bertos/cpu/frame.h

   1 /**
   2  * \file
   3  * <!--
   4  * This file is part of BeRTOS.
   5  *
   6  * Bertos is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  *
  20  * As a special exception, you may use this file as part of a free software
  21  * library without restriction.  Specifically, if other files instantiate
  22  * templates or use macros or inline functions from this file, or you compile
  23  * this file and link it with other files to produce an executable, this
  24  * file does not by itself cause the resulting executable to be covered by
  25  * the GNU General Public License.  This exception does not however
  26  * invalidate any other reasons why the executable file might be covered by
  27  * the GNU General Public License.
  28  *
  29  * Copyright 2008 Bernie Innocenti <bernie@codewiz.org>
  30  * Copyright 2004, 2005, 2006, 2007, 2008 Develer S.r.l. (http://www.develer.com/)
  31  * Copyright 2004 Giovanni Bajo
  32  *
  33  * -->
  34  *
  35  * \brief CPU-specific stack frame handling macros.
  36  *
  37  * These are mainly used by the portable part of the scheduler
  38  * to work with the process stack frames.
  39  *
  40  * \author Giovanni Bajo <rasky@develer.com>
  41  * \author Bernie Innocenti <bernie@codewiz.org>
  42  * \author Stefano Fedrigo <aleph@develer.com>
  43  * \author Francesco Sacchi <batt@develer.com>
  44  */
  45 #ifndef CPU_FRAME_H
  46 #define CPU_FRAME_H
  47
  48 #include <cpu/detect.h>
  49
  50 #include "cfg/cfg_arch.h"      /* ARCH_EMUL */
  51 #include <cfg/compiler.h>      /* for uintXX_t */
  52
  53 #if CPU_X86
  54         #if CPU_X86_32
  55                 #define CPU_SAVED_REGS_CNT      2
  56         #elif CPU_X86_64
  57                 #define CPU_SAVED_REGS_CNT      8
  58         #else
  59                 #error "unknown CPU"
  60         #endif
  61         #define CPU_STACK_GROWS_UPWARD  0
  62         #define CPU_SP_ON_EMPTY_SLOT    0
  63
  64 #elif CPU_ARM
  65
  66         #define CPU_SAVED_REGS_CNT     8
  67         #define CPU_STACK_GROWS_UPWARD 0
  68         #define CPU_SP_ON_EMPTY_SLOT   0
  69
  70 #elif CPU_CM3
  71
  72         #define CPU_SAVED_REGS_CNT     8
  73         #define CPU_STACK_GROWS_UPWARD 0
  74         #define CPU_SP_ON_EMPTY_SLOT   0
  75
  76 #elif CPU_PPC
  77
  78         #define CPU_SAVED_REGS_CNT     1
  79         #define CPU_STACK_GROWS_UPWARD 0
  80         #define CPU_SP_ON_EMPTY_SLOT   1
  81
  82 #elif CPU_DSP56K
  83
  84         #define CPU_SAVED_REGS_CNT      8
  85         #define CPU_STACK_GROWS_UPWARD  1
  86         #define CPU_SP_ON_EMPTY_SLOT    0
  87
  88 #elif CPU_AVR
  89
  90         #define CPU_SAVED_REGS_CNT     18
  91         #define CPU_STACK_GROWS_UPWARD  0
  92         #define CPU_SP_ON_EMPTY_SLOT    1
  93
  94 #else
  95         #error No CPU_... defined.
  96 #endif
  97
  98 #ifndef CPU_STACK_GROWS_UPWARD
  99         #error CPU_STACK_GROWS_UPWARD should have been defined to either 0 or 1
 100 #endif
 101
 102 #ifndef CPU_SP_ON_EMPTY_SLOT
 103         #error CPU_SP_ON_EMPTY_SLOT should have been defined to either 0 or 1
 104 #endif
 105
 106 /// Default for macro not defined in the right arch section
 107 #ifndef CPU_REG_INIT_VALUE
 108         #define CPU_REG_INIT_VALUE(reg)     (reg)
 109 #endif
 110
 111 /*
 112  * Support stack handling peculiarities of a few CPUs.
 113  *
 114  * Most processors let their stack grow downward and
 115  * keep SP pointing at the last pushed value.
 116  */
 117 #if !CPU_STACK_GROWS_UPWARD
 118         #if !CPU_SP_ON_EMPTY_SLOT
 119                 /* Most microprocessors (x86, m68k...) */
 120                 #define CPU_PUSH_WORD(sp, data) \
 121                         do { *--(sp) = (data); } while (0)
 122                 #define CPU_POP_WORD(sp) \
 123                         (*(sp)++)
 124         #else
 125                 /* AVR insanity */
 126                 #define CPU_PUSH_WORD(sp, data) \
 127                         do { *(sp)-- = (data); } while (0)
 128                 #define CPU_POP_WORD(sp) \
 129                         (*++(sp))
 130         #endif
 131
 132 #else /* CPU_STACK_GROWS_UPWARD */
 133
 134         #if !CPU_SP_ON_EMPTY_SLOT
 135                 /* DSP56K and other weirdos */
 136                 #define CPU_PUSH_WORD(sp, data) \
 137                         do { *++(sp) = (cpu_stack_t)(data); } while (0)
 138                 #define CPU_POP_WORD(sp) \
 139                         (*(sp)--)
 140         #else
 141                 #error I bet you cannot find a CPU like this
 142         #endif
 143 #endif
 144
 145
 146 #if CPU_DSP56K
 147         /*
 148          * DSP56k pushes both PC and SR to the stack in the JSR instruction, but
 149          * RTS discards SR while returning (it does not restore it). So we push
 150          * 0 to fake the same context.
 151          */
 152         #define CPU_PUSH_CALL_FRAME(sp, func) \
 153                 do { \
 154                         CPU_PUSH_WORD((sp), (func)); \
 155                         CPU_PUSH_WORD((sp), 0x100); \
 156                 } while (0);
 157
 158 #elif CPU_CM3
 159
 160         #if CONFIG_KERN_PREEMPT
 161                 INLINE void asm_switch_context(cpu_stack_t **new_sp, cpu_stack_t **old_sp)
 162                 {
 163                         register cpu_stack_t **__new_sp asm ("r0") = new_sp;
 164                         register cpu_stack_t **__old_sp asm ("r1") = old_sp;
 165
 166                         asm volatile ("svc #0"
 167                                 : : "r"(__new_sp), "r"(__old_sp) : "memory", "cc");
 168                 }
 169                 #define asm_switch_context asm_switch_context
 170
 171                 #define CPU_PUSH_CALL_FRAME(sp, func) \
 172                         do { \
 173                                 CPU_PUSH_WORD((sp), 0x01000000);                /* xPSR    */   \
 174                                 CPU_PUSH_WORD((sp), (cpu_stack_t)(func));       /* pc      */   \
 175                                 CPU_PUSH_WORD((sp), 0);                         /* lr      */   \
 176                                 CPU_PUSH_WORD((sp), 0);                         /* ip      */   \
 177                                 CPU_PUSH_WORD((sp), 0);                         /* r3      */   \
 178                                 CPU_PUSH_WORD((sp), 0);                         /* r2      */   \
 179                                 CPU_PUSH_WORD((sp), 0);                         /* r1      */   \
 180                                 CPU_PUSH_WORD((sp), 0);                         /* r0      */   \
 181                                 CPU_PUSH_WORD((sp), 0xfffffffd);                /* lr_exc  */   \
 182                         } while (0);
 183
 184                 #define CPU_CREATE_NEW_STACK(stack) \
 185                         do { \
 186                                 size_t i; \
 187                                 /* Initialize process stack frame */ \
 188                                 CPU_PUSH_CALL_FRAME(stack, proc_entry); \
 189                                 /* Push a clean set of CPU registers for asm_switch_context() */ \
 190                                 for (i = 0; i < CPU_SAVED_REGS_CNT; i++) \
 191                                         CPU_PUSH_WORD(stack, CPU_REG_INIT_VALUE(i)); \
 192                                 CPU_PUSH_WORD(stack, IRQ_PRIO_DISABLED); \
 193                         } while (0)
 194
 195         #else /* !CONFIG_KERN_PREEMPT */
 196                 #define CPU_PUSH_CALL_FRAME(sp, func) \
 197                         do { \
 198                                 CPU_PUSH_WORD((sp), 0x01000000);                /* xPSR    */   \
 199                                 CPU_PUSH_WORD((sp), (cpu_stack_t)(func));       /* pc      */   \
 200                         } while (0);
 201         #endif /* CONFIG_KERN_PREEMPT */
 202
 203 #elif CPU_AVR
 204         /*
 205          * On AVR, addresses are pushed into the stack as little-endian, while
 206          * memory accesses are big-endian (actually, it's a 8-bit CPU, so there is
 207          * no natural endianess).
 208          */
 209         #define CPU_PUSH_CALL_FRAME(sp, func) \
 210                 do { \
 211                         uint16_t funcaddr = (uint16_t)(func); \
 212                         CPU_PUSH_WORD((sp), funcaddr); \
 213                         CPU_PUSH_WORD((sp), funcaddr>>8); \
 214                 } while (0)
 215
 216         /*
 217          * If the kernel is in idle-spinning, the processor executes:
 218          *
 219          * IRQ_ENABLE;
 220          * CPU_IDLE;
 221          * IRQ_DISABLE;
 222          *
 223          * IRQ_ENABLE is translated in asm as "sei" and IRQ_DISABLE as "cli".
 224          * We could define CPU_IDLE to expand to none, so the resulting
 225          * asm code would be:
 226          *
 227          * sei;
 228          * cli;
 229          *
 230          * But Atmel datasheet states:
 231          * "When using the SEI instruction to enable interrupts,
 232          * the instruction following SEI will be executed *before*
 233          * any pending interrupts", so "cli" is executed before any
 234          * pending interrupt with the result that IRQs will *NOT*
 235          * be enabled!
 236          * To ensure that IRQ will run a NOP is required.
 237          */
 238         #define CPU_IDLE NOP
 239
 240 #elif CPU_PPC
 241
 242         #define CPU_PUSH_CALL_FRAME(sp, func) \
 243                 do { \
 244                         CPU_PUSH_WORD((sp), (cpu_stack_t)(func)); /* LR -> 8(SP) */ \
 245                         CPU_PUSH_WORD((sp), 0);                  /* CR -> 4(SP) */ \
 246                 } while (0)
 247
 248 #else
 249         #define CPU_PUSH_CALL_FRAME(sp, func) \
 250                 CPU_PUSH_WORD((sp), (cpu_stack_t)(func))
 251 #endif
 252
 253 /**
 254  * \def CPU_IDLE
 255  *
 256  * \brief Invoked by the scheduler to stop the CPU when idle.
 257  *
 258  * This hook can be redefined to put the CPU in low-power mode, or to
 259  * profile system load with an external strobe, or to save CPU cycles
 260  * in hosted environments such as emulators.
 261  */
 262 #ifndef CPU_IDLE
 263         #define CPU_IDLE PAUSE
 264 #endif /* !CPU_IDLE */
 265
 266 /**
 267  * Default macro for creating a new Process stack
 268  */
 269 #ifndef CPU_CREATE_NEW_STACK
 270
 271         #define CPU_CREATE_NEW_STACK(stack) \
 272                 do { \
 273                         size_t i; \
 274                         /* Initialize process stack frame */ \
 275                         CPU_PUSH_CALL_FRAME(stack, proc_entry); \
 276                         /* Push a clean set of CPU registers for asm_switch_context() */ \
 277                         for (i = 0; i < CPU_SAVED_REGS_CNT; i++) \
 278                                 CPU_PUSH_WORD(stack, CPU_REG_INIT_VALUE(i)); \
 279                 } while (0)
 280 #endif
 281
 282 #endif /* CPU_ATTR_H */