summaryrefslogtreecommitdiffstats
path: root/arch/arc/kernel/entry-arcv2.S
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arc/kernel/entry-arcv2.S')
-rw-r--r--arch/arc/kernel/entry-arcv2.S19
1 files changed, 18 insertions, 1 deletions
diff --git a/arch/arc/kernel/entry-arcv2.S b/arch/arc/kernel/entry-arcv2.S
index cbfec79..b178302 100644
--- a/arch/arc/kernel/entry-arcv2.S
+++ b/arch/arc/kernel/entry-arcv2.S
@@ -211,7 +211,11 @@ debug_marker_syscall:
; (since IRQ NOT allowed in DS in ARCv2, this can only happen if orig
; entry was via Exception in DS which got preempted in kernel).
;
-; IRQ RTIE won't reliably restore DE bit and/or BTA, needs handling
+; IRQ RTIE won't reliably restore DE bit and/or BTA, needs workaround
+;
+; Solution is return from Intr w/o any delay slot quirks into a kernel trampoline
+; and from pure kernel mode return to delay slot which handles DS bit/BTA correctly
+
.Lintr_ret_to_delay_slot:
debug_marker_ds:
@@ -222,18 +226,23 @@ debug_marker_ds:
ld r2, [sp, PT_ret]
ld r3, [sp, PT_status32]
+ ; STAT32 for Int return created from scratch
+ ; (No delay dlot, disable Further intr in trampoline)
+
bic r0, r3, STATUS_U_MASK|STATUS_DE_MASK|STATUS_IE_MASK|STATUS_L_MASK
st r0, [sp, PT_status32]
mov r1, .Lintr_ret_to_delay_slot_2
st r1, [sp, PT_ret]
+ ; Orig exception PC/STAT32 safekept @orig_r0 and @event stack slots
st r2, [sp, 0]
st r3, [sp, 4]
b .Lisr_ret_fast_path
.Lintr_ret_to_delay_slot_2:
+ ; Trampoline to restore orig exception PC/STAT32/BTA/AUX_USER_SP
sub sp, sp, SZ_PT_REGS
st r9, [sp, -4]
@@ -243,11 +252,19 @@ debug_marker_ds:
ld r9, [sp, 4]
sr r9, [erstatus]
+ ; restore AUX_USER_SP if returning to U mode
+ bbit0 r9, STATUS_U_BIT, 1f
+ ld r9, [sp, PT_sp]
+ sr r9, [AUX_USER_SP]
+
+1:
ld r9, [sp, 8]
sr r9, [erbta]
ld r9, [sp, -4]
add sp, sp, SZ_PT_REGS
+
+ ; return from pure kernel mode to delay slot
rtie
END(ret_from_exception)
OpenPOWER on IntegriCloud