1 files changed, 253 insertions, 121 deletions

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 28ad7ab1c0c..eb8830a4c5e 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -11,16 +11,24 @@
 #include <linux/module.h>
 #include <linux/signal.h>
 #include <linux/mm.h>
+#include <linux/hardirq.h>
 #include <linux/init.h>
 #include <linux/kprobes.h>
+#include <linux/uaccess.h>
+#include <linux/page-flags.h>
+#include <linux/sched.h>
+#include <linux/highmem.h>
+#include <linux/perf_event.h>
 
-#include <asm/system.h>
+#include <asm/exception.h>
 #include <asm/pgtable.h>
+#include <asm/system_misc.h>
+#include <asm/system_info.h>
 #include <asm/tlbflush.h>
-#include <asm/uaccess.h>
 
 #include "fault.h"
 
+#ifdef CONFIG_MMU
 
 #ifdef CONFIG_KPROBES
 static inline int notify_page_fault(struct pt_regs *regs, unsigned int fsr)
@@ -57,9 +65,11 @@ void show_pte(struct mm_struct *mm, unsigned long addr)
 
 	printk(KERN_ALERT "pgd = %p\n", mm->pgd);
 	pgd = pgd_offset(mm, addr);
-	printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
+	printk(KERN_ALERT "[%08lx] *pgd=%08llx",
+			addr, (long long)pgd_val(*pgd));
 
 	do {
+		pud_t *pud;
 		pmd_t *pmd;
 		pte_t *pte;
 
@@ -71,10 +81,21 @@ void show_pte(struct mm_struct *mm, unsigned long addr)
 			break;
 		}
 
-		pmd = pmd_offset(pgd, addr);
-#if PTRS_PER_PMD != 1
-		printk(", *pmd=%08lx", pmd_val(*pmd));
-#endif
+		pud = pud_offset(pgd, addr);
+		if (PTRS_PER_PUD != 1)
+			printk(", *pud=%08llx", (long long)pud_val(*pud));
+
+		if (pud_none(*pud))
+			break;
+
+		if (pud_bad(*pud)) {
+			printk("(bad)");
+			break;
+		}
+
+		pmd = pmd_offset(pud, addr);
+		if (PTRS_PER_PMD != 1)
+			printk(", *pmd=%08llx", (long long)pmd_val(*pmd));
 
 		if (pmd_none(*pmd))
 			break;
@@ -84,17 +105,25 @@ void show_pte(struct mm_struct *mm, unsigned long addr)
 			break;
 		}
 
-#ifndef CONFIG_HIGHMEM
 		/* We must not map this if we have highmem enabled */
+		if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
+			break;
+
 		pte = pte_offset_map(pmd, addr);
-		printk(", *pte=%08lx", pte_val(*pte));
-		printk(", *ppte=%08lx", pte_val(pte[-PTRS_PER_PTE]));
-		pte_unmap(pte);
+		printk(", *pte=%08llx", (long long)pte_val(*pte));
+#ifndef CONFIG_ARM_LPAE
+		printk(", *ppte=%08llx",
+		       (long long)pte_val(pte[PTE_HWTABLE_PTRS]));
 #endif
+		pte_unmap(pte);
 	} while(0);
 
 	printk("\n");
 }
+#else					/* CONFIG_MMU */
+void show_pte(struct mm_struct *mm, unsigned long addr)
+{ }
+#endif					/* CONFIG_MMU */
 
 /*
  * Oops.  The kernel tried to access some page that wasn't present.
@@ -136,7 +165,8 @@ __do_user_fault(struct task_struct *tsk, unsigned long addr,
 	struct siginfo si;
 
 #ifdef CONFIG_DEBUG_USER
-	if (user_debug & UDBG_SEGV) {
+	if (((user_debug & UDBG_SEGV) && (sig == SIGSEGV)) ||
+	    ((user_debug & UDBG_BUS)  && (sig == SIGBUS))) {
 		printk(KERN_DEBUG "%s: unhandled page fault (%d) at 0x%08lx, code 0x%03x\n",
 		       tsk->comm, sig, addr, fsr);
 		show_pte(tsk->mm, addr);
@@ -169,21 +199,39 @@ void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 		__do_kernel_fault(mm, addr, fsr, regs);
 }
 
+#ifdef CONFIG_MMU
 #define VM_FAULT_BADMAP		0x010000
 #define VM_FAULT_BADACCESS	0x020000
 
-static int
+/*
+ * Check that the permissions on the VMA allow for the fault which occurred.
+ * If we encountered a write fault, we must have write permission, otherwise
+ * we allow any permission.
+ */
+static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
+{
+	unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
+
+	if (fsr & FSR_WRITE)
+		mask = VM_WRITE;
+	if (fsr & FSR_LNX_PF)
+		mask = VM_EXEC;
+
+	return vma->vm_flags & mask ? false : true;
+}
+
+static int __kprobes
 __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
-		struct task_struct *tsk)
+		unsigned int flags, struct task_struct *tsk)
 {
 	struct vm_area_struct *vma;
-	int fault, mask;
+	int fault;
 
 	vma = find_vma(mm, addr);
 	fault = VM_FAULT_BADMAP;
-	if (!vma)
+	if (unlikely(!vma))
 		goto out;
-	if (vma->vm_start > addr)
+	if (unlikely(vma->vm_start > addr))
 		goto check_stack;
 
 	/*
@@ -191,49 +239,17 @@ __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
 	 * memory access, so we can handle it.
 	 */
 good_area:
-	if (fsr & (1 << 11)) /* write? */
-		mask = VM_WRITE;
-	else
-		mask = VM_READ|VM_EXEC|VM_WRITE;
-
-	fault = VM_FAULT_BADACCESS;
-	if (!(vma->vm_flags & mask))
+	if (access_error(fsr, vma)) {
+		fault = VM_FAULT_BADACCESS;
 		goto out;
-
-	/*
-	 * If for any reason at all we couldn't handle
-	 * the fault, make sure we exit gracefully rather
-	 * than endlessly redo the fault.
-	 */
-survive:
-	fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, fsr & (1 << 11));
-	if (unlikely(fault & VM_FAULT_ERROR)) {
-		if (fault & VM_FAULT_OOM)
-			goto out_of_memory;
-		else if (fault & VM_FAULT_SIGBUS)
-			return fault;
-		BUG();
 	}
-	if (fault & VM_FAULT_MAJOR)
-		tsk->maj_flt++;
-	else
-		tsk->min_flt++;
-	return fault;
-
-out_of_memory:
-	if (!is_global_init(tsk))
-		goto out;
 
-	/*
-	 * If we are out of memory for pid1, sleep for a while and retry
-	 */
-	up_read(&mm->mmap_sem);
-	yield();
-	down_read(&mm->mmap_sem);
-	goto survive;
+	return handle_mm_fault(mm, vma, addr & PAGE_MASK, flags);
 
 check_stack:
-	if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
+	/* Don't allow expansion below FIRST_USER_ADDRESS */
+	if (vma->vm_flags & VM_GROWSDOWN &&
+	    addr >= FIRST_USER_ADDRESS && !expand_stack(vma, addr))
 		goto good_area;
 out:
 	return fault;
@@ -245,6 +261,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	struct task_struct *tsk;
 	struct mm_struct *mm;
 	int fault, sig, code;
+	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 
 	if (notify_page_fault(regs, fsr))
 		return 0;
@@ -252,6 +269,10 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	tsk = current;
 	mm  = tsk->mm;
 
+	/* Enable interrupts if they were enabled in the parent context. */
+	if (interrupts_enabled(regs))
+		local_irq_enable();
+
 	/*
 	 * If we're in an interrupt or have no user
 	 * context, we must not take the fault..
@@ -259,6 +280,11 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	if (in_atomic() || !mm)
 		goto no_context;
 
+	if (user_mode(regs))
+		flags |= FAULT_FLAG_USER;
+	if (fsr & FSR_WRITE)
+		flags |= FAULT_FLAG_WRITE;
+
 	/*
 	 * As per x86, we may deadlock here.  However, since the kernel only
 	 * validly references user space from well defined areas of the code,
@@ -267,10 +293,57 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	if (!down_read_trylock(&mm->mmap_sem)) {
 		if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
 			goto no_context;
+retry:
 		down_read(&mm->mmap_sem);
+	} else {
+		/*
+		 * The above down_read_trylock() might have succeeded in
+		 * which case, we'll have missed the might_sleep() from
+		 * down_read()
+		 */
+		might_sleep();
+#ifdef CONFIG_DEBUG_VM
+		if (!user_mode(regs) &&
+		    !search_exception_tables(regs->ARM_pc))
+			goto no_context;
+#endif
+	}
+
+	fault = __do_page_fault(mm, addr, fsr, flags, tsk);
+
+	/* If we need to retry but a fatal signal is pending, handle the
+	 * signal first. We do not need to release the mmap_sem because
+	 * it would already be released in __lock_page_or_retry in
+	 * mm/filemap.c. */
+	if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+		return 0;
+
+	/*
+	 * Major/minor page fault accounting is only done on the
+	 * initial attempt. If we go through a retry, it is extremely
+	 * likely that the page will be found in page cache at that point.
+	 */
+
+	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
+	if (!(fault & VM_FAULT_ERROR) && flags & FAULT_FLAG_ALLOW_RETRY) {
+		if (fault & VM_FAULT_MAJOR) {
+			tsk->maj_flt++;
+			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
+					regs, addr);
+		} else {
+			tsk->min_flt++;
+			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
+					regs, addr);
+		}
+		if (fault & VM_FAULT_RETRY) {
+			/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
+			* of starvation. */
+			flags &= ~FAULT_FLAG_ALLOW_RETRY;
+			flags |= FAULT_FLAG_TRIED;
+			goto retry;
+		}
 	}
 
-	fault = __do_page_fault(mm, addr, fsr, tsk);
 	up_read(&mm->mmap_sem);
 
 	/*
@@ -288,14 +361,14 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 
 	if (fault & VM_FAULT_OOM) {
 		/*
-		 * We ran out of memory, or some other thing
-		 * happened to us that made us unable to handle
-		 * the page fault gracefully.
+		 * We ran out of memory, call the OOM killer, and return to
+		 * userspace (which will retry the fault, or kill us if we
+		 * got oom-killed)
 		 */
-		printk("VM: killing process %s\n", tsk->comm);
-		do_group_exit(SIGKILL);
+		pagefault_out_of_memory();
 		return 0;
 	}
+
 	if (fault & VM_FAULT_SIGBUS) {
 		/*
 		 * We had some memory, but were unable to
@@ -320,6 +393,13 @@ no_context:
 	__do_kernel_fault(mm, addr, fsr, regs);
 	return 0;
 }
+#else					/* CONFIG_MMU */
+static int
+do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+	return 0;
+}
+#endif					/* CONFIG_MMU */
 
 /*
  * First Level Translation Fault Handler
@@ -338,35 +418,60 @@ no_context:
  * interrupt or a critical region, and should only copy the information
  * from the master page table, nothing more.
  */
+#ifdef CONFIG_MMU
 static int __kprobes
 do_translation_fault(unsigned long addr, unsigned int fsr,
 		     struct pt_regs *regs)
 {
 	unsigned int index;
 	pgd_t *pgd, *pgd_k;
+	pud_t *pud, *pud_k;
 	pmd_t *pmd, *pmd_k;
 
 	if (addr < TASK_SIZE)
 		return do_page_fault(addr, fsr, regs);
 
+	if (user_mode(regs))
+		goto bad_area;
+
 	index = pgd_index(addr);
 
-	/*
-	 * FIXME: CP15 C1 is write only on ARMv3 architectures.
-	 */
 	pgd = cpu_get_pgd() + index;
 	pgd_k = init_mm.pgd + index;
 
 	if (pgd_none(*pgd_k))
 		goto bad_area;
-
 	if (!pgd_present(*pgd))
 		set_pgd(pgd, *pgd_k);
 
-	pmd_k = pmd_offset(pgd_k, addr);
-	pmd   = pmd_offset(pgd, addr);
+	pud = pud_offset(pgd, addr);
+	pud_k = pud_offset(pgd_k, addr);
 
-	if (pmd_none(*pmd_k))
+	if (pud_none(*pud_k))
+		goto bad_area;
+	if (!pud_present(*pud))
+		set_pud(pud, *pud_k);
+
+	pmd = pmd_offset(pud, addr);
+	pmd_k = pmd_offset(pud_k, addr);
+
+#ifdef CONFIG_ARM_LPAE
+	/*
+	 * Only one hardware entry per PMD with LPAE.
+	 */
+	index = 0;
+#else
+	/*
+	 * On ARM one Linux PGD entry contains two hardware entries (see page
+	 * tables layout in pgtable.h). We normally guarantee that we always
+	 * fill both L1 entries. But create_mapping() doesn't follow the rule.
+	 * It can create inidividual L1 entries, so here we have to call
+	 * pmd_none() check for the entry really corresponded to address, not
+	 * for the first of pair.
+	 */
+	index = (addr >> SECTION_SHIFT) & 1;
+#endif
+	if (pmd_none(pmd_k[index]))
 		goto bad_area;
 
 	copy_pmd(pmd, pmd_k);
@@ -376,17 +481,27 @@ bad_area:
 	do_bad_area(addr, fsr, regs);
 	return 0;
 }
+#else					/* CONFIG_MMU */
+static int
+do_translation_fault(unsigned long addr, unsigned int fsr,
+		     struct pt_regs *regs)
+{
+	return 0;
+}
+#endif					/* CONFIG_MMU */
 
 /*
  * Some section permission faults need to be handled gracefully.
  * They can happen due to a __{get,put}_user during an oops.
  */
+#ifndef CONFIG_ARM_LPAE
 static int
 do_sect_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 {
 	do_bad_area(addr, fsr, regs);
 	return 0;
 }
+#endif /* CONFIG_ARM_LPAE */
 
 /*
  * This abort handler always returns "fault".
@@ -397,64 +512,31 @@ do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	return 1;
 }
 
-static struct fsr_info {
+struct fsr_info {
 	int	(*fn)(unsigned long addr, unsigned int fsr, struct pt_regs *regs);
 	int	sig;
 	int	code;
 	const char *name;
-} fsr_info[] = {
-	/*
-	 * The following are the standard ARMv3 and ARMv4 aborts.  ARMv5
-	 * defines these to be "precise" aborts.
-	 */
-	{ do_bad,		SIGSEGV, 0,		"vector exception"		   },
-	{ do_bad,		SIGILL,	 BUS_ADRALN,	"alignment exception"		   },
-	{ do_bad,		SIGKILL, 0,		"terminal exception"		   },
-	{ do_bad,		SIGILL,	 BUS_ADRALN,	"alignment exception"		   },
-	{ do_bad,		SIGBUS,	 0,		"external abort on linefetch"	   },
-	{ do_translation_fault,	SIGSEGV, SEGV_MAPERR,	"section translation fault"	   },
-	{ do_bad,		SIGBUS,	 0,		"external abort on linefetch"	   },
-	{ do_page_fault,	SIGSEGV, SEGV_MAPERR,	"page translation fault"	   },
-	{ do_bad,		SIGBUS,	 0,		"external abort on non-linefetch"  },
-	{ do_bad,		SIGSEGV, SEGV_ACCERR,	"section domain fault"		   },
-	{ do_bad,		SIGBUS,	 0,		"external abort on non-linefetch"  },
-	{ do_bad,		SIGSEGV, SEGV_ACCERR,	"page domain fault"		   },
-	{ do_bad,		SIGBUS,	 0,		"external abort on translation"	   },
-	{ do_sect_fault,	SIGSEGV, SEGV_ACCERR,	"section permission fault"	   },
-	{ do_bad,		SIGBUS,	 0,		"external abort on translation"	   },
-	{ do_page_fault,	SIGSEGV, SEGV_ACCERR,	"page permission fault"		   },
-	/*
-	 * The following are "imprecise" aborts, which are signalled by bit
-	 * 10 of the FSR, and may not be recoverable.  These are only
-	 * supported if the CPU abort handler supports bit 10.
-	 */
-	{ do_bad,		SIGBUS,  0,		"unknown 16"			   },
-	{ do_bad,		SIGBUS,  0,		"unknown 17"			   },
-	{ do_bad,		SIGBUS,  0,		"unknown 18"			   },
-	{ do_bad,		SIGBUS,  0,		"unknown 19"			   },
-	{ do_bad,		SIGBUS,  0,		"lock abort"			   }, /* xscale */
-	{ do_bad,		SIGBUS,  0,		"unknown 21"			   },
-	{ do_bad,		SIGBUS,  BUS_OBJERR,	"imprecise external abort"	   }, /* xscale */
-	{ do_bad,		SIGBUS,  0,		"unknown 23"			   },
-	{ do_bad,		SIGBUS,  0,		"dcache parity error"		   }, /* xscale */
-	{ do_bad,		SIGBUS,  0,		"unknown 25"			   },
-	{ do_bad,		SIGBUS,  0,		"unknown 26"			   },
-	{ do_bad,		SIGBUS,  0,		"unknown 27"			   },
-	{ do_bad,		SIGBUS,  0,		"unknown 28"			   },
-	{ do_bad,		SIGBUS,  0,		"unknown 29"			   },
-	{ do_bad,		SIGBUS,  0,		"unknown 30"			   },
-	{ do_bad,		SIGBUS,  0,		"unknown 31"			   }
 };
 
+/* FSR definition */
+#ifdef CONFIG_ARM_LPAE
+#include "fsr-3level.c"
+#else
+#include "fsr-2level.c"
+#endif
+
 void __init
 hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
-		int sig, const char *name)
+		int sig, int code, const char *name)
 {
-	if (nr >= 0 && nr < ARRAY_SIZE(fsr_info)) {
-		fsr_info[nr].fn   = fn;
-		fsr_info[nr].sig  = sig;
-		fsr_info[nr].name = name;
-	}
+	if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
+		BUG();
+
+	fsr_info[nr].fn   = fn;
+	fsr_info[nr].sig  = sig;
+	fsr_info[nr].code = code;
+	fsr_info[nr].name = name;
 }
 
 /*
@@ -463,10 +545,10 @@ hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *)
 asmlinkage void __exception
 do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 {
-	const struct fsr_info *inf = fsr_info + (fsr & 15) + ((fsr & (1 << 10)) >> 6);
+	const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
 	struct siginfo info;
 
-	if (!inf->fn(addr, fsr, regs))
+	if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
 		return;
 
 	printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
@@ -479,9 +561,59 @@ do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	arm_notify_die("", regs, &info, fsr, 0);
 }
 
+void __init
+hook_ifault_code(int nr, int (*fn)(unsigned long, unsigned int, struct pt_regs *),
+		 int sig, int code, const char *name)
+{
+	if (nr < 0 || nr >= ARRAY_SIZE(ifsr_info))
+		BUG();
+
+	ifsr_info[nr].fn   = fn;
+	ifsr_info[nr].sig  = sig;
+	ifsr_info[nr].code = code;
+	ifsr_info[nr].name = name;
+}
+
 asmlinkage void __exception
-do_PrefetchAbort(unsigned long addr, struct pt_regs *regs)
+do_PrefetchAbort(unsigned long addr, unsigned int ifsr, struct pt_regs *regs)
 {
-	do_translation_fault(addr, 0, regs);
+	const struct fsr_info *inf = ifsr_info + fsr_fs(ifsr);
+	struct siginfo info;
+
+	if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
+		return;
+
+	printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
+		inf->name, ifsr, addr);
+
+	info.si_signo = inf->sig;
+	info.si_errno = 0;
+	info.si_code  = inf->code;
+	info.si_addr  = (void __user *)addr;
+	arm_notify_die("", regs, &info, ifsr, 0);
+}
+
+#ifndef CONFIG_ARM_LPAE
+static int __init exceptions_init(void)
+{
+	if (cpu_architecture() >= CPU_ARCH_ARMv6) {
+		hook_fault_code(4, do_translation_fault, SIGSEGV, SEGV_MAPERR,
+				"I-cache maintenance fault");
+	}
+
+	if (cpu_architecture() >= CPU_ARCH_ARMv7) {
+		/*
+		 * TODO: Access flag faults introduced in ARMv6K.
+		 * Runtime check for 'K' extension is needed
+		 */
+		hook_fault_code(3, do_bad, SIGSEGV, SEGV_MAPERR,
+				"section access flag fault");
+		hook_fault_code(6, do_bad, SIGSEGV, SEGV_MAPERR,
+				"section access flag fault");
+	}
+
+	return 0;
 }
 
+arch_initcall(exceptions_init);
+#endif