Kernel debug shell

include/arch/x86.h

@@ -59,4 +59,6 @@ struct cpu_status_t {
     uint64_t iret_ss;
 };
 
+struct cpu_status_t* syscall_handler(struct cpu_status_t* regs);
+
 #endif

include/config.h

@@ -20,6 +20,10 @@
 "\x1b[38;5;196m/_/        /_/   /_/                             \r\n\x1b[0m"\
 "     --- version \x1b[38;5;220m"PEPPEROS_VERSION_MAJOR"."PEPPEROS_VERSION_MINOR"."PEPPEROS_VERSION_PATCH"\x1b[0m built on \x1b[38;5;40m"__DATE__" "__TIME__"\x1b[0m\r\n"
 
+/* pedicel */
+#define PEDICEL_PROMPT "pedicel$ "
+#define PEDICEL_INPUT_SIZE 128
+
 /* process */
 #define PROCESS_NAME_MAX 64
 #define PROCESS_STACK_SIZE 0x10000 // 64kb

include/io/term/term.h

@@ -11,5 +11,6 @@ void kputs(const char* str);
 void term_init(void);
 int printf(const char* fmt, ...);
 void internal_putc(int c, void *_);
+int kprintf(const char* fmt, ...);
 
 #endif

include/kernel.h

@@ -21,7 +21,7 @@ enum ErrorCodes {
 #include <stdbool.h>
 
 extern volatile uint64_t ticks;
-#define DEBUG(log, ...) printf("[%8u] debug: <%s>: " log "\r\n", ticks, __func__, ##__VA_ARGS__)
+#define DEBUG(log, ...) kprintf("[%8u] debug: <%s>: " log "\r\n", ticks, __func__, ##__VA_ARGS__)
 
 /* #define DEBUG(log, ...) \
 	printf("debug: [%s]: " log "\r\n", __FILE__, ##__VA_ARGS__); \
@@ -38,6 +38,8 @@ void panic(struct cpu_status_t* ctx, const char* str);
 void hcf(void);
 void idle(void);
 
+void pedicel_main(void* arg);
+
 /* debug */
 void debug_stack_trace(unsigned int max_frames);
 const char* debug_find_symbol(uintptr_t rip, uintptr_t* offset);
@@ -58,6 +60,7 @@ struct init_status {
 	bool serial;
 	bool keyboard;
 	bool timer;
+	bool all;
 };
 
 #endif

include/string/string.h

@@ -12,5 +12,6 @@
 char *strcpy(char *dest, const char *src);
 char *strcat(char *dest, const char *src);
 void strncpy(char* dst, const char* src, size_t n);
+int strncmp(const char* s1, const char* s2, size_t n);
 
 #endif

src/arch/x86/idt.c

@@ -24,6 +24,8 @@ extern char vector_0_handler[];
 // Timer ticks
 extern volatile uint64_t ticks;
 
+extern struct init_status init;
+
 /*
  * idt_set_entry - Sets an Interrupt Descriptor Table entry
  * @vector:  Vector number in the IDT
@@ -72,6 +74,9 @@ void idt_init()
         // Each vector handler is 16-byte aligned, so <vector_no>*16 = address of that handler
         idt_set_entry(i, vector_0_handler + (i*16), 0);
     }
+
+    idt_set_entry(0x80, syscall_handler, 0);
+
     idt_load(&idt);
     DEBUG("IDT initialized");
 }
@@ -119,6 +124,19 @@ static void page_fault_handler(struct cpu_status_t* ctx)
     CHECK_BIT(ctx->error_code, 7) ? " SGX_VIOLATION" : "",
     cr2);
 
+    if (init.all) {
+        printf("\x1b[38;5;231mPage Fault at rip=0x%p, err=%u (%s%s%s%s%s%s%s%s) when accessing addr=0x%p\x1b[0m", ctx->iret_rip, ctx->error_code,
+        CHECK_BIT(ctx->error_code, 0) ? "PAGE_PROTECTION_VIOLATION " : "PAGE_NOT_PRESENT ",
+        CHECK_BIT(ctx->error_code, 1) ? "ON_WRITE " : "ON_READ ",
+        CHECK_BIT(ctx->error_code, 2) ? "IN_USER_MODE" : "IN_KERNEL_MODE",
+        CHECK_BIT(ctx->error_code, 3) ? " WAS_RESERVED" : "",
+        CHECK_BIT(ctx->error_code, 4) ? " ON_INSTRUCTION_FETCH" : "",
+        CHECK_BIT(ctx->error_code, 5) ? " PK_VIOLATION" : "",
+        CHECK_BIT(ctx->error_code, 6) ? " ON_SHADOWSTACK_ACCESS" : "",
+        CHECK_BIT(ctx->error_code, 7) ? " SGX_VIOLATION" : "",
+        cr2);
+    }
+
     panic(ctx, "page fault");
 }
 
@@ -154,12 +172,6 @@ static void gp_fault_handler(struct cpu_status_t* ctx)
     panic(ctx, "gp fault");
 }
 
-// DEBUG
-void kbdproc_main(void* arg)
-{
-    printf("Key pressed/released.\r\n");
-}
-
 /*
  * interrupt_dispatch - Interrupt dispatcher
  * @context: CPU context
@@ -258,7 +270,7 @@ struct cpu_status_t* interrupt_dispatch(struct cpu_status_t* context)
 
         case 33: // Keyboard Interrupt
             keyboard_handler();
-            process_create("keyboard-initiated", kbdproc_main, NULL); // DEBUG
+            //process_create("keyboard-initiated", kbdproc_main, NULL); // DEBUG
             outb(0x20, 0x20);
             break;
 

src/arch/x86/syscall.c

@@ -0,0 +1,26 @@
+/*
+ * @author  xamidev <xamidev@riseup.net>
+ * @brief   System call handling
+ * @license GPL-3.0-only
+ */
+
+#include <arch/x86.h>
+#include <kernel.h>
+
+struct cpu_status_t* syscall_handler(struct cpu_status_t* regs)
+{
+    DEBUG("Syscall %lx with argument %lx", regs->rdi, regs->rsi);
+
+    switch (regs->rdi)
+    {
+        case 0:
+            break;
+        case 1:
+            break;
+        default:
+            regs->rsi = 0xdeadbeef;
+            break;
+    }
+
+    return regs;
+}

src/io/term/term.c

@@ -65,6 +65,38 @@ void internal_putc(int c, void *_)
     }
 }
 
+/*
+ * debug_putc - Internal DEBUG putchar function
+ * @c: char to print
+ * @_: (unused, for nanoprintf)
+ *
+ * Prints a character to the terminal if it's ready and if 
+ * the kernel is still initializing, and also always to the
+ * serial interface if it's ready.
+ */
+void debug_putc(int c, void *_)
+{
+    (void)_;
+    char ch = (char)c;
+
+    if (init.terminal && (!init.all || panic_count > 0)) {
+        if (panic_count == 0) {
+            spinlock_acquire(&term_lock);
+            flanterm_write(ft_ctx, &ch, 1);
+            spinlock_release(&term_lock);
+        } else {
+            flanterm_write(ft_ctx, &ch, 1);
+        }
+    }
+
+    if (init.serial) {
+        if (ch == '\n') {
+            skputc('\r');
+        }
+        skputc(ch);
+    }
+}
+
 /*
  * printf - Fromatted printing
  * @fmt: format string
@@ -96,6 +128,38 @@ int printf(const char* fmt, ...)
     return -1;
 }
 
+/*
+ * kprintf - Fromatted DEBUG printing 
+ * @fmt: format string
+ * @...: variadic arguments
+ *
+ * Wrapper for nanoprintf; to be used only for
+ * kernel/debug messages.
+ *
+ * Return:
+ * <ret> - number of characters sent to the callback
+ * %-1   - error
+ */
+int kprintf(const char* fmt, ...)
+{
+    if (panic_count == 0) {
+        spinlock_acquire(&printf_lock);
+        va_list args;
+        va_start(args, fmt);
+        int ret = npf_vpprintf(debug_putc, NULL, fmt, args);
+        va_end(args);
+        spinlock_release(&printf_lock);
+        return ret;
+    } else {
+        va_list args;
+        va_start(args, fmt);
+        int ret = npf_vpprintf(debug_putc, NULL, fmt, args);
+        va_end(args);
+        return ret;
+    }
+    return -1;
+}
+
 /*
  * kputs - Kernel puts
  * @str: String to write

src/kapps/kshell.c

@@ -0,0 +1,56 @@
+/*
+ * @author  xamidev <xamidev@riseup.net>
+ * @brief   PepperOS kernel shell
+ * @license GPL-3.0-only
+ */
+
+#include <io/term/term.h>
+#include <config.h>
+#include <io/kbd/ps2.h>
+#include <string/string.h>
+#include <stdint.h>
+#include <kernel.h>
+
+/*
+ * pedicel_main - Kernel shell main function
+ * @arg: argument (optional)
+ *
+ * This is the entry point for the kernel shell process.
+ * It is used to start programs and to test different things
+ * on different real hardware easily.
+ *
+ * Named after the root part of the pepper.
+ */
+void pedicel_main(void* arg)
+{
+    printf("Welcome to the kernel shell!\r\nType 'help' for a list of commands.\r\n");
+
+    for (;;) {
+        char input_buf[PEDICEL_INPUT_SIZE] = {0};
+        printf(PEDICEL_PROMPT);
+        keyboard_getline(input_buf, PEDICEL_INPUT_SIZE);
+        
+        if (strncmp(input_buf, "help", 4) == 0) {
+            printf("\r\npanic   - trigger a test panic\r\n"
+                            "syscall - trigger int 0x80\r\n"
+                            "pf      - trigger a page fault\r\n");
+            continue;
+        }
+
+        if (strncmp(input_buf, "panic", 5) == 0) {
+            panic(NULL, "test panic");
+        }
+
+        if (strncmp(input_buf, "syscall", 7) == 0) {
+            __asm__ volatile("int $0x80");
+            continue;
+        }
+
+        if (strncmp(input_buf, "pf", 2) == 0) {
+            volatile uint64_t* fault = (uint64_t*)0xdeadbeef;
+            fault[0] = 1;
+        }
+
+        printf("%s: command not found\r\n", input_buf);
+    }
+}

src/kmain.c

@@ -66,12 +66,6 @@ extern struct process_t* processes_list;
 extern struct process_t* current_process;
 struct process_t* idle_proc;
 
-// Never gets executed although pedicel is scheduled?
-void pedicel_main(void* arg)
-{
-	printf("\n\n\rWelcome to PepperOS! Pedicel speaking.\r\nNothing left to do, let's go idle!\r\n");
-}
-
 void idle_main(void* arg)
 {
 	for (;;) {
@@ -125,10 +119,10 @@ void kmain()
 	process_init();
 	idle_proc = process_create("idle", (void*)idle_main, 0);
 	process_create("pedicel", (void*)pedicel_main, 0);
-	process_create("thing", thing_main, NULL);
 
 	scheduler_init();
 
 	printf(PEPPEROS_SPLASH);
+	init.all = true;
 	idle();
 }

src/string/string.c

@@ -69,4 +69,33 @@ void strncpy(char* dst, const char* src, size_t n)
 {
    size_t i = 0;
    while(i++ != n && (*dst++ = *src++));
+}
+
+
+/*
+ * strncmp - compare two strings up to n characters
+ * @s1: first string
+ * @s2: second string
+ * @n:  number of bytes to compare
+ *
+ * Taken from: https://github.com/DevSolar/pdclib/blob/master/functions/string/strncmp.c
+ *
+ * Return:
+ * $0  - @s1 and @s2 are equal
+ * $<0 - @s1 is less than @s2
+ * $>0 - @s1 is greater than @s2 
+ */
+int strncmp(const char* s1, const char* s2, size_t n)
+{
+    while ( n && *s1 && ( *s1 == *s2 ) ) {
+        ++s1;
+        ++s2;
+        --n;
+    }
+    if ( n == 0 ) {
+        return 0;
+    }
+    else {
+        return ( *(unsigned char *)s1 - *(unsigned char *)s2 );
+    }
 }