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/*
* context switching
* 2003-10 by SONE Takeshi
*/
#include "config.h"
#include "kernel/kernel.h"
#include "context.h"
#include "libopenbios/sys_info.h"
#include "boot.h"
#include "openbios.h"
#define MAIN_STACK_SIZE 16384
#define IMAGE_STACK_SIZE 4096*4
#define debug printk
static void start_main(void); /* forward decl. */
void __exit_context(void); /* assembly routine */
/*
* Main context structure
* It is placed at the bottom of our stack, and loaded by assembly routine
* to start us up.
*/
static struct context main_ctx = {
.regs[REG_SP] = (uint64_t) &_estack - STACK_BIAS - 96,
.pc = (uint64_t) start_main,
.npc = (uint64_t) start_main + 4,
.return_addr = (uint64_t) __exit_context,
};
/* This is used by assembly routine to load/store the context which
* it is to switch/switched. */
struct context * volatile __context = &main_ctx;
/* Stack for loaded ELF image */
static uint8_t image_stack[IMAGE_STACK_SIZE];
/* Pointer to startup context (physical address) */
unsigned long __boot_ctx;
/* Pointer to Forth context stack */
void *_fcstack_ptr = &_efcstack;
/*
* Main starter
* This is the C function that runs first.
*/
static void start_main(void)
{
/* Save startup context, so we can refer to it later.
* We have to keep it in physical address since we will relocate. */
__boot_ctx = virt_to_phys(__context);
/* Start the real fun */
openbios();
/* Returning from here should jump to __exit_context */
__context = boot_ctx;
}
static uint64_t ALIGN_SIZE(uint64_t x, uint64_t a)
{
return (x + a - 1) & ~(a-1);
}
/* Setup a new context using the given stack.
*/
struct context *
init_context(uint8_t *stack, uint64_t stack_size, int num_params)
{
struct context *ctx;
uint8_t *stack_top = stack + stack_size;
ctx = (struct context *)
(stack_top - ALIGN_SIZE(sizeof(*ctx) + num_params*sizeof(uint64_t), sizeof(uint64_t)));
memset(ctx, 0, sizeof(*ctx));
/* Fill in reasonable default for flat memory model */
ctx->regs[REG_SP] = virt_to_phys(stack_top - STACK_BIAS - 192);
ctx->return_addr = virt_to_phys(__exit_context);
return ctx;
}
/* Switch to another context. */
struct context *switch_to(struct context *ctx)
{
struct context *save, *ret;
debug("switching to new context: entry point %#llx stack 0x%016llx\n", ctx->pc, ctx->regs[REG_SP]);
save = __context;
__context = ctx;
//asm ("pushl %cs; call __switch_context");
asm ("call __switch_context_nosave; nop");
ret = __context;
__context = save;
return ret;
}
/* Start ELF Boot image */
uint64_t start_elf(uint64_t entry_point, uint64_t param)
{
struct context *ctx;
ctx = init_context(image_stack, sizeof image_stack, 1);
ctx->pc = entry_point;
ctx->param[0] = param;
//ctx->eax = 0xe1fb007;
//ctx->ebx = param;
ctx = switch_to(ctx);
//return ctx->eax;
return 0;
}
/* Start client image */
uint64_t start_client_image(uint64_t entry_point, uint64_t cif_handler)
{
struct context *ctx;
ctx = init_context(image_stack, sizeof image_stack, 0);
ctx->pc = entry_point;
ctx->npc = entry_point+4;
ctx->regs[REG_O0] = 0;
ctx->regs[REG_O0+4] = cif_handler;
ctx = switch_to(ctx);
return 0;
}
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