kjarna runtime

7 files changed, 384 insertions, 0 deletions

diff --git a/kjarna_runtime/Makefile b/kjarna_runtime/Makefile
new file mode 100644
index 0000000..568beba
--- /dev/null
+++ b/kjarna_runtime/Makefile
@@ -0,0 +1,36 @@
+include ../defaults.mk
+
+LDFLAGS += -z max-page-size=4096 --export-dynamic -pic \
+	   -z separate-code -pie -Bsymbolic -shared \
+	   -z noexecstack -g
+
+VPATH := ../lib
+
+TARGET := kjarna.os
+.DEFAULT: $(TARGET)
+
+CPPFLAGS += -I../api -I. 
+
+CFLAGS += -fPIC -fvisibility=hidden -mgeneral-regs-only
+
+LDSCRIPT := kc.ld
+
+CRT_OBJS := start_x86_64.o reloc_x86_64.o dynamic_x86_64.o elf64.o
+LIB_OBJS := memcmp.o memcpy.o memmove.o memset.o string.o
+APP_OBJS := kc_main.o
+
+OBJS := $(CRT_OBJS) $(LIB_OBJS) $(APP_OBJS) 
+
+DEPS := $(patsubst %.o,%.d,$(OBJS))
+
+$(TARGET): $(LDSCRIPT) $(MAKEFILE_LIST)
+$(TARGET): $(OBJS)
+
+CLEANLIST := $(wildcard $(OBJS) $(TARGET)) 
+DCLEANLIST := $(wildcard $(DEPS))
+
+include ../rules.mk
+-include $(DEPS)
+
+.DEFAULT: $(TARGET)
+
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;
+}
+
diff --git a/kjarna_runtime/kc.h b/kjarna_runtime/kc.h
new file mode 100644
index 0000000..842d7be
--- /dev/null
+++ b/kjarna_runtime/kc.h
@@ -0,0 +1,45 @@
+#pragma once
+
+#ifndef __ASSEMBLER__
+
+#include <elf/elf64.h>
+
+#include <stddef.h>
+
+#include <kjarna/interface.h>
+
+extern struct kjarna_entry_params *entry_params;
+
+#define KC_EXPORT __attribute__((visibility("default")))
+
+extern unsigned char kc_image_base;
+extern unsigned char kc_text_begin;
+extern unsigned char kc_text_end;
+extern unsigned char kc_rodata_begin;
+extern unsigned char kc_data_begin;
+extern unsigned char kc_data_end;
+extern unsigned char kc_image_end;
+
+struct elf64_dso_info;
+
+extern void kc_dynamic_init(char *base, Elf64_Dyn *dyn);
+extern void *kc_dynamic_link(struct elf64_dso_info *dso, int index);
+extern void kc_reloc(void *base, Elf64_Rela *entries, size_t size, size_t entsize);
+
+#else
+
+.extern kc_image_base
+.extern kc_text_begin
+.extern kc_text_end
+.extern kc_rodata_begin
+.extern kc_rodata_end
+.extern kc_data_begin
+.extern kc_data_end
+.extern kc_image_end
+.extern _DYNAMIC
+
+.extern kc_dynamic_init
+.extern kc_dynamic_link
+
+#endif // __ASSEMBLER__
+
diff --git a/kjarna_runtime/kc.ld b/kjarna_runtime/kc.ld
new file mode 100644
index 0000000..f7b0339
--- /dev/null
+++ b/kjarna_runtime/kc.ld
@@ -0,0 +1,97 @@
+ENTRY(_start)
+
+SECTIONS
+{
+    PROVIDE_HIDDEN(kc_image_base = .);
+
+    . = SIZEOF_HEADERS;
+
+    .rela.plt :
+    {
+        *(.rela.plt)
+    }
+
+    .rela.dyn :
+    {
+        *(.rela.dyn)
+    }
+
+    .hash :
+    {
+        *(.hash)
+    }
+    
+    .dynsym :
+    {
+        *(.dynsym)
+    }
+
+    .dynstr :
+    {
+        *(.dynstr)
+    }
+
+    .rodata :
+    {
+        *(.rodata)
+        *(.rodata.*)
+    }
+
+    .text : ALIGN(4K)
+    {
+        PROVIDE_HIDDEN(kc_text_begin = .);
+        *(.text.start)
+        *(.text)
+    }
+
+    .plt :
+    {
+        *(.plt)
+        . = ALIGN(4K);
+        PROVIDE_HIDDEN(kc_text_end = .);
+    } =0xcc
+    
+    .dynamic : ALIGN(4K)
+    {
+        PROVIDE_HIDDEN(kc_data_begin = .);
+        *(.dynamic)
+    }
+
+    .got :
+    {
+        *(.got)
+    }
+
+    .got.plt :
+    {
+        *(.got.plt)
+    }
+
+    .data :
+    {
+        *(.data)
+    }
+
+    .data.rel :
+    {
+        *(.data.rel)
+        *(.data.rel.*)
+    }
+
+    .bss :
+    {
+        *(.bss)
+        *(.dynbss)
+        . = ALIGN(4K);
+        PROVIDE_HIDDEN(kc_data_end = .);
+    }
+
+    PROVIDE_HIDDEN(kc_image_end = .);
+
+    /DISCARD/ :
+    {
+        *(.eh_frame)
+        *(.comment)
+    }
+}
+
diff --git a/kjarna_runtime/kc_main.c b/kjarna_runtime/kc_main.c
new file mode 100644
index 0000000..acfcdc1
--- /dev/null
+++ b/kjarna_runtime/kc_main.c
@@ -0,0 +1,26 @@
+#include <kjarna/interface.h>
+
+extern int write(int, void *, size_t);
+
+int main(int argc, char **argv)
+{
+	(void)argc;
+	(void)argv;
+
+	write(1, "hello, runtime world!\r\n", -1);
+
+	while (1);
+
+	return 0;
+}
+
+struct kjarna_entry_params *entry_params;
+
+int kjarna_entry(struct kjarna_entry_params *params)
+{
+	entry_params = params;
+	entry_params->interface->write(1, "hello, entry world\r\n", -1);
+
+	return main(params->argc, params->argv);
+}
+
diff --git a/kjarna_runtime/reloc_x86_64.c b/kjarna_runtime/reloc_x86_64.c
new file mode 100644
index 0000000..63dc6e7
--- /dev/null
+++ b/kjarna_runtime/reloc_x86_64.c
@@ -0,0 +1,42 @@
+#include <kc.h>
+
+#define STARTCODE __attribute__((section(".text.start")))
+
+STARTCODE 
+static void do_rela(void *base, Elf64_Rela *rela)
+{
+    union
+    {
+        Elf_Byte word8;
+        Elf64_Half word16;
+        Elf64_Word word32;
+        Elf64_Xword word64;
+    }
+    *fixup;
+
+    switch (ELF64_R_TYPE(rela->r_info))
+    {
+        case R_X86_64_JUMP_SLOT:
+            fixup = (void *)(rela->r_offset + (uintptr_t)base);
+            fixup->word64 += (uintptr_t)base;
+            break;
+        case R_X86_64_RELATIVE:
+            fixup = (void *)(rela->r_offset + (uintptr_t)base);
+            fixup->word64 = (rela->r_addend + (uintptr_t)base);
+            break;
+        default:
+            break;
+    }
+}
+
+STARTCODE
+void kc_reloc(void *base, Elf64_Rela *entries, size_t size, size_t entsize)
+{
+    // perform the actual relocation
+
+    for (size_t i = 0; entries && (i < size / entsize); i++)
+    {
+        do_rela(base, &entries[i]);
+    }
+}
+
diff --git a/kjarna_runtime/start_x86_64.S b/kjarna_runtime/start_x86_64.S
new file mode 100644
index 0000000..f7725c6
--- /dev/null
+++ b/kjarna_runtime/start_x86_64.S
@@ -0,0 +1,57 @@
+#include <kc.h>
+
+.section .text.start
+
+.extern kjarna_entry
+
+.hidden _start
+.global _start
+.type _start, @function
+_start:
+    push %rbp
+    push %rdi
+    push %rsi
+    mov %rsp, %rbp
+    and $-0x10, %rsp
+    lea kc_image_base(%rip), %rdi
+    lea _DYNAMIC(%rip), %rsi
+    call kc_dynamic_init
+    mov %rbp, %rsp
+    pop %rsi
+    pop %rdi
+    mov %rsp, %rbp
+    and $-0x10, %rsp
+	call kjarna_entry
+    mov %rbp, %rsp
+    pop %rbp
+    ret
+.size _start, . - _start
+
+.section .text
+
+.hidden _rtld_link
+.global _rtld_link
+.type _rtld_link, @function
+_rtld_link:
+	push %rbp
+	mov %rsp, %rbp
+	push %rdx
+	push %rsi
+	push %rdi
+	mov 8(%rbp), %rdi
+	mov 16(%rbp), %rsi
+	push %rbp
+	mov %rsp, %rbp
+	and $-0x10, %rsp
+	call kc_dynamic_link
+	mov %rbp, %rsp
+	pop %rbp
+	pop %rdi
+	pop %rsi
+	pop %rdx
+	mov %rbp, %rsp
+	pop %rbp
+	add $0x10, %rsp
+	jmp *(%rax)
+.size _rtld_link, . - _rtld_link
+