148 lines
3.6 KiB
C
148 lines
3.6 KiB
C
/*
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* context switching
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* 2003-10 by SONE Takeshi
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*/
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#include "config.h"
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#include "kernel/kernel.h"
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#include "context.h"
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#include "libopenbios/bindings.h"
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#include "libopenbios/initprogram.h"
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#include "libopenbios/sys_info.h"
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#include "boot.h"
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#include "openbios.h"
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#define MAIN_STACK_SIZE 16384
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#define IMAGE_STACK_SIZE 4096*4
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#define debug printk
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static void start_main(void); /* forward decl. */
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void __exit_context(void); /* assembly routine */
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/*
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* Main context structure
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* It is placed at the bottom of our stack, and loaded by assembly routine
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* to start us up.
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*/
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static struct context main_ctx = {
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.pc = (uint64_t) start_main,
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.npc = (uint64_t) start_main + 4,
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.return_addr = (uint64_t) __exit_context,
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};
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/* This is used by assembly routine to load/store the context which
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* it is to switch/switched. */
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struct context * volatile __context = &main_ctx;
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/* Client program context */
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static struct context *client_ctx;
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/* Stack for loaded ELF image */
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static uint8_t image_stack[IMAGE_STACK_SIZE];
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/* Pointer to startup context (physical address) */
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unsigned long __boot_ctx;
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/* Pointer to Forth context stack */
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void *_fcstack_ptr = &_efcstack;
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/*
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* Main starter
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* This is the C function that runs first.
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*/
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static void start_main(void)
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{
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/* Save startup context, so we can refer to it later.
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* We have to keep it in physical address since we will relocate. */
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__boot_ctx = virt_to_phys(__context);
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/* Set up client context */
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client_ctx = init_context(image_stack, sizeof image_stack, 1);
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__context = client_ctx;
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/* Start the real fun */
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openbios();
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/* Returning from here should jump to __exit_context */
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__context = boot_ctx;
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}
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static uint64_t ALIGN_SIZE(uint64_t x, uint64_t a)
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{
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return (x + a - 1) & ~(a-1);
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}
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#define CTX_OFFSET(n) ALIGN_SIZE(sizeof(struct context) + n * sizeof(uint64_t), sizeof(uint64_t))
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/* Setup a new context using the given stack.
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*/
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struct context *
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init_context(uint8_t *stack, uint64_t stack_size, int num_params)
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{
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struct context *ctx;
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uint8_t *stack_top = stack + stack_size;
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ctx = (struct context *)(stack_top - CTX_OFFSET(num_params));
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/* Use valid window state from startup */
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memcpy(ctx, &main_ctx, sizeof(struct context));
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/* Fill in reasonable default for flat memory model */
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ctx->return_addr = virt_to_phys(__exit_context);
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return ctx;
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}
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/* init-program */
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extern uint64_t sparc64_of_client_interface;
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int
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arch_init_program(void)
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{
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volatile struct context *ctx = __context;
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ucell entry, param;
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ctx->regs[REG_O0] = 0;
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ctx->regs[REG_O0+4] = (uint64_t)&sparc64_of_client_interface;
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ctx->regs[REG_SP] = (uint64_t)malloc(IMAGE_STACK_SIZE) + IMAGE_STACK_SIZE - CTX_OFFSET(0) - STACK_BIAS;
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/* Set param */
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feval("load-state >ls.param @");
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param = POP();
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ctx->param[0] = param;
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/* Set entry point */
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feval("load-state >ls.entry @");
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entry = POP();
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ctx->pc = entry;
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ctx->npc = entry+4;
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return 0;
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}
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/* Switch to another context. */
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struct context *switch_to(struct context *ctx)
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{
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volatile struct context *save;
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struct context *ret;
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//debug("switching to new context: entry point %#llx stack 0x%016llx\n", ctx->pc, ctx->regs[REG_SP]);
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save = __context;
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__context = ctx;
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//asm ("pushl %cs; call __switch_context");
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asm ("call __switch_context; nop");
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ret = __context;
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__context = (struct context *)save;
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return ret;
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}
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/* Start ELF Boot image */
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unsigned int start_elf(void)
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{
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volatile struct context *ctx = __context;
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ctx = switch_to((struct context *)ctx);
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return 0;
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}
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