From 20c7b5be3bbb5f56a31536c018e20706100f57ae Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Sat, 23 Jul 2022 19:28:43 +0200
Subject: user_bootstrap: pass the initrd in an argument to init's main

---
 src/user/app/main.c       |  9 +++++----
 src/user/lib/elfload.c    | 51 +++++++++++++++++++++++++++++++----------------
 src/user/lib/elfload.h    |  1 +
 src/user_bootstrap/main.c | 12 +++++++----
 4 files changed, 48 insertions(+), 25 deletions(-)

diff --git a/src/user/app/main.c b/src/user/app/main.c
index 28c4aa0..9f4d50c 100644
--- a/src/user/app/main.c
+++ b/src/user/app/main.c
@@ -9,16 +9,17 @@
 #include <user/lib/stdlib.h>
 #include <user/tests/main.h>
 
-// extern char _initrd;
+__attribute__((visibility("hidden")))
+extern char _image_base[];
 
 void read_file(const char *path, size_t len);
 
 __attribute__((section(".text.startup")))
-int main(void) {
+int main(void *initrd) {
 	elf_selfreloc();
 
 	file_reopen(stdout, "/com1", 0);
-	printf("preinit\n");
+	printf("in init, loaded at 0x%x\n", &_image_base);
 
 	/* move everything provided by the kernel to /kdev */
 	MOUNT("/kdev/", fs_passthru(NULL));
@@ -28,7 +29,7 @@ int main(void) {
 	}
 	if (!fork2_n_mount("/")) fs_dir_inject("/kdev/"); // TODO should be part of fs_whitelist
 
-	// MOUNT("/init/", tar_driver(&_initrd));
+	MOUNT("/init/", tar_driver(initrd));
 	MOUNT("/tmp/", tmpfs_drv());
 	MOUNT("/keyboard", ps2_drv());
 	MOUNT("/vga_tty", ansiterm_drv());
diff --git a/src/user/lib/elfload.c b/src/user/lib/elfload.c
index 6c75268..ef14388 100644
--- a/src/user/lib/elfload.c
+++ b/src/user/lib/elfload.c
@@ -62,41 +62,58 @@ static size_t elf_spread(const void *elf) {
 	return high - low;
 }
 
-/* frees memory outside of [low; high] and jumps to *entry */
-static void freejmp(void *entry, void *low, void *high) {
+/* frees memory outside of [low; low + len] and jumps to *entry */
+static void freejmp(void *entry, void *low, size_t len) {
+	uintptr_t high = (uintptr_t)low + len;
 	uint64_t buf[] = {
 		EXECBUF_SYSCALL, _SYSCALL_MEMFLAG, 0, (uintptr_t)low, 0, 0,
-		EXECBUF_SYSCALL, _SYSCALL_MEMFLAG, (uintptr_t)high, ~0 - 0xF000 - (uintptr_t)high, 0, 0,
+		EXECBUF_SYSCALL, _SYSCALL_MEMFLAG, high, ~0 - 0xF000 - high, 0, 0,
 		EXECBUF_JMP, (uintptr_t)entry,
 	};
 	_syscall_execbuf(buf, sizeof buf);
+	// should never return
 }
 
-void elf_exec(void *base) {
-	struct Elf64_Ehdr *ehdr = base;
+static void *elf_loadmem(struct Elf64_Ehdr *ehdr) {
 	void *exebase;
-	if (!valid_ehdr(ehdr)) return;
-	_syscall_debug_klog("here", 4);
-	size_t spread = elf_spread(base);
+	size_t spread = elf_spread(ehdr);
 	switch (ehdr->e_type) {
 		case ET_EXEC:
 			exebase = (void*)0;
 			break;
 		case ET_DYN:
 			exebase = _syscall_memflag((void*)0x1000, spread, MEMFLAG_FINDFREE);
-			if (!exebase) {
-				printf("elf: out of memory\n");
-				_syscall_exit(1);
-			}
+			if (!exebase)
+				return NULL;
 			break;
 		default:
-			return;
+			return NULL;
 	}
 	for (size_t phi = 0; phi < ehdr->e_phnum; phi++) {
-		if (!load_phdr(base, exebase, phi))
-			return;
+		if (!load_phdr((void*)ehdr, exebase, phi)) {
+			_syscall_memflag(exebase, spread, 0);
+			return NULL;
+		}
 	}
+	return exebase;
+}
+
+void elf_exec(void *base) {
+	struct Elf64_Ehdr *ehdr = base;
+	if (!valid_ehdr(ehdr)) return;
+
+	void *exebase = elf_loadmem(ehdr);
+	if (!exebase) return;
+
+	freejmp(exebase + ehdr->e_entry, exebase, elf_spread(ehdr) + 0x1000);
+}
+
+void *elf_partialexec(void *base) {
+	struct Elf64_Ehdr *ehdr = base;
+	if (!valid_ehdr(ehdr)) return NULL;
+
+	void *exebase = elf_loadmem(ehdr);
+	if (!exebase) return NULL;
 
-	freejmp(exebase + ehdr->e_entry, exebase, exebase + spread + 0x1000);
-	printf("elf: execbuf failed?");
+	return exebase + ehdr->e_entry;
 }
diff --git a/src/user/lib/elfload.h b/src/user/lib/elfload.h
index f79be6e..40c4874 100644
--- a/src/user/lib/elfload.h
+++ b/src/user/lib/elfload.h
@@ -3,5 +3,6 @@
 
 void elf_execf(libc_file *f);
 void elf_exec(void *elf);
+void *elf_partialexec(void *elf); /* returns pointer to entry point */
 
 void elf_selfreloc(void); // elfreloc.c
diff --git a/src/user_bootstrap/main.c b/src/user_bootstrap/main.c
index 71647c4..52d7058 100644
--- a/src/user_bootstrap/main.c
+++ b/src/user_bootstrap/main.c
@@ -10,7 +10,7 @@ extern char _initrd;
 /* libc stubs */
 int printf(const char *fmt, ...) {(void)fmt; return 0;}
 void *malloc(size_t size) {(void)size; _syscall_exit(1);}
-void free(void *ptr) {}
+void free(void *ptr) {(void)ptr;}
 int file_read(libc_file *f, char *buf, size_t len) {(void)f; (void)buf; (void)len; _syscall_exit(1);}
 
 
@@ -52,8 +52,12 @@ int main(void) {
 	_syscall_memflag(&_bss_start, &_bss_end - &_bss_start, MEMFLAG_PRESENT);
 
 	void *init = tar_find(&_initrd, "init.elf");
-	elf_exec(init);
-	_syscall_debug_klog("bootstrap failed", sizeof("bootstrap failed"));
-
+	void (*entry)(void*) = elf_partialexec(init);
+	if (entry) {
+		// TODO dynamically link initrd
+		entry(&_initrd);
+	} else {
+		_syscall_debug_klog("bootstrap failed", sizeof("bootstrap failed"));
+	}
 	_syscall_exit(0);
 }
-- 
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