175 lines
6.1 KiB
Diff
175 lines
6.1 KiB
Diff
From: Thomas Gleixner <tglx@linutronix.de>
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Date: Thu, 1 Nov 2012 10:14:11 +0100
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Subject: powerpc: Add support for lazy preemption
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.8/older/patches-4.8.6-rt5.tar.xz
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Implement the powerpc pieces for lazy preempt.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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arch/powerpc/Kconfig | 1 +
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arch/powerpc/include/asm/thread_info.h | 11 ++++++++---
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arch/powerpc/kernel/asm-offsets.c | 1 +
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arch/powerpc/kernel/entry_32.S | 17 ++++++++++++-----
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arch/powerpc/kernel/entry_64.S | 14 +++++++++++---
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5 files changed, 33 insertions(+), 11 deletions(-)
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--- a/arch/powerpc/Kconfig
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+++ b/arch/powerpc/Kconfig
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@@ -141,6 +141,7 @@ config PPC
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select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
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select GENERIC_STRNCPY_FROM_USER
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select GENERIC_STRNLEN_USER
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+ select HAVE_PREEMPT_LAZY
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select HAVE_MOD_ARCH_SPECIFIC
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select MODULES_USE_ELF_RELA
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select CLONE_BACKWARDS
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--- a/arch/powerpc/include/asm/thread_info.h
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+++ b/arch/powerpc/include/asm/thread_info.h
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@@ -43,6 +43,8 @@ struct thread_info {
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int cpu; /* cpu we're on */
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int preempt_count; /* 0 => preemptable,
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<0 => BUG */
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+ int preempt_lazy_count; /* 0 => preemptable,
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+ <0 => BUG */
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unsigned long local_flags; /* private flags for thread */
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#ifdef CONFIG_LIVEPATCH
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unsigned long *livepatch_sp;
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@@ -88,8 +90,7 @@ static inline struct thread_info *curren
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#define TIF_SYSCALL_TRACE 0 /* syscall trace active */
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#define TIF_SIGPENDING 1 /* signal pending */
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#define TIF_NEED_RESCHED 2 /* rescheduling necessary */
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-#define TIF_POLLING_NRFLAG 3 /* true if poll_idle() is polling
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- TIF_NEED_RESCHED */
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+#define TIF_NEED_RESCHED_LAZY 3 /* lazy rescheduling necessary */
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#define TIF_32BIT 4 /* 32 bit binary */
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#define TIF_RESTORE_TM 5 /* need to restore TM FP/VEC/VSX */
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#define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */
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@@ -107,6 +108,8 @@ static inline struct thread_info *curren
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#if defined(CONFIG_PPC64)
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#define TIF_ELF2ABI 18 /* function descriptors must die! */
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#endif
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+#define TIF_POLLING_NRFLAG 19 /* true if poll_idle() is polling
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+ TIF_NEED_RESCHED */
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/* as above, but as bit values */
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#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
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@@ -125,14 +128,16 @@ static inline struct thread_info *curren
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#define _TIF_SYSCALL_TRACEPOINT (1<<TIF_SYSCALL_TRACEPOINT)
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#define _TIF_EMULATE_STACK_STORE (1<<TIF_EMULATE_STACK_STORE)
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#define _TIF_NOHZ (1<<TIF_NOHZ)
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+#define _TIF_NEED_RESCHED_LAZY (1<<TIF_NEED_RESCHED_LAZY)
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#define _TIF_SYSCALL_DOTRACE (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \
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_TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
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_TIF_NOHZ)
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#define _TIF_USER_WORK_MASK (_TIF_SIGPENDING | _TIF_NEED_RESCHED | \
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_TIF_NOTIFY_RESUME | _TIF_UPROBE | \
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- _TIF_RESTORE_TM)
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+ _TIF_RESTORE_TM | _TIF_NEED_RESCHED_LAZY)
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#define _TIF_PERSYSCALL_MASK (_TIF_RESTOREALL|_TIF_NOERROR)
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+#define _TIF_NEED_RESCHED_MASK (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY)
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/* Bits in local_flags */
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/* Don't move TLF_NAPPING without adjusting the code in entry_32.S */
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--- a/arch/powerpc/kernel/asm-offsets.c
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+++ b/arch/powerpc/kernel/asm-offsets.c
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@@ -156,6 +156,7 @@ int main(void)
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DEFINE(TI_FLAGS, offsetof(struct thread_info, flags));
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DEFINE(TI_LOCAL_FLAGS, offsetof(struct thread_info, local_flags));
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DEFINE(TI_PREEMPT, offsetof(struct thread_info, preempt_count));
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+ DEFINE(TI_PREEMPT_LAZY, offsetof(struct thread_info, preempt_lazy_count));
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DEFINE(TI_TASK, offsetof(struct thread_info, task));
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DEFINE(TI_CPU, offsetof(struct thread_info, cpu));
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--- a/arch/powerpc/kernel/entry_32.S
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+++ b/arch/powerpc/kernel/entry_32.S
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@@ -835,7 +835,14 @@ user_exc_return: /* r10 contains MSR_KE
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cmpwi 0,r0,0 /* if non-zero, just restore regs and return */
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bne restore
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andi. r8,r8,_TIF_NEED_RESCHED
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+ bne+ 1f
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+ lwz r0,TI_PREEMPT_LAZY(r9)
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+ cmpwi 0,r0,0 /* if non-zero, just restore regs and return */
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+ bne restore
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+ lwz r0,TI_FLAGS(r9)
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+ andi. r0,r0,_TIF_NEED_RESCHED_LAZY
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beq+ restore
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+1:
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lwz r3,_MSR(r1)
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andi. r0,r3,MSR_EE /* interrupts off? */
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beq restore /* don't schedule if so */
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@@ -846,11 +853,11 @@ user_exc_return: /* r10 contains MSR_KE
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*/
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bl trace_hardirqs_off
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#endif
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-1: bl preempt_schedule_irq
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+2: bl preempt_schedule_irq
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CURRENT_THREAD_INFO(r9, r1)
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lwz r3,TI_FLAGS(r9)
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- andi. r0,r3,_TIF_NEED_RESCHED
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- bne- 1b
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+ andi. r0,r3,_TIF_NEED_RESCHED_MASK
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+ bne- 2b
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#ifdef CONFIG_TRACE_IRQFLAGS
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/* And now, to properly rebalance the above, we tell lockdep they
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* are being turned back on, which will happen when we return
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@@ -1171,7 +1178,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_NEED_PAIRE
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#endif /* !(CONFIG_4xx || CONFIG_BOOKE) */
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do_work: /* r10 contains MSR_KERNEL here */
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- andi. r0,r9,_TIF_NEED_RESCHED
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+ andi. r0,r9,_TIF_NEED_RESCHED_MASK
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beq do_user_signal
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do_resched: /* r10 contains MSR_KERNEL here */
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@@ -1192,7 +1199,7 @@ do_resched: /* r10 contains MSR_KERNEL
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MTMSRD(r10) /* disable interrupts */
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CURRENT_THREAD_INFO(r9, r1)
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lwz r9,TI_FLAGS(r9)
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- andi. r0,r9,_TIF_NEED_RESCHED
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+ andi. r0,r9,_TIF_NEED_RESCHED_MASK
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bne- do_resched
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andi. r0,r9,_TIF_USER_WORK_MASK
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beq restore_user
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--- a/arch/powerpc/kernel/entry_64.S
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+++ b/arch/powerpc/kernel/entry_64.S
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@@ -657,7 +657,7 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEG
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bl restore_math
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b restore
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#endif
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-1: andi. r0,r4,_TIF_NEED_RESCHED
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+1: andi. r0,r4,_TIF_NEED_RESCHED_MASK
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beq 2f
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bl restore_interrupts
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SCHEDULE_USER
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@@ -719,10 +719,18 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEG
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#ifdef CONFIG_PREEMPT
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/* Check if we need to preempt */
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+ lwz r8,TI_PREEMPT(r9)
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+ cmpwi 0,r8,0 /* if non-zero, just restore regs and return */
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+ bne restore
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andi. r0,r4,_TIF_NEED_RESCHED
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+ bne+ check_count
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+
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+ andi. r0,r4,_TIF_NEED_RESCHED_LAZY
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beq+ restore
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+ lwz r8,TI_PREEMPT_LAZY(r9)
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+
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/* Check that preempt_count() == 0 and interrupts are enabled */
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- lwz r8,TI_PREEMPT(r9)
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+check_count:
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cmpwi cr1,r8,0
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ld r0,SOFTE(r1)
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cmpdi r0,0
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@@ -739,7 +747,7 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEG
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/* Re-test flags and eventually loop */
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CURRENT_THREAD_INFO(r9, r1)
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ld r4,TI_FLAGS(r9)
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- andi. r0,r4,_TIF_NEED_RESCHED
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+ andi. r0,r4,_TIF_NEED_RESCHED_MASK
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bne 1b
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/*
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