powerpc: Rename slb0_limit() to safe_stack_limit() and add Book3E support
slb0_limit() wasn't a very descriptive name. This changes it along with
a comment explaining what it's used for, and provides a 64-bit BookE
implementation.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 959c63c..c2ec0a1 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -434,17 +434,30 @@
DBG(" <- setup_system()\n");
}
-static u64 slb0_limit(void)
+/* This returns the limit below which memory accesses to the linear
+ * mapping are guarnateed not to cause a TLB or SLB miss. This is
+ * used to allocate interrupt or emergency stacks for which our
+ * exception entry path doesn't deal with being interrupted.
+ */
+static u64 safe_stack_limit(void)
{
- if (mmu_has_feature(MMU_FTR_1T_SEGMENT)) {
+#ifdef CONFIG_PPC_BOOK3E
+ /* Freescale BookE bolts the entire linear mapping */
+ if (mmu_has_feature(MMU_FTR_TYPE_FSL_E))
+ return linear_map_top;
+ /* Other BookE, we assume the first GB is bolted */
+ return 1ul << 30;
+#else
+ /* BookS, the first segment is bolted */
+ if (mmu_has_feature(MMU_FTR_1T_SEGMENT))
return 1UL << SID_SHIFT_1T;
- }
return 1UL << SID_SHIFT;
+#endif
}
static void __init irqstack_early_init(void)
{
- u64 limit = slb0_limit();
+ u64 limit = safe_stack_limit();
unsigned int i;
/*
@@ -497,7 +510,7 @@
* bringup, we need to get at them in real mode. This means they
* must also be within the RMO region.
*/
- limit = min(slb0_limit(), ppc64_rma_size);
+ limit = min(safe_stack_limit(), ppc64_rma_size);
for_each_possible_cpu(i) {
unsigned long sp;