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2017-09-15MIPS: Fix IRQ tracing & lockdep when reschedulingPaul Burton
commit d8550860d910c6b7b70f830f59003b33daaa52c9 upstream. When the scheduler sets TIF_NEED_RESCHED & we call into the scheduler from arch/mips/kernel/entry.S we disable interrupts. This is true regardless of whether we reach work_resched from syscall_exit_work, resume_userspace or by looping after calling schedule(). Although we disable interrupts in these paths we don't call trace_hardirqs_off() before calling into C code which may acquire locks, and we therefore leave lockdep with an inconsistent view of whether interrupts are disabled or not when CONFIG_PROVE_LOCKING & CONFIG_DEBUG_LOCKDEP are both enabled. Without tracing this interrupt state lockdep will print warnings such as the following once a task returns from a syscall via syscall_exit_partial with TIF_NEED_RESCHED set: [ 49.927678] ------------[ cut here ]------------ [ 49.934445] WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:3687 check_flags.part.41+0x1dc/0x1e8 [ 49.946031] DEBUG_LOCKS_WARN_ON(current->hardirqs_enabled) [ 49.946355] CPU: 0 PID: 1 Comm: init Not tainted 4.10.0-00439-gc9fd5d362289-dirty #197 [ 49.963505] Stack : 0000000000000000 ffffffff81bb5d6a 0000000000000006 ffffffff801ce9c4 [ 49.974431] 0000000000000000 0000000000000000 0000000000000000 000000000000004a [ 49.985300] ffffffff80b7e487 ffffffff80a24498 a8000000ff160000 ffffffff80ede8b8 [ 49.996194] 0000000000000001 0000000000000000 0000000000000000 0000000077c8030c [ 50.007063] 000000007fd8a510 ffffffff801cd45c 0000000000000000 a8000000ff127c88 [ 50.017945] 0000000000000000 ffffffff801cf928 0000000000000001 ffffffff80a24498 [ 50.028827] 0000000000000000 0000000000000001 0000000000000000 0000000000000000 [ 50.039688] 0000000000000000 a8000000ff127bd0 0000000000000000 ffffffff805509bc [ 50.050575] 00000000140084e0 0000000000000000 0000000000000000 0000000000040a00 [ 50.061448] 0000000000000000 ffffffff8010e1b0 0000000000000000 ffffffff805509bc [ 50.072327] ... [ 50.076087] Call Trace: [ 50.079869] [<ffffffff8010e1b0>] show_stack+0x80/0xa8 [ 50.086577] [<ffffffff805509bc>] dump_stack+0x10c/0x190 [ 50.093498] [<ffffffff8015dde0>] __warn+0xf0/0x108 [ 50.099889] [<ffffffff8015de34>] warn_slowpath_fmt+0x3c/0x48 [ 50.107241] [<ffffffff801c15b4>] check_flags.part.41+0x1dc/0x1e8 [ 50.114961] [<ffffffff801c239c>] lock_is_held_type+0x8c/0xb0 [ 50.122291] [<ffffffff809461b8>] __schedule+0x8c0/0x10f8 [ 50.129221] [<ffffffff80946a60>] schedule+0x30/0x98 [ 50.135659] [<ffffffff80106278>] work_resched+0x8/0x34 [ 50.142397] ---[ end trace 0cb4f6ef5b99fe21 ]--- [ 50.148405] possible reason: unannotated irqs-off. [ 50.154600] irq event stamp: 400463 [ 50.159566] hardirqs last enabled at (400463): [<ffffffff8094edc8>] _raw_spin_unlock_irqrestore+0x40/0xa8 [ 50.171981] hardirqs last disabled at (400462): [<ffffffff8094eb98>] _raw_spin_lock_irqsave+0x30/0xb0 [ 50.183897] softirqs last enabled at (400450): [<ffffffff8016580c>] __do_softirq+0x4ac/0x6a8 [ 50.195015] softirqs last disabled at (400425): [<ffffffff80165e78>] irq_exit+0x110/0x128 Fix this by using the TRACE_IRQS_OFF macro to call trace_hardirqs_off() when CONFIG_TRACE_IRQFLAGS is enabled. This is done before invoking schedule() following the work_resched label because: 1) Interrupts are disabled regardless of the path we take to reach work_resched() & schedule(). 2) Performing the tracing here avoids the need to do it in paths which disable interrupts but don't call out to C code before hitting a path which uses the RESTORE_SOME macro that will call trace_hardirqs_on() or trace_hardirqs_off() as appropriate. We call trace_hardirqs_on() using the TRACE_IRQS_ON macro before calling syscall_trace_leave() for similar reasons, ensuring that lockdep has a consistent view of state after we re-enable interrupts. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/15385/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2011-05-19MIPS: Split do_syscall_trace into two functions.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2011-05-19MIPS: Use single define for pending work on syscall exitRalf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2008-10-03[MIPS] SMTC: Close tiny holes in the SMTC IPI replay system.Kevin D. Kissell
Signed-off-by: Kevin D. Kissell <kevink@paralogos.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-07-12[MIPS] SMTC: Interrupt mask backstop hackKevin D. Kissell
To support multiple TC microthreads acting as "CPUs" within a VPE, VPE-wide interrupt mask bits must be specially manipulated during interrupt handling. To support legacy drivers and interrupt controller management code, SMTC has a "backstop" to track and if necessary restore the interrupt mask. This has some performance impact on interrupt service overhead. Disable it only if you know what you are doing. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-03-29[MIPS] lockdep: Handle interrupts in R3000 style c0_status register.Chris Dearman
Check the IEP bit for R3000 style processors when checking to see if interrupts will be reenabled in restore_all. Signed-off-by: Chris Dearman <chris@mips.com> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-02-13[MIPS] Make entry.S a little more readable.Franck Bui-Huu
When CONFIG_PREEMPT is not set, it also moves one branch instruction from ret_from_irq() to ret_from_exception(). Therefore we favour the return from irq case which should be more common than the other one. Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com> Acked-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-11-01[MIPS] SMTC: Fix crash if # of TC's > # of VPE's after pt_regs irq cleanup.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-10-09[MIPS] ret_from_irq adjustmentAtsushi Nemoto
Make sure that RA on top of interrupt stack is an address of ret_from_irq, so that dump_stack etc. can trace info interrupted context. Also this patch fixes except_vec_vi_handler and __smtc_ipi_vector which seems broken. Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-10-08[MIPS] Complete fixes after removal of pt_regs argument to int handlers.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-07-13[MIPS] TRACE_IRQFLAGS_SUPPORT support.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-07-03[PATCH] sched: cleanup, remove task_t, convert to struct task_structIngo Molnar
cleanup: remove task_t and convert all the uses to struct task_struct. I introduced it for the scheduler anno and it was a mistake. Conversion was mostly scripted, the result was reviewed and all secondary whitespace and style impact (if any) was fixed up by hand. Signed-off-by: Ingo Molnar <mingo@elte.hu> 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>
2006-06-29[MIPS] Fix use of ehb instruction for non-R2 configurations.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-06-01[MIPS] Fix typoRalf Baechle
Found by Chris Dearman (chris@mips.com). Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-04-19[MIPS] MT: Improved multithreading support.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-04-19[MIPS] R2: Instruction hazard barrier.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-04-19[MIPS] Rewrite spurious_interrupt from assembler to C.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2005-10-29Fix excessive signal latencies.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2005-10-29Fix preemption bug.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2005-10-29Use preempt_schedule_irq.Ralf Baechle
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2005-10-29Remove unused arguments from preempt_{start,stop}/local_irq_{en,dis}able.Thiemo Seufer
Don't clobber the preloaded TI_FLAGS in a2 needlessly. Unexport local functions. Signed-off-by: Thiemo Seufer <ths@networkno.de> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2005-10-29De-optimize and decomplicate the spurious interrupt handler.Thiemo Seufer
Signed-off-by: Thiemo Seufer <ths@networkno.de> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2005-04-16Linux-2.6.12-rc2Linus Torvalds
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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