1 files changed, 276 insertions, 0 deletions
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
new file mode 100644
index 00000000..dafc9471
--- /dev/null
+++ b/arch/um/kernel/trap.c
@@ -0,0 +1,276 @@
+/*
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/hardirq.h>
+#include <linux/module.h>
+#include <asm/current.h>
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+#include "arch.h"
+#include "as-layout.h"
+#include "kern_util.h"
+#include "os.h"
+#include "skas.h"
+
+/*
+ * Note this is constrained to return 0, -EFAULT, -EACCESS, -ENOMEM by
+ * segv().
+ */
+int handle_page_fault(unsigned long address, unsigned long ip,
+		      int is_write, int is_user, int *code_out)
+{
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+	int err = -EFAULT;
+
+	*code_out = SEGV_MAPERR;
+
+	/*
+	 * If the fault was during atomic operation, don't take the fault, just
+	 * fail.
+	 */
+	if (in_atomic())
+		goto out_nosemaphore;
+
+	down_read(&mm->mmap_sem);
+	vma = find_vma(mm, address);
+	if (!vma)
+		goto out;
+	else if (vma->vm_start <= address)
+		goto good_area;
+	else if (!(vma->vm_flags & VM_GROWSDOWN))
+		goto out;
+	else if (is_user && !ARCH_IS_STACKGROW(address))
+		goto out;
+	else if (expand_stack(vma, address))
+		goto out;
+
+good_area:
+	*code_out = SEGV_ACCERR;
+	if (is_write && !(vma->vm_flags & VM_WRITE))
+		goto out;
+
+	/* Don't require VM_READ|VM_EXEC for write faults! */
+	if (!is_write && !(vma->vm_flags & (VM_READ | VM_EXEC)))
+		goto out;
+
+	do {
+		int fault;
+
+		fault = handle_mm_fault(mm, vma, address, is_write ? FAULT_FLAG_WRITE : 0);
+		if (unlikely(fault & VM_FAULT_ERROR)) {
+			if (fault & VM_FAULT_OOM) {
+				goto out_of_memory;
+			} else if (fault & VM_FAULT_SIGBUS) {
+				err = -EACCES;
+				goto out;
+			}
+			BUG();
+		}
+		if (fault & VM_FAULT_MAJOR)
+			current->maj_flt++;
+		else
+			current->min_flt++;
+
+		pgd = pgd_offset(mm, address);
+		pud = pud_offset(pgd, address);
+		pmd = pmd_offset(pud, address);
+		pte = pte_offset_kernel(pmd, address);
+	} while (!pte_present(*pte));
+	err = 0;
+	/*
+	 * The below warning was added in place of
+	 *	pte_mkyoung(); if (is_write) pte_mkdirty();
+	 * If it's triggered, we'd see normally a hang here (a clean pte is
+	 * marked read-only to emulate the dirty bit).
+	 * However, the generic code can mark a PTE writable but clean on a
+	 * concurrent read fault, triggering this harmlessly. So comment it out.
+	 */
+#if 0
+	WARN_ON(!pte_young(*pte) || (is_write && !pte_dirty(*pte)));
+#endif
+	flush_tlb_page(vma, address);
+out:
+	up_read(&mm->mmap_sem);
+out_nosemaphore:
+	return err;
+
+out_of_memory:
+	/*
+	 * We ran out of memory, call the OOM killer, and return the userspace
+	 * (which will retry the fault, or kill us if we got oom-killed).
+	 */
+	up_read(&mm->mmap_sem);
+	pagefault_out_of_memory();
+	return 0;
+}
+EXPORT_SYMBOL(handle_page_fault);
+
+static void show_segv_info(struct uml_pt_regs *regs)
+{
+	struct task_struct *tsk = current;
+	struct faultinfo *fi = UPT_FAULTINFO(regs);
+
+	if (!unhandled_signal(tsk, SIGSEGV))
+		return;
+
+	if (!printk_ratelimit())
+		return;
+
+	printk("%s%s[%d]: segfault at %lx ip %p sp %p error %x",
+		task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG,
+		tsk->comm, task_pid_nr(tsk), FAULT_ADDRESS(*fi),
+		(void *)UPT_IP(regs), (void *)UPT_SP(regs),
+		fi->error_code);
+
+	print_vma_addr(KERN_CONT " in ", UPT_IP(regs));
+	printk(KERN_CONT "\n");
+}
+
+static void bad_segv(struct faultinfo fi, unsigned long ip)
+{
+	struct siginfo si;
+
+	si.si_signo = SIGSEGV;
+	si.si_code = SEGV_ACCERR;
+	si.si_addr = (void __user *) FAULT_ADDRESS(fi);
+	current->thread.arch.faultinfo = fi;
+	force_sig_info(SIGSEGV, &si, current);
+}
+
+void fatal_sigsegv(void)
+{
+	force_sigsegv(SIGSEGV, current);
+	do_signal();
+	/*
+	 * This is to tell gcc that we're not returning - do_signal
+	 * can, in general, return, but in this case, it's not, since
+	 * we just got a fatal SIGSEGV queued.
+	 */
+	os_dump_core();
+}
+
+void segv_handler(int sig, struct uml_pt_regs *regs)
+{
+	struct faultinfo * fi = UPT_FAULTINFO(regs);
+
+	if (UPT_IS_USER(regs) && !SEGV_IS_FIXABLE(fi)) {
+		show_segv_info(regs);
+		bad_segv(*fi, UPT_IP(regs));
+		return;
+	}
+	segv(*fi, UPT_IP(regs), UPT_IS_USER(regs), regs);
+}
+
+/*
+ * We give a *copy* of the faultinfo in the regs to segv.
+ * This must be done, since nesting SEGVs could overwrite
+ * the info in the regs. A pointer to the info then would
+ * give us bad data!
+ */
+unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user,
+		   struct uml_pt_regs *regs)
+{
+	struct siginfo si;
+	jmp_buf *catcher;
+	int err;
+	int is_write = FAULT_WRITE(fi);
+	unsigned long address = FAULT_ADDRESS(fi);
+
+	if (!is_user && (address >= start_vm) && (address < end_vm)) {
+		flush_tlb_kernel_vm();
+		return 0;
+	}
+	else if (current->mm == NULL) {
+		show_regs(container_of(regs, struct pt_regs, regs));
+		panic("Segfault with no mm");
+	}
+
+	if (SEGV_IS_FIXABLE(&fi) || SEGV_MAYBE_FIXABLE(&fi))
+		err = handle_page_fault(address, ip, is_write, is_user,
+					&si.si_code);
+	else {
+		err = -EFAULT;
+		/*
+		 * A thread accessed NULL, we get a fault, but CR2 is invalid.
+		 * This code is used in __do_copy_from_user() of TT mode.
+		 * XXX tt mode is gone, so maybe this isn't needed any more
+		 */
+		address = 0;
+	}
+
+	catcher = current->thread.fault_catcher;
+	if (!err)
+		return 0;
+	else if (catcher != NULL) {
+		current->thread.fault_addr = (void *) address;
+		UML_LONGJMP(catcher, 1);
+	}
+	else if (current->thread.fault_addr != NULL)
+		panic("fault_addr set but no fault catcher");
+	else if (!is_user && arch_fixup(ip, regs))
+		return 0;
+
+	if (!is_user) {
+		show_regs(container_of(regs, struct pt_regs, regs));
+		panic("Kernel mode fault at addr 0x%lx, ip 0x%lx",
+		      address, ip);
+	}
+
+	show_segv_info(regs);
+
+	if (err == -EACCES) {
+		si.si_signo = SIGBUS;
+		si.si_errno = 0;
+		si.si_code = BUS_ADRERR;
+		si.si_addr = (void __user *)address;
+		current->thread.arch.faultinfo = fi;
+		force_sig_info(SIGBUS, &si, current);
+	} else {
+		BUG_ON(err != -EFAULT);
+		si.si_signo = SIGSEGV;
+		si.si_addr = (void __user *) address;
+		current->thread.arch.faultinfo = fi;
+		force_sig_info(SIGSEGV, &si, current);
+	}
+	return 0;
+}
+
+void relay_signal(int sig, struct uml_pt_regs *regs)
+{
+	if (!UPT_IS_USER(regs)) {
+		if (sig == SIGBUS)
+			printk(KERN_ERR "Bus error - the host /dev/shm or /tmp "
+			       "mount likely just ran out of space\n");
+		panic("Kernel mode signal %d", sig);
+	}
+
+	arch_examine_signal(sig, regs);
+
+	current->thread.arch.faultinfo = *UPT_FAULTINFO(regs);
+	force_sig(sig, current);
+}
+
+void bus_handler(int sig, struct uml_pt_regs *regs)
+{
+	if (current->thread.fault_catcher != NULL)
+		UML_LONGJMP(current->thread.fault_catcher, 1);
+	else relay_signal(sig, regs);
+}
+
+void winch(int sig, struct uml_pt_regs *regs)
+{
+	do_IRQ(WINCH_IRQ, regs);
+}
+
+void trap_init(void)
+{
+}