examples/standalone/stubs.c

   1 #include <common.h>
   2 #include <exports.h>
   3 #include <linux/compiler.h>
   4
   5 #define FO(x) offsetof(struct jt_funcs, x)
   6
   7 #if defined(CONFIG_X86)
   8 /*
   9  * x86 does not have a dedicated register to store the pointer to
  10  * the global_data. Thus the jump table address is stored in a
  11  * global variable, but such approach does not allow for execution
  12  * from flash memory. The global_data address is passed as argv[-1]
  13  * to the application program.
  14  */
  15 static struct jt_funcs *jt;
  16 gd_t *global_data;
  17
  18 #define EXPORT_FUNC(f, a, x, ...) \
  19         asm volatile (                  \
  20 "       .globl " #x "\n"                \
  21 #x ":\n"                                \
  22 "       movl    %0, %%eax\n"            \
  23 "       movl    jt, %%ecx\n"            \
  24 "       jmp     *(%%ecx, %%eax)\n"      \
  25         : : "i"(FO(x)) : "eax", "ecx");
  26 #elif defined(CONFIG_PPC)
  27 /*
  28  * r2 holds the pointer to the global_data, r11 is a call-clobbered
  29  * register
  30  */
  31 #define EXPORT_FUNC(f, a, x, ...) \
  32         asm volatile (                  \
  33 "       .globl " #x "\n"                \
  34 #x ":\n"                                \
  35 "       lwz     %%r11, %0(%%r2)\n"      \
  36 "       lwz     %%r11, %1(%%r11)\n"     \
  37 "       mtctr   %%r11\n"                \
  38 "       bctr\n"                         \
  39         : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "r11");
  40 #elif defined(CONFIG_ARM)
  41 #ifdef CONFIG_ARM64
  42 /*
  43  * x18 holds the pointer to the global_data, x9 is a call-clobbered
  44  * register
  45  */
  46 #define EXPORT_FUNC(f, a, x, ...) \
  47         asm volatile (                  \
  48 "       .globl " #x "\n"                \
  49 #x ":\n"                                \
  50 "       ldr     x9, [x18, %0]\n"                \
  51 "       ldr     x9, [x9, %1]\n"         \
  52 "       br      x9\n"           \
  53         : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "x9");
  54 #else
  55 /*
  56  * r9 holds the pointer to the global_data, ip is a call-clobbered
  57  * register
  58  */
  59 #define EXPORT_FUNC(f, a, x, ...) \
  60         asm volatile (                  \
  61 "       .globl " #x "\n"                \
  62 #x ":\n"                                \
  63 "       ldr     ip, [r9, %0]\n"         \
  64 "       ldr     pc, [ip, %1]\n"         \
  65         : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "ip");
  66 #endif
  67 #elif defined(CONFIG_MIPS)
  68 /*
  69  * k0 ($26) holds the pointer to the global_data; t9 ($25) is a call-
  70  * clobbered register that is also used to set gp ($26). Note that the
  71  * jr instruction also executes the instruction immediately following
  72  * it; however, GCC/mips generates an additional `nop' after each asm
  73  * statement
  74  */
  75 #define EXPORT_FUNC(f, a, x, ...) \
  76         asm volatile (                  \
  77 "       .globl " #x "\n"                \
  78 #x ":\n"                                \
  79 "       lw      $25, %0($26)\n"         \
  80 "       lw      $25, %1($25)\n"         \
  81 "       jr      $25\n"                  \
  82         : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "t9");
  83 #elif defined(CONFIG_NIOS2)
  84 /*
  85  * gp holds the pointer to the global_data, r8 is call-clobbered
  86  */
  87 #define EXPORT_FUNC(f, a, x, ...) \
  88         asm volatile (                  \
  89 "       .globl " #x "\n"                \
  90 #x ":\n"                                \
  91 "       movhi   r8, %%hi(%0)\n"         \
  92 "       ori     r8, r0, %%lo(%0)\n"     \
  93 "       add     r8, r8, gp\n"           \
  94 "       ldw     r8, 0(r8)\n"            \
  95 "       ldw     r8, %1(r8)\n"           \
  96 "       jmp     r8\n"                   \
  97         : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "gp");
  98 #elif defined(CONFIG_M68K)
  99 /*
 100  * d7 holds the pointer to the global_data, a0 is a call-clobbered
 101  * register
 102  */
 103 #define EXPORT_FUNC(f, a, x, ...) \
 104         asm volatile (                  \
 105 "       .globl " #x "\n"                \
 106 #x ":\n"                                \
 107 "       move.l  %%d7, %%a0\n"           \
 108 "       adda.l  %0, %%a0\n"             \
 109 "       move.l  (%%a0), %%a0\n"         \
 110 "       adda.l  %1, %%a0\n"             \
 111 "       move.l  (%%a0), %%a0\n"         \
 112 "       jmp     (%%a0)\n"                       \
 113         : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "a0");
 114 #elif defined(CONFIG_MICROBLAZE)
 115 /*
 116  * r31 holds the pointer to the global_data. r5 is a call-clobbered.
 117  */
 118 #define EXPORT_FUNC(f, a, x, ...)                               \
 119         asm volatile (                          \
 120 "       .globl " #x "\n"                        \
 121 #x ":\n"                                        \
 122 "       lwi     r5, r31, %0\n"                  \
 123 "       lwi     r5, r5, %1\n"                   \
 124 "       bra     r5\n"                           \
 125         : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "r5");
 126 #elif defined(CONFIG_BLACKFIN)
 127 /*
 128  * P3 holds the pointer to the global_data, P0 is a call-clobbered
 129  * register
 130  */
 131 #define EXPORT_FUNC(f, a, x, ...)                       \
 132         asm volatile (                  \
 133 "       .globl _" #x "\n_"              \
 134 #x ":\n"                                \
 135 "       P0 = [P3 + %0]\n"               \
 136 "       P0 = [P0 + %1]\n"               \
 137 "       JUMP (P0)\n"                    \
 138         : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "P0");
 139 #elif defined(CONFIG_AVR32)
 140 /*
 141  * r6 holds the pointer to the global_data. r8 is call clobbered.
 142  */
 143 #define EXPORT_FUNC(f, a, x, ...)                                       \
 144         asm volatile(                                   \
 145                 "       .globl\t" #x "\n"               \
 146                 #x ":\n"                                \
 147                 "       ld.w    r8, r6[%0]\n"           \
 148                 "       ld.w    pc, r8[%1]\n"           \
 149                 :                                       \
 150                 : "i"(offsetof(gd_t, jt)), "i"(FO(x))   \
 151                 : "r8");
 152 #elif defined(CONFIG_SH)
 153 /*
 154  * r13 holds the pointer to the global_data. r1 is a call clobbered.
 155  */
 156 #define EXPORT_FUNC(f, a, x, ...)                                       \
 157         asm volatile (                                  \
 158                 "       .align  2\n"                    \
 159                 "       .globl " #x "\n"                \
 160                 #x ":\n"                                \
 161                 "       mov     r13, r1\n"              \
 162                 "       add     %0, r1\n"               \
 163                 "       mov.l @r1, r2\n"        \
 164                 "       add     %1, r2\n"               \
 165                 "       mov.l @r2, r1\n"        \
 166                 "       jmp     @r1\n"                  \
 167                 "       nop\n"                          \
 168                 "       nop\n"                          \
 169                 : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "r1", "r2");
 170 #elif defined(CONFIG_SPARC)
 171 /*
 172  * g7 holds the pointer to the global_data. g1 is call clobbered.
 173  */
 174 #define EXPORT_FUNC(f, a, x, ...)                                       \
 175         asm volatile(                                   \
 176 "       .globl\t" #x "\n"                               \
 177 #x ":\n"                                                \
 178 "       set %0, %%g1\n"                                 \
 179 "       or %%g1, %%g7, %%g1\n"                          \
 180 "       ld [%%g1], %%g1\n"                              \
 181 "       ld [%%g1 + %1], %%g1\n"                         \
 182 "       jmp %%g1\n"                                     \
 183 "       nop\n"                                          \
 184         : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "g1");
 185 #elif defined(CONFIG_NDS32)
 186 /*
 187  * r16 holds the pointer to the global_data. gp is call clobbered.
 188  * not support reduced register (16 GPR).
 189  */
 190 #define EXPORT_FUNC(f, a, x, ...) \
 191         asm volatile (                  \
 192 "       .globl " #x "\n"                \
 193 #x ":\n"                                \
 194 "       lwi     $r16, [$gp + (%0)]\n"   \
 195 "       lwi     $r16, [$r16 + (%1)]\n"  \
 196 "       jr      $r16\n"                 \
 197         : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "$r16");
 198 #elif defined(CONFIG_OPENRISC)
 199 /*
 200  * r10 holds the pointer to the global_data, r13 is a call-clobbered
 201  * register
 202  */
 203 #define EXPORT_FUNC(f, a, x, ...) \
 204         asm volatile (                  \
 205 "       .globl " #x "\n"                \
 206 #x ":\n"                                \
 207 "       l.lwz   r13, %0(r10)\n" \
 208 "       l.lwz   r13, %1(r13)\n" \
 209 "       l.jr    r13\n"          \
 210 "       l.nop\n"                                \
 211         : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "r13");
 212 #elif defined(CONFIG_ARC)
 213 /*
 214  * r25 holds the pointer to the global_data. r10 is call clobbered.
 215   */
 216 #define EXPORT_FUNC(f, a, x, ...) \
 217         asm volatile( \
 218 "       .align 4\n" \
 219 "       .globl " #x "\n" \
 220 #x ":\n" \
 221 "       ld      r10, [r25, %0]\n" \
 222 "       ld      r10, [r10, %1]\n" \
 223 "       j       [r10]\n" \
 224         : : "i"(offsetof(gd_t, jt)), "i"(FO(x)) : "r10");
 225 #else
 226 /*"     addi    $sp, $sp, -24\n"        \
 227 "       br      $r16\n"                 \*/
 228
 229 #error stubs definition missing for this architecture
 230 #endif
 231
 232 /* This function is necessary to prevent the compiler from
 233  * generating prologue/epilogue, preparing stack frame etc.
 234  * The stub functions are special, they do not use the stack
 235  * frame passed to them, but pass it intact to the actual
 236  * implementation. On the other hand, asm() statements with
 237  * arguments can be used only inside the functions (gcc limitation)
 238  */
 239 #if GCC_VERSION < 30400
 240 static
 241 #endif /* GCC_VERSION */
 242 void __attribute__((unused)) dummy(void)
 243 {
 244 #include <_exports.h>
 245 }
 246
 247 #include <asm/sections.h>
 248
 249 void app_startup(char * const *argv)
 250 {
 251         char *cp = __bss_start;
 252
 253         /* Zero out BSS */
 254         while (cp < _end)
 255                 *cp++ = 0;
 256
 257 #if defined(CONFIG_X86)
 258         /* x86 does not have a dedicated register for passing global_data */
 259         global_data = (gd_t *)argv[-1];
 260         jt = global_data->jt;
 261 #endif
 262 }
 263
 264 #undef EXPORT_FUNC