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hex0.S: add argument parsing and open root device.

This commit is contained in:
Andrius Štikonas 2022-07-13 22:47:20 +01:00
parent 1dc9b13294
commit 8a344b7275
1 changed files with 56 additions and 4 deletions
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60
amd64/Development/hex0.S
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@ -2,34 +2,80 @@
#
# SPDX-License-Identifier: GPL-3.0-or-later
# Usage hex0 file.hex0 file
# Does not validate the arguments
# Calling convention:
# First four arguments are passed via registers but we need to leave stack space
# First four arguments are passed via registers rcx, rdx, r8, r9 (if they fit in 64-bits)
# but we need to leave stack space
.global _start
.text
_start:
sub rsp, 64
mov [ImageHandle], rcx # ImageHandle *image_handle
mov rax, [rdx+96] # system->boot
mov [SystemBoot], rax # save system->boot
# Open Loaded Image protocol
sub rsp, 72 # allocate stack
# arg1 = ImageHandle
mov rdx, [LOADED_IMAGE_PROTOCOL] # EFI_LOADED_IMAGE_PROTOCOL_GUID (first 64 bits)
mov [rsp+48], rdx # save onto stack
mov rdx, [LOADED_IMAGE_PROTOCOL+8]# EFI_LOADED_IMAGE_PROTOCOL_GUID (last 64 bits)
mov [rsp+56], rdx # save onto stack
lea rdx, [rsp+48] # arg2 = &EFI_LOADED_IMAGE_PROTOCOL_GUID
# arg3 = &image
lea r8, [rsp+64] # arg3 = &image
mov r9, rcx # arg4 = image_handle
mov qword ptr [rsp+32], 0 # arg5 = NULL
mov qword ptr [rsp+40], 1 # arg6 = EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL
call [rax+280] # system->boot->open_protocol();
add rsp, 64
# Command line args
mov rax, [rsp+64] # get image
mov rcx, rax # save image
mov rax, [rax+56] # options = image->load_options
loop_options1: # Skip application name
add rax, 2 # ++options
mov bl, [rax] # *options
cmp bl, 0x20 # if *options != ' '
jne loop_options1 # then jump
add rax, 2 # ++options
push rax # in = options
loop_options2: # Skip argv[1]
add rax, 2 # ++options
mov bl, [rax] # *options
cmp bl, 0x20 # if *options != ' '
jne loop_options2 # then jump
mov qword ptr [rax], # *options = 0;
add rax, 2 # ++options
push rax # out = options
# Get root device
sub rsp, 72 # allocate stack
mov rcx, [rcx+24] # arg1 = root_device = image->device
mov rdx, [SIMPLE_FS_PROTOCOL] # EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID (first 64 bits)
mov [rsp+48], rdx # save onto stack
mov rdx, [SIMPLE_FS_PROTOCOL+8] # EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID (last 64 bits)
mov [rsp+56], rdx # save onto stack
lea rdx, [rsp+48] # arg2 = &EFI_SIMPLE_FILE_SYSTEM_PROTOCOL_GUID
lea r8, [rsp+64] # arg3 = &root_fs
mov r9, [ImageHandle] # arg4 = image_handle
mov qword ptr [rsp+32], 0 # arg5 = NULL
mov qword ptr [rsp+40], 1 # arg6 = EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL
mov rax, [SystemBoot] # system->boot
call [rax+280] # system->boot->open_protocol();
mov r8, [rsp+64] # get root_fs
add rsp, 144 # deallocate stack
pop r8 # out
pop r8 # in
Done:
ret
@ -45,3 +91,9 @@ LOADED_IMAGE_PROTOCOL:
.short 0x9562
.short 0x11d2
.byte 0x8e, 0x3f, 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b
SIMPLE_FS_PROTOCOL:
.long 0x0964e5b22
.short 0x6459
.short 0x11d2
.byte 0x8e, 0x39, 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b