Elf tests (#42)

.github/workflows/makefile.yml

@@ -10,9 +10,12 @@ jobs:
   build:
 
     runs-on: ubuntu-latest
-    
+
     steps:
     - uses: actions/checkout@v3
 
     - name: Default target
-      run: make
+      run: make
+
+    - name: Run tests
+      run: make tests

.gitignore

@@ -1,2 +1,5 @@
 blue
-a.out
+*.out
+
+elf_test
+elf_test_hello_world

Makefile

@@ -3,7 +3,7 @@ MY_GROUP := $(shell id -g)
 ME := $(MY_USER):$(MY_GROUP)
 
 BLUE := blue
-DEMO := demo
+WHAT ?= $(BLUE)
 
 DEV_CONTAINER ?= $(BLUE)-dev
 DEV_DOCKER_FILE ?= dev.Dockerfile
@@ -27,18 +27,23 @@ dev-stop:
 	docker rm -f $(DEV_CONTAINER) || true
 
 compile:
-	$(IN_DEV_CONTAINER) $(FASM) $(BLUE).asm $(BLUE)
+	$(IN_DEV_CONTAINER) $(FASM) $(WHAT).asm $(WHAT) && chmod +x $(WHAT)
 
-start:
-	$(IN_DEV_CONTAINER) ./$(BLUE)
+run:
+	$(IN_DEV_CONTAINER) ./$(WHAT)
 
 dis:
 	$(DISASM) a.out
 
 watch:
-	watch -d make compile start
+	watch -d make compile run
+
+watch-tests:
+	watch -d make tests
 
 .PHONY:
 	dev-env dev-start dev-stop \
-	compile start dis \
-	watch
+	compile run dis \
+	watch watch-tests
+
+include test.mk

blue.asm

@@ -1,11 +1,8 @@
 format elf64 executable 3
 
+include "linux.inc"
 include "elf.inc"
 
-;
-; compiler entry point
-;
-
 segment readable writeable
 
 ;
@@ -38,16 +35,7 @@ output_file:
 	db	"a.out"
 	db	0x00
 
-SYS_WRITE = 1
-SYS_OPEN = 2
-SYS_CLOSE = 3
-SYS_EXIT = 60
-
-entry $
-	mov eax, program_code.entry_offset
-	mov ecx, program_code.length
-	call elf_binary_calculate_fields
-	
+entry $	
 	;
 	; write the output to ./a.out
 	;
@@ -58,27 +46,10 @@ entry $
 	syscall
 
 	mov	rdi, rax
-
-	mov	rsi, elf_binary_headers
-	mov	rdx, elf_binary_headers_length
-	mov	eax, SYS_WRITE
-	syscall
-
-	mov	rsi, program_code
-	mov	rdx, program_code.length
-	mov	eax, SYS_WRITE
-	syscall
-
-	mov	rsi, shstrtab
-	mov	rdx, shstrtab.length
-	mov	eax, SYS_WRITE
-	syscall
-
-	mov	rsi, elf_binary_section_headers
-	mov	rdx, elf_binary_section_headers_length
-	mov	eax, SYS_WRITE
-	syscall
-
+	mov	eax, program_code.entry_offset
+	mov	ecx, program_code.length
+	call	elf_binary_write
+	
 	mov	eax, SYS_CLOSE
 	syscall
 

elf.inc

@@ -42,7 +42,9 @@ program_header:
 	dq	elf_binary.base_address	; load position in virtual memory
 	dq	elf_binary.base_address	; load position in physical memory
 	.sizes:
+	.size_in_file:
 	dq	-0x01			; size of the loaded section (file)
+	.size_in_memory:
 	dq	-0x01			; size of the loaded section (memory)
 	dq	0x200000		; alignment boundary for sections
 
@@ -102,6 +104,7 @@ shstrtab_section_header:
 elf_binary_length = $ - elf_binary
 elf_binary_headers_length = elf_header.length + program_header.length
 elf_binary_section_headers_length = elf_binary_length - elf_binary_section_headers
+elf_binary_section_headers_offset = elf_binary_section_headers - elf_binary 
 
 segment readable executable
 
@@ -136,7 +139,41 @@ elf_binary_calculate_fields:
 	mov	eax, shstrtab.length
 	stosq
 
-	add	ecx, elf_header.length + program_header.length
+	add	ecx, elf_binary_section_headers_offset
 	mov	qword [elf_header.section_header_offset], rcx
 
 	ret
+;
+; expects
+; 	- program code entry offset in eax
+;	- program code length in ecx
+;	- file descriptor in edi
+;
+elf_binary_write:
+	push	rdi
+	call	elf_binary_calculate_fields
+	pop	rdi
+
+	mov	rsi, elf_binary_headers
+	mov	rdx, elf_binary_headers_length
+	mov	eax, SYS_WRITE
+	syscall
+
+	mov	rsi, program_code
+	mov	rdx, program_code.length
+	mov	eax, SYS_WRITE
+	syscall
+
+	mov	rsi, shstrtab
+	mov	rdx, shstrtab.length
+	mov	eax, SYS_WRITE
+	syscall
+
+	mov	rsi, elf_binary_section_headers
+	mov	rdx, elf_binary_section_headers_length
+	mov	eax, SYS_WRITE
+	syscall
+
+	ret
+
+	

elf_test.asm

@@ -0,0 +1,79 @@
+format elf64 executable 3
+
+include "linux.inc"
+include "elf.inc"
+
+segment readable writeable
+
+program_code:
+	.entry_offset = $ - program_code
+	db	0x48, 0xc7, 0xc0	; mov rax, 1 - sys_write
+	dd	0x01
+	db	0x48, 0xc7, 0xc7	; mov rdi, 1 - stdout fd
+	dd	0x01
+	db	0x48, 0xc7, 0xc6	; mov rsi, 0x4000a2 - location of string
+	dd	0x4000a2
+	db	0x48, 0xc7, 0xc2	; mov rdx, 13 - size of string
+	dd	0x0d
+	db	0x0f, 0x05		; syscall
+	db	0x48, 0xc7, 0xc0	; mov rax, 60 - sys_exit
+	dd	0x3c
+	db	0x48, 0x31, 0xff	; xor rdi, rdi
+	db	0x0f, 0x05		; syscall
+
+	db	"Hello, world"
+	db	0x0a, 0x00
+
+	.length = $ - program_code
+
+segment readable executable
+
+entry $	
+	mov	eax, program_code.entry_offset
+	mov	ecx, program_code.length
+	call	elf_binary_calculate_fields
+
+	mov	edi, 1
+	cmp	qword [elf_header.start_address], 0x400078
+	jne	exit
+
+	mov	edi, 2
+	cmp	qword [elf_header.section_header_offset], 0xc0
+	jne	exit
+
+	mov	edi, 3
+	cmp	qword [program_header.size_in_file], 0xb0
+	jne	exit
+
+	mov	edi, 4
+	cmp	qword [program_header.size_in_memory], 0xb0
+	jne	exit
+
+	mov	edi, 5
+	cmp	qword [program_code_section_header.address], 0x400078
+	jne	exit
+
+	mov	edi, 6
+	cmp	qword [program_code_section_header.offset], 0x78
+	jne	exit
+
+	mov	edi, 7
+	cmp	qword [program_code_section_header.size], 0x38
+	jne	exit
+
+	mov	edi, 8
+	cmp	qword [shstrtab_section_header.offset], 0xb0
+	jne	exit
+
+	mov	edi, 9
+	cmp	qword [shstrtab_section_header.size], 0x10
+	jne	exit
+
+	;
+	; exit cleanly
+	;
+	xor 	edi, edi
+
+exit:
+	mov 	eax, SYS_EXIT
+	syscall

elf_test_hello_world.asm

@@ -0,0 +1,58 @@
+format elf64 executable 3
+
+include "linux.inc"
+include "elf.inc"
+
+segment readable writeable
+
+program_code:
+	.entry_offset = $ - program_code
+	db	0x48, 0xc7, 0xc0	; mov rax, 1 - sys_write
+	dd	0x01
+	db	0x48, 0xc7, 0xc7	; mov rdi, 1 - stdout fd
+	dd	0x01
+	db	0x48, 0xc7, 0xc6	; mov rsi, 0x4000a2 - location of string
+	dd	0x4000a2
+	db	0x48, 0xc7, 0xc2	; mov rdx, 13 - size of string
+	dd	0x0d
+	db	0x0f, 0x05		; syscall
+	db	0x48, 0xc7, 0xc0	; mov rax, 60 - sys_exit
+	dd	0x3c
+	db	0x48, 0x31, 0xff	; xor rdi, rdi
+	db	0x0f, 0x05		; syscall
+
+	db	"Hello, world"
+	db	0x0a, 0x00
+
+	.length = $ - program_code
+
+segment readable executable
+
+output_file:
+	db	"elf_test_hello_world.out"
+	db	0x00
+
+execve_args:
+	dq	output_file
+	dq	0x0
+
+entry $	
+	mov	rdi, output_file
+	mov	esi, 0x01 or 0x40 or 0x200
+	mov	edx, 0x1ed
+	mov	eax, SYS_OPEN
+	syscall
+
+	mov	rdi, rax
+	mov	eax, program_code.entry_offset
+	mov	ecx, program_code.length
+	call	elf_binary_write
+	
+	mov	eax, SYS_CLOSE
+	syscall
+
+    	mov 	rdi, output_file
+    	mov 	rsi, execve_args
+    	xor 	rdx, rdx
+	mov	eax, SYS_EXECVE
+    	syscall

linux.inc

@@ -0,0 +1,6 @@
+
+SYS_WRITE 	= 1
+SYS_OPEN 	= 2
+SYS_CLOSE 	= 3
+SYS_EXECVE 	= 59
+SYS_EXIT 	= 60

test.mk

@@ -0,0 +1,12 @@
+
+TESTS := \
+	elf_test \
+	elf_test_hello_world
+
+$(TESTS):
+	echo "Testing $@... " && make WHAT=$@ compile run && echo ""
+
+tests: $(TESTS)
+	@/bin/true
+
+.PHONY: tests $(TESTS)