patch-2.4.20 linux-2.4.20/arch/x86_64/mm/fault.c

• Lines: 358
• Date: Thu Nov 28 15:53:12 2002
• Orig file: linux-2.4.19/arch/x86_64/mm/fault.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.19/arch/x86_64/mm/fault.c linux-2.4.20/arch/x86_64/mm/fault.c
@@ -0,0 +1,357 @@
+/*
+ *  linux/arch/x86-64/mm/fault.c
+ *
+ *  Copyright (C) 1995  Linus Torvalds
+ *  Copyright (C) 2001,2002 Andi Kleen, SuSE Labs.
+ */
+
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/tty.h>
+#include <linux/vt_kern.h>		/* For unblank_screen() */
+#include <linux/compiler.h>
+
+#include <asm/system.h>
+#include <asm/uaccess.h>
+#include <asm/pgalloc.h>
+#include <asm/hardirq.h>
+#include <asm/smp.h>
+#include <asm/proto.h>
+#include <asm/kdebug.h>
+
+spinlock_t pcrash_lock; 
+int crashing_cpu;
+
+extern spinlock_t console_lock, timerlist_lock;
+
+void bust_spinlocks(int yes)
+{
+ 	spin_lock_init(&timerlist_lock);
+	if (yes) {
+		oops_in_progress = 1;
+#ifdef CONFIG_SMP
+		global_irq_lock = 0;	/* Many serial drivers do __global_cli() */
+#endif
+	} else {
+	int loglevel_save = console_loglevel;
+#ifdef CONFIG_VT
+		unblank_screen();
+#endif
+		oops_in_progress = 0;
+		/*
+		 * OK, the message is on the console.  Now we call printk()
+		 * without oops_in_progress set so that printk will give klogd
+		 * a poke.  Hold onto your hats...
+		 */
+		console_loglevel = 15;		/* NMI oopser may have shut the console up */
+		printk(" ");
+		console_loglevel = loglevel_save;
+	}
+}
+
+void dump_pagetable(unsigned long address)
+{
+	static char *name[] = { "PML4", "PGD", "PDE", "PTE" }; 
+	int i, shift;
+	unsigned long page;
+
+	shift = 9+9+9+12;
+	address &= ~0xFFFF000000000000UL;
+	asm("movq %%cr3,%0" : "=r" (page)); 
+	for (i = 0; i < 4; i++) { 	
+		unsigned long *padr = (unsigned long *) __va(page); 
+		padr += (address >> shift) & 0x1FFU;
+		if (__get_user(page, padr)) { 
+			printk("%s: bad %p\n", name[i], padr); 
+			break;
+		}
+		printk("%s: %016lx ", name[i], page); 
+		if ((page & (1 | (1<<7))) != 1) /* Not present or 2MB page */
+			break;
+		page &= ~0xFFFUL;
+		shift -= (i == 0) ? 12 : 9;
+	} 
+	printk("\n");
+}
+
+int page_fault_trace; 
+int exception_trace = 1;
+
+/*
+ * This routine handles page faults.  It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ *
+ * error_code:
+ *	bit 0 == 0 means no page found, 1 means protection fault
+ *	bit 1 == 0 means read, 1 means write
+ *	bit 2 == 0 means kernel, 1 means user-mode
+ *      bit 3 == 1 means fault was an instruction fetch
+ */
+asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code)
+{
+	struct task_struct *tsk;
+	struct mm_struct *mm;
+	struct vm_area_struct * vma;
+	unsigned long address;
+	unsigned long fixup;
+	int write;
+	siginfo_t info;
+
+	/* get the address */
+	__asm__("movq %%cr2,%0":"=r" (address));
+
+#ifdef CONFIG_CHECKING
+	if (page_fault_trace) 
+		printk("pfault %d rip:%lx rsp:%lx cs:%lu ss:%lu addr %lx error %lx\n",
+		       stack_smp_processor_id(), regs->rip,regs->rsp,regs->cs,
+			   regs->ss,address,error_code); 
+
+	{ 
+		unsigned long gs; 
+		struct x8664_pda *pda = cpu_pda + stack_smp_processor_id(); 
+		rdmsrl(MSR_GS_BASE, gs); 
+		if (gs != (unsigned long)pda) { 
+			wrmsrl(MSR_GS_BASE, pda); 
+			printk("page_fault: wrong gs %lx expected %p\n", gs, pda);
+		}
+	}
+#endif
+			
+	tsk = current;
+	mm = tsk->mm;
+	info.si_code = SEGV_MAPERR;
+
+	/* 5 => page not present and from supervisor mode */
+	if (unlikely(!(error_code & 5) &&
+		     ((address >= VMALLOC_START && address <= VMALLOC_END) ||
+		      (address >= MODULES_VADDR && address <= MODULES_END))))
+		goto vmalloc_fault;
+  
+	/*
+	 * If we're in an interrupt or have no user
+	 * context, we must not take the fault..
+	 */
+	if (in_interrupt() || !mm)
+		goto no_context;
+
+again:
+	down_read(&mm->mmap_sem);
+
+	vma = find_vma(mm, address);
+	if (!vma)
+		goto bad_area;
+	if (vma->vm_start <= address)
+		goto good_area;
+	if (!(vma->vm_flags & VM_GROWSDOWN))
+		goto bad_area;
+	if (error_code & 4) {
+		// XXX: align red zone size with ABI 
+		if (address + 128 < regs->rsp)
+			goto bad_area;
+	}
+	if (expand_stack(vma, address))
+		goto bad_area;
+/*
+ * Ok, we have a good vm_area for this memory access, so
+ * we can handle it..
+ */
+good_area:
+	info.si_code = SEGV_ACCERR;
+	write = 0;
+	switch (error_code & 3) {
+		default:	/* 3: write, present */
+			/* fall through */
+		case 2:		/* write, not present */
+			if (!(vma->vm_flags & VM_WRITE))
+				goto bad_area;
+			write++;
+			break;
+		case 1:		/* read, present */
+			goto bad_area;
+		case 0:		/* read, not present */
+			if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
+				goto bad_area;
+	}
+
+	/*
+	 * If for any reason at all we couldn't handle the fault,
+	 * make sure we exit gracefully rather than endlessly redo
+	 * the fault.
+	 */
+	switch (handle_mm_fault(mm, vma, address, write)) {
+	case 1:
+		tsk->min_flt++;
+		break;
+	case 2:
+		tsk->maj_flt++;
+		break;
+	case 0:
+		goto do_sigbus;
+	default:
+		goto out_of_memory;
+	}
+
+	up_read(&mm->mmap_sem);
+	return;
+
+/*
+ * Something tried to access memory that isn't in our memory map..
+ * Fix it, but check if it's kernel or user first..
+ */
+bad_area:
+	up_read(&mm->mmap_sem);
+
+bad_area_nosemaphore:
+
+	/* User mode accesses just cause a SIGSEGV */
+	if (error_code & 4) {
+		if (exception_trace) {
+#if 1
+			dump_pagetable(address);
+#endif	
+			printk("%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n",
+					current->comm, current->pid, address, regs->rip,
+					regs->rsp, error_code);
+		}
+		tsk->thread.cr2 = address;
+		tsk->thread.error_code = error_code;
+		tsk->thread.trap_no = 14;
+		info.si_signo = SIGSEGV;
+		info.si_errno = 0;
+		/* info.si_code has been set above */
+		info.si_addr = (void *)address;
+		force_sig_info(SIGSEGV, &info, tsk);
+		return;
+	}
+
+no_context:
+	
+	/* Are we prepared to handle this kernel fault?  */
+	if ((fixup = search_exception_table(regs->rip)) != 0) {
+		regs->rip = fixup;
+		if (0 && exception_trace) 
+		printk(KERN_ERR 
+		       "%s: fixed kernel exception at %lx address %lx err:%ld\n", 
+		       current->comm, regs->rip, address, error_code);
+		return;
+	}
+
+/*
+ * Oops. The kernel tried to access some bad page. We'll have to
+ * terminate things with extreme prejudice.
+ */
+
+	console_verbose();
+	bust_spinlocks(1); 
+
+	if (!in_interrupt()) { 
+		if (!spin_trylock(&pcrash_lock)) { 
+			if (crashing_cpu != smp_processor_id()) 
+				spin_lock(&pcrash_lock);  		    
+		} 
+		crashing_cpu = smp_processor_id();
+	} 
+
+	if (address < PAGE_SIZE)
+		printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
+	else
+		printk(KERN_ALERT "Unable to handle kernel paging request");
+	printk(" at virtual address %016lx\n",address);
+	printk(" printing rip:\n");
+	printk("%016lx\n", regs->rip);
+	dump_pagetable(address);
+
+	die("Oops", regs, error_code);
+
+	if (!in_interrupt()) { 
+		crashing_cpu = -1;  /* small harmless window */ 
+		spin_unlock(&pcrash_lock);
+	}
+
+	bust_spinlocks(0); 
+	do_exit(SIGKILL);
+
+/*
+ * We ran out of memory, or some other thing happened to us that made
+ * us unable to handle the page fault gracefully.
+ */
+out_of_memory:
+	up_read(&mm->mmap_sem);
+	if (current->pid == 1) { 
+		tsk->policy |= SCHED_YIELD;
+		schedule();
+		goto again;
+	}
+	printk("VM: killing process %s\n", tsk->comm);
+	if (error_code & 4)
+		do_exit(SIGKILL);
+	goto no_context;
+
+do_sigbus:
+	up_read(&mm->mmap_sem);
+
+	/*
+	 * Send a sigbus, regardless of whether we were in kernel
+	 * or user mode.
+	 */
+	tsk->thread.cr2 = address;
+	tsk->thread.error_code = error_code;
+	tsk->thread.trap_no = 14;
+	info.si_signo = SIGBUS;
+	info.si_errno = 0;
+	info.si_code = BUS_ADRERR;
+	info.si_addr = (void *)address;
+	force_sig_info(SIGBUS, &info, tsk);
+
+	/* Kernel mode? Handle exceptions or die */
+	if (!(error_code & 4))
+		goto no_context;
+	return;
+
+
+vmalloc_fault:
+	{
+		pgd_t *pgd;
+		pmd_t *pmd;
+		pte_t *pte; 
+
+		/* 
+		 * x86-64 has the same kernel 3rd level pages for all CPUs.
+		 * But for vmalloc/modules the TLB synchronization works lazily,
+		 * so it can happen that we get a page fault for something
+		 * that is really already in the page table. Just check if it
+		 * is really there and when yes flush the local TLB. 
+		 */
+#if 0
+		printk("vmalloc fault %lx index %lu\n",address,pml4_index(address));
+		dump_pagetable(address);
+#endif
+
+		pgd = pgd_offset_k(address);
+		if (pgd != current_pgd_offset_k(address)) 
+			goto bad_area_nosemaphore;	 
+		if (!pgd_present(*pgd))
+			goto bad_area_nosemaphore;
+		pmd = pmd_offset(pgd, address);
+		if (!pmd_present(*pmd))
+			goto bad_area_nosemaphore;
+		pte = pte_offset(pmd, address); 
+		if (!pte_present(*pte))
+			goto bad_area_nosemaphore; 
+
+		__flush_tlb_all();		
+		return;
+	}
+}