Some work on the elf loader

1 files changed, 68 insertions, 0 deletions

diff --git a/src/kernel/fs/elf.c b/src/kernel/fs/elf.c
new file mode 100644
index 0000000..2f1b463
--- /dev/null
+++ b/src/kernel/fs/elf.c
@@ -0,0 +1,68 @@
+#include <kernel/system.h>
+#include <kernel/fs/elf.h>
+#include <kernel/lib/stdio.h>
+#include <kernel/memory/alloc.h>
+#include <kernel/lib/lib.h>
+#include <kernel/memory/paging.h>
+
+#define USER_OFFSET 0x40000000
+#define USER_STACK 0xF0000000
+#define PT_LOAD 0x1
+
+int is_elf(char *elf_data)
+{
+	elf_header_t *header = (elf_header_t *)elf_data;
+	if (header->ident[0] == 0x7f && header->ident[1] == 'E' && header->ident[2] == 'L' &&
+	    header->ident[3] == 'F') {
+		serial_printf("Buffer is valid ELF file!");
+		return 1;
+	}
+	return 0;
+}
+
+uint32_t load_elf(char *elf_data)
+{
+	uint32_t v_begin, v_end;
+	elf_header_t *hdr;
+	elf_program_header_t *p_entry;
+	elf_section_header_t *s_entry;
+
+	hdr = (elf_header_t *)elf_data;
+	p_entry = (elf_program_header_t *)(elf_data + hdr->phoff);
+
+	s_entry = (elf_section_header_t *)(elf_data + hdr->shoff);
+
+	if (is_elf(elf_data) == 0)
+		return 0;
+
+	for (int pe = 0; pe < hdr->phnum; pe++, p_entry++) {
+		if (p_entry->type == PT_LOAD) {
+			v_begin = p_entry->vaddr;
+			v_end = p_entry->vaddr + p_entry->memsz;
+			if (v_begin < USER_OFFSET) {
+				printf("INFO: load_elf(): can't load executable below %x\n",
+				       USER_OFFSET);
+				return 0;
+			}
+
+			if (v_end > USER_STACK) {
+				printf("INFO: load_elf(): can't load executable above %x\n",
+				       USER_STACK);
+				return 0;
+			}
+
+			printf("ELF: entry flags: %x (%d)\n", p_entry->flags, p_entry->flags);
+
+			memcpy((uint8_t *)v_begin, (uint8_t *)(elf_data + p_entry->offset),
+			       p_entry->filesz);
+			if (p_entry->memsz > p_entry->filesz) {
+				char *p = (char *)p_entry->vaddr;
+				for (int i = p_entry->filesz; i < (int)(p_entry->memsz); i++) {
+					p[i] = 0;
+				}
+			}
+		}
+	}
+
+	return hdr->entry;
+}