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

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>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S
index bc08c98d008d..4845d51e88a6 100644
--- a/arch/blackfin/mach-common/entry.S
+++ b/arch/blackfin/mach-common/entry.S
@@ -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)