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Make hex1.S relocatable. 

Also make sure we reserve memory for label table.
This commit is contained in:
Andrius Štikonas 2022-08-08 23:55:02 +01:00
parent 95ab016383
commit 943881a73b
1 changed files with 30 additions and 7 deletions
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37
amd64/Development/hex1.S
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@ -11,7 +11,20 @@ _start:
mov rbp, rsp # save stack pointer
mov r15, rcx # save image_handle
mov r14, [rdx+96] # system->boot
mov r14, [r14+280] # system->boot->open_protocol
mov [SystemBoot], r14 # save system->boot
# Allocate pool for single-character label table
push rdx # allocate stack for table
mov r8, rsp # arg3 = &table
xor edx, edx # zero rdx
mov dh, 0x8 # arg2 = 256 * 8 = 2048 = 0x800
push 2
pop rcx # arg1 = EFI_LOADER_DATA
sub rsp, 24 # allocate shadow stack space for UEFI
call [r14+64] # system->boot->allocate_pool(EFI_LOADER_DATA, 2048, &table)
add rsp, 24 # deallocate stack
pop rax # get table
mov [table], rax # save table
# Open Loaded Image protocol
push rax # allocate stack for image
@ -23,10 +36,10 @@ _start:
mov rdx, rsp # arg2 = &guid
push 1 # arg6 = EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL
push 0 # arg5 = NULL
mov r9, rcx # arg4 = image_handle
# arg1 = ImageHandle (already set)
mov r9, r15 # arg4 = image_handle
mov rcx, r15 # arg1 = image_handle
sub rsp, 32 # allocate shadow stack space for UEFI function
call r14 # system->boot->open_protocol(image_handle, &guid, &image, image_handle, 0, EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL)
call [r14+280] # system->boot->open_protocol(image_handle, &guid, &image, image_handle, 0, EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL)
mov rax, [rsp+64] # get image
mov rcx, rax # save image
@ -65,7 +78,7 @@ loop_options2: # Skip argv[1]
mov r9, r15 # arg4 = image_handle
mov rcx, [rcx+24] # arg1 = root_device = image->device
sub rsp, 32 # allocate shadow stack space for UEFI function
call r14 # system->boot->open_protocol(root_device, &guid, &rootfs, image_handle, 0, EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL)
call [r14+280] # system->boot->open_protocol(root_device, &guid, &rootfs, image_handle, 0, EFI_OPEN_PROTOCOL_BY_HANDLE_PROTOCOL)
mov rcx, [rsp+64] # get rootfs
# Get root directory
@ -281,7 +294,7 @@ print:
add rax, r14
# flip the toggle
not r15 # rbx = -1
not r15 # r15 = -1
mov rdx, 1 # set the size of chars we want
call print_chars
@ -332,7 +345,8 @@ print_chars:
Get_table_target:
call Read_byte # Get single char label
shl rax, 3 # Each label in table takes 8 bytes to store
add rax, table # Calculate offset
mov rcx, [rip+table]
add rax, rcx # Calculate offset
ret
StoreLabel:
@ -350,6 +364,12 @@ StorePointer:
ret
Done:
# Free pool
mov rcx, [table] # arg1 = table
push rax # allocate shadow stack space for UEFI function
mov r14, [SystemBoot] # get system->boot
call [r14+72] # system->boot->free_pool(commmand)
push rbx # allocate stack
mov rcx, rdi # arg1 = fin
call [rcx+16] # fin->close()
@ -376,3 +396,6 @@ SIMPLE_FS_PROTOCOL:
table:
.long 0, 0
SystemBoot:
.long 0, 0