kjarna runtime

1 files changed, 81 insertions, 0 deletions

diff --git a/kjarna_runtime/dynamic_x86_64.c b/kjarna_runtime/dynamic_x86_64.c
new file mode 100644
index 0000000..e49f13d
--- /dev/null
+++ b/kjarna_runtime/dynamic_x86_64.c
@@ -0,0 +1,81 @@
+#include <kc.h>
+
+#include <libc/string.h>
+#include <lib/elf.h>
+
+extern void _rtld_link(void);
+
+struct elf64_relatab
+{
+	Elf64_Rela *entries;
+	size_t size;
+	size_t entsize;
+};
+
+struct elf64_symtab
+{
+	Elf64_Sym *entries;
+	const char *strings;
+	size_t strsize;
+};
+
+struct elf64_dso_info
+{
+	char *base;
+	struct elf64_relatab jmprel;
+	struct elf64_relatab reladyn;
+	struct elf64_symtab dynsym;
+	Elf64_Addr *pltgot;
+};
+
+static struct elf64_dso_info dso_info;
+
+void kc_dynamic_init(char *base, Elf64_Dyn *dyn)
+{
+	dso_info = (struct elf64_dso_info)
+	{
+		base,
+		{
+			elf64_dt_ptr(base, dyn, DT_JMPREL),
+			elf64_dt_val(dyn, DT_PLTRELSZ),
+			elf64_dt_val(dyn, DT_PLTREL) == DT_RELA ? sizeof(Elf64_Rela) : -1 
+		},
+		{
+			elf64_dt_ptr(base, dyn, DT_RELA),
+			elf64_dt_val(dyn, DT_RELASZ),
+			elf64_dt_val(dyn, DT_RELAENT)
+		},
+		{
+			elf64_dt_ptr(base, dyn, DT_SYMTAB),
+			elf64_dt_ptr(base, dyn, DT_STRTAB),
+			elf64_dt_val(dyn, DT_STRSZ)
+		},
+		elf64_dt_ptr(base, dyn, DT_PLTGOT)
+	};
+
+	if (dso_info.pltgot != nullptr)
+	{
+		dso_info.pltgot[1] = (uintptr_t)&dso_info;
+		dso_info.pltgot[2] = (uintptr_t)_rtld_link;
+	}
+
+	kc_reloc(dso_info.base, dso_info.reladyn.entries, dso_info.reladyn.size, dso_info.reladyn.entsize);
+	kc_reloc(dso_info.base, dso_info.jmprel.entries, dso_info.jmprel.size, dso_info.jmprel.entsize);
+}
+
+void *kc_dynamic_link(struct elf64_dso_info *dso, int index)
+{
+	int symindex = ELF64_R_SYM(dso->jmprel.entries[index].r_info);
+	int strindex = dso->dynsym.entries[symindex].st_name;
+	const char *name = &dso->dynsym.strings[strindex];
+	uintptr_t *fixup = (uintptr_t *)dso->base + dso->jmprel.entries[index].r_offset;
+
+	if (strcmp(name, "write") == 0)
+	{
+		*fixup = (uintptr_t)*entry_params->interface->write;
+		return fixup;
+	}
+
+	return nullptr;
+}
+