examples/standalone/stubs.c

   1 #include <common.h>
   2 #include <exports.h>
   3
   4 #ifndef GCC_VERSION
   5 #define GCC_VERSION (__GNUC__ * 1000 + __GNUC_MINOR__)
   6 #endif /* GCC_VERSION */
   7
   8 #if defined(CONFIG_X86)
   9 /*
  10  * x86 does not have a dedicated register to store the pointer to
  11  * the global_data. Thus the jump table address is stored in a
  12  * global variable, but such approach does not allow for execution
  13  * from flash memory. The global_data address is passed as argv[-1]
  14  * to the application program.
  15  */
  16 static void **jt;
  17 gd_t *global_data;
  18
  19 #define EXPORT_FUNC(x) \
  20         asm volatile (                  \
  21 "       .globl " #x "\n"                \
  22 #x ":\n"                                \
  23 "       movl    %0, %%eax\n"            \
  24 "       movl    jt, %%ecx\n"            \
  25 "       jmp     *(%%ecx, %%eax)\n"      \
  26         : : "i"(XF_ ## x * sizeof(void *)) : "eax", "ecx");
  27 #elif defined(CONFIG_PPC)
  28 /*
  29  * r2 holds the pointer to the global_data, r11 is a call-clobbered
  30  * register
  31  */
  32 #define EXPORT_FUNC(x) \
  33         asm volatile (                  \
  34 "       .globl " #x "\n"                \
  35 #x ":\n"                                \
  36 "       lwz     %%r11, %0(%%r2)\n"      \
  37 "       lwz     %%r11, %1(%%r11)\n"     \
  38 "       mtctr   %%r11\n"                \
  39 "       bctr\n"                         \
  40         : : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "r11");
  41 #elif defined(CONFIG_ARM)
  42 /*
  43  * r8 holds the pointer to the global_data, ip is a call-clobbered
  44  * register
  45  */
  46 #define EXPORT_FUNC(x) \
  47         asm volatile (                  \
  48 "       .globl " #x "\n"                \
  49 #x ":\n"                                \
  50 "       ldr     ip, [r8, %0]\n"         \
  51 "       ldr     pc, [ip, %1]\n"         \
  52         : : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "ip");
  53 #elif defined(CONFIG_MIPS)
  54 /*
  55  * k0 ($26) holds the pointer to the global_data; t9 ($25) is a call-
  56  * clobbered register that is also used to set gp ($26). Note that the
  57  * jr instruction also executes the instruction immediately following
  58  * it; however, GCC/mips generates an additional `nop' after each asm
  59  * statement
  60  */
  61 #define EXPORT_FUNC(x) \
  62         asm volatile (                  \
  63 "       .globl " #x "\n"                \
  64 #x ":\n"                                \
  65 "       lw      $25, %0($26)\n"         \
  66 "       lw      $25, %1($25)\n"         \
  67 "       jr      $25\n"                  \
  68         : : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "t9");
  69 #elif defined(CONFIG_NIOS2)
  70 /*
  71  * gp holds the pointer to the global_data, r8 is call-clobbered
  72  */
  73 #define EXPORT_FUNC(x) \
  74         asm volatile (                  \
  75 "       .globl " #x "\n"                \
  76 #x ":\n"                                \
  77 "       movhi   r8, %%hi(%0)\n"         \
  78 "       ori     r8, r0, %%lo(%0)\n"     \
  79 "       add     r8, r8, gp\n"           \
  80 "       ldw     r8, 0(r8)\n"            \
  81 "       ldw     r8, %1(r8)\n"           \
  82 "       jmp     r8\n"                   \
  83         : : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "gp");
  84 #elif defined(CONFIG_M68K)
  85 /*
  86  * d7 holds the pointer to the global_data, a0 is a call-clobbered
  87  * register
  88  */
  89 #define EXPORT_FUNC(x) \
  90         asm volatile (                  \
  91 "       .globl " #x "\n"                \
  92 #x ":\n"                                \
  93 "       move.l  %%d7, %%a0\n"           \
  94 "       adda.l  %0, %%a0\n"             \
  95 "       move.l  (%%a0), %%a0\n"         \
  96 "       adda.l  %1, %%a0\n"             \
  97 "       move.l  (%%a0), %%a0\n"         \
  98 "       jmp     (%%a0)\n"                       \
  99         : : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "a0");
 100 #elif defined(CONFIG_MICROBLAZE)
 101 /*
 102  * r31 holds the pointer to the global_data. r5 is a call-clobbered.
 103  */
 104 #define EXPORT_FUNC(x)                          \
 105         asm volatile (                          \
 106 "       .globl " #x "\n"                        \
 107 #x ":\n"                                        \
 108 "       lwi     r5, r31, %0\n"                  \
 109 "       lwi     r5, r5, %1\n"                   \
 110 "       bra     r5\n"                           \
 111         : : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "r5");
 112 #elif defined(CONFIG_BLACKFIN)
 113 /*
 114  * P3 holds the pointer to the global_data, P0 is a call-clobbered
 115  * register
 116  */
 117 #define EXPORT_FUNC(x)                  \
 118         asm volatile (                  \
 119 "       .globl _" #x "\n_"              \
 120 #x ":\n"                                \
 121 "       P0 = [P3 + %0]\n"               \
 122 "       P0 = [P0 + %1]\n"               \
 123 "       JUMP (P0)\n"                    \
 124         : : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "P0");
 125 #elif defined(CONFIG_AVR32)
 126 /*
 127  * r6 holds the pointer to the global_data. r8 is call clobbered.
 128  */
 129 #define EXPORT_FUNC(x)                                  \
 130         asm volatile(                                   \
 131                 "       .globl\t" #x "\n"               \
 132                 #x ":\n"                                \
 133                 "       ld.w    r8, r6[%0]\n"           \
 134                 "       ld.w    pc, r8[%1]\n"           \
 135                 :                                       \
 136                 : "i"(offsetof(gd_t, jt)), "i"(XF_ ##x) \
 137                 : "r8");
 138 #elif defined(CONFIG_SH)
 139 /*
 140  * r13 holds the pointer to the global_data. r1 is a call clobbered.
 141  */
 142 #define EXPORT_FUNC(x)                                  \
 143         asm volatile (                                  \
 144                 "       .align  2\n"                    \
 145                 "       .globl " #x "\n"                \
 146                 #x ":\n"                                \
 147                 "       mov     r13, r1\n"              \
 148                 "       add     %0, r1\n"               \
 149                 "       mov.l @r1, r2\n"        \
 150                 "       add     %1, r2\n"               \
 151                 "       mov.l @r2, r1\n"        \
 152                 "       jmp     @r1\n"                  \
 153                 "       nop\n"                          \
 154                 "       nop\n"                          \
 155                 : : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "r1", "r2");
 156 #elif defined(CONFIG_SPARC)
 157 /*
 158  * g7 holds the pointer to the global_data. g1 is call clobbered.
 159  */
 160 #define EXPORT_FUNC(x)                                  \
 161         asm volatile(                                   \
 162 "       .globl\t" #x "\n"                               \
 163 #x ":\n"                                                \
 164 "       set %0, %%g1\n"                                 \
 165 "       or %%g1, %%g7, %%g1\n"                          \
 166 "       ld [%%g1], %%g1\n"                              \
 167 "       ld [%%g1 + %1], %%g1\n"                         \
 168 "       jmp %%g1\n"                                     \
 169 "       nop\n"                                          \
 170         : : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "g1" );
 171 #elif defined(CONFIG_NDS32)
 172 /*
 173  * r16 holds the pointer to the global_data. gp is call clobbered.
 174  * not support reduced register (16 GPR).
 175  */
 176 #define EXPORT_FUNC(x) \
 177         asm volatile (                  \
 178 "       .globl " #x "\n"                \
 179 #x ":\n"                                \
 180 "       lwi     $r16, [$gp + (%0)]\n"   \
 181 "       lwi     $r16, [$r16 + (%1)]\n"  \
 182 "       jr      $r16\n"                 \
 183         : : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "$r16");
 184 #elif defined(CONFIG_OPENRISC)
 185 /*
 186  * r10 holds the pointer to the global_data, r13 is a call-clobbered
 187  * register
 188  */
 189 #define EXPORT_FUNC(x) \
 190         asm volatile (                  \
 191 "       .globl " #x "\n"                \
 192 #x ":\n"                                \
 193 "       l.lwz   r13, %0(r10)\n" \
 194 "       l.lwz   r13, %1(r13)\n" \
 195 "       l.jr    r13\n"          \
 196 "       l.nop\n"                                \
 197         : : "i"(offsetof(gd_t, jt)), "i"(XF_ ## x * sizeof(void *)) : "r13");
 198 #else
 199 /*"     addi    $sp, $sp, -24\n"        \
 200 "       br      $r16\n"                 \*/
 201
 202 #error stubs definition missing for this architecture
 203 #endif
 204
 205 /* This function is necessary to prevent the compiler from
 206  * generating prologue/epilogue, preparing stack frame etc.
 207  * The stub functions are special, they do not use the stack
 208  * frame passed to them, but pass it intact to the actual
 209  * implementation. On the other hand, asm() statements with
 210  * arguments can be used only inside the functions (gcc limitation)
 211  */
 212 #if GCC_VERSION < 3004
 213 static
 214 #endif /* GCC_VERSION */
 215 void __attribute__((unused)) dummy(void)
 216 {
 217 #include <_exports.h>
 218 }
 219
 220 #include <asm/sections.h>
 221
 222 void app_startup(char * const *argv)
 223 {
 224         char *cp = __bss_start;
 225
 226         /* Zero out BSS */
 227         while (cp < _end)
 228                 *cp++ = 0;
 229
 230 #if defined(CONFIG_X86)
 231         /* x86 does not have a dedicated register for passing global_data */
 232         global_data = (gd_t *)argv[-1];
 233         jt = global_data->jt;
 234 #endif
 235 }
 236
 237 #undef EXPORT_FUNC