arch/tile: use interrupt critical sections less
In general we want to avoid ever touching memory while within an
interrupt critical section, since the page fault path goes through
a different path from the hypervisor when in an interrupt critical
section, and we carefully decided with tilegx that we didn't need
to support this path in the kernel. (On tilepro we did implement
that path as part of supporting atomic instructions in software.)
In practice we always need to touch the kernel stack, since that's
where we store the interrupt state before releasing the critical
section, but this change cleans up a few things. The IRQ_ENABLE
macro is split up so that when we want to enable interrupts in a
deferred way (e.g. for cpu_idle or for interrupt return) we can
read the per-cpu enable mask before entering the critical section.
The cache-migration code is changed to use interrupt masking instead
of interrupt critical sections. And, the interrupt-entry code is
changed so that we defer loading "tp" from per-cpu data until after
we have released the interrupt critical section.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
diff --git a/arch/tile/mm/migrate_64.S b/arch/tile/mm/migrate_64.S
index e76fea6..1d15b108 100644
--- a/arch/tile/mm/migrate_64.S
+++ b/arch/tile/mm/migrate_64.S
@@ -38,8 +38,7 @@
#define FRAME_R30 16
#define FRAME_R31 24
#define FRAME_R32 32
-#define FRAME_R33 40
-#define FRAME_SIZE 48
+#define FRAME_SIZE 40
@@ -60,10 +59,9 @@
#define r_my_cpumask r3
/* Locals (callee-save); must not be more than FRAME_xxx above. */
-#define r_save_ics r30
-#define r_context r31
-#define r_access r32
-#define r_asid r33
+#define r_context r30
+#define r_access r31
+#define r_asid r32
/*
* Caller-save locals and frame constants are the same as
@@ -93,11 +91,7 @@
st r_tmp, r31
addi r_tmp, sp, FRAME_R32
}
- {
- st r_tmp, r32
- addi r_tmp, sp, FRAME_R33
- }
- st r_tmp, r33
+ st r_tmp, r32
/* Move some arguments to callee-save registers. */
{
@@ -106,13 +100,6 @@
}
move r_asid, r_asid_in
- /* Disable interrupts, since we can't use our stack. */
- {
- mfspr r_save_ics, INTERRUPT_CRITICAL_SECTION
- movei r_tmp, 1
- }
- mtspr INTERRUPT_CRITICAL_SECTION, r_tmp
-
/* First, flush our L2 cache. */
{
move r0, zero /* cache_pa */
@@ -147,7 +134,7 @@
}
{
move r2, r_asid
- movei r3, HV_CTX_DIRECTIO
+ moveli r3, HV_CTX_DIRECTIO | CTX_PAGE_FLAG
}
jal hv_install_context
bnez r0, 1f
@@ -158,10 +145,7 @@
jal hv_flush_all
}
-1: /* Reset interrupts back how they were before. */
- mtspr INTERRUPT_CRITICAL_SECTION, r_save_ics
-
- /* Restore the callee-saved registers and return. */
+1: /* Restore the callee-saved registers and return. */
addli lr, sp, FRAME_SIZE
{
ld lr, lr
@@ -177,10 +161,6 @@
}
{
ld r32, r_tmp
- addli r_tmp, sp, FRAME_R33
- }
- {
- ld r33, r_tmp
addi sp, sp, FRAME_SIZE
}
jrp lr