对下面的地址空间创建3级页表
// level 1 table, 4 entries:
// 0000 0000 - 3FFF FFFF, 1GB block, DDR
// 4000 0000 - 7FFF FFFF, 1GB block, DDR
// 8000 0000 - BFFF FFFF, 1GB block, DDR
// C000 0000 - FFFF FFFF, point to level2 tabel
//
// level 2 table, 512 entries:
// C000 0000 - DFFF FFFF, 256 entries, 512MB DDR, 2MB block
// E000 0000 - EFFF FFFF, 128 entries, 256MB OSPI0 flash, 2MB block
// F000 0000 - F01F FFFF, 1 entries, resever , 2MB block, device
// F020 0000 - F03F FFFF, 1 entry, point to level 3_1
// F040 0000 - F05F FFFF, 1 entry, point to level 3_2
// F060 0000 - F07F FFFF, 1 entry, point to level 3_3
// F080 0000 - F09F FFFF, 1 entries, 2MB block, normal memory, RNE_MEM, 1.5M acture, SRAM
// F0A0 0000 - F0BF FFFF, 1 entries, 2MB block, device, RNE_CFG1
下面是创建过程与添加的注释。
#include "v8_mmu.h".text.cfi_sections .debug_frame // put stack frame info into .debug_frame instead of .eh_frame.global setup_ttb.global ZeroBlock.global __ttb0_l1.global __ttb0_l2_ram.global __ttb0_l3_ram_1.global __ttb0_l3_ram_2.global __ttb0_l3_ram_3//----------------------------------------------------------------
// setup translation table
// level 1 table, 4 entries:
// 0000 0000 - 3FFF FFFF, 1GB block, DDR
// 4000 0000 - 7FFF FFFF, 1GB block, DDR
// 8000 0000 - BFFF FFFF, 1GB block, DDR
// C000 0000 - FFFF FFFF, point to level2 tabel
//
// level 2 table, 512 entries:
// C000 0000 - DFFF FFFF, 256 entries, 512MB DDR, 2MB block
// E000 0000 - EFFF FFFF, 128 entries, 256MB OSPI0 flash, 2MB block
// F000 0000 - F01F FFFF, 1 entries, resever , 2MB block, device
// F020 0000 - F03F FFFF, 1 entry, point to level 3_1
// F040 0000 - F05F FFFF, 1 entry, point to level 3_2
// F060 0000 - F07F FFFF, 1 entry, point to level 3_3
// F080 0000 - F09F FFFF, 1 entries, 2MB block, normal memory, RNE_MEM, 1.5M acture, SRAM
// F0A0 0000 - F0BF FFFF, 1 entries, 2MB block, device, RNE_CFG1
//----------------------------------------------------------------.type setup_ttb, "function".cfi_startproc
setup_ttb://// x21 = address of L1 tables// x22 = address of L2 tables// x23 = address of L3 tables F02// x24 = address of L3 tables F04// x25 = address of L3 tables F06//ldr x2, =0 // x2 = 0 (用于清零内存)ldr x3, =0 // x3 = 0 (同上)// 清零 L1 页表 (__ttb0_l1) (L1 页表(32 字节,4 个条目))ldr x21, =__ttb0_l1 // x21 = L1 页表基地址mov x0, x21 // x0 = 当前操作地址mov x1, #(4 << 3) // x1 = 4个条目 * 8字节 = 32字节 (L1页表大小)add x0, x0, x1 // x0 指向区域末尾 (预递减清零准备)// can not call func ZeroBlock, not support nesting
loop_zero_0:subs x1, x1, #16 // 每次处理16字节 (2个条目),更新计数器stp x2, x3, [x0, #-16]! // 存储双零并递减地址: [x0-16] = (0,0), x0-=16b.ne loop_zero_0 // 循环直到x1=0// 清零 L2 页表 (__ttb0_l2_ram) (L2 页表(4096 字节,512 条目))ldr x22, =__ttb0_l2_ram // x22 = L2 页表基地址mov x1, #(512 << 3) // x1 = 512条目 * 8字节 = 4096字节 (标准2MB块大小)mov x0, x22 // x0 = 当前操作地址add x0, x0, x1 // x0 指向区域末尾//循环使用 subs + b.ne 实现精确计数(当 x1 减至 0 时退出)
loop_zero_1:subs x1, x1, #16 // 每次16字节stp x2, x3, [x0, #-16]! // 存储双零并前移指针b.ne loop_zero_1 // 循环// 清零第一个 L3 页表 (__ttb0_l3_ram_1) (三个 L3 页表(各 4096 字节))ldr x23, =__ttb0_l3_ram_1 // x23 = L3 页表1基地址mov x1, #(512 << 3) // 4096字节 (标准4KB页表大小)mov x0, x23add x0, x0, x1 // 指向末尾
loop_zero_2:subs x1, x1, #16stp x2, x3, [x0, #-16]!b.ne loop_zero_2// 清零第二个 L3 页表 (__ttb0_l3_ram_2)ldr x24, =__ttb0_l3_ram_2 // x24 = L3 页表2基地址mov x1, #(512 << 3) // 4096字节mov x0, x24add x0, x0, x1 // 指向末尾
loop_zero_3:subs x1, x1, #16stp x2, x3, [x0, #-16]!b.ne loop_zero_3// 清零第三个 L3 页表 (__ttb0_l3_ram_3)ldr x25, =__ttb0_l3_ram_3 // x25 = L3 页表3基地址mov x1, #(512 << 3) // 4096字节mov x0, x25add x0, x0, x1 // 指向末尾
loop_zero_4:subs x1, x1, #16stp x2, x3, [x0, #-16]!b.ne loop_zero_4// 设置 L1 页表项配置// 0000 0000 - 3FFF FFFF, 1GB block, DDR// 4000 0000 - 7FFF FFFF, 1GB block, DDR// 8000 0000 - BFFF FFFF, 1GB block, DDR// 3 1G block, write to l1 table//ldr x1, =3 // x1 = 3 (需要配置的页表项数量)ldr x2, =0x40000000 // x2 = 1GB 地址增量 (每个 L1 条目映射 1GB 空间)// 构建 L1 块描述符属性值:// - 物理地址基址: 0x00000000// - 块描述符类型 (TT_S1_ATTR_BLOCK) TT_S1_ATTR_BLOCK:使用块描述符 (1GB/2MB 大页)// - 内存属性索引 1 (MATTR=1) 普通内存,适用于ddr// - 非安全状态 (NS)// - 特权读写权限 (AP_RW_PL1)// - 内部可共享 (SH_INNER)// - 访问标志 (AF)// - 非全局映射 (nG)ldr x3, =(0x00000000 | \TT_S1_ATTR_BLOCK | \(1 << TT_S1_ATTR_MATTR_LSB) | \TT_S1_ATTR_NS | \TT_S1_ATTR_AP_RW_PL1 | \TT_S1_ATTR_SH_INNER | \TT_S1_ATTR_AF | \TT_S1_ATTR_nG)mov x4, x21 // x4 = L1 页表基址指针 (x21 来自前段代码)#if 1 // enable after ddr ready
loop1:str x3, [x4], #8 // 存储每次的x3描述符到 L1 页表并后移指针add x3, x3, x2 // 物理地址增加 1GB (0x40000000)subs x1, x1, #1 // 递减计数器bne loop1 // 循环直到 3 个条目配置完成
#else
loop1:add x4, x4, #8 // 仅移动指针 (不存储)add x3, x3, x2 // 物理地址增加 1GBsubs x1, x1, #1bne loop1
#endif// 配置 L1 页表中 C0000000-FFFFFFFF 区域的条目// C000 0000 - FFFF FFFF, point to level2 tabel, write to l1 tableorr x1, x22, #TT_S1_ATTR_PAGE // 将 L2 表基址(x22)与页表描述符属性组合。TT_S1_ATTR_PAGE:页表描述符 (指向下级页表)str x1, [x4] // 存储到 L1 页表 (指向 L2 页表)// 配置 L2 页表:DDR 区域 (C0000000-DFFFFFFF, 512MB)// level 2 table: C000 0000 - DFFF FFFF, 256 entries, 512MB DDR, 2MB blockldr x1, =256 // 256 个条目 (256 * 2MB = 512MB)ldr x2, =0x200000 // x2 = 2MB 地址增量 (块大小)// 构建 DDR 区域的 L2 块描述符:// - 物理地址基址: 0xC0000000// - 块描述符类型// - 内存属性索引 1 (普通内存)ldr x3, =(0xC0000000 | \TT_S1_ATTR_BLOCK | \(1 << TT_S1_ATTR_MATTR_LSB) | \TT_S1_ATTR_NS | \TT_S1_ATTR_AP_RW_PL1 | \TT_S1_ATTR_SH_INNER | \TT_S1_ATTR_AF | \TT_S1_ATTR_nG)mov x4, x22 // x4 = L2 页表基址指针 (x22)
loop2_ddr:str x3, [x4], #8 // 存储每次的x3到描述符到 L2 页表并后移指针add x3, x3, x2 // 物理地址增加 2MBsubs x1, x1, #1 // 递减计数器bne loop2_ddr // 循环配置 256 个条目// 配置 L2 页表:OSPI0 Flash 区域 (E0000000-EFFFFFFF, 256MB)// level 2 table: E000 0000 - EFFF FFFF, 64 entries, 128MB OSPI0 flash, 2MB blockldr x1, =128 // 128 个条目 (128 * 2MB = 256MB)ldr x2, =0x200000 // 2MB 块大小// 构建 OSPI Flash 的 L2 块描述符:// - 物理地址基址: 0xE0000000// - 内存属性索引TT_S1_ATTR_MATTR_LSB 2 (通常用于设备内存)//AP_RW_PL1:特权读写权限//SH_INNER:内部可共享//AF:访问标志 (Access Flag)//nG:非全局映射ldr x3, =(0xE0000000 | \TT_S1_ATTR_BLOCK | \(2 << TT_S1_ATTR_MATTR_LSB) | \TT_S1_ATTR_NS | \TT_S1_ATTR_AP_RW_PL1 | \TT_S1_ATTR_SH_INNER | \TT_S1_ATTR_AF | \TT_S1_ATTR_nG)
loop2_ospi0:str x3, [x4], #8 // 继续在 L2 页表存储 (紧接 DDR 区域之后)add x3, x3, x2 // 物理地址增加 2MBsubs x1, x1, #1 // 递减计数器bne loop2_ospi0 // 循环配置 128 个条目// F0800000-F09FFFFF 区域:2MB 块映射 (普通内存)// F000 0000 - F01F FFFF, resever, no need to set this block// F080 0000 - F09F FFFF, 1 entries, 2MB block, normal memory, RNE_MEM, 1.5M acture, SRAM// 物理地址 + 属性ldr x1, =(0xF0800000 | \TT_S1_ATTR_BLOCK | \(1 << TT_S1_ATTR_MATTR_LSB) | \TT_S1_ATTR_NS | \TT_S1_ATTR_AP_RW_PL1 | \TT_S1_ATTR_SH_INNER | \TT_S1_ATTR_AF | \TT_S1_ATTR_nG)ldr x2, =0xF0800000 // 目标虚拟地址ubfx x3, x2, #21, #9 // 提取 L2 索引 (位[29:21]) ?str x1, [x22, x3, lsl #3] // 写入 L2 页表 (x22) ?// F0A00000-F0BFFFFF 区域:2MB 块映射 (设备内存)// F0A0 0000 - F0BF FFFF, 1 entries, 2MB block, device, RNE_CFG1// 物理地址 + 属性ldr x1, =(0xF0A00000 | \TT_S1_ATTR_BLOCK | \(2 << TT_S1_ATTR_MATTR_LSB) | \TT_S1_ATTR_NS | \TT_S1_ATTR_AP_RW_PL1 | \TT_S1_ATTR_SH_INNER | \TT_S1_ATTR_AF | \TT_S1_ATTR_nG)ldr x2, =0xF0A00000 // 目标虚拟地址ubfx x3, x2, #21, #9 // 提取 L2 索引str x1, [x22, x3, lsl #3] // 写入 L2 页表/*0x00000000 ~ 0xc0000000 ----l10xc0000000 ~ 0xe0000000 ----l20xe0000000 ~ 0xf0000000 ----l20xf0800000 ~ 0xf0870000 rne_mem ----l20xf0a00000 ~ 0xf0bfffff rne_cfg ----l20xf0000000 ~ 0xf02fffff rsv0xf0314000 ~ 0xf03effff peri -----0xf0200000 ~ 0xf03fffff : l2 -> l3 3_10xf0400000 ~ 0xf04fffff usb -----0xf0500000 ~ 0xf0517fff peri -----0xf0400000 ~ 0xf05fffff : l2 -> l3 3_20xf0600000 ~ 0xf062ffff ddr gic noc acodec -----0xf0600000 ~ 0xf07fffff : l2 -> l3 3_3地址转换:L2 索引:ubfx 提取位[29:21] (#21, #9)L3 索引:ubfx 提取位[20:12] (#12, #9)页表项位置:基址 + 索引 × 8 (lsl #3)*/// 设置 L2 页表项:F0200000-F03FFFFF 指向 L3 页表 (x23)// level 2 table: F020 0000 - F03F FFFF, 1 entry, point to level 3_1orr x1, x23, #TT_S1_ATTR_TABLE // 组合 L3 基址和表描述符属性ldr x2, =0xF0200000 // 虚拟地址范围起始ubfx x3, x2, #21, #9 // 提取 L2 索引str x1, [x22, x3, lsl #3] // 写入 L2 页表// 设置 L2 页表项:F0400000-F05FFFFF 指向 L3 页表 (x24)// level 2 table: F040 0000 - F05F FFFF, 1 entry, point to level 3_2orr x1, x24, #TT_S1_ATTR_TABLE // 组合 L3 基址和表描述符属性ldr x2, =0xF0400000 // 虚拟地址范围起始ubfx x3, x2, #21, #9 // 提取 L2 索引str x1, [x22, x3, lsl #3] // 写入 L2 页表// 设置 L2 页表项:F0600000-F12A5FFF 指向 L3 页表 (x25)// level 2 table: F060 0000 - F12A 5FFF, 1 entry, point to level 3_3orr x1, x25, #TT_S1_ATTR_TABLE // 组合 L3 基址和表描述符属性ldr x2, =0xF0600000 // 虚拟地址范围起始ubfx x3, x2, #21, #9 // 提取 L2 索引str x1, [x22, x3, lsl #3] // 写入 L2 页表// 填充 L3 页表 (x23):F0200000-F03FFFFF 区域 (512 个 4KB 页)// level 3 table: F02 0000 - F03F FFFF, 512 entry, x24// valid addr F020 0000 - F03F FFFFldr x1, =0x1000 // 页大小:4KBldr x2, =((0xF03FFFFF + 1 - 0xF0200000) >> 12) // 计算页数ldr x3, =0xF0200000 // 物理地址起始// 页描述符属性// 设备内存属性ldr x4, = (TT_S1_ATTR_PAGE | \(2 << TT_S1_ATTR_MATTR_LSB) | \TT_S1_ATTR_NS | \TT_S1_ATTR_AP_RW_PL1 | \TT_S1_ATTR_SH_INNER | \TT_S1_ATTR_AF | \TT_S1_ATTR_nG)
loop3_1:ubfx x5, x3, #12, #9 // 提取页内索引 (位[20:12])orr x6, x3, x4 // 组合物理地址和属性str x6, [x23, x5, lsl #3] // 存储到 L3 页表 (x23)add x3, x3, x1 // 移动到下一页subs x2, x2, #1 // 递减页计数器bne loop3_1 // 循环直到所有页映射完成// 填充 L3 页表 (x24):F0400000-F05FFFFF 区域 (512 个 4KB 页)// level 3 table: F040 0000 - F05F FFFF,, 512 entry, x25// valid addr F040 0000 - F05F FFFFldr x1, =0x1000 // 页大小:4KBldr x2, =((0xF05FFFFF + 1 - 0xF0400000) >> 12) // 计算页数ldr x3, =0xF0400000 // 物理地址起始// 设备内存属性ldr x4, = (TT_S1_ATTR_PAGE | \(2 << TT_S1_ATTR_MATTR_LSB) | \TT_S1_ATTR_NS | \TT_S1_ATTR_AP_RW_PL1 | \TT_S1_ATTR_SH_INNER | \TT_S1_ATTR_AF | \TT_S1_ATTR_nG)
loop3_2:ubfx x5, x3, #12, #9 // 提取页内索引orr x6, x3, x4 // 组合物理地址和属性str x6, [x24, x5, lsl #3] // 存储到 L3 页表 (x24)add x3, x3, x1 // 下一页subs x2, x2, #1 // 递减页计数器bne loop3_2 // 循环// 填充 L3 页表 (x25):F0600000-F07FFFFF 区域 (512 个 4KB 页)// level 3 table: F060 0000 - F07F FFFF, 512 entry, x25// valid addr F060 0000 - F07F FFFFldr x1, =0x1000 // 页大小:4KBldr x2, =((0xF07FFFFF + 1 - 0xF0600000) >> 12) // 计算页数ldr x3, =0xF0600000 // 物理地址起始// 设备内存属性ldr x4, = (TT_S1_ATTR_PAGE | \(2 << TT_S1_ATTR_MATTR_LSB) | \TT_S1_ATTR_NS | \TT_S1_ATTR_AP_RW_PL1 | \TT_S1_ATTR_SH_INNER | \TT_S1_ATTR_AF | \TT_S1_ATTR_nG)
loop3_3:ubfx x5, x3, #12, #9 // 提取页内索引orr x6, x3, x4 // 组合物理地址和属性str x6, [x25, x5, lsl #3] // 存储到 L3 页表 (x25)add x3, x3, x1 // 下一页subs x2, x2, #1 // 递减页计数器bne loop3_3 // 循环ret.cfi_endproc