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https://gitlab.com/qemu-project/openbios.git
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3409ec8b13
git-svn-id: svn://coreboot.org/openbios/openbios-devel@190 f158a5a8-5612-0410-a976-696ce0be7e32
112 lines
2.6 KiB
C
112 lines
2.6 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 "openbios/config.h"
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#include "openbios/kernel.h"
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#include "context.h"
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#include "sys_info.h"
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#include "boot.h"
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#define MAIN_STACK_SIZE 16384
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#define IMAGE_STACK_SIZE 4096
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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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struct context main_ctx = {
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.regs[REG_SP] = (uint64_t) &_estack - 2047 - 96,
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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 *__context = &main_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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/*
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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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int retval;
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extern int openbios(void);
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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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/* Start the real fun */
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retval = openbios();
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/* Pass return value to startup context. Bootloader may see it. */
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//boot_ctx->eax = retval;
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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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/* 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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ctx = (struct context *)
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(stack + stack_size - (sizeof(*ctx) + num_params*sizeof(uint32_t)));
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memset(ctx, 0, sizeof(*ctx));
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/* Fill in reasonable default for flat memory model */
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ctx->regs[REG_SP] = virt_to_phys(SP_LOC(ctx));
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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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/* Switch to another context. */
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struct context *switch_to(struct context *ctx)
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{
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struct context *save, *ret;
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debug("switching to new context:\n");
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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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ret = __context;
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__context = save;
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return ret;
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}
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/* Start ELF Boot image */
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uint64_t start_elf(uint64_t entry_point, uint64_t param)
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{
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struct context *ctx;
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ctx = init_context(image_stack, sizeof image_stack, 1);
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ctx->pc = entry_point;
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ctx->param[0] = param;
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//ctx->eax = 0xe1fb007;
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//ctx->ebx = param;
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ctx = switch_to(ctx);
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//return ctx->eax;
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return 0;
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}
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