| /* |
| * context switching |
| * 2003-10 by SONE Takeshi |
| */ |
| |
| #include "config.h" |
| #include "kernel/kernel.h" |
| #include "context.h" |
| #include "libopenbios/bindings.h" |
| #include "libopenbios/initprogram.h" |
| #include "libopenbios/sys_info.h" |
| #include "boot.h" |
| #include "openbios.h" |
| |
| #define MAIN_STACK_SIZE 16384 |
| #define IMAGE_STACK_SIZE 4096*2 |
| |
| #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 = { |
| .pc = (uint32_t) start_main, |
| .npc = (uint32_t) start_main + 4, |
| .return_addr = (uint32_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; |
| |
| /* Client program context */ |
| static struct context *client_ctx; |
| |
| /* Stack for loaded ELF image */ |
| static uint8_t image_stack[IMAGE_STACK_SIZE]; |
| |
| /* Pointer to startup context (physical address) */ |
| unsigned long __boot_ctx; |
| |
| /* |
| * 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); |
| |
| /* Set up client context */ |
| client_ctx = init_context(image_stack, sizeof image_stack, 1); |
| __context = client_ctx; |
| |
| /* Start the real fun */ |
| openbios(); |
| |
| /* Returning from here should jump to __exit_context */ |
| __context = boot_ctx; |
| } |
| |
| #define CTX_OFFSET(n) (sizeof(struct context) + n * sizeof(uint32_t)) |
| |
| /* Setup a new context using the given stack. |
| */ |
| struct context * |
| init_context(uint8_t *stack, uint32_t stack_size, int num_params) |
| { |
| struct context *ctx; |
| |
| ctx = (struct context *) |
| (stack + stack_size - CTX_OFFSET(num_params)); |
| /* Use valid window state from startup */ |
| memcpy(ctx, &main_ctx, sizeof(struct context)); |
| |
| /* Fill in reasonable default for flat memory model */ |
| ctx->regs[REG_SP] = virt_to_phys(SP_LOC(ctx)); |
| ctx->return_addr = virt_to_phys(__exit_context); |
| |
| return ctx; |
| } |
| |
| /* init-program */ |
| int |
| arch_init_program(void) |
| { |
| volatile struct context *ctx = __context; |
| ucell entry; |
| |
| ctx->regs[REG_O0] = (unsigned long)romvec; |
| ctx->regs[REG_SP] = (unsigned long)malloc(IMAGE_STACK_SIZE) + IMAGE_STACK_SIZE - CTX_OFFSET(1); |
| |
| /* Set entry point */ |
| feval("load-state >ls.entry @"); |
| entry = POP(); |
| ctx->pc = entry; |
| |
| return 0; |
| } |
| |
| /* Switch to another context. */ |
| struct context *switch_to(struct context *ctx) |
| { |
| volatile struct context *save; |
| struct context *ret; |
| |
| debug("switching to new context:\n"); |
| save = __context; |
| __context = ctx; |
| asm __volatile__ ("\n\tcall __switch_context" |
| "\n\tnop" ::: "g1", "g2", "g3", "g4", "g5", "g6", "g7", |
| "o0", "o1", "o2", "o3", "o4", "o5", "o7", |
| "l0", "l1", "l2", "l3", "l4", "l5", "l6", "l7", |
| "i0", "i1", "i2", "i3", "i4", "i5", "i7", |
| "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", "f8", "f9", |
| "f10", "f11", "f12", "f13", "f14", "f15", "f16", "f17", "f18", "f19", |
| "f20", "f21", "f22", "f23", "f24", "f25", "f26", "f27", "f28", "f29", |
| "f30", "f31", |
| "memory"); |
| ret = __context; |
| __context = (struct context *)save; |
| return ret; |
| } |
| |
| /* Start ELF Boot image */ |
| unsigned int start_elf(void) |
| { |
| volatile struct context *ctx = __context;; |
| |
| ctx = switch_to((struct context *)ctx); |
| return ctx->regs[REG_O0]; |
| } |