optee内存管理和页表建立

文章目录

1、armv8的页表定义
2、rodata section指向内存的结构体
3、内存的分类和注册
3、内存的属性(type)
4、页表的构建

1、armv8的页表定义

透过事务看本质，页表里都有什么？如下图描述了页表中的一个entry信息，而我们软件做的工作，其实就是针对每一个页面的管理，去填充一个entry, 一个entry对应一个页面， entry中包含页面地址和内存的一些属性。把所有的entry放到一起，就构成了页表www

2、rodata section指向内存的结构体

rodata section的地址段

     *(.rodata .rodata.*)/** 8 to avoid unwanted padding between __start_ta_head_section* and the first structure in ta_head_section, in 64-bit* builds*/. = ALIGN(8);__start_ta_head_section = . ;KEEP(*(ta_head_section))__stop_ta_head_section = . ;. = ALIGN(8);__start_phys_mem_map_section = . ;KEEP(*(phys_mem_map_section))__end_phys_mem_map_section = . ;. = ALIGN(8);__start_phys_sdp_mem_section = . ;KEEP(*(phys_sdp_mem_section))__end_phys_sdp_mem_section = . ;. = ALIGN(8);__start_phys_nsec_ddr_section = . ;KEEP(*(phys_nsec_ddr_section))__end_phys_nsec_ddr_section = . ;. = ALIGN(8);__start_phys_ddr_overall_section = . ;KEEP(*(phys_ddr_overall_section))__end_phys_ddr_overall_section = . ;

可以看出在rodata中定义了如下section:

ta_head_section
phys_mem_map_section
phys_sdp_mem_section
phys_nsec_ddr_section
phys_ddr_overall_section

指向内存的结构体：

struct core_mmu_phys_mem {const char *name;enum teecore_memtypes type;__extension__ union {paddr_t addr;};__extension__ union {paddr_size_t size;};
};

注:在section段落中的，每一个core_mmu_phys_mem数据类型，都代表这一块region.

3、内存的分类和注册

在optee中注册内存的宏有：

register_phys_mem 将注册的内存地址添加到phys_mem_map_section段
register_sdp_mem 将注册的内存地址添加到phys_sdp_mem_section段，注意：sdp 应该是 secure device peripheral的意思
register_dynamic_shm 将注册的内存地址添加到phys_nsec_ddr_section段
register_ddr 将注册的内存地址添加到phys_ddr_overall_section段

以为register_phys_mem为例，该宏就是在.rodata的__start_phys_mem_map_section的section段定义一个struct core_mmu_phys_mem结构体类型的数据中，指向注册的这块mem的物理地址.

#define __register_memory2(_name, _type, _addr, _size, _section, _id) \static const struct core_mmu_phys_mem __phys_mem_ ## _id \__used __section(_section) = \{ .name = _name, .type = _type, .addr = _addr, .size = _size }#define __register_memory2_ul(_name, _type, _addr, _size, _section, _id) \__register_memory2(_name, _type, _addr, _size, _section, _id)
#endif#define __register_memory1(name, type, addr, size, section, id) \__register_memory2(name, type, addr, size, #section, id)#define __register_memory1_ul(name, type, addr, size, section, id) \__register_memory2_ul(name, type, addr, size, #section, id)#define register_phys_mem(type, addr, size) \__register_memory1(#addr, (type), (addr), (size), \phys_mem_map_section, __COUNTER__)

在core/arch/arm/plat_xxx/main.c中，注册这些内存：
可以注册多块物理内存:

register_phys_mem(xxx0_TYPE, xxx0_PA_BASE, xxx_SIZE);
register_phys_mem(xxx1_TYPE, xxx1_PA_BASE, xxx1_SIZE);

可以注册多个IO设备:

register_sdp_mem(DRM_VPU1_BASE, DRM_VPU1_BASE);
register_sdp_mem(DRM_VPU2_BASE, DRM_VPU2_BASE);

3、内存的属性(type)

在注册内存的时候，其实就是将包含name、type、addr、size四个元素的结构体，填写到了section段落，而type对应的就是内存的属性，对应着teecore_memtypes类型：

在optee中，有如下十几种type

enum teecore_memtypes {MEM_AREA_END = 0,MEM_AREA_TEE_RAM,MEM_AREA_TEE_RAM_RX,MEM_AREA_TEE_RAM_RO,MEM_AREA_TEE_RAM_RW,MEM_AREA_TEE_COHERENT,MEM_AREA_TEE_ASAN,MEM_AREA_TA_RAM,MEM_AREA_NSEC_SHM,MEM_AREA_RAM_NSEC,MEM_AREA_RAM_SEC,MEM_AREA_IO_NSEC,MEM_AREA_IO_SEC,MEM_AREA_RES_VASPACE,MEM_AREA_SHM_VASPACE,MEM_AREA_TA_VASPACE,MEM_AREA_PAGER_VASPACE,MEM_AREA_SDP_MEM,MEM_AREA_DDR_OVERALL,MEM_AREA_MAXTYPE
};

4、页表的构建

在optee中，定义一个region的静态数组，CFG_MMAP_REGIONS=127, 可以存放127块region

static struct tee_mmap_regionstatic_memory_map[CFG_MMAP_REGIONS + 1];struct tee_mmap_region {unsigned int type; /* enum teecore_memtypes */unsigned int region_size;paddr_t pa;vaddr_t va;size_t size;uint32_t attr; /* TEE_MATTR_* above */
};

在构建页表之前，先调用init_mem_map函数，将内存中已注册了的region读取到static_memory_map这个静态数组中

init_mem_map(static_memory_map, ARRAY_SIZE(static_memory_map));

init_mem_map()函数原型

在init_mem_map读取section region到static_memory_map的过程中，还会调用core_mmu_type_to_attr函数，将注册时写入的内存属性(type)转换位memory attribute
这里返回的memory attribute是一个32bit的值，而armv8要求的是64bit的。

uint32_t core_mmu_type_to_attr(enum teecore_memtypes t)
{const uint32_t attr = TEE_MATTR_VALID_BLOCK;const uint32_t cached = TEE_MATTR_CACHE_CACHED << TEE_MATTR_CACHE_SHIFT;const uint32_t noncache = TEE_MATTR_CACHE_NONCACHE <<TEE_MATTR_CACHE_SHIFT;switch (t) {case MEM_AREA_TEE_RAM:return attr | TEE_MATTR_SECURE | TEE_MATTR_PRWX | cached;case MEM_AREA_TEE_RAM_RX:return attr | TEE_MATTR_SECURE | TEE_MATTR_PRX | cached;case MEM_AREA_TEE_RAM_RO:return attr | TEE_MATTR_SECURE | TEE_MATTR_PR | cached;case MEM_AREA_TEE_RAM_RW:case MEM_AREA_TEE_ASAN:return attr | TEE_MATTR_SECURE | TEE_MATTR_PRW | cached;case MEM_AREA_TEE_COHERENT:return attr | TEE_MATTR_SECURE | TEE_MATTR_PRWX | noncache;case MEM_AREA_TA_RAM:return attr | TEE_MATTR_SECURE | TEE_MATTR_PRW | cached;case MEM_AREA_NSEC_SHM:return attr | TEE_MATTR_PRW | cached;case MEM_AREA_IO_NSEC:return attr | TEE_MATTR_PRW | noncache;case MEM_AREA_IO_SEC:return attr | TEE_MATTR_SECURE | TEE_MATTR_PRW | noncache;case MEM_AREA_RAM_NSEC:return attr | TEE_MATTR_PRW | cached;case MEM_AREA_RAM_SEC:return attr | TEE_MATTR_SECURE | TEE_MATTR_PRW | cached;case MEM_AREA_RES_VASPACE:case MEM_AREA_SHM_VASPACE:return 0;case MEM_AREA_PAGER_VASPACE:return TEE_MATTR_SECURE;default:panic("invalid type");}
}

在创建页表的时候会将32位的内存属性，转换成64的内存属性之后，再填充到页表的entry中
core_init_mmu_tables()—>core_mmu_map_region()—>core_mmu_set_entry()—>core_mmu_set_entry_primitive()

void core_mmu_set_entry_primitive(void *table, size_t level, size_t idx,paddr_t pa, uint32_t attr)
{uint64_t *tbl = table;uint64_t desc = mattr_to_desc(level, attr);tbl[idx] = desc | pa;
}static uint64_t mattr_to_desc(unsigned level, uint32_t attr)
{uint64_t desc;uint32_t a = attr;if (a & TEE_MATTR_HIDDEN_BLOCK)return INVALID_DESC | HIDDEN_DESC;if (a & TEE_MATTR_HIDDEN_DIRTY_BLOCK)return INVALID_DESC | HIDDEN_DIRTY_DESC;if (a & TEE_MATTR_TABLE)return TABLE_DESC;if (!(a & TEE_MATTR_VALID_BLOCK))return 0;if (a & (TEE_MATTR_PX | TEE_MATTR_PW))a |= TEE_MATTR_PR;if (a & (TEE_MATTR_UX | TEE_MATTR_UW))a |= TEE_MATTR_UR;if (a & TEE_MATTR_UR)a |= TEE_MATTR_PR;if (a & TEE_MATTR_UW)a |= TEE_MATTR_PW;if (level == 3)desc = L3_BLOCK_DESC;elsedesc = BLOCK_DESC;if (!(a & (TEE_MATTR_PX | TEE_MATTR_UX)))desc |= UPPER_ATTRS(XN);if (!(a & TEE_MATTR_PX))desc |= UPPER_ATTRS(PXN);if (a & TEE_MATTR_UR)desc |= LOWER_ATTRS(AP_UNPRIV);if (!(a & TEE_MATTR_PW))desc |= LOWER_ATTRS(AP_RO);/* Keep in sync with core_mmu.c:core_mmu_mattr_is_ok */switch ((a >> TEE_MATTR_CACHE_SHIFT) & TEE_MATTR_CACHE_MASK) {case TEE_MATTR_CACHE_NONCACHE:desc |= LOWER_ATTRS(ATTR_DEVICE_INDEX | OSH);break;case TEE_MATTR_CACHE_CACHED:desc |= LOWER_ATTRS(ATTR_IWBWA_OWBWA_NTR_INDEX | ISH);break;default:/** "Can't happen" the attribute is supposed to be checked* with core_mmu_mattr_is_ok() before.*/panic();}if (a & (TEE_MATTR_UR | TEE_MATTR_PR))desc |= LOWER_ATTRS(ACCESS_FLAG);if (!(a & TEE_MATTR_GLOBAL))desc |= LOWER_ATTRS(NON_GLOBAL);desc |= a & TEE_MATTR_SECURE ? 0 : LOWER_ATTRS(NS);return desc;
}

下图是一个页表创建的过程：