a-b-kernel.S (1796B)
1 # 2 # Copyright (c) 2018 Red Hat, Inc. and/or its affiliates 3 # 4 # Author: 5 # Wei Huang <wei@redhat.com> 6 # 7 # This work is licensed under the terms of the GNU GPL, version 2 or later. 8 # See the COPYING file in the top-level directory. 9 # 10 # Note: Please make sure the compiler compiles the assembly code below with 11 # pc-relative address. Also the branch instructions should use relative 12 # addresses only. 13 14 #include "../migration-test.h" 15 16 .section .text 17 18 .globl _start 19 20 _start: 21 /* disable MMU to use phys mem address */ 22 mrs x0, sctlr_el1 23 bic x0, x0, #(1<<0) 24 msr sctlr_el1, x0 25 isb 26 27 /* traverse test memory region */ 28 mov x0, #ARM_TEST_MEM_START 29 mov x1, #ARM_TEST_MEM_END 30 31 /* output char 'A' to PL011 */ 32 mov w3, 'A' 33 mov x2, #ARM_MACH_VIRT_UART 34 strb w3, [x2] 35 36 /* clean up memory */ 37 mov w3, #0 38 mov x4, x0 39 clean: 40 strb w3, [x4] 41 add x4, x4, #TEST_MEM_PAGE_SIZE 42 cmp x4, x1 43 ble clean 44 45 /* w5 keeps a counter so we can limit the output speed */ 46 mov w5, #0 47 48 /* main body */ 49 mainloop: 50 mov x4, x0 51 52 innerloop: 53 /* increment the first byte of each page by 1 */ 54 ldrb w3, [x4] 55 add w3, w3, #1 56 strb w3, [x4] 57 58 /* make sure QEMU user space can see consistent data as MMU is off */ 59 dc civac, x4 60 61 add x4, x4, #TEST_MEM_PAGE_SIZE 62 cmp x4, x1 63 blt innerloop 64 65 add w5, w5, #1 66 and w5, w5, #0x1f 67 cmp w5, #0 68 bne mainloop 69 70 /* output char 'B' to PL011 */ 71 mov w3, 'B' 72 strb w3, [x2] 73 74 b mainloop