Kernel debug shell

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/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
@@ -122,6 +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");
 }
 
@@ -157,12 +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
@@ -261,7 +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/kapps/kshell.c

@@ -5,6 +5,11 @@
  */
 
 #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
@@ -13,8 +18,39 @@
  * 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("Entering the kernel shell...\r\n");
+    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/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 );
+    }
 }