From 4e7dc15d06a158d8d0b0fd32b4536626b3090de0 Mon Sep 17 00:00:00 2001
From: Stefan Bucur <stefan@stefan-mac.(none)>
Date: Sun, 5 Jul 2009 23:46:23 +0300
Subject: elf: Replaced symbol offsets with module base address.

---
 com32/elflink/test_com32.c            |  4 +---
 com32/include/sys/exec.h              |  2 +-
 com32/include/sys/module.h            |  2 +-
 com32/lib/sys/module/exec.c           |  7 +++++--
 com32/lib/sys/module/shallow_module.c | 26 ++------------------------
 5 files changed, 10 insertions(+), 31 deletions(-)

diff --git a/com32/elflink/test_com32.c b/com32/elflink/test_com32.c
index 20c19cf7..115bba87 100644
--- a/com32/elflink/test_com32.c
+++ b/com32/elflink/test_com32.c
@@ -8,8 +8,6 @@
 
 #define INFO_PRINT(fmt, args...)	printf("[COM32] " fmt, ##args)
 
-#define COM32_OFFSET		0x110000
-
 #define MAX_COMMAND_SIZE 	80					 // Maximum size of the cmd line
 #define COMMAND_DELIM		" \t\n"				 // Whitespace delimiters
 #define MAX_COMMAND_ARGS	(MAX_COMMAND_SIZE/2) // Maximum argument count for
@@ -181,7 +179,7 @@ int main(int argc, char **argv) {
 	// Open a standard r/w console
 	openconsole(&dev_stdcon_r, &dev_stdcon_w);
 
-	res = exec_init(COM32_OFFSET);
+	res = exec_init();
 	if (res != 0) {
 		printf("Failed to initialize the execution environment.\n");
 		return res;
diff --git a/com32/include/sys/exec.h b/com32/include/sys/exec.h
index d76ae74c..24379d96 100644
--- a/com32/include/sys/exec.h
+++ b/com32/include/sys/exec.h
@@ -42,7 +42,7 @@
  *  loaded by the lower module layer gets to be executed by the CPU,
  *  thus becoming part of the SYSLINUX environment.
  */
-extern int exec_init(size_t root_addr);
+extern int exec_init();
 
 
 /**
diff --git a/com32/include/sys/module.h b/com32/include/sys/module.h
index 97f7ce09..4de57105 100644
--- a/com32/include/sys/module.h
+++ b/com32/include/sys/module.h
@@ -229,7 +229,7 @@ extern int module_load(struct elf_module *module);
  * Its current use is to describe the root COM32 module to the rest of the
  * module subsystem.
  */
-extern int module_load_shallow(struct elf_module *module, Elf32_Off offset);
+extern int module_load_shallow(struct elf_module *module, Elf32_Addr base_addr);
 
 /**
  * module_unload - unloads the module from the system.
diff --git a/com32/lib/sys/module/exec.c b/com32/lib/sys/module/exec.c
index 9da1d572..cbd81d42 100644
--- a/com32/lib/sys/module/exec.c
+++ b/com32/lib/sys/module/exec.c
@@ -11,6 +11,9 @@
 #include <string.h>
 #include <stdarg.h>
 
+// The symbol declared in the linker script that indicates the loading point
+// of the COM32R module
+extern char _start[];
 
 
 #define DBG_PRINT(fmt, args...)	fprintf(stderr, "[EXEC] " fmt, ##args)
@@ -30,7 +33,7 @@ static char *module_get_fullname(const char *name) {
 	return name_buff;
 }
 
-int exec_init(size_t root_addr) {
+int exec_init() {
 	int res;
 
 	res = modules_init();
@@ -44,7 +47,7 @@ int exec_init(size_t root_addr) {
 	if (mod_root == NULL)
 		return -1;
 
-	res = module_load_shallow(mod_root, root_addr);
+	res = module_load_shallow(mod_root, (Elf32_Addr)_start);
 
 	if (res != 0) {
 		mod_root = NULL;
diff --git a/com32/lib/sys/module/shallow_module.c b/com32/lib/sys/module/shallow_module.c
index f43582c4..fdcb20f8 100644
--- a/com32/lib/sys/module/shallow_module.c
+++ b/com32/lib/sys/module/shallow_module.c
@@ -115,29 +115,8 @@ out:
 	return res;
 }
 
-static int offset_symbols(struct elf_module *module, Elf32_Off offset) {
-	unsigned int i;
-	Elf32_Sym *crt_sym = NULL;
-
-	for (i = 1; i < module->symtable_size; i++) {
-		crt_sym = (Elf32_Sym*)(module->sym_table + i*module->syment_size);
-
-		// Skip the undefined or absolute symbols
-		if (crt_sym->st_shndx == SHN_UNDEF || crt_sym->st_shndx == SHN_ABS)
-			continue;
-		// Also skip the non-local symbols
-		if (ELF32_ST_BIND(crt_sym->st_info) != STB_GLOBAL &&
-				ELF32_ST_BIND(crt_sym->st_info) != STB_WEAK)
-			continue;
-
-		crt_sym->st_value += offset;
-	}
-
-	return 0;
-}
-
 
-int module_load_shallow(struct elf_module *module, Elf32_Off offset) {
+int module_load_shallow(struct elf_module *module, Elf32_Addr base_addr) {
 	int res;
 	Elf32_Ehdr elf_hdr;
 
@@ -160,12 +139,11 @@ int module_load_shallow(struct elf_module *module, Elf32_Off offset) {
 	CHECKED(res, check_header_shallow(&elf_hdr), error);
 
 	CHECKED(res, load_shallow_sections(module, &elf_hdr), error);
+	module->base_addr = base_addr;
 
 	// Check the symbols for duplicates / missing definitions
 	CHECKED(res, check_symbols(module), error);
 
-	CHECKED(res, offset_symbols(module, offset), error);
-
 	// Add the module at the beginning of the module list
 	list_add(&module->list, &modules_head);
 
-- 
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