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* ARC: document memory clobber in irq control macrosVineet Gupta2014-12-121-0/+9
| | | | Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* ARC: remove extraneous __KERNEL__ guardsVineet Gupta2014-10-131-4/+0
| | | | | Verified by doing make headers_install as none of these files are exported to userspace
* ARC: [intc] mask/unmask can be hidden againVineet Gupta2014-07-231-18/+0
| | | | Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* ARC: Add support for irqflags tracing and lockdepVineet Gupta2013-11-061-0/+22
| | | | | | | Lockdep required a small fix to stacktrace API which was incorrectly unwindign out of __switch_to for the current call frame. Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* ARC: Entry Handler tweaks: Optimize away redundant IRQ_DISABLE_SAVEVineet Gupta2013-08-261-7/+0
| | | | | | | | | | | | | | | | | | | In the exception return path, for both U/K cases, intr are already disabled (for various existing reasons). So when we drop down to @restore_regs, we need not redo that. There was subtle issue - when intr were NOT being disabled for ret-to-kernel-but-no-preemption case - now fixed by moving the IRQ_DISABLE further up in @resume_kernel_mode. So what do we gain: * Shaves off a few insn in return path. * Eliminates the need for IRQ_DISABLE_SAVE assembler macro for ARCv2 hence allows for entry code sharing. Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* ARC: Disintegrate arcregs.hVineet Gupta2013-06-221-0/+20
| | | | | | | | | * Move the various sub-system defines/types into relevant files/functions (reduces compilation time) * move CPU specific stuff out of asm/tlb.h into asm/mmu.h Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* ARC: Add implicit compiler barrier to raw_local_irq* functionsChristian Ruppert2013-04-081-4/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ARC irqsave/restore macros were missing the compiler barrier, causing a stale load in irq-enabled region be used in irq-safe region, despite being changed, because the register holding the value was still live. The problem manifested as random crashes in timer code when stress testing ARCLinux (3.9-rc3) on a !SMP && !PREEMPT_COUNT Here's the exact sequence which caused this: (0). tv1[x] <----> t1 <---> t2 (1). mod_timer(t1) interrupted after it calls timer_pending() (2). mod_timer(t2) completes (3). mod_timer(t1) resumes but messes up the list (4). __runt_timers( ) uses bogus timer_list entry / crashes in timer->function Essentially mod_timer() was racing against itself and while the spinlock serialized the tv1[] timer link list, timer_pending() called outside the spinlock, cached timer link list element in a register. With low register pressure (and a deep register file), lack of barrier in raw_local_irqsave() as well as preempt_disable (!PREEMPT_COUNT version), there was nothing to force gcc to reload across the spinlock, causing a stale value in reg be used for link list manipulation - ensuing a corruption. ARcompact disassembly which shows the culprit generated code: mod_timer: push_s blink mov_s r13,r0 # timer, timer .. ###### timer_pending( ) ld_s r3,[r13] # <------ <variable>.entry.next LOADED brne r3, 0, @.L163 .L163: .. ###### spin_lock_irq( ) lr r5, [status32] # flags bic r4, r5, 6 # temp, flags, and.f 0, r5, 6 # flags, flag.nz r4 ###### detach_if_pending( ) begins tst_s r3,r3 <-------------- # timer_pending( ) checks timer->entry.next # r3 is NOT reloaded by gcc, using stale value beq.d @.L169 mov.eq r0,0 ##### detach_timer( ): __list_del( ) ld r4,[r13,4] # <variable>.entry.prev, D.31439 st r4,[r3,4] # <variable>.prev, D.31439 st r3,[r4] # <variable>.next, D.30246 We initially tried to fix this by adding barrier() to preempt_* macros for !PREEMPT_COUNT but Linus clarified that it was anything but wrong. http://www.spinics.net/lists/kernel/msg1512709.html [vgupta: updated commitlog] Reported-by/Signed-off-by: Christian Ruppert <christian.ruppert@abilis.com> Cc: Christian Ruppert <christian.ruppert@abilis.com> Cc: Pierrick Hascoet <pierrick.hascoet@abilis.com> Debugged-by/Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* ARC: Support for high priority interrupts in the in-core intcVineet Gupta2013-02-151-1/+5
| | | | | | | | | There is a bit of hack/kludge right now where we disable preemption if a L2 (High prio) IRQ is taken while L1 (Low prio) is active. Need to revisit this Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
* ARC: irqflags - Interrupt enabling/disabling at in-core intcVineet Gupta2013-02-111-0/+149
ARC700 has an in-core intc which provides 2 priorities (a.k.a.) "levels" of interrupts (per IRQ) hencforth referred to as L1/L2 interrupts. CPU flags register STATUS32 has Interrupt Enable bits per level (E1/E2) to globally enable (or disable) all IRQs at a level. Hence the implementation of arch_local_irq_{save,restore,enable,disable}( ) The STATUS32 reg can be r/w only using the AUX Interface of ARC, hence the use of LR/SR instructions. Further, E1/E2 bits in there can only be updated using the FLAG insn. The intc supports 32 interrupts - and per IRQ enabling is controlled by a bit in the AUX_IENABLE register, hence the implmentation of arch_{,un}mask_irq( ) routines. Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Thomas Gleixner <tglx@linutronix.de>
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