optee内存管理和页表建立
文章目录
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- 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
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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_region
static_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;
else
desc = 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：
