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2019-03-20MIPS: entry: Remove unneeded need_resched() loopValentin Schneider1-3/+2
Since the enabling and disabling of IRQs within preempt_schedule_irq() is contained in a need_resched() loop, we don't need the outer arch code loop. Note that commit a18815abcdfd ("Use preempt_schedule_irq.") initially removed the existing loop, but missed the final branch to restore_all. Commit cdaed73afb61 ("Fix preemption bug.") missed that and reintroduced the loop. Signed-off-by: Valentin Schneider <valentin.schneider@arm.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Burton <paul.burton@mips.com> Cc: James Hogan <jhogan@kernel.org> Cc: linux-mips@vger.kernel.org Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: linux-kernel@vger.kernel.org
2018-06-20MIPS: Add syscall detection for restartable sequencesPaul Burton1-0/+8
Syscalls are not allowed inside restartable sequences, so add a call to rseq_syscall() at the very beginning of the system call exit path when CONFIG_DEBUG_RSEQ=y. This will help us to detect whether there is a syscall issued erroneously inside a restartable sequence. Signed-off-by: Paul Burton <paul.burton@mips.com> Reviewed-by: James Hogan <jhogan@kernel.org> Patchwork: https://patchwork.linux-mips.org/patch/19522/ Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org
2017-06-30MIPS: Fix IRQ tracing & lockdep when reschedulingPaul Burton1-0/+3
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 Cc: stable <stable@vger.kernel.org> Patchwork: https://patchwork.linux-mips.org/patch/15385/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2017-01-03MIPS: Remove r2_emul_return from struct thread_infoPaul Burton1-18/+0
The r2_emul_return field in struct thread_info was used in order to take an alternate codepath when returning to userland, which (besides not implementing certain features) effectively used the eretnc instruction in place of eret. The difference is that eretnc doesn't clear LLBit, and therefore doesn't cause a linked load & store sequence to fail due to emulation like eret would. The reason eret would usually be used to clear LLBit is so that after context switching we ensure that a load performed by one task doesn't influence another task. However commit 7c151d3d5d7a ("MIPS: Make use of the ERETNC instruction on MIPS R6") which introduced the r2_emul_return field and conditional use of eretnc also for some reason began explicitly clearing LLBit during context switches - despite retaining the use of eret for everything but returns from the pre-r6 instruction emulation code. As LLBit is cleared upon context switches anyway, simplify this by using eretnc unconditionally for MIPSr6 kernels. This allows us to remove the 4 byte r2_emul_return boolean from struct thread_info, simplify the return to user code in entry.S and avoid the overhead of tracking & checking state which we don't need. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/14408/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-04-10MIPS: kernel: entry.S: Set correct ISA level for mips_ihbMarkos Chandras1-1/+2
Commit 6ebb496ffc7e("MIPS: kernel: entry.S: Add MIPS R6 related definitions") added the MIPSR6 definition but it did not update the ISA level of the actual assembly code so a pre-MIPSR6 jr.hb instruction was generated instead. Fix this by using the MISP_ISA_LEVEL_RAW macro. Signed-off-by: Markos Chandras <markos.chandras@imgtec.com> Fixes: 6ebb496ffc7e("MIPS: kernel: entry.S: Add MIPS R6 related definitions") Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/9386/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-02-17MIPS: Make use of the ERETNC instruction on MIPS R6Markos Chandras1-0/+18
The ERETNC instruction, introduced in MIPS R5, is similar to the ERET one, except it does not clear the LLB bit in the LLADDR register. This feature is necessary to safely emulate R2 LL/SC instructions. However, on context switches, we need to clear the LLAddr/LLB bit in order to make sure that an SC instruction from the new thread will never succeed if it happens to interrupt an LL operation on the same address from the previous thread. Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
2015-02-17MIPS: kernel: entry.S: Add MIPS R6 related definitionsMarkos Chandras1-2/+3
The instruction hazard barrier in the form of: jr.hb ra nop is valid on MIPS R6 as well. Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
2014-05-24MIPS: MT: Remove SMTC supportRalf Baechle1-38/+0
Nobody is maintaining SMTC anymore and there also seems to be no userbase. Which is a pity - the SMTC technology primarily developed by Kevin D. Kissell <kevink@paralogos.com> is an ingenious demonstration for the MT ASE's power and elegance. Based on Markos Chandras <Markos.Chandras@imgtec.com> patch https://patchwork.linux-mips.org/patch/6719/ which while very similar did no longer apply cleanly when I tried to merge it plus some additional post-SMTC cleanup - SMTC was a feature as tricky to remove as it was to merge once upon a time. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2012-12-13Merge branch 'for-linus' of ↵Linus Torvalds1-0/+6
git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal Pull big execve/kernel_thread/fork unification series from Al Viro: "All architectures are converted to new model. Quite a bit of that stuff is actually shared with architecture trees; in such cases it's literally shared branch pulled by both, not a cherry-pick. A lot of ugliness and black magic is gone (-3KLoC total in this one): - kernel_thread()/kernel_execve()/sys_execve() redesign. We don't do syscalls from kernel anymore for either kernel_thread() or kernel_execve(): kernel_thread() is essentially clone(2) with callback run before we return to userland, the callbacks either never return or do successful do_execve() before returning. kernel_execve() is a wrapper for do_execve() - it doesn't need to do transition to user mode anymore. As a result kernel_thread() and kernel_execve() are arch-independent now - they live in kernel/fork.c and fs/exec.c resp. sys_execve() is also in fs/exec.c and it's completely architecture-independent. - daemonize() is gone, along with its parts in fs/*.c - struct pt_regs * is no longer passed to do_fork/copy_process/ copy_thread/do_execve/search_binary_handler/->load_binary/do_coredump. - sys_fork()/sys_vfork()/sys_clone() unified; some architectures still need wrappers (ones with callee-saved registers not saved in pt_regs on syscall entry), but the main part of those suckers is in kernel/fork.c now." * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal: (113 commits) do_coredump(): get rid of pt_regs argument print_fatal_signal(): get rid of pt_regs argument ptrace_signal(): get rid of unused arguments get rid of ptrace_signal_deliver() arguments new helper: signal_pt_regs() unify default ptrace_signal_deliver flagday: kill pt_regs argument of do_fork() death to idle_regs() don't pass regs to copy_process() flagday: don't pass regs to copy_thread() bfin: switch to generic vfork, get rid of pointless wrappers xtensa: switch to generic clone() openrisc: switch to use of generic fork and clone unicore32: switch to generic clone(2) score: switch to generic fork/vfork/clone c6x: sanitize copy_thread(), get rid of clone(2) wrapper, switch to generic clone() take sys_fork/sys_vfork/sys_clone prototypes to linux/syscalls.h mn10300: switch to generic fork/vfork/clone h8300: switch to generic fork/vfork/clone tile: switch to generic clone() ... Conflicts: arch/microblaze/include/asm/Kbuild
2012-12-05MIPS: Fix endless loop when processing signals for kernel tasksDmitry Adamushko1-1/+6
The problem occurs [1] when a kernel-mode task returns from a system call with a pending signal. A real-life scenario is a child of 'khelper' returning from a failed kernel_execve() in ____call_usermodehelper() [ kernel/kmod.c ]. kernel_execve() fails due to a pending SIGKILL, which is the result of "kill -9 -1" (at least, busybox's init does it upon reboot). The loop is as follows: * syscall_exit_work: - work_pending: // start_of_the_loop - work_notifysig: - do_notify_resume() - do_signal() - if (!user_mode(regs)) return; - resume_userspace // TIF_SIGPENDING is still set - work_pending // so we call work_pending => goto // start_of_the_loop More information can be found in another LKML thread: http://www.serverphorums.com/read.php?12,457826 [1] The problem was also reproduced on !CONFIG_VM86 x86, and the following fix was accepted. http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=29a2e2836ff9ea65a603c89df217f4198973a74f Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/3571/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2012-10-16mips: switch to saner kernel_execve() semanticsAl Viro1-11/+1
Acked-by: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-10-15MIPS: Switch over to generic sys_execve and kernel_execve.Ralf Baechle1-0/+9
This version contains a few updates by David Daney, in particular it's now using __builtin_frame_address() instead of asm() which depending on personal taste, is slightly more appealing. Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2012-10-15mips: switch to generic kernel_thread()Al Viro1-0/+7
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-09-22MIPS: Merge the identical "return from syscall" per-ABI codeAl Viro1-3/+9
No need to keep 4 copies of that stuff; merged and taken to entry.S, unused public symbols there killed off. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2012-09-22MIPS: Prevent hitting do_notify_resume() with !user_mode(regs).Al Viro1-0/+3
Too late to do anything there... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2011-05-19MIPS: Split do_syscall_trace into two functions.Ralf Baechle1-3/+2
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2011-05-19MIPS: Use single define for pending work on syscall exitRalf Baechle1-1/+1
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. Kissell1-5/+5
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. Kissell1-0/+2
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>
2007-03-30[MIPS] lockdep: Handle interrupts in R3000 style c0_status register.Chris Dearman1-1/+5
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>
2007-02-14[MIPS] Make entry.S a little more readable.Franck Bui-Huu1-11/+8
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 Baechle1-0/+3
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-10-10[MIPS] ret_from_irq adjustmentAtsushi Nemoto1-5/+9
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 Baechle1-1/+0
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-07-14[MIPS] TRACE_IRQFLAGS_SUPPORT support.Ralf Baechle1-0/+15
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-07-04[PATCH] sched: cleanup, remove task_t, convert to struct task_structIngo Molnar1-1/+1
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 Engel1-1/+0
Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-06-30[MIPS] Fix use of ehb instruction for non-R2 configurations.Ralf Baechle1-3/+3
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-06-01[MIPS] Fix typoRalf Baechle1-1/+1
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 Baechle1-0/+34
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-04-19[MIPS] R2: Instruction hazard barrier.Ralf Baechle1-0/+15
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2006-04-19[MIPS] Rewrite spurious_interrupt from assembler to C.Ralf Baechle1-26/+0
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2005-10-29Fix excessive signal latencies.Ralf Baechle1-1/+1
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2005-10-29Fix preemption bug.Ralf Baechle1-2/+1
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2005-10-29Use preempt_schedule_irq.Ralf Baechle1-5/+2
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2005-10-29Remove unused arguments from preempt_{start,stop}/local_irq_{en,dis}able.Thiemo Seufer1-18/+17
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 Seufer1-8/+5
Signed-off-by: Thiemo Seufer <ths@networkno.de> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2005-04-17Linux-2.6.12-rc2Linus Torvalds1-0/+155
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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