[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>

diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
index 8552e67e3a8bebc9da26b01840dd996e1b2f6d0f..f2cf60d38f78953a2273785c4d19fc61f279fa2a 100644 (file)
--- a/arch/powerpc/kernel/head_40x.S
+++ b/arch/powerpc/kernel/head_40x.S
@@ -148,14 +148,14 @@ _ENTRY(crit_r11)
        mfcr    r10;                    /* save CR in r10 for now          */\
        mfspr   r11,SPRN_SRR3;          /* check whether user or kernel    */\
        andi.   r11,r11,MSR_PR;                                              \
-       lis     r11,critical_stack_top@h;                                    \
-       ori     r11,r11,critical_stack_top@l;                                \
+       lis     r11,critirq_ctx@ha;                                          \
+       tophys(r11,r11);                                                     \
+       lwz     r11,critirq_ctx@l(r11);                                      \
        beq     1f;                                                          \
        /* COMING FROM USER MODE */                                          \
        mfspr   r11,SPRN_SPRG3;         /* if from user, start at top of   */\
        lwz     r11,THREAD_INFO-THREAD(r11); /* this thread's kernel stack */\
-       addi    r11,r11,THREAD_SIZE;                                         \
-1:     subi    r11,r11,INT_FRAME_SIZE; /* Allocate an exception frame     */\
+1:     addi    r11,r11,THREAD_SIZE-INT_FRAME_SIZE; /* Alloc an excpt frm  */\
        tophys(r11,r11);                                                     \
        stw     r10,_CCR(r11);          /* save various registers          */\
        stw     r12,GPR12(r11);                                              \
@@ -996,16 +996,6 @@ empty_zero_page:
 swapper_pg_dir:
        .space  PGD_TABLE_SIZE
 
-
-/* Stack for handling critical exceptions from kernel mode */
-       .section .bss
-        .align 12
-exception_stack_bottom:
-       .space  4096
-critical_stack_top:
-       .globl  exception_stack_top
-exception_stack_top:
-
 /* Room for two PTE pointers, usually the kernel and current user pointers
  * to their respective root page table.
  */

diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
index c2b9dc4fce5d24a4021972f5337d66828faca918..47ea8affad232e08f880a69490841069e4133fe8 100644 (file)
--- a/arch/powerpc/kernel/head_44x.S
+++ b/arch/powerpc/kernel/head_44x.S
@@ -737,15 +737,6 @@ empty_zero_page:
 swapper_pg_dir:
        .space  PGD_TABLE_SIZE
 
-/* Reserved 4k for the critical exception stack & 4k for the machine
- * check stack per CPU for kernel mode exceptions */
-       .section .bss
-        .align 12
-exception_stack_bottom:
-       .space  BOOKE_EXCEPTION_STACK_SIZE
-       .globl  exception_stack_top
-exception_stack_top:
-
 /*
  * Room for two PTE pointers, usually the kernel and current user pointers
  * to their respective root page table.

diff --git a/arch/powerpc/kernel/head_booke.h b/arch/powerpc/kernel/head_booke.h
index 721faef870954459ac2cafafa10397c835a95d48..9eacf4ca442a3106684159eeba845506fcc6dddf 100644 (file)
--- a/arch/powerpc/kernel/head_booke.h
+++ b/arch/powerpc/kernel/head_booke.h
@@ -43,9 +43,7 @@
        SAVE_2GPRS(7, r11)
 
 /* To handle the additional exception priority levels on 40x and Book-E
- * processors we allocate a 4k stack per additional priority level. The various
- * head_xxx.S files allocate space (exception_stack_top) for each priority's
- * stack times the number of CPUs
+ * processors we allocate a stack per additional priority level.
  *
  * On 40x critical is the only additional level
  * On 44x/e500 we have critical and machine check
@@ -61,36 +59,31 @@
  * going to critical or their own debug level we aren't currently
  * providing configurations that micro-optimize space usage.
  */
-#ifdef CONFIG_44x
-#define NUM_EXCEPTION_LVLS     2
-#else
-#define NUM_EXCEPTION_LVLS     3
-#endif
-#define BOOKE_EXCEPTION_STACK_SIZE     (4096 * NUM_EXCEPTION_LVLS)
 
 /* CRIT_SPRG only used in critical exception handling */
 #define CRIT_SPRG      SPRN_SPRG2
 /* MCHECK_SPRG only used in machine check exception handling */
 #define MCHECK_SPRG    SPRN_SPRG6W
 
-#define MCHECK_STACK_TOP       (exception_stack_top - 4096)
-#define CRIT_STACK_TOP         (exception_stack_top)
+#define MCHECK_STACK_BASE      mcheckirq_ctx
+#define CRIT_STACK_BASE                critirq_ctx
 
 /* only on e200 for now */
-#define DEBUG_STACK_TOP                (exception_stack_top - 8192)
+#define DEBUG_STACK_BASE       dbgirq_ctx
 #define DEBUG_SPRG             SPRN_SPRG6W
 
 #ifdef CONFIG_SMP
 #define BOOKE_LOAD_EXC_LEVEL_STACK(level)              \
        mfspr   r8,SPRN_PIR;                            \
-       mulli   r8,r8,BOOKE_EXCEPTION_STACK_SIZE;       \
-       neg     r8,r8;                                  \
-       addis   r8,r8,level##_STACK_TOP@ha;             \
-       addi    r8,r8,level##_STACK_TOP@l
+       slwi    r8,r8,2;                                \
+       addis   r8,r8,level##_STACK_BASE@ha;            \
+       lwz     r8,level##_STACK_BASE@l(r8);            \
+       addi    r8,r8,THREAD_SIZE;
 #else
 #define BOOKE_LOAD_EXC_LEVEL_STACK(level)              \
-       lis     r8,level##_STACK_TOP@h;                 \
-       ori     r8,r8,level##_STACK_TOP@l
+       lis     r8,level##_STACK_BASE@ha;               \
+       lwz     r8,level##_STACK_BASE@l(r8);            \
+       addi    r8,r8,THREAD_SIZE;
 #endif
 
 /*

diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
index e581524d85bc9ee040bef175426d85c4a03b0cc6..503f86030b6eff6243dac7fbc3c0914960a2cda6 100644 (file)
--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -1080,15 +1080,6 @@ empty_zero_page:
 swapper_pg_dir:
        .space  PGD_TABLE_SIZE
 
-/* Reserved 4k for the critical exception stack & 4k for the machine
- * check stack per CPU for kernel mode exceptions */
-       .section .bss
-       .align 12
-exception_stack_bottom:
-       .space  BOOKE_EXCEPTION_STACK_SIZE * NR_CPUS
-       .globl  exception_stack_top
-exception_stack_top:
-
 /*
  * Room for two PTE pointers, usually the kernel and current user pointers
  * to their respective root page table.

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 2f73f705d56449a3c4416f14180264f0e981d0ca..b5199752ac60369b28a948f4fb2d55ba76fb8919 100644 (file)
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -356,9 +356,42 @@ void __init init_IRQ(void)
 {
        if (ppc_md.init_IRQ)
                ppc_md.init_IRQ();
+
+       exc_lvl_ctx_init();
+
        irq_ctx_init();
 }
 
+#if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
+struct thread_info   *critirq_ctx[NR_CPUS] __read_mostly;
+struct thread_info    *dbgirq_ctx[NR_CPUS] __read_mostly;
+struct thread_info *mcheckirq_ctx[NR_CPUS] __read_mostly;
+
+void exc_lvl_ctx_init(void)
+{
+       struct thread_info *tp;
+       int i;
+
+       for_each_possible_cpu(i) {
+               memset((void *)critirq_ctx[i], 0, THREAD_SIZE);
+               tp = critirq_ctx[i];
+               tp->cpu = i;
+               tp->preempt_count = 0;
+
+#ifdef CONFIG_BOOKE
+               memset((void *)dbgirq_ctx[i], 0, THREAD_SIZE);
+               tp = dbgirq_ctx[i];
+               tp->cpu = i;
+               tp->preempt_count = 0;
+
+               memset((void *)mcheckirq_ctx[i], 0, THREAD_SIZE);
+               tp = mcheckirq_ctx[i];
+               tp->cpu = i;
+               tp->preempt_count = HARDIRQ_OFFSET;
+#endif
+       }
+}
+#endif
 
 #ifdef CONFIG_IRQSTACKS
 struct thread_info *softirq_ctx[NR_CPUS] __read_mostly;

diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index 5112a4aa801d7d6843c2202c7815147831a74d2e..bef0be3fd98be8f81d237c00b2d4a84f5abc76fc 100644 (file)
--- 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 */

diff --git a/include/asm-powerpc/irq.h b/include/asm-powerpc/irq.h
index 5089deb8fec3f0fcf744d1647eea5475202555a1..1ef8e304e0eac06cbc4561fdab63800a291cb7cd 100644 (file)
--- a/include/asm-powerpc/irq.h
+++ b/include/asm-powerpc/irq.h
@@ -619,6 +619,19 @@ struct pt_regs;
 
 #define __ARCH_HAS_DO_SOFTIRQ
 
+#if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
+/*
+ * Per-cpu stacks for handling critical, debug and machine check
+ * level interrupts.
+ */
+extern struct thread_info *critirq_ctx[NR_CPUS];
+extern struct thread_info *dbgirq_ctx[NR_CPUS];
+extern struct thread_info *mcheckirq_ctx[NR_CPUS];
+extern void exc_lvl_ctx_init(void);
+#else
+#define exc_lvl_ctx_init()
+#endif
+
 #ifdef CONFIG_IRQSTACKS
 /*
  * Per-cpu stacks for handling hard and soft interrupts.