_keyring to save space] Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andi Kleen <ak@suse.de> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org>
2006-09-26[PATCH] Check for end of stack trace before falling backAndi Kleen
Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26[PATCH] Merge stacktrace and show_traceAndi Kleen
This unifies the standard backtracer and the new stacktrace in memory backtracer. The standard one is converted to use callbacks and then reimplement stacktrace using new callbacks. The main advantage is that stacktrace can now use the new dwarf2 unwinder and avoid false positives in many cases. I kept it simple to make sure the standard backtracer stays reliable. Cc: mingo@elte.hu Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26[PATCH] Convert x86-64 to early paramAndi Kleen
Instead of hackish manual parsing Requires earlier i386 patchkit, but also fixes i386 early_printk again. I removed some obsolete really early parameters which didn't do anything useful. Also made a few parameters that needed it early (mostly oops printing setup) Also removed one panic check that wasn't visible without early console anyways (the early console is now initialized after that panic) This cleans up a lot of code. Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26[PATCH] Remove all ifdefs for local/io apicAndi Kleen
IO-APIC or local APIC can only be disabled at runtime anyways and Kconfig has forced these options on for a long time now. The Kconfigs are kept only now for the benefit of the shared acpi boot.c code. Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26[PATCH] Fix up panic messages for different NMI panicsAndi Kleen
When a unknown NMI happened the panic would claim a NMI watchdog timeout. Also it would check the variable set by nmi_watchdog=panic and panic then. Fix up the panic message to be generic Unconditionally panic on unknown NMI when panic on unknown nmi is enabled. Noticed by Jan Beulich Cc: jbeulich@novell.com Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26[PATCH] x86: x86 clean up nmi panic messagesDon Zickus
Clean up some of the output messages on the nmi error paths to make more sense when they are displayed. This is mainly a cosmetic fix and shouldn't impact any normal code path. Signed-off-by: Don Zickus <dzickus@redhat.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26[PATCH] x86: Allow users to force a panic on NMIDon Zickus
To quote Alan Cox: The default Linux behaviour on an NMI of either memory or unknown is to continue operation. For many environments such as scientific computing it is preferable that the box is taken out and the error dealt with than an uncorrected parity/ECC error get propogated. A small number of systems do generate NMI's for bizarre random reasons such as power management so the default is unchanged. In other respects the new proc/sys entry works like the existing panic controls already in that directory. This is separate to the edac support - EDAC allows supported chipsets to handle ECC errors well, this change allows unsupported cases to at least panic rather than cause problems further down the line. Signed-off-by: Don Zickus <dzickus@redhat.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-09-26[PATCH] x86: Cleanup NMI interrupt pathDon Zickus
This patch cleans up the NMI interrupt path. Instead of being gated by if the 'nmi callback' is set, the interrupt handler now calls everyone who is registered on the die_chain and additionally checks the nmi watchdog, reseting it if enabled. This allows more subsystems to hook into the NMI if they need to (without being block by set_nmi_callback). Signed-off-by: Don Zickus <dzickus@redhat.com> Signed-off-by: Andi Kleen <ak@suse.de>
2006-08-30[PATCH] x86_64: Save original IST values for checking stack addressesKeith Owens
The values in init_tss.ist[] can change when an IST event occurs. Save the original IST values for checking stack addresses when debugging or doing stack traces. Signed-off-by: Keith Owens <kaos@ocs.com.au> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-08-30[PATCH] x86: Make backtracer fallback logic more bullet-proofJan Beulich
The unwinder fallback logic still had potential for falling through to the legacy stack trace code without printing an indication (at once serving as a separator) of this. Further, the stack pointer retrieval for the fallback should be as restrictive as possible (in order to avoid having the legacy stack tracer try to access invalid memory). The patch tightens that, but this could certainly be further improved. Also making the call_trace command line option now conditional upon CONFIG_STACK_UNWIND (as it's meaningless otherwise). Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-08-14[PATCH] Change panic_on_oops message to "Fatal exception"Horms
Previously the message was "Fatal exception: panic_on_oops", as introduced in a recent patch whith removed a somewhat dangerous call to ssleep() in the panic_on_oops path. However, Paul Mackerras suggested that this was somewhat confusing, leadind people to believe that it was panic_on_oops that was the root cause of the fatal exception. On his suggestion, this patch changes the message to simply "Fatal exception". A suitable oops message should already have been displayed. Signed-off-by: Simon Horman <horms@verge.net.au> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2006-07-31[PATCH] panic_on_oops: remove ssleep()Horms
This patch is part of an effort to unify the panic_on_oops behaviour across all architectures that implement it. It was pointed out to me by Andi Kleen that if an oops has occured in interrupt context, then calling sleep() in the oops path will only cause a panic, and that it would be really better for it not to be in the path at all. This patch removes the ssleep() call and reworks the console message accordinly. I have a slght concern that the resulting console message is too long, feedback welcome. For powerpc it also unifies the 32bit and 64bit behaviour. Fror x86_64, this patch only updates the console message, as ssleep() is already not present. Signed-off-by: Horms <horms@verge.net.au> Acked-by: Paul Mackerras <paulus@samba.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Andi Kleen <ak@muc.de> Cc: Chris Zankel <chris@zankel.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-28[PATCH] x86_64: Dump leftover backtrace entries when dwarf2 unwinder got stuckAndi Kleen
The dwarf2 unwinder currently often gets stuck because a lot of assembly code doesn't have proper dwarf2 annotiation yet. This currently often happens with __down. Should fix this by adding proper dwarf2 annotation to all inline assembly. However until that's done we need a quick fix for 2.6.18 to avoid incomplete backtraces. So when this happens dump the rest of the stack with the old unwinder instead of silently not dumping it. There was already a optional "both" mode that dumped both, but that was too ugly. I also clarified the headers for the different backtraces a bit. Also add a clear error message for missing dwarf2 annotation that people can work on. And I removed a dead variable left over from Ingo's changes. Cc: mingo@elte.hu Cc: jbeulich@novell.com Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-10[PATCH] put a comment at register_die_notifier that the export is usedArjan van de Ven
{un}register_die_notifier() is used by kdb... document this so that future "remove dead export" rounds can skip this export. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-03[PATCH] lockdep: x86_64 document stack frame internalsIngo Molnar
Document stack frame nesting internals some more. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-03[PATCH] lockdep: beautify x86_64 stacktracesIngo Molnar
Beautify x86_64 stacktraces to be more readable. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Acked-by: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-30Remove obsolete #include <linux/config.h>Jörn Engel
Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-06-26[PATCH] x86_64: Move export symbols to their C functionsAndi Kleen
Only exports for assembler files are left in x8664_ksyms.c Originally inspired by a patch from Al Viro Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26[PATCH] x86_64: adjust kstack_depth_to_print defaultJan Beulich
Defaulting to a value not evenly divisible by four makes little sense, as four values are displayed per line (and hence the rest of the line would otherwise be wasted). Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26[PATCH] i386/x86-64: fall back to old-style call trace if no unwindingJan Beulich
If no unwinding is possible at all for a certain exception instance, fall back to the old style call trace instead of not showing any trace at all. Also, allow setting the stack trace mode at the command line. Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26[PATCH] x86_64: reliable stack trace support (x86-64)Jan Beulich
These are the x86_64-specific pieces to enable reliable stack traces. The only restriction with this is that it currently cannot unwind across the interrupt->normal stack boundary, as that transition is lacking proper annotation. Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26[PATCH] x86_64: Remove long obsolete CVSAndi Kleen
Early development of x86-64 Linux was in CVS, but that hasn't been the case for a long time now. Remove the obsolete $Id$s. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-05-16[PATCH] x86_64: Don't schedule on exception stack on preemptive kernelsAndi Kleen
Extends an earlier patch from John Blackwood to more exception handlers that also run on the exception stacks. Expand the use of preempt_conditional_{sti,cli} to all cases where interrupts are to be re-enabled during exception handling while running on an IST stack. Based on original patch from Jan Beulich. Cc: John Blackwood <john.blackwood@ccur.com> Cc: jbeulich@novell.com Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-05-08[PATCH] x86_64: add nmi_exit to die_nmiCorey Minyard
Playing with NMI watchdog on x86_64, I discovered that it didn't do what I expected. It always panic-ed, even when it didn't happen from interrupt context. This patch solves that problem for me. Also, in this case, do_exit() will be called with interrupts disabled, I believe. Would it be wise to also call local_irq_enable() after nmi_exit()? [Yes I added it -AK] Currently, on x86_64, any NMI watchdog timeout will cause a panic because the irq count will always be set to be in an interrupt when do_exit() is called from die_nmi(). If we add nmi_exit() to the die_nmi() call (since the nmi will never exit "normally") it seems to solve this problem. The following small program can be used to trigger the NMI watchdog to reproduce this: main () { iopl(3); for (;;) asm("cli"); } Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-05-08[PATCH] x86_64: fix die_lock nestingCorey Minyard
I noticed this when poking around in this area. The oops_begin() function in x86_64 would only conditionally claim the die_lock if the call is nested, but oops_end() would always release the spinlock. This patch adds a nest count for the die lock so that the release of the lock is only done on the final oops_end(). Signed-off-by: Corey Minyard <minyard@acm.org> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-18[PATCH] x86_64: x86_64 add crashdump trigger pointsVivek Goyal
o Start booting into the capture kernel after an Oops if system is in a unrecoverable state. System will boot into the capture kernel, if one is pre-loaded by the user, and capture the kernel core dump. o One of the following conditions should be true to trigger the booting of capture kernel. - panic_on_oops is set. - pid of current thread is 0 - pid of current thread is 1 - Oops happened inside interrupt context. Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-31[PATCH] Don't pass boot parameters to argv_init[]OGAWA Hirofumi
The boot cmdline is parsed in parse_early_param() and parse_args(,unknown_bootoption). And __setup() is used in obsolete_checksetup(). start_kernel() -> parse_args() -> unknown_bootoption() -> obsolete_checksetup() If __setup()'s callback (->setup_func()) returns 1 in obsolete_checksetup(), obsolete_checksetup() thinks a parameter was handled. If ->setup_func() returns 0, obsolete_checksetup() tries other ->setup_func(). If all ->setup_func() that matched a parameter returns 0, a parameter is seted to argv_init[]. Then, when runing /sbin/init or init=app, argv_init[] is passed to the app. If the app doesn't ignore those arguments, it will warning and exit. This patch fixes a wrong usage of it, however fixes obvious one only. Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27[PATCH] Notifier chain update: API changesAlan Stern
The kernel's implementation of notifier chains is unsafe. There is no protection against entries being added to or removed from a chain while the chain is in use. The issues were discussed in this thread: http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2 We noticed that notifier chains in the kernel fall into two basic usage classes: "Blocking" chains are always called from a process context and the callout routines are allowed to sleep; "Atomic" chains can be called from an atomic context and the callout routines are not allowed to sleep. We decided to codify this distinction and make it part of the API. Therefore this set of patches introduces three new, parallel APIs: one for blocking notifiers, one for atomic notifiers, and one for "raw" notifiers (which is really just the old API under a new name). New kinds of data structures are used for the heads of the chains, and new routines are defined for registration, unregistration, and calling a chain. The three APIs are explained in include/linux/notifier.h and their implementation is in kernel/sys.c. With atomic and blocking chains, the implementation guarantees that the chain links will not be corrupted and that chain callers will not get messed up by entries being added or removed. For raw chains the implementation provides no guarantees at all; users of this API must provide their own protections. (The idea was that situations may come up where the assumptions of the atomic and blocking APIs are not appropriate, so it should be possible for users to handle these things in their own way.) There are some limitations, which should not be too hard to live with. For atomic/blocking chains, registration and unregistration must always be done in a process context since the chain is protected by a mutex/rwsem. Also, a callout routine for a non-raw chain must not try to register or unregister entries on its own chain. (This did happen in a couple of places and the code had to be changed to avoid it.) Since atomic chains may be called from within an NMI handler, they cannot use spinlocks for synchronization. Instead we use RCU. The overhead falls almost entirely in the unregister routine, which is okay since unregistration is much less frequent that calling a chain. Here is the list of chains that we adjusted and their classifications. None of them use the raw API, so for the moment it is only a placeholder. ATOMIC CHAINS ------------- arch/i386/kernel/traps.c: i386die_chain arch/ia64/kernel/traps.c: ia64die_chain arch/powerpc/kernel/traps.c: powerpc_die_chain arch/sparc64/kernel/traps.c: sparc64die_chain arch/x86_64/kernel/traps.c: die_chain drivers/char/ipmi/ipmi_si_intf.c: xaction_notifier_list kernel/panic.c: panic_notifier_list kernel/profile.c: task_free_notifier net/bluetooth/hci_core.c: hci_notifier net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_chain net/ipv4/netfilter/ip_conntrack_core.c: ip_conntrack_expect_chain net/ipv6/addrconf.c: inet6addr_chain net/netfilter/nf_conntrack_core.c: nf_conntrack_chain net/netfilter/nf_conntrack_core.c: nf_conntrack_expect_chain net/netlink/af_netlink.c: netlink_chain BLOCKING CHAINS --------------- arch/powerpc/platforms/pseries/reconfig.c: pSeries_reconfig_chain arch/s390/kernel/process.c: idle_chain arch/x86_64/kernel/process.c idle_notifier drivers/base/memory.c: memory_chain drivers/cpufreq/cpufreq.c cpufreq_policy_notifier_list drivers/cpufreq/cpufreq.c cpufreq_transition_notifier_list drivers/macintosh/adb.c: adb_client_list drivers/macintosh/via-pmu.c sleep_notifier_list drivers/macintosh/via-pmu68k.c sleep_notifier_list drivers/macintosh/windfarm_core.c wf_client_list drivers/usb/core/notify.c usb_notifier_list drivers/video/fbmem.c fb_notifier_list kernel/cpu.c cpu_chain kernel/module.c module_notify_list kernel/profile.c munmap_notifier kernel/profile.c task_exit_notifier kernel/sys.c reboot_notifier_list net/core/dev.c netdev_chain net/decnet/dn_dev.c: dnaddr_chain net/ipv4/devinet.c: inetaddr_chain It's possible that some of these classifications are wrong. If they are, please let us know or submit a patch to fix them. Note that any chain that gets called very frequently should be atomic, because the rwsem read-locking used for blocking chains is very likely to incur cache misses on SMP systems. (However, if the chain's callout routines may sleep then the chain cannot be atomic.) The patch set was written by Alan Stern and Chandra Seetharaman, incorporating material written by Keith Owens and suggestions from Paul McKenney and Andrew Morton. [jes@sgi.com: restructure the notifier chain initialization macros] Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Signed-off-by: Jes Sorensen <jes@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-25[PATCH] x86_64: miscellaneous cleanupJan Beulich
- adjust limits of GDT/IDT pseudo-descriptors (some were off by one) - move empty_zero_page into .bss.page_aligned - move cpu_gdt_table into .data.page_aligned - move idt_table into .bss - align inital_code and init_rsp - eliminate pointless (re-)declaration of idt_table in traps.c Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-25[PATCH] x86_64: Clean up white space in traps.cRoberto Nibali
Attached is a small code style cleanup patch that resulted from my skimming through the arch/x86_64/kernel/traps.c code to figure out what went haywire. Signed-off-by: Roberto Nibali <ratz@drugphish.ch> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>