From 09f90f6685cd88b6b904c141035d096169958cc4 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 11 Nov 2013 21:01:03 +0100 Subject: m68k: Simplify low level interrupt handling code The low level interrupt entry code of m68k contains the following: add_preempt_count(HARDIRQ_OFFSET); do_IRQ(); irq_enter(); add_preempt_count(HARDIRQ_OFFSET); handle_interrupt(); irq_exit(); sub_preempt_count(HARDIRQ_OFFSET); if (in_interrupt()) return; <---- On m68k always taken! if (local_softirq_pending()) do_softirq(); sub_preempt_count(HARDIRQ_OFFSET); if (in_hardirq()) return; if (status_on_stack_has_interrupt_priority_mask > 0) return; if (local_softirq_pending()) do_softirq(); ret_from_exception: if (interrupted_context_is_kernel) return: .... I tried to find a proper explanation for this, but the changelog is sparse and there are no mails explaining it further. But obviously this relates to the interrupt priority levels of the m68k and tries to be extra clever with nested interrupts. Though this cleverness just adds code bloat to the interrupt hotpath. For the common case of non nested interrupts the code runs through two extra conditionals to the only important one, which checks whether the return is to kernel or user space. For the nested case the checks for in_hardirq() and the priority mask value on stack catch only the case where the nested interrupt happens inside the hard irq context of the first interrupt. If the nested interrupt happens while the first interrupt handles soft interrupts, then these extra checks buy nothing. The nested interrupt will fall through to the final kernel/user space return check at ret_from_exception. Changing the code flow in the following way: do_IRQ(); irq_enter(); add_preempt_count(HARDIRQ_OFFSET); handle_interrupt(); irq_exit(); sub_preempt_count(HARDIRQ_OFFSET); if (in_interrupt()) return; if (local_softirq_pending()) do_softirq(); ret_from_exception: if (interrupted_context_is_kernel) return: makes the region protected by the hardirq count slightly smaller and the softirq handling is invoked with a minimal deeper stack. But otherwise it's completely functional equivalent and saves 104 bytes of text in arch/m68k/kernel/entry.o. This modification allows us further to get rid of the limitations which m68k puts on the preempt_count layout, so we can make the preempt count bits completely generic. Signed-off-by: Thomas Gleixner Tested-by: Michael Schmitz Acked-by: Geert Uytterhoeven Cc: Linux/m68k Cc: Andreas Schwab Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1311112052360.30673@ionos.tec.linutronix.de --- arch/m68k/kernel/entry.S | 40 ++++------------------------------------ arch/m68k/kernel/ints.c | 6 ------ arch/m68k/platform/68000/entry.S | 33 ++++++++------------------------- arch/m68k/platform/68360/entry.S | 24 +++--------------------- 4 files changed, 15 insertions(+), 88 deletions(-) (limited to 'arch/m68k') diff --git a/arch/m68k/kernel/entry.S b/arch/m68k/kernel/entry.S index a78f564..b54ac7a 100644 --- a/arch/m68k/kernel/entry.S +++ b/arch/m68k/kernel/entry.S @@ -45,7 +45,7 @@ .globl system_call, buserr, trap, resume .globl sys_call_table .globl __sys_fork, __sys_clone, __sys_vfork -.globl ret_from_interrupt, bad_interrupt +.globl bad_interrupt .globl auto_irqhandler_fixup .globl user_irqvec_fixup @@ -275,8 +275,6 @@ do_delayed_trace: ENTRY(auto_inthandler) SAVE_ALL_INT GET_CURRENT(%d0) - movel %d0,%a1 - addqb #1,%a1@(TINFO_PREEMPT+1) | put exception # in d0 bfextu %sp@(PT_OFF_FORMATVEC){#4,#10},%d0 subw #VEC_SPUR,%d0 @@ -286,32 +284,13 @@ ENTRY(auto_inthandler) auto_irqhandler_fixup = . + 2 jsr do_IRQ | process the IRQ addql #8,%sp | pop parameters off stack - -ret_from_interrupt: - movel %curptr@(TASK_STACK),%a1 - subqb #1,%a1@(TINFO_PREEMPT+1) - jeq ret_from_last_interrupt -2: RESTORE_ALL - - ALIGN -ret_from_last_interrupt: - moveq #(~ALLOWINT>>8)&0xff,%d0 - andb %sp@(PT_OFF_SR),%d0 - jne 2b - - /* check if we need to do software interrupts */ - tstl irq_stat+CPUSTAT_SOFTIRQ_PENDING - jeq .Lret_from_exception - pea ret_from_exception - jra do_softirq + jra ret_from_exception /* Handler for user defined interrupt vectors */ ENTRY(user_inthandler) SAVE_ALL_INT GET_CURRENT(%d0) - movel %d0,%a1 - addqb #1,%a1@(TINFO_PREEMPT+1) | put exception # in d0 bfextu %sp@(PT_OFF_FORMATVEC){#4,#10},%d0 user_irqvec_fixup = . + 2 @@ -321,29 +300,18 @@ user_irqvec_fixup = . + 2 movel %d0,%sp@- | put vector # on stack jsr do_IRQ | process the IRQ addql #8,%sp | pop parameters off stack - - movel %curptr@(TASK_STACK),%a1 - subqb #1,%a1@(TINFO_PREEMPT+1) - jeq ret_from_last_interrupt - RESTORE_ALL + jra ret_from_exception /* Handler for uninitialized and spurious interrupts */ ENTRY(bad_inthandler) SAVE_ALL_INT GET_CURRENT(%d0) - movel %d0,%a1 - addqb #1,%a1@(TINFO_PREEMPT+1) movel %sp,%sp@- jsr handle_badint addql #4,%sp - - movel %curptr@(TASK_STACK),%a1 - subqb #1,%a1@(TINFO_PREEMPT+1) - jeq ret_from_last_interrupt - RESTORE_ALL - + jra ret_from_exception resume: /* diff --git a/arch/m68k/kernel/ints.c b/arch/m68k/kernel/ints.c index 4d7da38..077d3a7 100644 --- a/arch/m68k/kernel/ints.c +++ b/arch/m68k/kernel/ints.c @@ -58,12 +58,6 @@ void __init init_IRQ(void) { int i; - /* assembly irq entry code relies on this... */ - if (HARDIRQ_MASK != 0x00ff0000) { - extern void hardirq_mask_is_broken(void); - hardirq_mask_is_broken(); - } - for (i = IRQ_AUTO_1; i <= IRQ_AUTO_7; i++) irq_set_chip_and_handler(i, &auto_irq_chip, handle_simple_irq); diff --git a/arch/m68k/platform/68000/entry.S b/arch/m68k/platform/68000/entry.S index 7f91c2f..23ac054 100644 --- a/arch/m68k/platform/68000/entry.S +++ b/arch/m68k/platform/68000/entry.S @@ -27,7 +27,6 @@ .globl ret_from_exception .globl ret_from_signal .globl sys_call_table -.globl ret_from_interrupt .globl bad_interrupt .globl inthandler1 .globl inthandler2 @@ -137,7 +136,7 @@ inthandler1: movel #65,%sp@- /* put vector # on stack*/ jbsr process_int /* process the IRQ*/ 3: addql #8,%sp /* pop parameters off stack*/ - bra ret_from_interrupt + bra ret_from_exception inthandler2: SAVE_ALL_INT @@ -148,7 +147,7 @@ inthandler2: movel #66,%sp@- /* put vector # on stack*/ jbsr process_int /* process the IRQ*/ 3: addql #8,%sp /* pop parameters off stack*/ - bra ret_from_interrupt + bra ret_from_exception inthandler3: SAVE_ALL_INT @@ -159,7 +158,7 @@ inthandler3: movel #67,%sp@- /* put vector # on stack*/ jbsr process_int /* process the IRQ*/ 3: addql #8,%sp /* pop parameters off stack*/ - bra ret_from_interrupt + bra ret_from_exception inthandler4: SAVE_ALL_INT @@ -170,7 +169,7 @@ inthandler4: movel #68,%sp@- /* put vector # on stack*/ jbsr process_int /* process the IRQ*/ 3: addql #8,%sp /* pop parameters off stack*/ - bra ret_from_interrupt + bra ret_from_exception inthandler5: SAVE_ALL_INT @@ -181,7 +180,7 @@ inthandler5: movel #69,%sp@- /* put vector # on stack*/ jbsr process_int /* process the IRQ*/ 3: addql #8,%sp /* pop parameters off stack*/ - bra ret_from_interrupt + bra ret_from_exception inthandler6: SAVE_ALL_INT @@ -192,7 +191,7 @@ inthandler6: movel #70,%sp@- /* put vector # on stack*/ jbsr process_int /* process the IRQ*/ 3: addql #8,%sp /* pop parameters off stack*/ - bra ret_from_interrupt + bra ret_from_exception inthandler7: SAVE_ALL_INT @@ -203,7 +202,7 @@ inthandler7: movel #71,%sp@- /* put vector # on stack*/ jbsr process_int /* process the IRQ*/ 3: addql #8,%sp /* pop parameters off stack*/ - bra ret_from_interrupt + bra ret_from_exception inthandler: SAVE_ALL_INT @@ -214,23 +213,7 @@ inthandler: movel %d0,%sp@- /* put vector # on stack*/ jbsr process_int /* process the IRQ*/ 3: addql #8,%sp /* pop parameters off stack*/ - bra ret_from_interrupt - -ret_from_interrupt: - jeq 1f -2: - RESTORE_ALL -1: - moveb %sp@(PT_OFF_SR), %d0 - and #7, %d0 - jhi 2b - - /* check if we need to do software interrupts */ - jeq ret_from_exception - - pea ret_from_exception - jra do_softirq - + bra ret_from_exception /* * Handler for uninitialized and spurious interrupts. diff --git a/arch/m68k/platform/68360/entry.S b/arch/m68k/platform/68360/entry.S index 904fd9a..447c33e 100644 --- a/arch/m68k/platform/68360/entry.S +++ b/arch/m68k/platform/68360/entry.S @@ -29,7 +29,6 @@ .globl ret_from_exception .globl ret_from_signal .globl sys_call_table -.globl ret_from_interrupt .globl bad_interrupt .globl inthandler @@ -132,26 +131,9 @@ inthandler: movel %sp,%sp@- movel %d0,%sp@- /* put vector # on stack*/ - jbsr do_IRQ /* process the IRQ*/ -3: addql #8,%sp /* pop parameters off stack*/ - bra ret_from_interrupt - -ret_from_interrupt: - jeq 1f -2: - RESTORE_ALL -1: - moveb %sp@(PT_OFF_SR), %d0 - and #7, %d0 - jhi 2b - /* check if we need to do software interrupts */ - - movel irq_stat+CPUSTAT_SOFTIRQ_PENDING,%d0 - jeq ret_from_exception - - pea ret_from_exception - jra do_softirq - + jbsr do_IRQ /* process the IRQ */ + addql #8,%sp /* pop parameters off stack*/ + jra ret_from_exception /* * Handler for uninitialized and spurious interrupts. -- cgit v1.1 From 54197e43a4a9a0f3fc406d72d9815754e84fab1e Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 17 Sep 2013 18:53:05 +0000 Subject: hardirq: Make hardirq bits generic There is no reason for per arch hardirq bits. Make them all generic Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20130917183628.534494408@linutronix.de --- arch/m68k/include/asm/hardirq.h | 11 ----------- 1 file changed, 11 deletions(-) (limited to 'arch/m68k') diff --git a/arch/m68k/include/asm/hardirq.h b/arch/m68k/include/asm/hardirq.h index db30ed2..6c61852 100644 --- a/arch/m68k/include/asm/hardirq.h +++ b/arch/m68k/include/asm/hardirq.h @@ -5,17 +5,6 @@ #include #include -#define HARDIRQ_BITS 8 - -/* - * The hardirq mask has to be large enough to have - * space for potentially all IRQ sources in the system - * nesting on a single CPU: - */ -#if (1 << HARDIRQ_BITS) < NR_IRQS -# error HARDIRQ_BITS is too low! -#endif - #ifdef CONFIG_MMU static inline void ack_bad_irq(unsigned int irq) -- cgit v1.1 From 00d1a39e69d5afa7523dad515a05b21abd17c389 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 17 Sep 2013 18:53:09 +0000 Subject: preempt: Make PREEMPT_ACTIVE generic No point in having this bit defined by architecture. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20130917183629.090698799@linutronix.de --- arch/m68k/include/asm/thread_info.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'arch/m68k') diff --git a/arch/m68k/include/asm/thread_info.h b/arch/m68k/include/asm/thread_info.h index 126131f..21a4784 100644 --- a/arch/m68k/include/asm/thread_info.h +++ b/arch/m68k/include/asm/thread_info.h @@ -35,8 +35,6 @@ struct thread_info { }; #endif /* __ASSEMBLY__ */ -#define PREEMPT_ACTIVE 0x4000000 - #define INIT_THREAD_INFO(tsk) \ { \ .task = &tsk, \ -- cgit v1.1