feat: No more kernel page table switching upon interrupt.

[lunaix-os.git] / lunaix-os / kernel / asm / x86 / pfault.c

diff --git a/lunaix-os/kernel/asm/x86/pfault.c b/lunaix-os/kernel/asm/x86/pfault.c
index c5ec07f5f37bdf9dd61bb9975d68c1b1c2f303b6..c16385a892c05a487b50465fbbbcea48112be00a 100644 (file)
--- a/lunaix-os/kernel/asm/x86/pfault.c
+++ b/lunaix-os/kernel/asm/x86/pfault.c
@@ -1,21 +1,66 @@
 #include <arch/x86/interrupts.h>
 #include <lunaix/mm/pmm.h>
+#include <lunaix/mm/mm.h>
+#include <lunaix/mm/region.h>
 #include <lunaix/mm/vmm.h>
 #include <lunaix/common.h>
+#include <lunaix/syslog.h>
+#include <lunaix/status.h>
+#include <lunaix/sched.h>
+
+static void kprintf(const char* fmt, ...) { va_list args; va_start(args, fmt); __kprintf("PFAULT", fmt, args); va_end(args); }
 
 extern void __print_panic_msg(const char* msg, const isr_param* param);
 
 void
 intr_routine_page_fault (const isr_param* param) 
 {
-    void* pg_fault_ptr = cpu_rcr2();
-    if (!pg_fault_ptr) {
-        __print_panic_msg("Null pointer reference", param);
-        goto done;
+    uintptr_t ptr = cpu_rcr2();
+    if (!ptr) {
+        goto segv_term;
     }
 
-    __print_panic_msg("Page fault", param);
+    struct mm_region* hit_region = region_get(__current, ptr);
+
+    if (!hit_region) {
+        // Into the void...
+        goto segv_term;
+    }
+
+    // if (param->eip == ptr && !(hit_region->attr & REGION_EXEC)) {
+    //     goto segv_term;
+    // }
+
+    x86_pte_t* pte = CURPROC_PTE(ptr >> 12);
+    if (*pte & PG_PRESENT) {
+        if ((hit_region->attr & REGION_PERM_MASK) == (REGION_RSHARED | REGION_READ)) {
+            // normal page fault, do COW
+                uintptr_t pa = (uintptr_t)vmm_dup_page(__current->pid, PG_ENTRY_ADDR(*pte));
+                pmm_free_page(__current->pid, *pte & ~0xFFF);
+                *pte = (*pte & 0xFFF) | pa | PG_WRITE;
+                return;
+        }
+        // impossible cases or accessing privileged page
+        goto segv_term;
+    }
+
+    if (!(*pte)) {
+        // Invalid location
+        goto segv_term;
+    }
+    uintptr_t loc = *pte & ~0xfff;
+    // a writable page, not present, pte attr is not null and no indication of cached page -> a new page need to be alloc
+    if ((hit_region->attr & REGION_WRITE) && (*pte & 0xfff) && !loc) {
+        uintptr_t pa = pmm_alloc_page(__current->pid, 0);
+        *pte = *pte | pa | PG_PRESENT;
+        return;
+    }
+    // page not present, bring it from disk or somewhere else
+    __print_panic_msg("WIP page fault route", param);
+    while (1);
 
-done:
-    while(1);
+segv_term:
+    kprintf(KERROR "(pid: %d) Segmentation fault on %p (%p:%p)\n", __current->pid, ptr, param->cs, param->eip);
+    terminate_proc(LXSEGFAULT);
+    // should not reach
 }
\ No newline at end of file