setos

commit bad712b2a7aa5f6bfdff6470b0d06d767385d1dd
parent 01fa94c59bee5c39464a2dc4df6acd26c7a3d45a
Author: Matsuda Kenji <info@mtkn.jp>
Date:   Fri, 29 Mar 2024 09:46:14 +0900

add load_elf

Diffstat:
M
loader.c
 | 
21
+++++++++++++++++----
M
uefi.h
 | 
4
+++-
M
utils.c
 | 
63
++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
M
utils.h
 | 
18
+++++++++++++++---

4 files changed, 91 insertions(+), 15 deletions(-)
diff --git a/loader.c b/loader.c
@@ -57,7 +57,7 @@ EfiMain(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *systab)
 	}
 	EFI_PHYSICAL_ADDRESS kernel_base = 0x100000;
 	UINTN fib_size = sizeof(EFI_FILE_INFO) + sizeof(CHAR16) * 11;
-	char fibuf[fib_size];
+	char fibuf[sizeof(EFI_FILE_INFO) + sizeof(CHAR16) * 11]; // determined at compile time?
 	EFI_FILE_INFO *fileInfo = (EFI_FILE_INFO *) fibuf;
 	stat = kernel->GetInfo(kernel, &EFI_FILE_INFO_ID, &fib_size, (VOID *)fibuf);
 	if (stat != EFI_SUCCESS) {
@@ -66,9 +66,22 @@ EfiMain(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *systab)
 	}
 	UINT64 kernel_size = fileInfo->FileSize;
 	ElfHdr kernel_ehdr;
-	Phdr   kernel_phdr;
-	read_elf_hdr(kernel, &kernel_ehdr, &kernel_phdr);
-	stat = kernel->SetPosition(kernel, kernel_ehdr.entry);
+	read_ehdr(kernel, &kernel_ehdr);
+	efi_printf("type:\t%x\nphoff:\t%x\nphentsize:\t%x\nphnum:\t%x\n",
+		kernel_ehdr.type, kernel_ehdr.phoff,
+		kernel_ehdr.phentsize, kernel_ehdr.phnum);
+	if (kernel_ehdr.phnum > 32) {
+		efi_printf("too many phdrs\n");
+		return EFI_BUFFER_TOO_SMALL;
+	}
+	Phdr kernel_phdr[32];
+	read_phdr(kernel, &kernel_ehdr, kernel_phdr);
+	for (UINT16 i = 0; i < kernel_ehdr.phnum; i++) {
+		efi_printf("type: %x, offset: %x, vaddr: %x\n",
+			kernel_phdr[i].type, kernel_phdr[i].offset, kernel_phdr[i].vaddr);
+	}
+
+	stat = kernel->SetPosition(kernel, 0x1000);
 	if (stat != EFI_SUCCESS) {
 		efi_printf("set position of \"kernel.elf\": %d\n", stat);
 		return stat;
diff --git a/uefi.h b/uefi.h
@@ -36,7 +36,9 @@ typedef struct EFI_GUID {
 // EFI_STATUS
 enum {
 	EFI_SUCCESS = 0,
-	EFI_INVALID_PARAMETER = 2,
+
+	EFI_INVALID_PARAMETER = 0x8000000000000002,
+	EFI_BUFFER_TOO_SMALL =  0x8000000000000005,
 };
 
 typedef struct _EFI_SYSTEM_TABLE EFI_SYSTEM_TABLE;
diff --git a/utils.c b/utils.c
@@ -125,27 +125,76 @@ efi_printf(char *fmt, ...)
 }
 
 EFI_STATUS
-read_elf_hdr(EFI_FILE_PROTOCOL *elf, ElfHdr *ehdr, Phdr *phdr)
+read_ehdr(EFI_FILE_PROTOCOL *elf, ElfHdr *ehdr)
 {
 	EFI_STATUS stat;
-	UINTN buf_size = 1024;
-	char buf[buf_size];
+	UINTN ehdr_size = sizeof(ElfHdr);
 
 	stat = elf->SetPosition(elf, 0);
 	if (stat != EFI_SUCCESS) {
 		efi_printf("set position: %d\n", stat);
 		return stat;
 	}
-	stat = elf->Read(elf, &buf_size, (VOID *) buf);
+	stat = elf->Read(elf, &ehdr_size, (VOID *) ehdr);
 	if (stat != EFI_SUCCESS) {
 		efi_printf("read: %d\n", stat);
 		return stat;
 	}
-	if (buf[0] != 0x7f || buf[1] != 'E' || buf[2] != 'L' || buf[3] != 'F') {
+	// TODO: check file format.
+	// 	for now, it assumes that elf is 2's complement, 64-bit little endian,
+	// 	System V ABI...
+	if (ehdr->ident[0] != 0x7f || ehdr->ident[1] != 'E' ||
+		ehdr->ident[2] != 'L' || ehdr->ident[3] != 'F') {
 		efi_printf("not an elf file\n");
 		return EFI_INVALID_PARAMETER;
 	}
-	efi_printf("it is an elf file\n");
-	ehdr->entry = 0x1000;
+
+	return EFI_SUCCESS;
+}
+
+EFI_STATUS
+read_phdr(EFI_FILE_PROTOCOL *elf, ElfHdr *ehdr, Phdr phdr[])
+{
+	EFI_STATUS stat;
+	UINTN      n;
+
+	stat = elf->SetPosition(elf, ehdr->phoff);
+	if (stat != EFI_SUCCESS) {
+		efi_printf("set position: %d\n", stat);
+		return stat;
+	}
+	// TODO: need overflow check??
+	n = ehdr->phentsize * ehdr->phnum;
+	stat = elf->Read(elf, &n, (VOID *) phdr);
+	if (stat != EFI_SUCCESS) {
+		efi_printf("read phdr: %d\n", stat);
+		return stat;
+	}
+	return EFI_SUCCESS;
+}
+
+EFI_STATUS
+load_elf(EFI_FILE_PROTOCOL *elf, ElfHdr *ehdr, Phdr phdr[])
+{
+	EFI_STATUS stat;
+	EFI_PHYSICAL_ADDRESS addr;
+	UINT64 size;
+	for (UINT16 i = 0; i < ehdr->phnum; i++) {
+		if (phdr[i].type != PT_LOAD) {
+			continue;
+		}
+		stat = elf->SetPosition(elf, phdr[i].offset);
+		if (stat != EFI_SUCCESS) {
+			efi_printf("set position: %d\n", stat);
+			return stat;
+		}
+		addr = (EFI_PHYSICAL_ADDRESS) phdr[i].vaddr;
+		size = phdr[i].filesz;
+		stat = elf->Read(elf, &size, (VOID *)addr);
+		if (stat != EFI_SUCCESS) {
+			efi_printf("read to memory: %d\n", stat);
+			return stat;
+		}
+	}
 	return EFI_SUCCESS;
 }
 \ No newline at end of file
diff --git a/utils.h b/utils.h
@@ -47,6 +47,18 @@ typedef struct {
 	UINT64 align;
 } Phdr;
 
-// Read_elf_hdr reads elf header and populates hdr struct.
+#define PT_LOAD 1
+
+// Read_ehdr reads elf header and populates ehdr.
+// It modifies elf's offset.
+EFI_STATUS read_ehdr(EFI_FILE_PROTOCOL *elf, ElfHdr *ehdr);
+
+// Read_phdr reads elf's program headers and populates phdr.
+// It uses ehdr to read phdr.
 // It modifies elf's offset.
-EFI_STATUS read_elf_hdr(EFI_FILE_PROTOCOL *elf, ElfHdr *ehdr, Phdr *phdr);
-\ No newline at end of file
+// Caller should allocate enough space in phdr.
+EFI_STATUS read_phdr(EFI_FILE_PROTOCOL *elf, ElfHdr *ehdr, Phdr phdr[]);
+
+// Load_elf copies loadable segments of elf to the memory specified by the
+// vaddr field of each Phdr.
+EFI_STATUS load_elf(EFI_FILE_PROTOCOL *elf, ElfHdr *ehdr, Phdr phdr[]);
+\ No newline at end of file