arch/sparc64/context.c

   1 /*
   2  * context switching
   3  * 2003-10 by SONE Takeshi
   4  */
   5
   6 #include "config.h"
   7 #include "kernel/kernel.h"
   8 #include "context.h"
   9 #include "libopenbios/sys_info.h"
  10 #include "boot.h"
  11 #include "openbios.h"
  12
  13 #define MAIN_STACK_SIZE 16384
  14 #define IMAGE_STACK_SIZE 4096*4
  15
  16 #define debug printk
  17
  18 static void start_main(void); /* forward decl. */
  19 void __exit_context(void); /* assembly routine */
  20
  21 /*
  22  * Main context structure
  23  * It is placed at the bottom of our stack, and loaded by assembly routine
  24  * to start us up.
  25  */
  26 static struct context main_ctx = {
  27     .regs[REG_SP] = (uint64_t) &_estack - STACK_BIAS - 96,
  28     .pc = (uint64_t) start_main,
  29     .npc = (uint64_t) start_main + 4,
  30     .return_addr = (uint64_t) __exit_context,
  31 };
  32
  33 /* This is used by assembly routine to load/store the context which
  34  * it is to switch/switched.  */
  35 struct context * volatile __context = &main_ctx;
  36
  37 /* Stack for loaded ELF image */
  38 static uint8_t image_stack[IMAGE_STACK_SIZE];
  39
  40 /* Pointer to startup context (physical address) */
  41 unsigned long __boot_ctx;
  42
  43 /*
  44  * Main starter
  45  * This is the C function that runs first.
  46  */
  47 static void start_main(void)
  48 {
  49     /* Save startup context, so we can refer to it later.
  50      * We have to keep it in physical address since we will relocate. */
  51     __boot_ctx = virt_to_phys(__context);
  52
  53     /* Start the real fun */
  54     openbios();
  55
  56     /* Returning from here should jump to __exit_context */
  57     __context = boot_ctx;
  58 }
  59
  60 static uint64_t ALIGN_SIZE(uint64_t x, uint64_t a)
  61 {
  62     return (x + a - 1) & ~(a-1);
  63 }
  64
  65 /* Setup a new context using the given stack.
  66  */
  67 struct context *
  68 init_context(uint8_t *stack, uint64_t stack_size, int num_params)
  69 {
  70     struct context *ctx;
  71     uint8_t *stack_top = stack + stack_size;
  72
  73     ctx = (struct context *)
  74         (stack_top - ALIGN_SIZE(sizeof(*ctx) + num_params*sizeof(uint64_t), sizeof(uint64_t)));
  75     memset(ctx, 0, sizeof(*ctx));
  76
  77     /* Fill in reasonable default for flat memory model */
  78     ctx->regs[REG_SP] = virt_to_phys(stack_top - STACK_BIAS - 192);
  79     ctx->return_addr = virt_to_phys(__exit_context);
  80
  81     return ctx;
  82 }
  83
  84 /* Switch to another context. */
  85 struct context *switch_to(struct context *ctx)
  86 {
  87     struct context *save, *ret;
  88
  89     debug("switching to new context: entry point %#llx stack 0x%016llx\n", ctx->pc, ctx->regs[REG_SP]);
  90     save = __context;
  91     __context = ctx;
  92     //asm ("pushl %cs; call __switch_context");
  93     asm ("call __switch_context_nosave; nop");
  94     ret = __context;
  95     __context = save;
  96     return ret;
  97 }
  98
  99 /* Start ELF Boot image */
 100 uint64_t start_elf(uint64_t entry_point, uint64_t param)
 101 {
 102     struct context *ctx;
 103
 104     ctx = init_context(image_stack, sizeof image_stack, 1);
 105     ctx->pc = entry_point;
 106     ctx->param[0] = param;
 107     //ctx->eax = 0xe1fb007;
 108     //ctx->ebx = param;
 109
 110     ctx = switch_to(ctx);
 111     //return ctx->eax;
 112     return 0;
 113 }
 114
 115 /* Start client image */
 116 uint64_t start_client_image(uint64_t entry_point, uint64_t cif_handler)
 117 {
 118     struct context *ctx;
 119
 120     ctx = init_context(image_stack, sizeof image_stack, 0);
 121     ctx->pc  = entry_point;
 122     ctx->npc = entry_point+4;
 123     ctx->regs[REG_O0] = 0;
 124     ctx->regs[REG_O0+4] = cif_handler;
 125
 126     ctx = switch_to(ctx);
 127
 128     return 0;
 129 }