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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /arch/arm/boot/bootp/init.S | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/arm/boot/bootp/init.S')
-rw-r--r-- | arch/arm/boot/bootp/init.S | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/arch/arm/boot/bootp/init.S b/arch/arm/boot/bootp/init.S new file mode 100644 index 000000000..b562da2f7 --- /dev/null +++ b/arch/arm/boot/bootp/init.S @@ -0,0 +1,85 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * linux/arch/arm/boot/bootp/init.S + * + * Copyright (C) 2000-2003 Russell King. + * + * "Header" file for splitting kernel + initrd. Note that we pass + * r0 through to r3 straight through. + * + * This demonstrates how to append code to the start of the kernel + * zImage, and boot the kernel without copying it around. This + * example would be simpler; if we didn't have an object of unknown + * size immediately following the kernel, we could build this into + * a binary blob, and concatenate the zImage using the cat command. + */ + .section .start, "ax" + .type _start, #function + .globl _start + +_start: add lr, pc, #-0x8 @ lr = current load addr + adr r13, data + ldmia r13!, {r4-r6} @ r5 = dest, r6 = length + add r4, r4, lr @ r4 = initrd_start + load addr + bl move @ move the initrd + +/* + * Setup the initrd parameters to pass to the kernel. This can only be + * passed in via the tagged list. + */ + ldmia r13, {r5-r9} @ get size and addr of initrd + @ r5 = ATAG_CORE + @ r6 = ATAG_INITRD2 + @ r7 = initrd start + @ r8 = initrd end + @ r9 = param_struct address + + ldr r10, [r9, #4] @ get first tag + teq r10, r5 @ is it ATAG_CORE? +/* + * If we didn't find a valid tag list, create a dummy ATAG_CORE entry. + */ + movne r10, #0 @ terminator + movne r4, #2 @ Size of this entry (2 words) + stmiane r9, {r4, r5, r10} @ Size, ATAG_CORE, terminator + +/* + * find the end of the tag list, and then add an INITRD tag on the end. + * If there is already an INITRD tag, then we ignore it; the last INITRD + * tag takes precedence. + */ +taglist: ldr r10, [r9, #0] @ tag length + teq r10, #0 @ last tag (zero length)? + addne r9, r9, r10, lsl #2 + bne taglist + + mov r5, #4 @ Size of initrd tag (4 words) + stmia r9, {r5, r6, r7, r8, r10} + b kernel_start @ call kernel + +/* + * Move the block of memory length r6 from address r4 to address r5 + */ +move: ldmia r4!, {r7 - r10} @ move 32-bytes at a time + stmia r5!, {r7 - r10} + ldmia r4!, {r7 - r10} + stmia r5!, {r7 - r10} + subs r6, r6, #8 * 4 + bcs move + mov pc, lr + + .size _start, . - _start + + .align + + .type data,#object +data: .word initrd_start @ source initrd address + .word initrd_phys @ destination initrd address + .word initrd_size @ initrd size + + .word 0x54410001 @ r5 = ATAG_CORE + .word 0x54420005 @ r6 = ATAG_INITRD2 + .word initrd_phys @ r7 + .word initrd_size @ r8 + .word params_phys @ r9 + .size data, . - data |