First syscall

.clang-format

@@ -1,11 +1,13 @@
 # options: https://clang.llvm.org/docs/ClangFormatStyleOptions.html
 BasedOnStyle: Mozilla
-IndentWidth: 4
 ColumnLimit: 120
+IndentWidth: 4
+
 AlignAfterOpenBracket: BlockIndent
 AlignConsecutiveMacros: true
 AlignTrailingComments:
   Kind: Always
 AllowAllArgumentsOnNextLine: true
+AllowShortBlocksOnASingleLine: Empty
 AlwaysBreakAfterReturnType: AllDefinitions
 InsertBraces: true

Makefile

@@ -53,6 +53,7 @@ copy:
 	hdiutil attach -imagekey diskimage-class=CRawDiskImage -mount required $(BUILD_DIR)/$(OS_IMG)
 	cp ./hello.txt "/Volumes/taiOS BOOT/"
 	cp $(USR_BIN_DIR)/blank/build/blank.bin "/Volumes/taiOS BOOT/"
+	cp $(USR_BIN_DIR)/syscall/build/syscall.bin "/Volumes/taiOS BOOT/"
 	hdiutil detach `hdiutil info | tail -n 1 | cut -f 1`
 
 usr_bin:

doc/13_calling_kernel_space_routines_from_user_space.md

@@ -26,4 +26,4 @@ print:
 ```
 
 - Interrupt 0x80 handler [commit](https://github.com/taikiy/kernel/commit/42c0b6374e21e096060d27e3255a2e007c55b0cd)
-- Register 0x80 handler in IDT [commit]()
+- Register 0x80 handler in IDT [commit](https://github.com/taikiy/kernel/commit/2020d58d9047f2584ab03d95ccfab2b221ff2ced)

programs/Makefile

@@ -1,5 +1,7 @@
 all:
 	$(MAKE) -C blank
+	$(MAKE) -C syscall
 
 clean:
-	$(MAKE) -C blank clean
+	$(MAKE) -C blank clean
+	$(MAKE) -C syscall clean

programs/syscall/Makefile

@@ -0,0 +1,35 @@
+TARGET = syscall.bin
+OBJ = syscall.o
+
+BUILD_DIR = ./build
+SRC_DIR = ./src
+
+LINKER_FILE = $(SRC_DIR)/linker.ld
+
+ASRCS = $(shell find $(SRC_DIR) -name *.asm)
+
+AOBJS = $(subst $(SRC_DIR),$(BUILD_DIR),$(ASRCS:.asm=.asm.o))
+OBJS = $(AOBJS)
+
+CC = i686-elf-gcc
+ASM = nasm
+LD = i686-elf-ld
+
+AFLAGS = -f elf -g
+CFLAGS = -g -ffreestanding -falign-jumps -falign-functions -falign-labels -falign-loops -fstrength-reduce -fomit-frame-pointer -finline-functions -Wno-unused-function -fno-builtin -Werror -Wno-unused-label -Wno-cpp -Wno-unused-parammeter -nostdlib -nostartfiles -nodefaultlibs -Wall -O0 -Iinc -std=gnu99
+LDFLAGS = -g -relocatable
+
+all: build
+
+build: $(BUILD_DIR)/$(TARGET)
+
+$(BUILD_DIR)/$(TARGET): $(OBJS)
+	$(LD) $(LDFLAGS) $(OBJS) -o $(BUILD_DIR)/$(OBJ)
+	$(CC) $(CFLAGS) -T $(SRC_DIR)/linker.ld -o $(BUILD_DIR)/$(TARGET) $(BUILD_DIR)/$(OBJ)
+
+$(BUILD_DIR)/%.asm.o: $(SRC_DIR)/%.asm
+	mkdir -p $(dir $@)
+	$(ASM) $(AFLAGS) $< -o $@
+
+clean:
+	rm -rf $(BUILD_DIR)

programs/syscall/src/linker.ld

@@ -0,0 +1,31 @@
+ENTRY(_start)
+OUTPUT_FORMAT(binary)
+SECTIONS
+{
+    . = 0x400000;          /* USER_PROGRAM_VIRTUAL_ADDRESS_START in config.h */
+    .text : ALIGN(4096)
+    {
+        *(.text)
+    }
+
+    .rodata : ALIGN(4096)
+    {
+        *(.rodata)
+    }
+
+    .data : ALIGN(4096)
+    {
+        *(.data)
+    }
+
+    .bss : ALIGN(4096)
+    {
+        *(COMMON)
+        *(.bss)
+    }
+
+    .asm : ALIGN(4096)
+    {
+        *(.asm)
+    }
+}

programs/syscall/src/syscall.asm

@@ -0,0 +1,10 @@
+ [BITS 32]
+
+ section .asm
+
+ global _start
+
+_start:
+   mov eax, 0     ; sys_print
+   int 0x80       ; call kernel
+   jmp $

src/idt/idt.c

@@ -3,14 +3,13 @@
 #include "io/io.h"
 #include "kernel.h"
 #include "memory/memory.h"
+#include "system/syscall.h"
 #include "task/task.h"
 #include "terminal/terminal.h"
 
 struct idt_desc idt_descriptors[TOTAL_INTERRUPTS];
 struct idtr_desc idtr_descriptor;
 
-static SYSCALL_HANDLER syscall_handlers[TOTAL_SYSCALL_COUNT];
-
 extern void load_idt(struct idtr_desc* ptr);
 extern void int_noop();
 extern void int21h();
@@ -35,37 +34,6 @@ int21h_handler()
     outb(0x20, 0x20);
 }
 
-static void*
-syscall(int command, struct interrupt_frame* frame)
-{
-    void* result = 0;
-
-    if (command < 0 || command >= TOTAL_SYSCALL_COUNT) {
-        return result;
-    }
-
-    SYSCALL_HANDLER handler = syscall_handlers[command];
-    if (handler) {
-        result = handler(frame);
-    }
-
-    return result;
-}
-
-void
-register_syscall(int command, SYSCALL_HANDLER handler)
-{
-    if (command < 0 || command >= TOTAL_SYSCALL_COUNT) {
-        panic("Invalid syscall command");
-    }
-
-    if (syscall_handlers[command]) {
-        panic("Syscall already registered");
-    }
-
-    syscall_handlers[command] = handler;
-}
-
 void*
 isr80h_handler(int command, struct interrupt_frame* frame)
 {

src/idt/idt.h

@@ -41,10 +41,7 @@ struct interrupt_frame
     uint32_t ss;
 } __attribute__((packed));
 
-typedef void* (*SYSCALL_HANDLER)(struct interrupt_frame*);
-
 void initialize_idt();
-void register_syscall(int command, SYSCALL_HANDLER handler);
 void enable_interrupts();
 void disable_interrupts();
 

src/kernel.c

@@ -12,6 +12,7 @@
 #include "memory/paging/paging.h"
 #include "status.h"
 #include "string/string.h"
+#include "system/syscall.h"
 #include "task/process.h"
 #include "task/task.h"
 #include "task/tss.h"
@@ -21,15 +22,15 @@ extern void set_kernel_segment_registers();
 void test_path_parser();
 void test_file_system();
 void test_user_space();
+void test_syscall();
 
 void
 panic(const char* message)
 {
     print("PANIC: ");
     print(message);
     print("\n");
-    while (1) {
-    };
+    while (1) {};
 }
 
 static struct paging_map* kernel_page = 0;
@@ -65,6 +66,8 @@ kernel_main()
 
     print("...IDT\n");
     initialize_idt();
+    print("...ISR\n");
+    initialize_syscall_handlers();
 
     print("...disks and file systems\n");
     initialize_file_systems();
@@ -75,14 +78,26 @@ kernel_main()
     // TESTS
     // test_path_parser();
     // test_file_system();
-    test_user_space();
+    // test_user_space();
+    test_syscall();
 
     print("...enabling interrupts\n");
     enable_interrupts();
 
     print("End of kernel_main\n");
 }
 
+void
+test_syscall()
+{
+    struct process* proc = kzalloc(sizeof(struct process));
+    status_t result = create_process("0:/syscall.bin", &proc);
+    if (result != ALL_OK || !proc) {
+        panic("Failed to create a process!");
+    }
+    start_tasks();
+}
+
 void
 test_user_space()
 {

src/system/syscall.c

@@ -0,0 +1,50 @@
+#include "syscall.h"
+#include "config.h"
+#include "kernel.h"
+#include "terminal/terminal.h"
+
+static SYSCALL_HANDLER syscall_handlers[TOTAL_SYSCALL_COUNT];
+
+void*
+sys_print(struct interrupt_frame* frame)
+{
+    print("sys_print\n");
+    return 0;
+}
+
+static void
+register_syscall_handler(int command, SYSCALL_HANDLER handler)
+{
+    if (command < 0 || command >= TOTAL_SYSCALL_COUNT) {
+        panic("Invalid syscall command");
+    }
+
+    if (syscall_handlers[command]) {
+        panic("Syscall already registered");
+    }
+
+    syscall_handlers[command] = handler;
+}
+
+void
+initialize_syscall_handlers()
+{
+    register_syscall_handler(SYSCALL_COMMAND_0_PRINT, sys_print);
+}
+
+void*
+syscall(int command, struct interrupt_frame* frame)
+{
+    void* result = 0;
+
+    if (command < 0 || command >= TOTAL_SYSCALL_COUNT) {
+        return result;
+    }
+
+    SYSCALL_HANDLER handler = syscall_handlers[command];
+    if (handler) {
+        result = handler(frame);
+    }
+
+    return result;
+}

src/system/syscall.h

@@ -0,0 +1,17 @@
+#ifndef SYSCALL_H
+#define SYSCALL_H
+
+#include "idt/idt.h"
+#include <stdint.h>
+
+typedef void* (*SYSCALL_HANDLER)(struct interrupt_frame*);
+
+enum SYSCALL_COMMAND
+{
+    SYSCALL_COMMAND_0_PRINT = 0,
+};
+
+void initialize_syscall_handlers();
+void* syscall(int command, struct interrupt_frame* frame);
+
+#endif