powerpc: Simplify context switch

PowerPC cores with the SPE (Signal Processing Extension) have 64-bit
general-purpose registers.  The SPE context switch code has been merged
with the standard context switch code.  The context switch may use cache
operations to increase the performance.  It will be ensured that the
context is 32-byte aligned (PPC_DEFAULT_CACHE_LINE_SIZE).  This
increases the overall memory size of the context area in the thread
control block slightly.  The general-purpose registers GPR2 and GPR13
are no longer part of the context.  The BSP must initialize these
registers during startup (usually initialized by the __eabi() function).

The new BSP option BSP_USE_DATA_CACHE_BLOCK_TOUCH can be used to enable
the dcbt instruction in the context switch.

The new BSP option BSP_USE_SYNC_IN_CONTEXT_SWITCH can be used to enable
sync and isync instructions in the context switch.  This should be not
necessary in most cases.

1 files changed, 96 insertions, 145 deletions

diff --git a/cpukit/score/cpu/powerpc/rtems/score/cpu.h b/cpukit/score/cpu/powerpc/rtems/score/cpu.h
index 3ed76dffb7..e845362266 100644
--- a/cpukit/score/cpu/powerpc/rtems/score/cpu.h
+++ b/cpukit/score/cpu/powerpc/rtems/score/cpu.h
@@ -23,7 +23,7 @@
  *
  *  Copyright (c) 2001 Surrey Satellite Technology Limited (SSTL).
  *
- *  Copyright (c) 2010-2011 embedded brains GmbH.
+ *  Copyright (c) 2010-2012 embedded brains GmbH.
  *
  *  The license and distribution terms for this file may be
  *  found in the file LICENSE in this distribution or at
@@ -249,159 +249,110 @@ extern "C" {
  *  a debugger such as gdb.  But that is another problem.
  */
 
-#ifndef ASM
-
-typedef struct {
-  #ifndef __SPE__
-    uint32_t   gpr1;	/* Stack pointer for all */
-    uint32_t   gpr2;	/* Reserved SVR4, section ptr EABI + */
-    uint32_t   gpr13;	/* Section ptr SVR4/EABI */
-    uint32_t   gpr14;	/* Non volatile for all */
-    uint32_t   gpr15;	/* Non volatile for all */
-    uint32_t   gpr16;	/* Non volatile for all */
-    uint32_t   gpr17;	/* Non volatile for all */
-    uint32_t   gpr18;	/* Non volatile for all */
-    uint32_t   gpr19;	/* Non volatile for all */
-    uint32_t   gpr20;	/* Non volatile for all */
-    uint32_t   gpr21;	/* Non volatile for all */
-    uint32_t   gpr22;	/* Non volatile for all */
-    uint32_t   gpr23;	/* Non volatile for all */
-    uint32_t   gpr24;	/* Non volatile for all */
-    uint32_t   gpr25;	/* Non volatile for all */
-    uint32_t   gpr26;	/* Non volatile for all */
-    uint32_t   gpr27;	/* Non volatile for all */
-    uint32_t   gpr28;	/* Non volatile for all */
-    uint32_t   gpr29;	/* Non volatile for all */
-    uint32_t   gpr30;	/* Non volatile for all */
-    uint32_t   gpr31;	/* Non volatile for all */
-    uint32_t   cr;	/* PART of the CR is non volatile for all */
-    uint32_t   pc;	/* Program counter/Link register */
-    uint32_t   msr;	/* Initial interrupt level */
-    #ifdef __ALTIVEC__
-      /*
-       * 12 non-volatile vector registers, cache-aligned area for vscr/vrsave
-       * and padding to ensure cache-alignment.  Unfortunately, we can't verify
-       * the cache line size here in the cpukit but altivec support code will
-       * produce an error if this is ever different from 32 bytes.
-       * 
-       * Note: it is the BSP/CPU-support's responsibility to save/restore
-       *       volatile vregs across interrupts and exceptions.
-       */
-      uint8_t altivec[16*12 + 32 + 32];
-    #endif
-  #else
-    /* Non-volatile context according to E500ABIUG and EABI */
-    uint32_t context [
-      8 /* Cache line padding */
-      + 1 /* Stack pointer */
-      + 1 /* MSR */
-      + 1 /* LR */
-      + 1 /* CR */
-      + 18 * 2 /* GPR 14 to GPR 31 */
-    ];
-  #endif
-} Context_Control;
-#endif /* ASM */
-
 #ifndef __SPE__
-  #define PPC_CONTEXT_SET_SP( _context, _sp ) \
-    do { \
-      (_context)->gpr1 = _sp; \
-    } while (0)
+  #define PPC_GPR_TYPE uint32_t
+  #define PPC_GPR_SIZE 4
+  #define PPC_GPR_LOAD lwz
+  #define PPC_GPR_STORE stw
+#else
+  #define PPC_GPR_TYPE uint64_t
+  #define PPC_GPR_SIZE 8
+  #define PPC_GPR_LOAD evldd
+  #define PPC_GPR_STORE evstdd
+#endif
 
-  #define PPC_CONTEXT_GET_CR( _context ) \
-    (_context)->cr
+#define PPC_DEFAULT_CACHE_LINE_SIZE 32
 
-  #define PPC_CONTEXT_GET_MSR( _context ) \
-    (_context)->msr
+#ifndef ASM
 
-  #define PPC_CONTEXT_SET_MSR( _context, _msr ) \
-    do { \
-      (_context)->msr = _msr; \
-    } while (0)
+/* Non-volatile context according to E500ABIUG and EABI */
+typedef struct {
+  uint32_t gpr1;
+  uint32_t msr;
+  uint32_t lr;
+  uint32_t cr;
+  PPC_GPR_TYPE gpr14;
+  PPC_GPR_TYPE gpr15;
+  PPC_GPR_TYPE gpr16;
+  PPC_GPR_TYPE gpr17;
+  PPC_GPR_TYPE gpr18;
+  PPC_GPR_TYPE gpr19;
+  PPC_GPR_TYPE gpr20;
+  PPC_GPR_TYPE gpr21;
+  PPC_GPR_TYPE gpr22;
+  PPC_GPR_TYPE gpr23;
+  PPC_GPR_TYPE gpr24;
+  PPC_GPR_TYPE gpr25;
+  PPC_GPR_TYPE gpr26;
+  PPC_GPR_TYPE gpr27;
+  PPC_GPR_TYPE gpr28;
+  PPC_GPR_TYPE gpr29;
+  PPC_GPR_TYPE gpr30;
+  PPC_GPR_TYPE gpr31;
+  #ifdef __ALTIVEC__
+    /*
+     * 12 non-volatile vector registers, cache-aligned area for vscr/vrsave
+     * and padding to ensure cache-alignment.  Unfortunately, we can't verify
+     * the cache line size here in the cpukit but altivec support code will
+     * produce an error if this is ever different from 32 bytes.
+     * 
+     * Note: it is the BSP/CPU-support's responsibility to save/restore
+     *       volatile vregs across interrupts and exceptions.
+     */
+    uint8_t altivec[16*12 + 32 + PPC_DEFAULT_CACHE_LINE_SIZE];
+  #endif
+} ppc_context;
 
-  #define PPC_CONTEXT_FIRST_SAVED_GPR 13
+typedef struct {
+  uint8_t context [
+    PPC_DEFAULT_CACHE_LINE_SIZE
+      + sizeof(ppc_context)
+      + (sizeof(ppc_context) % PPC_DEFAULT_CACHE_LINE_SIZE == 0
+        ? 0
+          : PPC_DEFAULT_CACHE_LINE_SIZE
+            - sizeof(ppc_context) % PPC_DEFAULT_CACHE_LINE_SIZE)
+  ];
+} Context_Control;
 
-  #define PPC_CONTEXT_GET_FIRST_SAVED( _context ) \
-    (_context)->gpr13
+static inline ppc_context *ppc_get_context( Context_Control *context )
+{
+  uintptr_t clsz = PPC_DEFAULT_CACHE_LINE_SIZE;
+  uintptr_t mask = clsz - 1;
+  uintptr_t addr = (uintptr_t) context;
 
-  #define PPC_CONTEXT_GET_PC( _context ) \
-    (_context)->pc
+  return (ppc_context *) ((addr & ~mask) + clsz);
+}
 
-  #define PPC_CONTEXT_SET_PC( _context, _pc ) \
-    do { \
-      (_context)->pc = _pc; \
-    } while (0)
+#define _CPU_Context_Get_SP( _context ) \
+  ppc_get_context(_context)->gpr1
+#endif /* ASM */
 
-  #define _CPU_Context_Get_SP( _context ) \
-    (_context)->gpr1
-#else
-  #define PPC_CONTEXT_CACHE_LINE_0 32
-  #define PPC_CONTEXT_OFFSET_SP 32
-  #define PPC_CONTEXT_OFFSET_MSR 36
-  #define PPC_CONTEXT_OFFSET_LR 40
-  #define PPC_CONTEXT_OFFSET_CR 44
-  #define PPC_CONTEXT_OFFSET_GPR14 48
-  #define PPC_CONTEXT_OFFSET_GPR15 56
-  #define PPC_CONTEXT_CACHE_LINE_1 64
-  #define PPC_CONTEXT_OFFSET_GPR16 64
-  #define PPC_CONTEXT_OFFSET_GPR17 72
-  #define PPC_CONTEXT_OFFSET_GPR18 80
-  #define PPC_CONTEXT_OFFSET_GPR19 88
-  #define PPC_CONTEXT_CACHE_LINE_2 96
-  #define PPC_CONTEXT_OFFSET_GPR20 96
-  #define PPC_CONTEXT_OFFSET_GPR21 104
-  #define PPC_CONTEXT_OFFSET_GPR22 112
-  #define PPC_CONTEXT_OFFSET_GPR23 120
-  #define PPC_CONTEXT_CACHE_LINE_3 128
-  #define PPC_CONTEXT_OFFSET_GPR24 128
-  #define PPC_CONTEXT_OFFSET_GPR25 136
-  #define PPC_CONTEXT_OFFSET_GPR26 144
-  #define PPC_CONTEXT_OFFSET_GPR27 152
-  #define PPC_CONTEXT_CACHE_LINE_4 160
-  #define PPC_CONTEXT_OFFSET_GPR28 160
-  #define PPC_CONTEXT_OFFSET_GPR29 168
-  #define PPC_CONTEXT_OFFSET_GPR30 176
-  #define PPC_CONTEXT_OFFSET_GPR31 184
-
-  #define PPC_CONTEXT_AREA( _context ) \
-    ((uint32_t *) (((uintptr_t) (_context)) & ~0x1fU))
-
-  #define PPC_CONTEXT_FIELD( _context, _offset ) \
-    PPC_CONTEXT_AREA( _context ) [(_offset) / 4]
-
-  #define PPC_CONTEXT_SET_SP( _context, _sp ) \
-    do { \
-      PPC_CONTEXT_FIELD( _context, PPC_CONTEXT_OFFSET_SP ) = _sp; \
-    } while (0)
-
-  #define PPC_CONTEXT_GET_CR( _context ) \
-    PPC_CONTEXT_FIELD( _context, PPC_CONTEXT_OFFSET_CR )
-
-  #define PPC_CONTEXT_GET_MSR( _context ) \
-    PPC_CONTEXT_FIELD( _context, PPC_CONTEXT_OFFSET_MSR )
-
-  #define PPC_CONTEXT_SET_MSR( _context, _msr ) \
-    do { \
-      PPC_CONTEXT_FIELD( _context, PPC_CONTEXT_OFFSET_MSR ) = _msr; \
-    } while (0)
-
-  #define PPC_CONTEXT_FIRST_SAVED_GPR 14
-
-  #define PPC_CONTEXT_GET_FIRST_SAVED( _context ) \
-    PPC_CONTEXT_FIELD( _context, PPC_CONTEXT_OFFSET_GPR14 )
-
-  #define PPC_CONTEXT_GET_PC( _context ) \
-    PPC_CONTEXT_FIELD( _context, PPC_CONTEXT_OFFSET_LR )
-
-  #define PPC_CONTEXT_SET_PC( _context, _pc ) \
-    do { \
-      PPC_CONTEXT_FIELD( _context, PPC_CONTEXT_OFFSET_LR ) = _pc; \
-    } while (0)
-
-  #define _CPU_Context_Get_SP( _context ) \
-    PPC_CONTEXT_FIELD( _context, PPC_CONTEXT_OFFSET_SP )
-#endif
+#define PPC_CONTEXT_OFFSET_GPR1 32
+#define PPC_CONTEXT_OFFSET_MSR 36
+#define PPC_CONTEXT_OFFSET_LR 40
+#define PPC_CONTEXT_OFFSET_CR 44
+
+#define PPC_CONTEXT_GPR_OFFSET( gpr ) \
+  (((gpr) - 14) * PPC_GPR_SIZE + 48)
+
+#define PPC_CONTEXT_OFFSET_GPR14 PPC_CONTEXT_GPR_OFFSET( 14 )
+#define PPC_CONTEXT_OFFSET_GPR15 PPC_CONTEXT_GPR_OFFSET( 15 )
+#define PPC_CONTEXT_OFFSET_GPR16 PPC_CONTEXT_GPR_OFFSET( 16 )
+#define PPC_CONTEXT_OFFSET_GPR17 PPC_CONTEXT_GPR_OFFSET( 17 )
+#define PPC_CONTEXT_OFFSET_GPR18 PPC_CONTEXT_GPR_OFFSET( 18 )
+#define PPC_CONTEXT_OFFSET_GPR19 PPC_CONTEXT_GPR_OFFSET( 19 )
+#define PPC_CONTEXT_OFFSET_GPR20 PPC_CONTEXT_GPR_OFFSET( 20 )
+#define PPC_CONTEXT_OFFSET_GPR21 PPC_CONTEXT_GPR_OFFSET( 21 )
+#define PPC_CONTEXT_OFFSET_GPR22 PPC_CONTEXT_GPR_OFFSET( 22 )
+#define PPC_CONTEXT_OFFSET_GPR23 PPC_CONTEXT_GPR_OFFSET( 23 )
+#define PPC_CONTEXT_OFFSET_GPR24 PPC_CONTEXT_GPR_OFFSET( 24 )
+#define PPC_CONTEXT_OFFSET_GPR25 PPC_CONTEXT_GPR_OFFSET( 25 )
+#define PPC_CONTEXT_OFFSET_GPR26 PPC_CONTEXT_GPR_OFFSET( 26 )
+#define PPC_CONTEXT_OFFSET_GPR27 PPC_CONTEXT_GPR_OFFSET( 27 )
+#define PPC_CONTEXT_OFFSET_GPR28 PPC_CONTEXT_GPR_OFFSET( 28 )
+#define PPC_CONTEXT_OFFSET_GPR29 PPC_CONTEXT_GPR_OFFSET( 29 )
+#define PPC_CONTEXT_OFFSET_GPR30 PPC_CONTEXT_GPR_OFFSET( 30 )
+#define PPC_CONTEXT_OFFSET_GPR31 PPC_CONTEXT_GPR_OFFSET( 31 )
 
 #ifndef ASM
 typedef struct {