From 895666a9920f19bc256340aaf58d01da6e677a16 Mon Sep 17 00:00:00 2001 From: Max Filippov Date: Tue, 26 Mar 2013 02:51:43 +0400 Subject: [PATCH] xtensa: disable IRQs while IRQ handler is running IRQ handlers are expected to run with IRQs disabled. See e.g. http://lwn.net/Articles/380931/ for a longer story. This was overlooked in the commit 2d1c645 xtensa: dispatch medium-priority interrupts Revert to old behavior and simplify interrupt entry and exit code. Interrupt handler still honours IRQ priority. do_notify_resume/schedule must be called with interrupts enabled, enable interrupts if we return from user exception. Signed-off-by: Max Filippov Signed-off-by: Chris Zankel --- arch/xtensa/kernel/entry.S | 54 ++++++++---------------------------- arch/xtensa/kernel/traps.c | 18 ++++++------ arch/xtensa/kernel/vectors.S | 13 +++++---- 3 files changed, 29 insertions(+), 56 deletions(-) diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S index 3729b48d798d..5082507d5631 100644 --- a/arch/xtensa/kernel/entry.S +++ b/arch/xtensa/kernel/entry.S @@ -354,16 +354,16 @@ common_exception: * so we can allow exceptions and interrupts (*) again. * Set PS(EXCM = 0, UM = 0, RING = 0, OWB = 0, WOE = 1, INTLEVEL = X) * - * (*) We only allow interrupts of higher priority than current IRQ + * (*) We only allow interrupts if they were previously enabled and + * we're not handling an IRQ */ rsr a3, ps - addi a0, a0, -4 - movi a2, 1 + addi a0, a0, -EXCCAUSE_LEVEL1_INTERRUPT + movi a2, LOCKLEVEL extui a3, a3, PS_INTLEVEL_SHIFT, PS_INTLEVEL_WIDTH # a3 = PS.INTLEVEL - movnez a2, a3, a3 # a2 = 1: level-1, > 1: high priority - moveqz a3, a2, a0 # a3 = IRQ level iff interrupt + moveqz a3, a2, a0 # a3 = LOCKLEVEL iff interrupt movi a2, 1 << PS_WOE_BIT or a3, a3, a2 rsr a0, exccause @@ -444,6 +444,8 @@ common_exception_return: 1: l32i a3, a1, PT_PS _bbci.l a3, PS_UM_BIT, 4f + rsil a2, 0 + /* Specific to a user exception exit: * We need to check some flags for signal handling and rescheduling, * and have to restore WB and WS, extra states, and all registers @@ -684,51 +686,19 @@ common_exception_exit: l32i a0, a1, PT_DEPC l32i a3, a1, PT_AREG3 - _bltui a0, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f - - wsr a0, depc l32i a2, a1, PT_AREG2 - l32i a0, a1, PT_AREG0 - l32i a1, a1, PT_AREG1 - rfde + _bgeui a0, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f -1: /* Restore a0...a3 and return */ - rsr a0, ps - extui a2, a0, PS_INTLEVEL_SHIFT, PS_INTLEVEL_WIDTH - movi a0, 2f - slli a2, a2, 4 - add a0, a2, a0 - l32i a2, a1, PT_AREG2 - jx a0 - - .macro irq_exit_level level - .align 16 - .if XCHAL_EXCM_LEVEL >= \level - l32i a0, a1, PT_PC - wsr a0, epc\level - l32i a0, a1, PT_AREG0 - l32i a1, a1, PT_AREG1 - rfi \level - .endif - .endm - - .align 16 -2: l32i a0, a1, PT_AREG0 l32i a1, a1, PT_AREG1 rfe - .align 16 - /* no rfi for level-1 irq, handled by rfe above*/ - nop - - irq_exit_level 2 - irq_exit_level 3 - irq_exit_level 4 - irq_exit_level 5 - irq_exit_level 6 +1: wsr a0, depc + l32i a0, a1, PT_AREG0 + l32i a1, a1, PT_AREG1 + rfde ENDPROC(kernel_exception) diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c index cf065e165ceb..30e53e609104 100644 --- a/arch/xtensa/kernel/traps.c +++ b/arch/xtensa/kernel/traps.c @@ -196,7 +196,6 @@ void do_multihit(struct pt_regs *regs, unsigned long exccause) /* * IRQ handler. - * PS.INTLEVEL is the current IRQ priority level. */ extern void do_IRQ(int, struct pt_regs *); @@ -213,18 +212,21 @@ void do_interrupt(struct pt_regs *regs) XCHAL_INTLEVEL6_MASK, XCHAL_INTLEVEL7_MASK, }; - unsigned level = get_sr(ps) & PS_INTLEVEL_MASK; - - if (WARN_ON_ONCE(level >= ARRAY_SIZE(int_level_mask))) - return; for (;;) { unsigned intread = get_sr(interrupt); unsigned intenable = get_sr(intenable); - unsigned int_at_level = intread & intenable & - int_level_mask[level]; + unsigned int_at_level = intread & intenable; + unsigned level; - if (!int_at_level) + for (level = LOCKLEVEL; level > 0; --level) { + if (int_at_level & int_level_mask[level]) { + int_at_level &= int_level_mask[level]; + break; + } + } + + if (level == 0) return; /* diff --git a/arch/xtensa/kernel/vectors.S b/arch/xtensa/kernel/vectors.S index a7e1d0834c68..f9e175382aa9 100644 --- a/arch/xtensa/kernel/vectors.S +++ b/arch/xtensa/kernel/vectors.S @@ -386,9 +386,12 @@ ENDPROC(_DebugInterruptVector) .if XCHAL_EXCM_LEVEL >= \level .section .Level\level\()InterruptVector.text, "ax" ENTRY(_Level\level\()InterruptVector) - wsr a0, epc1 + wsr a0, excsave2 rsr a0, epc\level - xsr a0, epc1 + wsr a0, epc1 + movi a0, EXCCAUSE_LEVEL1_INTERRUPT + wsr a0, exccause + rsr a0, eps\level # branch to user or kernel vector j _SimulateUserKernelVectorException .endif @@ -440,10 +443,8 @@ ENDPROC(_WindowOverflow4) */ .align 4 _SimulateUserKernelVectorException: - wsr a0, excsave2 - movi a0, 4 # LEVEL1_INTERRUPT cause - wsr a0, exccause - rsr a0, ps + addi a0, a0, (1 << PS_EXCM_BIT) + wsr a0, ps bbsi.l a0, PS_UM_BIT, 1f # branch if user mode rsr a0, excsave2 # restore a0 j _KernelExceptionVector # simulate kernel vector exception