From f092bf03baf3b2c13c9dc462bdc697caddccd347 Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Wed, 29 Jul 2020 15:55:13 +0200
Subject: Added elf loading and test app

---
 src/features/elf.c | 39 ++++++++++++++++++++++++++++++++++
 src/features/gui.c |  2 +-
 src/inc/elf.h      | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/main.c         |  3 +++
 src/test.c         |  5 +++++
 5 files changed, 109 insertions(+), 1 deletion(-)
 create mode 100644 src/features/elf.c
 create mode 100644 src/inc/elf.h
 create mode 100644 src/test.c

(limited to 'src')

diff --git a/src/features/elf.c b/src/features/elf.c
new file mode 100644
index 0000000..339add0
--- /dev/null
+++ b/src/features/elf.c
@@ -0,0 +1,39 @@
+#include <assert.h>
+#include <def.h>
+#include <elf.h>
+#include <fs.h>
+#include <mem.h>
+
+int elf_verify(struct elf_header *header)
+{
+	if (header->ident[0] == ELF_MAG && header->ident[1] == 'E' && header->ident[2] == 'L' &&
+	    header->ident[3] == 'F' && header->ident[4] == ELF_32 &&
+	    header->ident[5] == ELF_LITTLE && header->ident[6] == ELF_CURRENT &&
+	    header->machine == ELF_386 && (header->type == ET_REL || header->type == ET_EXEC)) {
+		return 1;
+	}
+	return 0;
+}
+
+void elf_load(char *path)
+{
+	u32 *data = read_file(path);
+
+	struct elf_header *h = (struct elf_header *)data;
+	assert(elf_verify(h));
+
+	struct elf_program_header *p = (struct elf_program_header *)((u32)data + h->phoff);
+	struct elf_program_header *p_end =
+		(struct elf_program_header *)((u32)p + (h->phentsize * h->phnum));
+
+	u32 offset = (p->vaddr - p->paddr);
+	while (p < p_end) {
+		memcpy((void *)p->paddr, (void *)((u32)data + p->offset), p->filesz);
+		p++;
+	}
+
+	void (*entry)();
+	entry = (void (*)())(h->entry - offset);
+
+	entry();
+}
diff --git a/src/features/gui.c b/src/features/gui.c
index fa0641c..d080cb1 100644
--- a/src/features/gui.c
+++ b/src/features/gui.c
@@ -37,7 +37,7 @@ void gui_write(int x, int y, const u32 c[3], char *text)
 }
 
 // Abstraction
-int x, y = 1;
+int x, y = 0;
 const u32 c[3] = { 0xff, 0xff, 0xff };
 void gui_term_write_char(char ch)
 {
diff --git a/src/inc/elf.h b/src/inc/elf.h
new file mode 100644
index 0000000..c10ba4e
--- /dev/null
+++ b/src/inc/elf.h
@@ -0,0 +1,61 @@
+// MIT License, Copyright (c) 2020 Marvin Borner
+
+#ifndef ELF_H
+#define ELF_H
+
+#include <def.h>
+
+#define ELF_MAG 0x7F // 0
+#define ELF_32 1 // 4: 32-bit Architecture
+#define ELF_LITTLE 1 // 5: Little Endian
+#define ELF_CURRENT 1 // 6: ELF Current Version
+#define ELF_386 3 // header->machine x86 machine type
+
+#define ET_NONE 0 // Unkown type
+#define ET_REL 1 // Relocatable file
+#define ET_EXEC 2 // Executable file
+
+struct elf_header {
+	u8 ident[16];
+	u16 type;
+	u16 machine;
+	u32 version;
+	u32 entry;
+	u32 phoff;
+	u32 shoff;
+	u32 flags;
+	u16 ehsize;
+	u16 phentsize;
+	u16 phnum;
+	u16 shentsize;
+	u16 shnum;
+	u16 shstrndx;
+};
+
+struct elf_section_header {
+	u32 name;
+	u32 type;
+	u32 flags;
+	u32 addr;
+	u32 offset;
+	u32 size;
+	u32 link;
+	u32 info;
+	u32 addralign;
+	u32 entsize;
+};
+
+struct elf_program_header {
+	u32 type;
+	u32 offset;
+	u32 vaddr;
+	u32 paddr;
+	u32 filesz;
+	u32 memsz;
+	u32 flags;
+	u32 align;
+};
+
+void elf_load(char *path);
+
+#endif
diff --git a/src/main.c b/src/main.c
index 92ec61c..665a11f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -3,6 +3,7 @@
 #include "config.h"
 #include <boot.h>
 #include <def.h>
+#include <elf.h>
 #include <fs.h>
 #include <gui.h>
 #include <interrupts.h>
@@ -41,6 +42,8 @@ void main(struct mem_info *mem_info, struct vid_info *vid_info)
 	gui_init(FONT_PATH);
 
 	gui_term_write("Wake up, " USERNAME "...\n");
+	elf_load("/test.o");
+	printf("loaded");
 
 	while (1) {
 	};
diff --git a/src/test.c b/src/test.c
new file mode 100644
index 0000000..c0f214b
--- /dev/null
+++ b/src/test.c
@@ -0,0 +1,5 @@
+void main()
+{
+	while (1) {
+	}
+}
-- 
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