feat: ported debug logging

yak-kernel/CMakeLists.txt

@@ -11,6 +11,7 @@ if (NOT ${CMAKE_C_COMPILER_ID} STREQUAL "Clang")
 endif ()
 
 # Define global options
+option(USE_DEBUG "Enable debug code" ON)
 option(USE_LIMINE "Enable support for the limine boot protocol" ON)
 
 # Find builtins
@@ -57,10 +58,17 @@ if (NOT ${USE_LIMINE})
 endif ()
 
 # Find sources
-file(GLOB KERNEL_SOURCES src/rt/*.c src/ulibc/*.c)
+file(GLOB KERNEL_SOURCES
+        src/rt/*.c
+        src/ulibc/*.c)
 file(GLOB PLATFORM_GENERIC_SOURCES src/platform/generic/*.c)
 
+if (${USE_DEBUG})
+    add_definitions(-DUSE_DEBUG)
+    file(GLOB DEBUG_KERNEL_SOURCES src/rt/debug/*.c)
+endif ()
 if (${USE_LIMINE})
+    add_definitions(-DUSE_LIMINE)
     file(GLOB LIMINE_KERNEL_SOURCES src/rt/limine/*.c)
 endif ()
 if (NOT IS_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/src/platform/${CMAKE_SYSTEM_PROCESSOR})
@@ -77,6 +85,7 @@ file(GLOB CRTN src/platform/generic/crt/crtn.c)
 set(KERNEL_SOURCE_FILES
         ${KERNEL_SOURCES}
         ${LIMINE_KERNEL_SOURCES}
+        ${DEBUG_KERNEL_SOURCES}
         ${PLATFORM_GENERIC_SOURCES}
         ${PLATFORM_SPECIFIC_SOURCES}
         ${PLATFORM_SPECIFIC_ASM_SOURCES}

yak-kernel/include/elf.h

@@ -0,0 +1,167 @@
+//
+// Created by rick on 07-03-21.
+//
+
+#ifndef NEW_KERNEL_ELF_H
+#define NEW_KERNEL_ELF_H
+
+#include <sys/types.h>
+
+// \x7FELF (little endian)
+#define ELF_MAGIC 0x464C457F
+
+#define ELF_CLASS_32 1
+#define ELF_CLASS_64 2
+
+#define ELF_ENDIAN_LITTLE 1
+#define ELF_ENDIAN_BIG 2
+
+#define SHT_NULL        0
+#define SHT_PROGBITS    1
+#define SHT_SYMTAB      2
+#define SHT_STRTAB      3
+#define SHT_RELA        4
+#define SHT_HASH        5
+#define SHT_DYNAMIC     6
+#define SHT_NOTE        7
+#define SHT_NOBITS      8
+#define SHT_REL         9
+#define SHT_SHLIB       10
+#define SHT_DYNSYM      11
+#define SHT_LOPROC      0x70000000
+#define SHT_HIPROC      0x7fffffff
+#define SHT_LOUSER      0x80000000
+#define SHT_HIUSER      0xffffffff
+
+#define SHF_WRITE       0x1
+#define SHF_ALLOC       0x2
+#define SHF_EXECINSTR   0x4
+#define SHF_MASKPROC    0xf0000000
+
+#define ELF32_ST_BIND(i)   ((i)>>4)
+#define ELF32_ST_TYPE(i)   ((i)&0xf)
+#define ELF32_ST_INFO(b, t) (((b)<<4)+((t)&0xf))
+
+#define STB_LOCAL   0
+#define STB_GLOBAL  1
+#define STB_WEAK    2
+#define STB_LOPROC  13
+#define STB_HIPROC  15
+
+#define STT_NOTYPE  0
+#define STT_OBJECT  1
+#define STT_FUNC    2
+#define STT_SECTION 3
+#define STT_FILE    4
+#define STT_LOPROC  13
+#define STT_HIPROC  15
+
+struct elf_file_header {
+    uint32_t ei_magic;
+    uint8_t ei_class;
+    uint8_t ei_data;
+    uint8_t ei_version;
+    uint8_t ei_osabi;
+    uint8_t ei_abiversion;
+    uint64_t: 56; // 7 bytes padding
+    union {
+        struct {
+            uint16_t e_type;
+            uint16_t e_machine;
+            uint32_t e_version;
+            uint32_t e_entry;
+            uint32_t e_phoff;
+            uint32_t e_shoff;
+            uint32_t e_flags;
+            uint16_t e_ehsize;
+            uint16_t e_phentsize;
+            uint16_t e_phnum;
+            uint16_t e_shentsize;
+            uint16_t e_shnum;
+            uint16_t e_shstrndx;
+        } elf32 __attribute((packed));
+        struct {
+            uint16_t e_type;
+            uint16_t e_machine;
+            uint32_t e_version;
+            uint64_t e_entry;
+            uint64_t e_phoff;
+            uint64_t e_shoff;
+            uint32_t e_flags;
+            uint16_t e_ehsize;
+            uint16_t e_phentsize;
+            uint16_t e_phnum;
+            uint16_t e_shentsize;
+            uint16_t e_shnum;
+            uint16_t e_shstrndx;
+        } elf64 __attribute((packed));
+    };
+} __attribute((packed));
+
+struct elf32_program_header {
+    uint32_t p_type;
+    uint32_t p_offset;
+    uint32_t p_vaddr;
+    uint32_t p_paddr;
+    uint32_t p_filesz;
+    uint32_t p_memsz;
+    uint32_t p_flags;
+    uint32_t p_align;
+} __attribute((packed));
+
+struct elf64_program_header {
+    uint32_t p_type;
+    uint32_t p_flags;
+    uint64_t p_offset;
+    uint64_t p_vaddr;
+    uint64_t p_paddr;
+    uint64_t p_filesz;
+    uint64_t p_memsz;
+    uint64_t p_align;
+} __attribute((packed));
+
+struct elf32_section_header {
+    uint32_t sh_name;
+    uint32_t sh_type;
+    uint32_t sh_flags;
+    uint32_t sh_addr;
+    uint32_t sh_offset;
+    uint32_t sh_size;
+    uint32_t sh_link;
+    uint32_t sh_info;
+    uint32_t sh_addr_align;
+    uint32_t sh_ent_size;
+}  __attribute((packed));
+
+struct elf64_section_header {
+    uint32_t sh_name;
+    uint32_t sh_type;
+    uint64_t sh_flags;
+    uint64_t sh_addr;
+    uint64_t sh_offset;
+    uint64_t sh_size;
+    uint32_t sh_link;
+    uint32_t sh_info;
+    uint64_t sh_addr_align;
+    uint64_t sh_ent_size;
+}  __attribute((packed));
+
+struct elf32_symtab_entry {
+    uint32_t st_name;
+    uint32_t st_value;
+    uint32_t st_size;
+    uint8_t st_info;
+    uint8_t st_other;
+    uint16_t st_shndx;
+} __attribute((packed));
+
+struct elf64_symtab_entry {
+    uint32_t st_name;
+    uint8_t st_info;
+    uint8_t st_other;
+    uint16_t st_shndx;
+    uint64_t st_value;
+    uint64_t st_size;
+} __attribute((packed));
+
+#endif //NEW_KERNEL_ELF_H

yak-kernel/include/yak/rt/debug/debug.h

@@ -0,0 +1,14 @@
+//
+// Created by rick on 08-03-21.
+//
+
+#ifndef NEW_KERNEL_DEBUG_H
+#define NEW_KERNEL_DEBUG_H
+
+#include <stdbool.h>
+
+void debug_store_info(void *kernel);
+
+void debug_backtrace(bool do_sync);
+
+#endif //NEW_KERNEL_DEBUG_H

yak-kernel/include/yak/rt/kprint.h

@@ -7,7 +7,9 @@
 
 typedef void (*print_function)(char c);
 
-void kprint_now(char* msg);
+void kprint(const char* msg);
+
+void kprint_now(const char* msg);
 
 void kprint_putc_now(char c);
 

yak-kernel/src/platform/x86_64/platform.c

@@ -5,7 +5,7 @@
 #include <yak/platform/generic/platform.h>
 
 void platform_init() {
-    printf("Init X86_64");
+    printf("Init X86_64\n");
 }
 
 void __attribute__((noreturn)) halt_forever() {

yak-kernel/src/rt/debug/debug.c

@@ -0,0 +1,123 @@
+//
+// Created by rick on 08-03-21.
+//
+
+#include <stdio.h>
+#include <string.h>
+#include <elf.h>
+#include <stdbool.h>
+
+#include <yak/rt/debug/debug.h>
+#include <yak/rt/kprint.h>
+
+static uintptr_t kernel_start;
+static struct elf64_section_header *elf_headers = NULL;
+static struct elf64_section_header *elf_shstrtab = NULL;
+static struct elf64_section_header *elf_symtab = NULL;
+static struct elf64_section_header *elf_strtab = NULL;
+static uint32_t elf_header_cnt;
+
+struct stackframe {
+    struct stackframe *ebp;
+    uintptr_t eip;
+};
+
+char *debug_get_shstrtab_entry(uint32_t ndx) {
+    if (elf_shstrtab == NULL) {
+        return NULL;
+    }
+    if (ndx > elf_shstrtab->sh_size) {
+        return NULL;
+    }
+    return ((char *) kernel_start + elf_shstrtab->sh_offset + ndx);
+}
+
+char *debug_get_strtab_entry(uint32_t ndx) {
+    if (elf_strtab == NULL) {
+        return NULL;
+    }
+    if (ndx > elf_strtab->sh_size) {
+        return NULL;
+    }
+    return ((char *) kernel_start + elf_strtab->sh_offset + ndx);
+}
+
+void debug_find_sections(uint32_t shndx) {
+    elf_shstrtab = &elf_headers[shndx];
+    for (uint32_t i = 0; i < elf_header_cnt; ++i) {
+        struct elf64_section_header *current = &elf_headers[i];
+        char *name = debug_get_shstrtab_entry(current->sh_name);
+        if (name == NULL) {
+            printf("Name was NULL\n");
+            continue;
+        }
+        if (strcmp(name, ".symtab") == 0) {
+            elf_symtab = current;
+            continue;
+        }
+        if (strcmp(name, ".strtab") == 0) {
+            elf_strtab = current;
+            continue;
+        }
+    }
+}
+
+void debug_store_info(void *kernel) {
+    struct elf_file_header* elf_header = (struct elf_file_header*)kernel;
+    if (elf_header->ei_magic != ELF_MAGIC) {
+        printf("Unsupported magic for kernel header\n");
+        return;
+    }
+    // todo support other then 64 little
+    if (elf_header->ei_class != ELF_CLASS_64 || elf_header->ei_data != ELF_ENDIAN_LITTLE) {
+        printf("Kernel not a 64bit little endian elf\n");
+        return;
+    }
+
+
+    if (elf_header->elf64.e_shentsize != sizeof(struct elf64_section_header)) {
+        printf("Elf section headers not correct size\n");
+    }
+
+    kernel_start = (uintptr_t) kernel;
+    elf_headers = (struct elf64_section_header *) (kernel_start + elf_header->elf64.e_shoff);
+    elf_header_cnt = elf_header->elf64.e_shnum;
+    debug_find_sections(elf_header->elf64.e_shstrndx);
+}
+
+struct elf64_symtab_entry *debug_get_entry_for_addr(uintptr_t addr) {
+    if (elf_symtab == NULL) {
+        return NULL;
+    }
+    struct elf64_symtab_entry *first = (struct elf64_symtab_entry *) (kernel_start + elf_symtab->sh_offset);
+    uint32_t num = elf_symtab->sh_size / sizeof(struct elf64_symtab_entry);
+    for (uint32_t i = 0; i < num; ++i) {
+        // only functions for now
+        if (ELF32_ST_TYPE(first[i].st_info) != STT_FUNC) {
+            continue;
+        }
+        if (addr >= first[i].st_value && addr < (first[i].st_value + first[i].st_size)) {
+            return &first[i];
+        }
+    }
+    return NULL;
+}
+
+void debug_backtrace(bool do_sync) {
+    // todo support non-x86
+    struct stackframe *frame = __builtin_frame_address(0);
+    void (*printer)(const char *) = do_sync ? kprint_now : kprint;
+    printer("\n\n## Stack Trace ##\n");
+    char msg[1024] = {0};
+    while (frame->ebp != NULL) {
+        struct elf64_symtab_entry *entry = debug_get_entry_for_addr(frame->eip);
+        if (entry == NULL) {
+            snprintf(msg, 1024,"#unknown (%lx)\n", frame->eip);
+        } else {
+            snprintf(msg, 1024, "%s (%lx)\n", debug_get_strtab_entry(entry->st_name), frame->eip);
+        };
+        printer(msg);
+        frame = frame->ebp;
+    }
+    printer("\n");
+}

yak-kernel/src/rt/kmain.c

@@ -1,6 +1,6 @@
 #include <yak/rt/kmain.h>
 #include <yak/rt/panic.h>
-#include "yak/platform/generic/platform.h"
+#include <yak/platform/generic/platform.h>
 
 void kmain() {
     _init();

yak-kernel/src/rt/kprint.c

@@ -9,8 +9,13 @@
 
 print_function print_functions[MAX_PRINT_FUNCTIONS] = {0};
 
-void kprint_now(char* msg) {
+void kprint(const char* msg) {
-    char* m = msg;
+    // todo async
+    kprint_now(msg);
+}
+
+void kprint_now(const char* msg) {
+    const char* m = msg;
     while (*m != 0) {
         kprint_putc_now(*m);
         m++;

yak-kernel/src/rt/limine/limine.c

@@ -5,8 +5,10 @@
 #include <stddef.h>
 #include <stdio.h>
 #include <limine.h>
-#include <yak/rt/kprint.h>
+
+#include <yak/rt/debug/debug.h>
 #include <yak/rt/kmain.h>
+#include <yak/rt/kprint.h>
 
 static struct limine_bootloader_info_request limine_bootloader_info_request = {
         .id = LIMINE_BOOTLOADER_INFO_REQUEST,
@@ -110,5 +112,9 @@ void limine_init() {
         printf("Booted using limine from an unknown bootloader\n");
     }
 
+    if (limine_kernel_file_request.response != NULL) {
+        debug_store_info(limine_kernel_file_request.response->kernel_file->address);
+    }
+
     kmain();
 }

yak-kernel/src/rt/panic.c

@@ -3,13 +3,18 @@
 //
 
 #include <yak/rt/panic.h>
-#include "yak/rt/kprint.h"
+#include <yak/rt/kprint.h>
-#include "yak/platform/generic/platform.h"
+#include <yak/platform/generic/platform.h>
+#ifdef USE_DEBUG
+#include <yak/rt/debug/debug.h>
+#endif
 
 void __attribute__((__noreturn__)) panic(char *reason) {
-    kprint_now(reason);
+#ifdef USE_DEBUG
+    debug_backtrace(true);
+#endif
 
-    // todo stack trace
+    kprint_now(reason);
 
     halt_forever();
 }