serial Kernel panic

src/idt/idt.c

@@ -53,6 +53,38 @@ void idt_init()
     DEBUG("IDT initialized");
 }
 
+static inline uint64_t read_cr2(void)
+{
+    uint64_t val;
+    asm volatile ("mov %%cr2, %0" : "=r"(val));
+    return val;
+}
+
+static void page_fault_handler(struct cpu_status_t* ctx)
+{
+    // It could be used to remap pages etc. to fix the fault, but right now what I'm more
+    // interested in is getting more info out of those numbers cause i'm lost each time i have 
+    // to read all this mess
+    uint64_t cr2 = read_cr2();
+    
+    DEBUG("\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);
+
+    /* if (CHECK_BIT(ctx->error_code, 0))
+    {
+        panic(ctx);
+    } */
+    panic(ctx);
+}
+
 struct cpu_status_t* interrupt_dispatch(struct cpu_status_t* context)
 {
     switch(context->vector_number)
@@ -100,7 +132,8 @@ struct cpu_status_t* interrupt_dispatch(struct cpu_status_t* context)
             DEBUG("General Protection Fault!");
             break;
         case 14:
-            DEBUG("Page Fault!");
+            // Better debugging for page faults...
+            page_fault_handler(context);
             break;
         case 15:
             DEBUG("Intel Reserved Interrupt! (Achievement unlocked: How Did We Get Here?)");

src/io/term/term.c

@@ -9,6 +9,7 @@ because this shitty implementation will be replaced one day by Flanterm
 #include <stddef.h>
 #include <kernel.h>
 #include "term.h"
+#include "mem/misc/utils.h"
 
 extern struct boot_context boot_ctx;
 
@@ -35,6 +36,8 @@ unsigned char* fb;
 
 struct limine_framebuffer* framebuffer;
 
+uint8_t lines_length[MAX_LINES];
+
 int term_init()
 {
 	// Get framebuffer address from Limine struct
@@ -87,10 +90,51 @@ static void erase_char(int px, int py)
 	}
 }
 
+static inline size_t term_max_lines(void)
+{
+	return framebuffer->height / FONT_HEIGHT;
+}
+
+void term_scroll()
+{
+	const size_t row_height = FONT_HEIGHT;
+	const size_t row_bytes  = framebuffer->pitch;
+	const size_t screen_rows = framebuffer->height;
+
+	// Move framebuffer up by one text row 
+	memmove(fb, fb + row_height * row_bytes, (screen_rows - row_height) * row_bytes);
+
+	// Clear last text row
+	size_t clear_start = (screen_rows - row_height) * row_bytes;
+	memset(fb + clear_start, 0, row_height * row_bytes);
+
+	// Shift line lengths by 1 (for backspace handling)
+	size_t max_lines = term_max_lines();
+	for (size_t i = 1; i < max_lines; i++)
+	{
+		lines_length[i - 1] = lines_length[i];
+	}
+
+	lines_length[max_lines - 1] = 0;
+
+	if (cursor.y > 0)
+	{
+		cursor.y--;
+	}
+}
+
+
 void putchar(char c)
 {
+	if ((c == '\n') && ((cursor.y+1)*FONT_HEIGHT >= framebuffer->height))
+	{
+		term_scroll();
+		return;
+	} 
+
 	if (c == '\n')
 	{
+		lines_length[cursor.y] = cursor.x;
 		cursor.x = 0;
 		cursor.y++;
 		return;
@@ -110,7 +154,8 @@ void putchar(char c)
 		if (cursor.x == 0)
 		{
 			cursor.y--;
-			cursor.x = (framebuffer->width / FONT_WIDTH) -1; // here
+			// cursor.x = (framebuffer->width / FONT_WIDTH) -1; // here
+			cursor.x = lines_length[cursor.y];
 		}
 		else {
 			cursor.x--;
@@ -128,6 +173,11 @@ void putchar(char c)
 		cursor.y++;
 	}
 
+	if ((cursor.y+1)*FONT_HEIGHT >= framebuffer->height)
+	{
+		term_scroll();
+	}
+
 	int px = cursor.x * FONT_WIDTH;
 	int py = cursor.y * FONT_HEIGHT;
 	draw_char(c, px, py, WHITE, BLACK);

src/io/term/term.h

@@ -11,6 +11,8 @@ enum TermColors
     WHITE = 0xffffff
 };
 
+#define MAX_LINES 256
+
 #define PSF1_FONT_MAGIC 0x0436
 
 typedef struct

src/kernel.h

@@ -16,11 +16,15 @@ enum ErrorCodes
 
 #include "io/serial/serial.h"
 #include "io/term/printf.h"
+#include "idt/idt.h"
 
 #define DEBUG(log, ...) fctprintf((void*)&skputc, 0, "debug: [%s]: " log "\r\n", __FILE__, ##__VA_ARGS__)
 
+#define CHECK_BIT(var,pos) ((var) & (1<<(pos)))
+
 // printf("debug: [%s]: " log "\n", __FILE__, ##__VA_ARGS__);
 
+void panic(struct cpu_status_t* ctx);
 void hcf();
 #define assert(check) do { if(!(check)) hcf(); } while(0)
 

src/kmain.c

@@ -62,6 +62,16 @@ void hcf()
 	}
 }
 
+void panic(struct cpu_status_t* ctx)
+{
+	DEBUG("\x1b[38;5;231m\x1b[48;5;196mKernel panic!!!\x1b[0m at rip=%p\nSomething went horribly wrong! vect=0x%.2x errcode=0x%x\nrax=%p rbx=%p rcx=%p rdx=%p\nrsi=%p rdi=%p  r8=%p  r9=%p\nr10=%p r11=%p r12=%p r13=%p\nr14=%p r15=%p\n\nflags=%p\nstack at rbp=%p\nHalting...",
+		ctx->iret_rip,
+		ctx->vector_number, ctx->error_code, ctx->rax, ctx->rbx, ctx->rcx, ctx->rdx, ctx->rsi, ctx->rdi,
+		ctx->r8, ctx->r9, ctx->r10, ctx->r11, ctx->r12, ctx->r13, ctx->r14, ctx->r15, ctx->iret_flags,
+		ctx->rbp);
+	hcf();
+}
+
 const char* splash = "pepperOS version "PEPPEROS_VERSION_MAJOR"."PEPPEROS_VERSION_MINOR"."PEPPEROS_VERSION_PATCH"\n";
 
 struct boot_context boot_ctx;
@@ -108,5 +118,11 @@ void kmain()
 	term_init();
 	kputs(splash);
 
+	for (int i=0; i<50; i++)
+	{
+		printf("testing, attention please %d\n", i);
+		timer_wait(1000);
+	}
+
 	hcf();
 }

src/time/timer.c

@@ -65,6 +65,17 @@ void pit_init()
     outb(0x40, (divisor >> 8) & 0xFF);
 }
 
+// Wait n ticks
+// Given that there's a tick every 1ms, wait n milliseconds
+void timer_wait(uint64_t wait_ticks)
+{
+    uint64_t then = ticks + wait_ticks;
+    while (ticks < then)
+    {
+        asm("hlt");
+    };
+}
+
 void timer_init()
 {
     // Remapping the PIC, because at startup it conflicts with

src/time/timer.h

@@ -2,5 +2,6 @@
 #define TIMER_H
 
 void timer_init();
+void timer_wait(unsigned int wait_ticks);
 
 #endif