elf sym loading

3 files changed, 82 insertions, 4 deletions

diff --git a/kernel/mboot/elf.c b/kernel/mboot/elf.c
new file mode 100644
index 0000000..88b61a7
--- /dev/null
+++ b/kernel/mboot/elf.c
@@ -0,0 +1,77 @@
+#include "lib/kio.h"
+#include <lib.h>
+#include <elf.h>
+#include <comus/mboot.h>
+
+#include "mboot.h"
+
+#define MULTIBOOT_TAG_TYPE_ELF_SECTIONS 9
+
+struct multiboot_tag_elf_sections {
+	uint32_t type;
+	uint32_t size;
+	uint32_t num;
+	uint32_t entsize;
+	uint32_t shndx;
+	Elf64_Shdr sections[];
+};
+
+static struct multiboot_tag_elf_sections *elf = NULL;
+static Elf64_Shdr *symtab = NULL;
+static Elf64_Shdr *symstrtab = NULL;
+
+static Elf64_Shdr *mboot_get_elf_sec(uint32_t sh_type)
+{
+	for (uint32_t i = 0; i < elf->num; i++) {
+		Elf64_Shdr *ent = &elf->sections[i];
+		if (ent->sh_type == sh_type)
+			return ent;
+	}
+
+	return NULL;
+}
+
+static int mboot_load_elf(void)
+{
+	void *tag = locate_mboot_table(MULTIBOOT_TAG_TYPE_ELF_SECTIONS);
+	if (tag == NULL)
+		return 1;
+
+	// found elf sections
+	elf = (struct multiboot_tag_elf_sections *)tag;
+
+	// load symtab
+	if ((symtab = mboot_get_elf_sec(SHT_SYMTAB)) == NULL)
+		return 1;
+
+	// load strsymtab
+	if ((symstrtab = mboot_get_elf_sec(symtab->sh_link)) == NULL)
+		return 1;
+
+	return 0;
+}
+
+const char *mboot_get_elf_sym(uint64_t addr)
+{
+	if (symstrtab == NULL)
+		if (mboot_load_elf())
+			return NULL;
+
+	// walk symbol table
+	Elf64_Sym *syms = (Elf64_Sym *)symtab->sh_addr;
+	Elf64_Sym *best = NULL;
+	for (uint32_t i = 0; i < symtab->sh_size / symtab->sh_entsize; i++) {
+		Elf64_Sym *sym = &syms[i];
+		if (sym->st_value < addr)
+			continue;
+		if (best == NULL || (best->st_value < sym->st_value))
+			best = sym;
+	}
+
+	if (best != NULL) {
+		char *buf = (char *)symstrtab->sh_addr;
+		return &buf[best->st_name];
+	}
+
+	return "???";
+}
diff --git a/kernel/mboot/mboot.c b/kernel/mboot/mboot.c
index e10f33c..949337d 100644
--- a/kernel/mboot/mboot.c
+++ b/kernel/mboot/mboot.c
@@ -3,7 +3,7 @@
 
 #include "mboot.h"
 
-static volatile void *mboot;
+static volatile void *mboot = NULL;
 
 void mboot_init(long magic, volatile void *ptr)
 {
@@ -14,9 +14,12 @@ void mboot_init(long magic, volatile void *ptr)
 
 void *locate_mboot_table(uint32_t type)
 {
+	if (mboot == NULL)
+		return NULL;
+
 	struct multiboot *info = (struct multiboot *)mboot;
-	const char *mboot_end = ((char *)info) + info->total_size;
 
+	const char *mboot_end = ((char *)info) + info->total_size;
 	char *tag_ptr = info->tags;
 
 	while (tag_ptr < mboot_end) {
diff --git a/kernel/mboot/mmap.c b/kernel/mboot/mmap.c
index 8959c49..e0963ca 100644
--- a/kernel/mboot/mmap.c
+++ b/kernel/mboot/mmap.c
@@ -30,11 +30,9 @@ int mboot_get_mmap(struct memory_map *res)
 
 	int idx = 0;
 	uintptr_t i = (uintptr_t)mmap->entries;
-	char buf[20];
 	for (; i < (uintptr_t)mmap->entries + mmap->size;
 		 i += mmap->entry_size, idx++) {
 		struct multiboot_mmap_entry *seg = (struct multiboot_mmap_entry *)i;
-		const char *type = NULL;
 		res->entries[idx].addr = seg->addr;
 		res->entries[idx].len = seg->len;
 		res->entries[idx].type = seg->type;