[POWERPC] Move to runtime allocated exception stacks

For the additonal exception levels (critical, debug, machine check) on
40x/book-e we were using "static" allocations of the stack in the
associated head.S.

Move to a runtime allocation to make the code a bit easier to read as
we mimic how we handle IRQ stacks.  Its also a bit easier to setup the
stack with a "dummy" thread_info in C code.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Paul Mackerras <paulus@samba.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 5112a4aa801d..bef0be3fd98b 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -248,6 +248,28 @@ static void __init irqstack_early_init(void)
 #define irqstack_early_init()
 #endif
 
+#if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
+static void __init exc_lvl_early_init(void)
+{
+        unsigned int i;
+
+        /* interrupt stacks must be in lowmem, we get that for free on ppc32
+         * as the lmb is limited to lowmem by LMB_REAL_LIMIT */
+        for_each_possible_cpu(i) {
+                critirq_ctx[i] = (struct thread_info *)
+                        __va(lmb_alloc(THREAD_SIZE, THREAD_SIZE));
+#ifdef CONFIG_BOOKE
+                dbgirq_ctx[i] = (struct thread_info *)
+                        __va(lmb_alloc(THREAD_SIZE, THREAD_SIZE));
+                mcheckirq_ctx[i] = (struct thread_info *)
+                        __va(lmb_alloc(THREAD_SIZE, THREAD_SIZE));
+#endif
+        }
+}
+#else
+#define exc_lvl_early_init()
+#endif
+
 /* Warning, IO base is not yet inited */
 void __init setup_arch(char **cmdline_p)
 {
@@ -305,6 +327,8 @@ void __init setup_arch(char **cmdline_p)
         init_mm.end_data = (unsigned long) _edata;
         init_mm.brk = klimit;
 
+        exc_lvl_early_init();
+
         irqstack_early_init();
 
         /* set up the bootmem stuff with available memory */