[ARM] Generic hook for page faults

Provide a method where various other parts of the kernel (eg,
alignment fault handler, PCI subsystems, etc) can hook into the
page fault processing to handle alignment and PCI faults
respectively.

7 files changed, 228 insertions, 224 deletions

diff --git a/arch/arm/mach-integrator/pci_v3.c b/arch/arm/mach-integrator/pci_v3.c
index 16c4544a322c..c7bdfa94e0ce 100644
--- a/arch/arm/mach-integrator/pci_v3.c
+++ b/arch/arm/mach-integrator/pci_v3.c
@@ -439,15 +439,16 @@ static int __init pci_v3_setup_resources(struct resource **resource)
 #define SC_LBFADDR (IO_ADDRESS(INTEGRATOR_SC_BASE) + 0x20)
 #define SC_LBFCODE (IO_ADDRESS(INTEGRATOR_SC_BASE) + 0x24)
 
-static int v3_fault(unsigned long addr, struct pt_regs *regs)
+static int
+v3_pci_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 {
 	unsigned long pc = instruction_pointer(regs);
 	unsigned long instr = *(unsigned long *)pc;
 #if 0
 	char buf[128];
 
-	sprintf(buf, "V3 fault: address=0x%08lx, pc=0x%08lx [%08lx] LBFADDR=%08x LBFCODE=%02x ISTAT=%02x\n",
-		addr, pc, instr, __raw_readl(SC_LBFADDR), __raw_readl(SC_LBFCODE) & 255,
+	sprintf(buf, "V3 fault: addr 0x%08lx, FSR 0x%03x, PC 0x%08lx [%08lx] LBFADDR=%08x LBFCODE=%02x ISTAT=%02x\n",
+		addr, fsr, pc, instr, __raw_readl(SC_LBFADDR), __raw_readl(SC_LBFCODE) & 255,
 		v3_readb(V3_LB_ISTAT));
 	printk(KERN_DEBUG "%s", buf);
 	printascii(buf);
@@ -515,8 +516,6 @@ static void v3_irq(int irq, void *devid, struct pt_regs *regs)
 #endif
 }
 
-extern int (*external_fault)(unsigned long addr, struct pt_regs *regs);
-
 int __init pci_v3_setup(int nr, struct pci_sys_data *sys)
 {
 	int ret = 0;
@@ -547,7 +546,10 @@ void __init pci_v3_preinit(void)
 	/*
 	 * Hook in our fault handler for PCI errors
 	 */
-	external_fault = v3_fault;
+	hook_fault_code(4, v3_pci_fault, SIGBUS, "external abort on linefetch");
+	hook_fault_code(6, v3_pci_fault, SIGBUS, "external abort on linefetch");
+	hook_fault_code(8, v3_pci_fault, SIGBUS, "external abort on non-linefetch");
+	hook_fault_code(10, v3_pci_fault, SIGBUS, "external abort on non-linefetch");
 
 	spin_lock_irqsave(&v3_lock, flags);
 
diff --git a/arch/arm/mach-iop310/iop310-pci.c b/arch/arm/mach-iop310/iop310-pci.c
index 3e1a5f6b4480..a92ff17fe834 100644
--- a/arch/arm/mach-iop310/iop310-pci.c
+++ b/arch/arm/mach-iop310/iop310-pci.c
@@ -106,19 +106,32 @@ static int iop310_pri_pci_status(void)
 	return ret;
 }
 
+static inline u32 iop310_pri_read(struct pci_dev *dev, int where)
+{
+	unsigned long addr = iop310_cfg_address(dev, where);
+	u32 val;
+
+	__asm__ __volatile__(
+		"str	%1, [%2]\n\t"
+		"ldr	%0, [%3]\n\t"
+		"nop\n\t"
+		"nop\n\t"
+		"nop\n\t"
+		"nop\n\t"
+		: "=r" (val)
+		: "r" (addr), "r" (IOP310_POCCAR), "r" (IOP310_POCCDR));
+
+	return val;
+}
+
 static int
 iop310_pri_rd_cfg_byte(struct pci_dev *dev, int where, u8 *p)
 {
-	int ret;
 	u8 val;
 
-	*IOP310_POCCAR = iop310_cfg_address(dev, where);
-
-	val = (*IOP310_POCCDR) >> ((where & 3) * 8);
-	__asm__ __volatile__("nop; nop; nop; nop");
+	val = iop310_pri_read(dev, where) >> ((where & 3) * 8);
 
-	ret = iop310_pri_pci_status();
-	if (ret)
+	if (iop310_pri_pci_status())
 		val = 0xff;
 
 	*p = val;
@@ -129,16 +142,11 @@ iop310_pri_rd_cfg_byte(struct pci_dev *dev, int where, u8 *p)
 static int
 iop310_pri_rd_cfg_word(struct pci_dev *dev, int where, u16 *p)
 {
-	int ret;
 	u16 val;
 
-	*IOP310_POCCAR = iop310_cfg_address(dev, where);
-
-	val = (*IOP310_POCCDR) >> ((where & 2) * 8);
-	__asm__ __volatile__("nop; nop; nop; nop");
+	val = iop310_pri_read(dev, where) >> ((where & 3) * 8);
 
-	ret = iop310_pri_pci_status();
-	if (ret)
+	if (iop310_pri_pci_status())
 		val = 0xffff;
 
 	*p = val;
@@ -149,16 +157,11 @@ iop310_pri_rd_cfg_word(struct pci_dev *dev, int where, u16 *p)
 static int
 iop310_pri_rd_cfg_dword(struct pci_dev *dev, int where, u32 *p)
 {
-	int ret;
 	u32 val;
 
-	*IOP310_POCCAR = iop310_cfg_address(dev, where);
+	val = iop310_pri_read(dev, where);
 
-	val = *IOP310_POCCDR;
-	__asm__ __volatile__("nop; nop; nop; nop");
-
-	ret = iop310_pri_pci_status();
-	if (ret)
+	if (iop310_pri_pci_status())
 		val = 0xffffffff;
 
 	*p = val;
@@ -169,16 +172,11 @@ iop310_pri_rd_cfg_dword(struct pci_dev *dev, int where, u32 *p)
 static int
 iop310_pri_wr_cfg_byte(struct pci_dev *dev, int where, u8 v)
 {
-	int ret;
 	u32 val;
 
-	*IOP310_POCCAR = iop310_cfg_address(dev, where);
+	val = iop310_pri_read(dev, where);
 
-	val = *IOP310_POCCDR;
-	__asm__ __volatile__("nop; nop; nop; nop");
-
-	ret = iop310_pri_pci_status();
-	if (ret == 0) {
+	if (iop310_pri_pci_status() == 0) {
 		where = (where & 3) * 8;
 		val &= ~(0xff << where);
 		val |= v << where;
@@ -191,16 +189,11 @@ iop310_pri_wr_cfg_byte(struct pci_dev *dev, int where, u8 v)
 static int
 iop310_pri_wr_cfg_word(struct pci_dev *dev, int where, u16 v)
 {
-	int ret;
 	u32 val;
 
-	*IOP310_POCCAR = iop310_cfg_address(dev, where);
-
-	val = *IOP310_POCCDR;
-	__asm__ __volatile__("nop; nop; nop; nop");
+	val = iop310_pri_read(dev, where);
 
-	ret = iop310_pri_pci_status();
-	if (ret == 0) {
+	if (iop310_pri_pci_status() == 0) {
 		where = (where & 2) * 8;
 		val &= ~(0xffff << where);
 		val |= v << where;
@@ -211,11 +204,21 @@ iop310_pri_wr_cfg_word(struct pci_dev *dev, int where, u16 v)
 }
 
 static int
-iop310_pri_wr_cfg_dword(struct pci_dev *dev, int where, u32 v)
+iop310_pri_wr_cfg_dword(struct pci_dev *dev, int where, u32 val)
 {
-	*IOP310_POCCAR = iop310_cfg_address(dev, where);
-	*IOP310_POCCDR = v;
-	__asm__ __volatile__("nop; nop; nop; nop");
+	unsigned long addr;
+
+	addr = iop310_cfg_address(dev, where);
+
+	__asm__ __volatile__(
+		"str	%1, [%2]\n\t"
+		"str	%0, [%3]\n\t"
+		"nop\n\t"
+		"nop\n\t"
+		"nop\n\t"
+		"nop\n\t"
+		:
+		: "r" (val), "r" (addr), "r" (IOP310_POCCAR), "r" (IOP310_POCCDR));
 
 	return PCIBIOS_SUCCESSFUL;
 }
@@ -248,28 +251,38 @@ static int iop310_sec_pci_status(void)
 		ret = 1;
 	}
 	if (ret)
-		DBG("ERROR (%08lx %08lx)", usr, uisr);
+		DBG("ERROR (%08x %08x)", usr, uisr);
 	return ret;
 }
 
+static inline u32 iop310_sec_read(struct pci_dev *dev, int where)
+{
+	unsigned long addr = iop310_cfg_address(dev, where);
+	u32 val;
+
+	__asm__ __volatile__(
+		"str	%1, [%2]\n\t"
+		"ldr	%0, [%3]\n\t"
+		"nop\n\t"
+		"nop\n\t"
+		"nop\n\t"
+		"nop\n\t"
+		: "=r" (val)
+		: "r" (addr), "r" (IOP310_SOCCAR), "r" (IOP310_SOCCDR));
+
+	return val;
+}
+
 static int
 iop310_sec_rd_cfg_byte(struct pci_dev *dev, int where, u8 *p)
 {
-	int ret;
 	u8 val;
 
-	DBG("rdb: %d:%02x.%x %02x ", dev->bus->number, PCI_SLOT(dev->devfn),
-	    PCI_FUNC(dev->devfn), where);
-	*IOP310_SOCCAR = iop310_cfg_address(dev, where);
+	val = iop310_sec_read(dev, where) >> ((where & 3) * 8);
 
-	val = (*IOP310_SOCCDR) >> ((where & 3) * 8);
-	__asm__ __volatile__("nop; nop; nop; nop");
-
-	DBG(">= %08lx ", val);
-	ret = iop310_sec_pci_status();
-	if (ret)
+	if (iop310_sec_pci_status())
 		val = 0xff;
-	DBG("\n");
+
 	*p = val;
 
 	return PCIBIOS_SUCCESSFUL;
@@ -278,21 +291,13 @@ iop310_sec_rd_cfg_byte(struct pci_dev *dev, int where, u8 *p)
 static int
 iop310_sec_rd_cfg_word(struct pci_dev *dev, int where, u16 *p)
 {
-	int ret;
 	u16 val;
 
-	DBG("rdw: %d:%02x.%x %02x ", dev->bus->number, PCI_SLOT(dev->devfn),
-	    PCI_FUNC(dev->devfn), where);
-	*IOP310_SOCCAR = iop310_cfg_address(dev, where);
-
-	val = (*IOP310_SOCCDR) >> ((where & 3) * 8);
-	__asm__ __volatile__("nop; nop; nop; nop");
+	val = iop310_sec_read(dev, where) >> ((where & 3) * 8);
 
-	DBG(">= %08lx ", val);
-	ret = iop310_sec_pci_status();
-	if (ret)
+	if (iop310_sec_pci_status())
 		val = 0xffff;
-	DBG("\n");
+
 	*p = val;
 
 	return PCIBIOS_SUCCESSFUL;
@@ -301,21 +306,13 @@ iop310_sec_rd_cfg_word(struct pci_dev *dev, int where, u16 *p)
 static int
 iop310_sec_rd_cfg_dword(struct pci_dev *dev, int where, u32 *p)
 {
-	int ret;
 	u32 val;
 
-	DBG("rdl: %d:%02x.%x %02x ", dev->bus->number, PCI_SLOT(dev->devfn),
-	    PCI_FUNC(dev->devfn), where);
-	*IOP310_SOCCAR = iop310_cfg_address(dev, where);
-
-	val = *IOP310_SOCCDR;
-	__asm__ __volatile__("nop; nop; nop; nop");
+	val = iop310_sec_read(dev, where);
 
-	DBG(">= %08lx ", val);
-	ret = iop310_sec_pci_status();
-	if (ret)
+	if (iop310_sec_pci_status())
 		val = 0xffffffff;
-	DBG("\n");
+
 	*p = val;
 
 	return PCIBIOS_SUCCESSFUL;
@@ -324,63 +321,54 @@ iop310_sec_rd_cfg_dword(struct pci_dev *dev, int where, u32 *p)
 static int
 iop310_sec_wr_cfg_byte(struct pci_dev *dev, int where, u8 v)
 {
-	int ret;
 	u32 val;
 
-	DBG("wrb: %d:%02x.%x %02x ", dev->bus->number, PCI_SLOT(dev->devfn),
-	    PCI_FUNC(dev->devfn), where);
-	*IOP310_SOCCAR = iop310_cfg_address(dev, where);
-
-	val = *IOP310_SOCCDR;
-	__asm__ __volatile__("nop; nop; nop; nop");
+	val = iop310_sec_read(dev, where);
 
-	DBG("<= %08lx", v);
-	ret = iop310_sec_pci_status();
-	if (ret == 0) {
+	if (iop310_sec_pci_status() == 0) {
 		where = (where & 3) * 8;
 		val &= ~(0xff << where);
 		val |= v << where;
 		*IOP310_SOCCDR = val;
 	}
-	DBG("\n");
+
 	return PCIBIOS_SUCCESSFUL;
 }
 
 static int
 iop310_sec_wr_cfg_word(struct pci_dev *dev, int where, u16 v)
 {
-	int ret;
 	u32 val;
 
-	DBG("wrw: %d:%02x.%x %02x ", dev->bus->number, PCI_SLOT(dev->devfn),
-	    PCI_FUNC(dev->devfn), where);
-	*IOP310_SOCCAR = iop310_cfg_address(dev, where);
+	val = iop310_sec_read(dev, where);
 
-	val = *IOP310_SOCCDR;
-	__asm__ __volatile__("nop; nop; nop; nop");
-
-	DBG("<= %08lx", v);
-	ret = iop310_sec_pci_status();
-	if (ret == 0) {
+	if (iop310_sec_pci_status() == 0) {
 		where = (where & 2) * 8;
 		val &= ~(0xffff << where);
 		val |= v << where;
 		*IOP310_SOCCDR = val;
 	}
-	DBG("\n");
+
 	return PCIBIOS_SUCCESSFUL;
 }
 
 static int
-iop310_sec_wr_cfg_dword(struct pci_dev *dev, int where, u32 v)
+iop310_sec_wr_cfg_dword(struct pci_dev *dev, int where, u32 val)
 {
-	DBG("wrl: %d:%02x.%x %02x ", dev->bus->number, PCI_SLOT(dev->devfn),
-	    PCI_FUNC(dev->devfn), where);
-	*IOP310_SOCCAR = iop310_cfg_address(dev, where);
-	*IOP310_SOCCDR = v;
-	__asm__ __volatile__("nop; nop; nop; nop");
+	unsigned long addr;
+
+	addr = iop310_cfg_address(dev, where);
+
+	__asm__ __volatile__(
+		"str	%1, [%2]\n\t"
+		"str	%0, [%3]\n\t"
+		"nop\n\t"
+		"nop\n\t"
+		"nop\n\t"
+		"nop\n\t"
+		:
+		: "r" (val), "r" (addr), "r" (IOP310_SOCCAR), "r" (IOP310_SOCCDR));
 
-	DBG("<= %08lx\n", v);
 	return PCIBIOS_SUCCESSFUL;
 }
 
@@ -394,13 +382,34 @@ static struct pci_ops iop310_secondary_ops = {
 };
 
 /*
- * When a PCI device does not exist during config cycles, the 80200 gets a
- * bus error instead of returning 0xffffffff. This handler simply returns.
+ * When a PCI device does not exist during config cycles, the 80200 gets
+ * an external abort instead of returning 0xffffffff.  If it was an
+ * imprecise abort, we need to correct the return address to point after
+ * the instruction.  Also note that the Xscale manual says:
+ *
+ *  "if a stall-until-complete LD or ST instruction triggers an
+ *  imprecise fault, then that fault will be seen by the program
+ *  within 3 instructions."
+ *
+ * This does not appear to be the case.  With 8 NOPs after the load, we
+ * see the imprecise abort occuring on the STM of iop310_sec_pci_status()
+ * which is about 10 instructions away.
+ *
+ * Always trust reality!
  */
-int iop310_pci_abort_handler(unsigned long addr, struct pt_regs *regs)
+static int
+iop310_pci_abort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 {
-	DBG("PCI abort: address = %08x PC = %08x LR = %08lx\n",
-		addr, regs->ARM_pc, regs->ARM_lr);
+	DBG("PCI abort: address = 0x%08lx fsr = 0x%03x PC = 0x%08lx LR = 0x%08lx\n",
+		addr, fsr, regs->ARM_pc, regs->ARM_lr);
+
+	/*
+	 * If it was an imprecise abort, then we need to correct the
+	 * return address to be _after_ the instruction.
+	 */
+	if (fsr & (1 << 10))
+		regs->ARM_pc += 4;
+
 	return 0;
 }
 
@@ -515,6 +524,5 @@ void iop310_init(void)
 	 */
 	*IOP310_PCR &= 0xfff8;
 
-	external_fault = iop310_pci_abort_handler;
+	hook_fault_code(6, iop310_pci_abort, SIGBUS, "imprecise external abort");
 }
-
diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
index 0e76c39dc3f5..0b678b1d7fdd 100644
--- a/arch/arm/mm/alignment.c
+++ b/arch/arm/mm/alignment.c
@@ -30,9 +30,7 @@
 #include <asm/pgtable.h>
 #include <asm/unaligned.h>
 
-extern void
-do_bad_area(struct task_struct *tsk, struct mm_struct *mm, unsigned long addr,
-	    int error_code, struct pt_regs *regs);
+#include "fault.h"
 
 /*
  * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998
@@ -130,31 +128,6 @@ static int proc_alignment_write(struct file *file, const char *buffer,
 	return count;
 }
 
-/*
- * This needs to be done after sysctl_init, otherwise sys/ will be
- * overwritten.  Actually, this shouldn't be in sys/ at all since
- * it isn't a sysctl, and it doesn't contain sysctl information.
- * We now locate it in /proc/cpu/alignment instead.
- */
-static int __init alignment_init(void)
-{
-	struct proc_dir_entry *res;
-
-	res = proc_mkdir("cpu", NULL);
-	if (!res)
-		return -ENOMEM;
-
-	res = create_proc_entry("alignment", S_IWUSR | S_IRUGO, res);
-	if (!res)
-		return -ENOMEM;
-
-	res->read_proc = proc_alignment_read;
-	res->write_proc = proc_alignment_write;
-
-	return 0;
-}
-
-__initcall(alignment_init);
 #endif /* CONFIG_PROC_FS */
 
 union offset_union {
@@ -486,7 +459,8 @@ bad:
 	return TYPE_ERROR;
 }
 
-int do_alignment(unsigned long addr, int error_code, struct pt_regs *regs)
+static int
+do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 {
 	union offset_union offset;
 	unsigned long instr, instrptr;
@@ -577,7 +551,7 @@ int do_alignment(unsigned long addr, int error_code, struct pt_regs *regs)
 	/*
 	 * We got a fault - fix it up, or die.
 	 */
-	do_bad_area(current, current->mm, addr, error_code, regs);
+	do_bad_area(current, current->mm, addr, fsr, regs);
 	return 0;
 
  bad:
@@ -594,8 +568,8 @@ int do_alignment(unsigned long addr, int error_code, struct pt_regs *regs)
 
 	if (ai_usermode & 1)
 		printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%08lx "
-		       "Address=0x%08lx Code 0x%02x\n", current->comm,
-			current->pid, instrptr, instr, addr, error_code);
+		       "Address=0x%08lx FSR 0x%03x\n", current->comm,
+			current->pid, instrptr, instr, addr, fsr);
 
 	if (ai_usermode & 2)
 		goto fixup;
@@ -607,3 +581,34 @@ int do_alignment(unsigned long addr, int error_code, struct pt_regs *regs)
 
 	return 0;
 }
+
+/*
+ * This needs to be done after sysctl_init, otherwise sys/ will be
+ * overwritten.  Actually, this shouldn't be in sys/ at all since
+ * it isn't a sysctl, and it doesn't contain sysctl information.
+ * We now locate it in /proc/cpu/alignment instead.
+ */
+static int __init alignment_init(void)
+{
+#ifdef CONFIG_PROC_FS
+	struct proc_dir_entry *res;
+
+	res = proc_mkdir("cpu", NULL);
+	if (!res)
+		return -ENOMEM;
+
+	res = create_proc_entry("alignment", S_IWUSR | S_IRUGO, res);
+	if (!res)
+		return -ENOMEM;
+
+	res->read_proc = proc_alignment_read;
+	res->write_proc = proc_alignment_write;
+#endif
+
+	hook_fault_code(1, do_alignment, SIGILL, "alignment exception");
+	hook_fault_code(3, do_alignment, SIGILL, "alignment exception");
+
+	return 0;
+}
+
+__initcall(alignment_init);
diff --git a/arch/arm/mm/fault-armv.c b/arch/arm/mm/fault-armv.c
index dea4ccc1e604..aa6333a7a659 100644
--- a/arch/arm/mm/fault-armv.c
+++ b/arch/arm/mm/fault-armv.c
@@ -2,102 +2,62 @@
  *  linux/arch/arm/mm/fault-armv.c
  *
  *  Copyright (C) 1995  Linus Torvalds
- *  Modifications for ARM processor (c) 1995-2001 Russell King
+ *  Modifications for ARM processor (c) 1995-2002 Russell King
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
  * published by the Free Software Foundation.
  */
-#include <linux/config.h>
-#include <linux/compiler.h>
-#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/interrupt.h>
-#include <linux/proc_fs.h>
 #include <linux/bitops.h>
 #include <linux/init.h>
 
-#include <asm/system.h>
-#include <asm/uaccess.h>
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>
 
-extern void die_if_kernel(const char *str, struct pt_regs *regs, int err);
-extern void show_pte(struct mm_struct *mm, unsigned long addr);
-extern int do_page_fault(unsigned long addr, int error_code,
-			 struct pt_regs *regs);
-extern int do_translation_fault(unsigned long addr, int error_code,
-				struct pt_regs *regs);
-extern void do_bad_area(struct task_struct *tsk, struct mm_struct *mm,
-			unsigned long addr, int error_code,
-			struct pt_regs *regs);
-
-#ifdef CONFIG_ALIGNMENT_TRAP
-extern int do_alignment(unsigned long addr, int error_code, struct pt_regs *regs);
-#else
-#define do_alignment do_bad
-#endif
-
+#include "fault.h"
 
 /*
  * Some section permission faults need to be handled gracefully.
  * They can happen due to a __{get,put}_user during an oops.
  */
 static int
-do_sect_fault(unsigned long addr, int error_code, struct pt_regs *regs)
+do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 {
 	struct task_struct *tsk = current;
-	do_bad_area(tsk, tsk->active_mm, addr, error_code, regs);
+	do_bad_area(tsk, tsk->active_mm, addr, fsr, regs);
 	return 0;
 }
 
 /*
- * Hook for things that need to trap external faults.  Note that
- * we don't guarantee that this will be the final version of the
- * interface.
- */
-int (*external_fault)(unsigned long addr, struct pt_regs *regs);
-
-static int
-do_external_fault(unsigned long addr, int error_code, struct pt_regs *regs)
-{
-	if (external_fault)
-		return external_fault(addr, regs);
-	return 1;
-}
-
-/*
  * This abort handler always returns "fault".
  */
 static int
-do_bad(unsigned long addr, int error_code, struct pt_regs *regs)
+do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 {
 	return 1;
 }
 
-static const struct fsr_info {
-	int	(*fn)(unsigned long addr, int error_code, struct pt_regs *regs);
+static struct fsr_info {
+	int	(*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
 	int	sig;
 	const char *name;
 } fsr_info[] = {
 	{ do_bad,		SIGSEGV, "vector exception"		   },
-	{ do_alignment,		SIGILL,	 "alignment exception"		   },
+	{ do_bad,		SIGILL,	 "alignment exception"		   },
 	{ do_bad,		SIGKILL, "terminal exception"		   },
-	{ do_alignment,		SIGILL,	 "alignment exception"		   },
-	{ do_external_fault,	SIGBUS,	 "external abort on linefetch"	   },
+	{ do_bad,		SIGILL,	 "alignment exception"		   },
+	{ do_bad,		SIGBUS,	 "external abort on linefetch"	   },
 	{ do_translation_fault,	SIGSEGV, "section translation fault"	   },
-	{ do_external_fault,	SIGBUS,	 "external abort on linefetch"	   },
+	{ do_bad,		SIGBUS,	 "external abort on linefetch"	   },
 	{ do_page_fault,	SIGSEGV, "page translation fault"	   },
-	{ do_external_fault,	SIGBUS,	 "external abort on non-linefetch" },
+	{ do_bad,		SIGBUS,	 "external abort on non-linefetch" },
 	{ do_bad,		SIGSEGV, "section domain fault"		   },
-	{ do_external_fault,	SIGBUS,	 "external abort on non-linefetch" },
+	{ do_bad,		SIGBUS,	 "external abort on non-linefetch" },
 	{ do_bad,		SIGSEGV, "page domain fault"		   },
 	{ do_bad,		SIGBUS,	 "external abort on translation"   },
 	{ do_sect_fault,	SIGSEGV, "section permission fault"	   },
@@ -105,6 +65,17 @@ static const struct fsr_info {
 	{ do_page_fault,	SIGSEGV, "page permission fault"	   }
 };
 
+void __init
+hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
+		int sig, const char *name)
+{
+	if (nr >= 0 && nr < 16) {
+		fsr_info[nr].fn   = fn;
+		fsr_info[nr].sig  = sig;
+		fsr_info[nr].name = name;
+	}
+}
+
 /*
  * Dispatch a data abort to the relevant handler.
  */
diff --git a/arch/arm/mm/fault-common.c b/arch/arm/mm/fault-common.c
index 37770f82b356..37c2d96302c4 100644
--- a/arch/arm/mm/fault-common.c
+++ b/arch/arm/mm/fault-common.c
@@ -23,9 +23,9 @@
 #include <linux/init.h>
 
 #include <asm/system.h>
-#include <asm/uaccess.h>
 #include <asm/pgtable.h>
-#include <asm/unaligned.h>
+
+#include "fault.h"
 
 #ifdef CONFIG_CPU_26
 #define FAULT_CODE_WRITE	0x02
@@ -43,8 +43,6 @@
 #define READ_FAULT(code)	(!DO_COW(code))
 #endif
 
-NORET_TYPE void die(const char *msg, struct pt_regs *regs, int err) ATTRIB_NORET;
-
 /*
  * This is useful to dump out the page tables associated with
  * 'addr' in mm 'mm'.
@@ -101,7 +99,7 @@ void show_pte(struct mm_struct *mm, unsigned long addr)
  * Oops.  The kernel tried to access some page that wasn't present.
  */
 static void
-__do_kernel_fault(struct mm_struct *mm, unsigned long addr, int error_code,
+__do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
 		  struct pt_regs *regs)
 {
 	unsigned long fixup;
@@ -127,7 +125,7 @@ __do_kernel_fault(struct mm_struct *mm, unsigned long addr, int error_code,
 		"paging request", addr);
 
 	show_pte(mm, addr);
-	die("Oops", regs, error_code);
+	die("Oops", regs, fsr);
 	do_exit(SIGKILL);
 }
 
@@ -136,20 +134,20 @@ __do_kernel_fault(struct mm_struct *mm, unsigned long addr, int error_code,
  * User mode accesses just cause a SIGSEGV
  */
 static void
-__do_user_fault(struct task_struct *tsk, unsigned long addr, int error_code,
-		int code, struct pt_regs *regs)
+__do_user_fault(struct task_struct *tsk, unsigned long addr,
+		unsigned int fsr, int code, struct pt_regs *regs)
 {
 	struct siginfo si;
 
 #ifdef CONFIG_DEBUG_USER
 	printk(KERN_DEBUG "%s: unhandled page fault at 0x%08lx, code 0x%03x\n",
-	       tsk->comm, addr, error_code);
+	       tsk->comm, addr, fsr);
 	show_pte(tsk->mm, addr);
 	show_regs(regs);
 #endif
 
 	tsk->thread.address = addr;
-	tsk->thread.error_code = error_code;
+	tsk->thread.error_code = fsr;
 	tsk->thread.trap_no = 14;
 	si.si_signo = SIGSEGV;
 	si.si_errno = 0;
@@ -160,20 +158,20 @@ __do_user_fault(struct task_struct *tsk, unsigned long addr, int error_code,
 
 void
 do_bad_area(struct task_struct *tsk, struct mm_struct *mm, unsigned long addr,
-	    int error_code, struct pt_regs *regs)
+	    unsigned int fsr, struct pt_regs *regs)
 {
 	/*
 	 * If we are in kernel mode at this point, we
 	 * have no context to handle this fault with.
 	 */
 	if (user_mode(regs))
-		__do_user_fault(tsk, addr, error_code, SEGV_MAPERR, regs);
+		__do_user_fault(tsk, addr, fsr, SEGV_MAPERR, regs);
 	else
-		__do_kernel_fault(mm, addr, error_code, regs);
+		__do_kernel_fault(mm, addr, fsr, regs);
 }
 
 static int
-__do_page_fault(struct mm_struct *mm, unsigned long addr, int error_code,
+__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
 		struct task_struct *tsk)
 {
 	struct vm_area_struct *vma;
@@ -191,7 +189,7 @@ __do_page_fault(struct mm_struct *mm, unsigned long addr, int error_code,
 	 * memory access, so we can handle it.
 	 */
 good_area:
-	if (READ_FAULT(error_code)) /* read? */
+	if (READ_FAULT(fsr)) /* read? */
 		mask = VM_READ|VM_EXEC;
 	else
 		mask = VM_WRITE;
@@ -206,7 +204,7 @@ good_area:
 	 * than endlessly redo the fault.
 	 */
 survive:
-	fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, DO_COW(error_code));
+	fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, DO_COW(fsr));
 
 	/*
 	 * Handle the "normal" cases first - successful and sigbus
@@ -239,7 +237,7 @@ out:
 	return fault;
 }
 
-int do_page_fault(unsigned long addr, int error_code, struct pt_regs *regs)
+int do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 {
 	struct task_struct *tsk;
 	struct mm_struct *mm;
@@ -256,7 +254,7 @@ int do_page_fault(unsigned long addr, int error_code, struct pt_regs *regs)
 		goto no_context;
 
 	down_read(&mm->mmap_sem);
-	fault = __do_page_fault(mm, addr, error_code, tsk);
+	fault = __do_page_fault(mm, addr, fsr, tsk);
 	up_read(&mm->mmap_sem);
 
 	/*
@@ -287,7 +285,7 @@ int do_page_fault(unsigned long addr, int error_code, struct pt_regs *regs)
 		printk("VM: killing process %s\n", tsk->comm);
 		do_exit(SIGKILL);
 	} else
-		__do_user_fault(tsk, addr, error_code, fault == -1 ?
+		__do_user_fault(tsk, addr, fsr, fault == -1 ?
 				SEGV_ACCERR : SEGV_MAPERR, regs);
 	return 0;
 
@@ -302,7 +300,7 @@ do_sigbus:
 	 * or user mode.
 	 */
 	tsk->thread.address = addr;
-	tsk->thread.error_code = error_code;
+	tsk->thread.error_code = fsr;
 	tsk->thread.trap_no = 14;
 	force_sig(SIGBUS, tsk);
 #ifdef CONFIG_DEBUG_USER
@@ -315,7 +313,7 @@ do_sigbus:
 		return 0;
 
 no_context:
-	__do_kernel_fault(mm, addr, error_code, regs);
+	__do_kernel_fault(mm, addr, fsr, regs);
 	return 0;
 }
 
@@ -336,7 +334,8 @@ no_context:
  * interrupt or a critical region, and should only copy the information
  * from the master page table, nothing more.
  */
-int do_translation_fault(unsigned long addr, int error_code, struct pt_regs *regs)
+int do_translation_fault(unsigned long addr, unsigned int fsr,
+			 struct pt_regs *regs)
 {
 	struct task_struct *tsk;
 	unsigned int offset;
@@ -344,7 +343,7 @@ int do_translation_fault(unsigned long addr, int error_code, struct pt_regs *reg
 	pmd_t *pmd, *pmd_k;
 
 	if (addr < TASK_SIZE)
-		return do_page_fault(addr, error_code, regs);
+		return do_page_fault(addr, fsr, regs);
 
 	offset = __pgd_offset(addr);
 
@@ -372,6 +371,6 @@ int do_translation_fault(unsigned long addr, int error_code, struct pt_regs *reg
 bad_area:
 	tsk = current;
 
-	do_bad_area(tsk, tsk->active_mm, addr, error_code, regs);
+	do_bad_area(tsk, tsk->active_mm, addr, fsr, regs);
 	return 0;
 }
diff --git a/arch/arm/mm/fault.h b/arch/arm/mm/fault.h
new file mode 100644
index 000000000000..b4d709819aae
--- /dev/null
+++ b/arch/arm/mm/fault.h
@@ -0,0 +1,8 @@
+void do_bad_area(struct task_struct *tsk, struct mm_struct *mm,
+		 unsigned long addr, unsigned int fsr, struct pt_regs *regs);
+
+void show_pte(struct mm_struct *mm, unsigned long addr);
+
+int do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
+
+int do_translation_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
diff --git a/include/asm-arm/system.h b/include/asm-arm/system.h
index 67f15f1be682..d9a68af9d5f9 100644
--- a/include/asm-arm/system.h
+++ b/include/asm-arm/system.h
@@ -24,6 +24,17 @@ extern int have_isa_bridge;
 #define have_isa_bridge		(0)
 #endif
 
+struct pt_regs;
+
+void die(const char *msg, struct pt_regs *regs, int err)
+		__attribute__((noreturn));
+
+void die_if_kernel(const char *str, struct pt_regs *regs, int err);
+
+void hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int,
+				       struct pt_regs *),
+		     int sig, const char *name);
+
 #include <asm/proc-fns.h>
 
 #define xchg(ptr,x) \