Qemu源码分析-mips-system-(1)-地址翻译过程
时间：2010-09-21 来源：wuxb45
target-mips里的hepler.c基本上包涵了模拟tlb的全部功能.
cpu_mips_translate_address传入虚地址和env,及rw,返回实地址.如果tlb翻译未成功,则产生一个异常.产生异常通过写env的相关域完成.
rw=1为写,0读
cpu_mips_translate_address函数包裹了get_physical_address
get_physical_address 的参数: env就是当前运行环境的env结构,大而全 *pyhsical 用于返回真实地址. *prot 用于返回访问权限. address是传入的虚拟地址. rw表示的是要进行的操作是r或w access_type始终未被使用.
这个函数包裹的真正的getaddress函数,在上面的代码里,如:
r4k_map_address 判断各个域,检查asid是否需要匹配,最后给出tlb查询的结果.
static int get_physical_address (CPUState *env, target_phys_addr_t *physical, int *prot, target_ulong address, int rw, int access_type) { /* User mode can only access useg/xuseg */ int user_mode = (env->hflags & MIPS_HFLAG_MODE) == MIPS_HFLAG_UM; int supervisor_mode = (env->hflags & MIPS_HFLAG_MODE) == MIPS_HFLAG_SM; int kernel_mode = !user_mode && !supervisor_mode; #if defined(TARGET_MIPS64) int UX = (env->CP0_Status & (1 << CP0St_UX)) != 0; int SX = (env->CP0_Status & (1 << CP0St_SX)) != 0; int KX = (env->CP0_Status & (1 << CP0St_KX)) != 0; #endif int ret = TLBRET_MATCH;
#if 0 qemu_log("user mode %d h %08x\n", user_mode, env->hflags); #endif
if (address <= (int32_t)0x7FFFFFFFUL) { /* useg */ if (env->CP0_Status & (1 << CP0St_ERL)) { *physical = address & 0xFFFFFFFF; *prot = PAGE_READ | PAGE_WRITE; } else { ret = env->tlb->map_address(env, physical, prot, address, rw, access_type); } #if defined(TARGET_MIPS64) } else if (address < 0x4000000000000000ULL) { /* xuseg */ if (UX && address <= (0x3FFFFFFFFFFFFFFFULL & env->SEGMask)) { ret = env->tlb->map_address(env, physical, prot, address, rw, access_type); } else { ret = TLBRET_BADADDR; } } else if (address < 0x8000000000000000ULL) { /* xsseg */ if ((supervisor_mode || kernel_mode) && SX && address <= (0x7FFFFFFFFFFFFFFFULL & env->SEGMask)) { ret = env->tlb->map_address(env, physical, prot, address, rw, access_type); } else { ret = TLBRET_BADADDR; } } else if (address < 0xC000000000000000ULL) { /* xkphys */ if (kernel_mode && KX && (address & 0x07FFFFFFFFFFFFFFULL) <= env->PAMask) { *physical = address & env->PAMask; *prot = PAGE_READ | PAGE_WRITE; } else { ret = TLBRET_BADADDR; } } else if (address < 0xFFFFFFFF80000000ULL) { /* xkseg */ if (kernel_mode && KX && address <= (0xFFFFFFFF7FFFFFFFULL & env->SEGMask)) { ret = env->tlb->map_address(env, physical, prot, address, rw, access_type); } else { ret = TLBRET_BADADDR; } #endif } else if (address < (int32_t)0xA0000000UL) { /* kseg0 */ if (kernel_mode) { *physical = address - (int32_t)0x80000000UL; *prot = PAGE_READ | PAGE_WRITE; } else { ret = TLBRET_BADADDR; } } else if (address < (int32_t)0xC0000000UL) { /* kseg1 */ if (kernel_mode) { *physical = address - (int32_t)0xA0000000UL; *prot = PAGE_READ | PAGE_WRITE; } else { ret = TLBRET_BADADDR; } } else if (address < (int32_t)0xE0000000UL) { /* sseg (kseg2) */ if (supervisor_mode || kernel_mode) { ret = env->tlb->map_address(env, physical, prot, address, rw, access_type); } else { ret = TLBRET_BADADDR; } } else { /* kseg3 */ /* XXX: debug segment is not emulated */ if (kernel_mode) { ret = env->tlb->map_address(env, physical, prot, address, rw, access_type); } else { ret = TLBRET_BADADDR; } } #if 0 qemu_log(TARGET_FMT_lx " %d %d => " TARGET_FMT_lx " %d (%d)\n", address, rw, access_type, *physical, *prot, ret); #endif
return ret; } #endif
CpuState结构在这里就是CPUMIPSState
其中的tlb项(CPUMIPSTLBContext)保存了指向地址映射的函数指针. struct CPUMIPSTLBContext { uint32_t nb_tlb; uint32_t tlb_in_use; int (*map_address) (struct CPUMIPSState *env, target_phys_addr_t *physical, int *prot, target_ulong address, int rw, int access_type); void (*helper_tlbwi) (void); void (*helper_tlbwr) (void); void (*helper_tlbp) (void); void (*helper_tlbr) (void); union { struct { r4k_tlb_t tlb[MIPS_TLB_MAX]; } r4k; } mmu; };
cpu_mips_translate_address传入虚地址和env,及rw,返回实地址.如果tlb翻译未成功,则产生一个异常.产生异常通过写env的相关域完成.
rw=1为写,0读
cpu_mips_translate_address函数包裹了get_physical_address
get_physical_address 的参数: env就是当前运行环境的env结构,大而全 *pyhsical 用于返回真实地址. *prot 用于返回访问权限. address是传入的虚拟地址. rw表示的是要进行的操作是r或w access_type始终未被使用.
这个函数包裹的真正的getaddress函数,在上面的代码里,如:
r4k_map_address 判断各个域,检查asid是否需要匹配,最后给出tlb查询的结果.
static int get_physical_address (CPUState *env, target_phys_addr_t *physical, int *prot, target_ulong address, int rw, int access_type) { /* User mode can only access useg/xuseg */ int user_mode = (env->hflags & MIPS_HFLAG_MODE) == MIPS_HFLAG_UM; int supervisor_mode = (env->hflags & MIPS_HFLAG_MODE) == MIPS_HFLAG_SM; int kernel_mode = !user_mode && !supervisor_mode; #if defined(TARGET_MIPS64) int UX = (env->CP0_Status & (1 << CP0St_UX)) != 0; int SX = (env->CP0_Status & (1 << CP0St_SX)) != 0; int KX = (env->CP0_Status & (1 << CP0St_KX)) != 0; #endif int ret = TLBRET_MATCH;
#if 0 qemu_log("user mode %d h %08x\n", user_mode, env->hflags); #endif
if (address <= (int32_t)0x7FFFFFFFUL) { /* useg */ if (env->CP0_Status & (1 << CP0St_ERL)) { *physical = address & 0xFFFFFFFF; *prot = PAGE_READ | PAGE_WRITE; } else { ret = env->tlb->map_address(env, physical, prot, address, rw, access_type); } #if defined(TARGET_MIPS64) } else if (address < 0x4000000000000000ULL) { /* xuseg */ if (UX && address <= (0x3FFFFFFFFFFFFFFFULL & env->SEGMask)) { ret = env->tlb->map_address(env, physical, prot, address, rw, access_type); } else { ret = TLBRET_BADADDR; } } else if (address < 0x8000000000000000ULL) { /* xsseg */ if ((supervisor_mode || kernel_mode) && SX && address <= (0x7FFFFFFFFFFFFFFFULL & env->SEGMask)) { ret = env->tlb->map_address(env, physical, prot, address, rw, access_type); } else { ret = TLBRET_BADADDR; } } else if (address < 0xC000000000000000ULL) { /* xkphys */ if (kernel_mode && KX && (address & 0x07FFFFFFFFFFFFFFULL) <= env->PAMask) { *physical = address & env->PAMask; *prot = PAGE_READ | PAGE_WRITE; } else { ret = TLBRET_BADADDR; } } else if (address < 0xFFFFFFFF80000000ULL) { /* xkseg */ if (kernel_mode && KX && address <= (0xFFFFFFFF7FFFFFFFULL & env->SEGMask)) { ret = env->tlb->map_address(env, physical, prot, address, rw, access_type); } else { ret = TLBRET_BADADDR; } #endif } else if (address < (int32_t)0xA0000000UL) { /* kseg0 */ if (kernel_mode) { *physical = address - (int32_t)0x80000000UL; *prot = PAGE_READ | PAGE_WRITE; } else { ret = TLBRET_BADADDR; } } else if (address < (int32_t)0xC0000000UL) { /* kseg1 */ if (kernel_mode) { *physical = address - (int32_t)0xA0000000UL; *prot = PAGE_READ | PAGE_WRITE; } else { ret = TLBRET_BADADDR; } } else if (address < (int32_t)0xE0000000UL) { /* sseg (kseg2) */ if (supervisor_mode || kernel_mode) { ret = env->tlb->map_address(env, physical, prot, address, rw, access_type); } else { ret = TLBRET_BADADDR; } } else { /* kseg3 */ /* XXX: debug segment is not emulated */ if (kernel_mode) { ret = env->tlb->map_address(env, physical, prot, address, rw, access_type); } else { ret = TLBRET_BADADDR; } } #if 0 qemu_log(TARGET_FMT_lx " %d %d => " TARGET_FMT_lx " %d (%d)\n", address, rw, access_type, *physical, *prot, ret); #endif
return ret; } #endif
CpuState结构在这里就是CPUMIPSState
其中的tlb项(CPUMIPSTLBContext)保存了指向地址映射的函数指针. struct CPUMIPSTLBContext { uint32_t nb_tlb; uint32_t tlb_in_use; int (*map_address) (struct CPUMIPSState *env, target_phys_addr_t *physical, int *prot, target_ulong address, int rw, int access_type); void (*helper_tlbwi) (void); void (*helper_tlbwr) (void); void (*helper_tlbp) (void); void (*helper_tlbr) (void); union { struct { r4k_tlb_t tlb[MIPS_TLB_MAX]; } r4k; } mmu; };
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