From: Matthias Kruk <m@m10k.eu>
Date: Tue, 10 Dec 2019 08:46:37 +0000 (+0900)
Subject: Print the affected page directory and page table entries, when a page fault occurs... 
X-Git-Url: https://git.corax.cc/?a=commitdiff_plain;h=59b9539c95343f6676e88a8a433be7a7bb242472;p=corax

Print the affected page directory and page table entries, when a page fault occurs; make sure PAGE_ATTR_WRITABLE is set on the page table, if it contains writable pages
---

diff --git a/kernel/arch/heap.c b/kernel/arch/heap.c
index 0a85534..8a248ae 100644
--- a/kernel/arch/heap.c
+++ b/kernel/arch/heap.c
@@ -30,7 +30,7 @@ struct heap_node {
 	u32_t hn_flags;
 };
 
-static struct {
+struct {
 	void *h_base;
 	u32_t h_size;
 	u32_t h_free;
diff --git a/kernel/arch/interrupt.c b/kernel/arch/interrupt.c
index 728c4ce..1ad7d04 100644
--- a/kernel/arch/interrupt.c
+++ b/kernel/arch/interrupt.c
@@ -25,6 +25,8 @@
 #include "cpu.h"
 #include "defs.h"
 
+extern void pg_fault_debug(pg_dir_t*, void*);
+
 void sched_tick(void);
 extern int sys_cxnet(long, long, long, long, long, long, long);
 extern int sys_cxipc(long, long, long);
@@ -139,9 +141,14 @@ void _exc_handle(stack_frame_t ctx)
 
     if(ctx.intn == EXC_PAGEFAULT) {
         u32_t cr2;
+		pg_dir_t *pd;
 
         asm volatile("movl %%cr2, %%eax; movl %%eax, %0" : "=r"(cr2));
         dbg_printf("Page fault address: 0x%08x\n", cr2);
+
+		if(process_get_pagedir(cproc, &pd) == 0) {
+			pg_fault_debug(pd, (void*)cr2);
+		}
     }
 
     PANIC("Unhandled exception");
diff --git a/kernel/arch/paging.c b/kernel/arch/paging.c
index 978cf54..fd64607 100644
--- a/kernel/arch/paging.c
+++ b/kernel/arch/paging.c
@@ -887,6 +887,10 @@ int _clone_kernel_region(pg_dir_t *kdir, region_t *reg, void *data)
 	dir = (pg_dir_t*)data;
 
 	switch(reg->reg_type) {
+	case REGION_DATA:
+		ret_val = pg_dir_clone_region(dir, kdir, reg);
+		break;
+
 	case REGION_TEXT:
 	case REGION_RODATA:
 	case REGION_HEAP:
@@ -895,7 +899,6 @@ int _clone_kernel_region(pg_dir_t *kdir, region_t *reg, void *data)
 		 * directory since they cannot be modified or removed anyways.
 		 */
 	case REGION_BSS:
-	case REGION_DATA:
 		/*
 		 * The way the interrupt handling is currently implemented, accesses to the
 		 * _cpu structure and _kernel_cr3 are made within the context (i.e. using
@@ -1090,6 +1093,11 @@ static int _pg_dir_map_legacy(page_table_t *pd, u32_t paddr, u32_t vaddr,
 			pd->pt_entries[pde] |= PAGE_ATTR_USER;
 		}
 
+		/* also make sure the page table is writable, if necessary */
+		if(flags & PAGE_ATTR_WRITABLE) {
+			pd->pt_entries[pde] |= PAGE_ATTR_WRITABLE;
+		}
+
 		if(pt->pt_entries[pte] & PAGE_ATTR_PRESENT) {
 			ret_val = -EALREADY;
 			break;
@@ -1098,7 +1106,6 @@ static int _pg_dir_map_legacy(page_table_t *pd, u32_t paddr, u32_t vaddr,
 		/* allocate new frames if caller didn't specify a physical address */
 		if(!paddr) {
 			pt->pt_entries[pte] = (u32_t)pg_frame_alloc_end();
-			dbg_printf("Allocating page: %04u - 0x%08x\n", pte, pt->pt_entries[pte]);
 		} else {
 			pt->pt_entries[pte] = paddr;
 			paddr += PAGE_SIZE;
@@ -1309,7 +1316,7 @@ int pg_dir_clone_region(pg_dir_t *dpd, pg_dir_t *spd, region_t *reg)
 
 	/* attempt to map the region */
 	ret_val = pg_dir_map(dpd, NULL, reg->reg_base,
-						 reg->reg_size, reg->reg_attrs);
+						 reg->reg_size, reg->reg_attrs | PAGE_ATTR_USER);
 
 	if(ret_val < 0) {
 		goto gtfo;
@@ -1323,7 +1330,7 @@ int pg_dir_clone_region(pg_dir_t *dpd, pg_dir_t *spd, region_t *reg)
 	if(ret_val >= 0) {
 		/* also keep track of the region */
 		ret_val = _pg_dir_add_region(dpd, reg->reg_base, reg->reg_size,
-									 reg->reg_type, reg->reg_attrs, reg->reg_flags);
+									 reg->reg_type, reg->reg_attrs, reg->reg_flags | PAGE_ATTR_USER);
 	}
 
 	if(ret_val < 0) {
@@ -1509,3 +1516,37 @@ void* pg_dir_sbrk(pg_dir_t *pd, i32_t increment)
 
 	return(ret_val);
 }
+
+void pg_fault_debug(pg_dir_t *pdir, void *addr)
+{
+	u64_t pde;
+	u64_t pte;
+	u32_t pdi;
+	u32_t pti;
+
+	switch(_pg_flags & PG_MODE_MASK) {
+	case PG_MODE_LEGACY:
+		pdi = ((u32_t)addr & 0xffc00000) >> 22;
+		pti = ((u32_t)addr & 0x003ff000) >> 12;
+
+		pde = ((page_table_t*)pdir->pd_base)->pt_entries[pdi];
+
+		dbg_printf("pdir[%03u]      = 0x%08x\n", pdi, (u32_t)pde);
+
+		if(!(pde & PAGE_ATTR_SIZE)) {
+			pte = ((page_table_t*)(pde & 0xfffff000))->pt_entries[pti];
+			dbg_printf("pdir[%03u][%03u] = 0x%08x\n", pdi, pti, (u32_t)pte);
+		}
+
+		break;
+
+	case PG_MODE_PAE:
+		break;
+
+	default:
+		/* not handled yet */
+		break;
+	}
+
+	return;
+}