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Blackfin/ipipe: fix deferred pipeline sync for the root stage

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This patch makes sure to sync the pipeline for the root stage only
from the outer interrupt level, when resuming kernel code after an
interrupt.

This fixes a bug causing EVT15 to be spuriously popped off upon nested
interrupts, which in turn would cause the preempted kernel code to
resume without supervisor privileges.

Signed-off-by: Philippe Gerum <rpm@xenomai.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
This commit is contained in:
Philippe Gerum 2011-03-17 02:15:24 -04:00 committed by Mike Frysinger
parent 5b5da4c4b8
commit 9169b51f8c
2 changed files with 14 additions and 3 deletions
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11
arch/blackfin/mach-common/entry.S
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@ -952,8 +952,17 @@ ENDPROC(_evt_up_evt14)
#ifdef CONFIG_IPIPE
_resume_kernel_from_int:
r1 = LO(~0x8000) (Z);
r1 = r0 & r1;
r0 = 1;
r0 = r1 - r0;
r2 = r1 & r0;
cc = r2 == 0;
/* Sync the root stage only from the outer interrupt level. */
if !cc jump .Lnosync;
r0.l = ___ipipe_sync_root;
r0.h = ___ipipe_sync_root;
[--sp] = reti;
[--sp] = rets;
[--sp] = ( r7:4, p5:3 );
SP += -12;
@ -961,6 +970,8 @@ _resume_kernel_from_int:
SP += 12;
( r7:4, p5:3 ) = [sp++];
rets = [sp++];
reti = [sp++];
.Lnosync:
rts
#elif defined(CONFIG_PREEMPT)

6
arch/blackfin/mach-common/interrupt.S
View File

@ -274,16 +274,16 @@ ENDPROC(_evt_system_call)
* level to EVT14 to prepare the caller for a normal interrupt
* return through RTI.
*
* We currently use this facility in two occasions:
* We currently use this feature in two occasions:
*
* - to branch to __ipipe_irq_tail_hook as requested by a high
* - before branching to __ipipe_irq_tail_hook as requested by a high
* priority domain after the pipeline delivered an interrupt,
* e.g. such as Xenomai, in order to start its rescheduling
* procedure, since we may not switch tasks when IRQ levels are
* nested on the Blackfin, so we have to fake an interrupt return
* so that we may reschedule immediately.
*
* - to branch to sync_root_irqs, in order to play any interrupt
* - before branching to __ipipe_sync_root(), in order to play any interrupt
* pending for the root domain (i.e. the Linux kernel). This lowers
* the core priority level enough so that Linux IRQ handlers may
* never delay interrupts handled by high priority domains; we defer