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Annotation of qemu/roms/openbios/arch/sparc32/context.c, revision 1.1

1.1     ! root        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*2
        !            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] = (uint32_t) &_estack - 96,
        !            28:     .pc = (uint32_t) start_main,
        !            29:     .npc = (uint32_t) start_main + 4,
        !            30:     .return_addr = (uint32_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 *__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: /* Setup a new context using the given stack.
        !            61:  */
        !            62: struct context *
        !            63: init_context(uint8_t *stack, uint32_t stack_size, int num_params)
        !            64: {
        !            65:     struct context *ctx;
        !            66: 
        !            67:     ctx = (struct context *)
        !            68:        (stack + stack_size - (sizeof(*ctx) + num_params*sizeof(uint32_t)));
        !            69:     memset(ctx, 0, sizeof(*ctx));
        !            70: 
        !            71:     /* Fill in reasonable default for flat memory model */
        !            72:     ctx->regs[REG_SP] = virt_to_phys(SP_LOC(ctx));
        !            73:     ctx->return_addr = virt_to_phys(__exit_context);
        !            74: 
        !            75:     return ctx;
        !            76: }
        !            77: 
        !            78: /* Switch to another context. */
        !            79: struct context *switch_to(struct context *ctx)
        !            80: {
        !            81:     volatile struct context *save;
        !            82:     struct context *ret;
        !            83: 
        !            84:     debug("switching to new context:\n");
        !            85:     save = __context;
        !            86:     __context = ctx;
        !            87:     asm __volatile__ ("\n\tcall __switch_context"
        !            88:                       "\n\tnop" ::: "g1", "g2", "g3", "g4", "g5", "g6", "g7",
        !            89:                       "o0", "o1", "o2", "o3", "o4", "o5", "sp", "o7",
        !            90:                       "l0", "l1", "l2", "l3", "l4", "l5", "l6", "l7",
        !            91:                       "i0", "i1", "i2", "i3", "i4", "i5", "i7",
        !            92:                       "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", "f8", "f9",
        !            93:                       "f10", "f11", "f12", "f13", "f14", "f15", "f16", "f17", "f18", "f19",
        !            94:                       "f20", "f21", "f22", "f23", "f24", "f25", "f26", "f27", "f28", "f29",
        !            95:                       "f30", "f31",
        !            96:                       "memory");
        !            97:     ret = __context;
        !            98:     __context = (struct context *)save;
        !            99:     return ret;
        !           100: }
        !           101: 
        !           102: /* Start ELF Boot image */
        !           103: unsigned int start_elf(unsigned long entry_point, unsigned long param)
        !           104: {
        !           105:     struct context *ctx;
        !           106: 
        !           107:     ctx = init_context(image_stack, sizeof image_stack, 1);
        !           108:     ctx->pc = entry_point;
        !           109:     ctx->param[0] = param;
        !           110: 
        !           111:     ctx = switch_to(ctx);
        !           112:     return ctx->regs[REG_O0];
        !           113: }

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