1 files changed, 117 insertions, 49 deletions

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index cc8829d7e116..10e06801afb3 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -25,6 +25,19 @@
 
 #include "fault.h"
 
+/*
+ * Fault status register encodings.  We steal bit 31 for our own purposes.
+ */
+#define FSR_LNX_PF              (1 << 31)
+#define FSR_WRITE               (1 << 11)
+#define FSR_FS4                 (1 << 10)
+#define FSR_FS3_0               (15)
+
+static inline int fsr_fs(unsigned int fsr)
+{
+        return (fsr & FSR_FS3_0) | (fsr & FSR_FS4) >> 6;
+}
+
 #ifdef CONFIG_MMU
 
 #ifdef CONFIG_KPROBES
@@ -182,18 +195,35 @@ void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 #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)
 {
         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;
 
         /*
@@ -201,47 +231,24 @@ __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.
+         * 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)) ? 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)
-                        return fault;
-                BUG();
-        }
+        fault = handle_mm_fault(mm, vma, addr & PAGE_MASK, (fsr & FSR_WRITE) ? FAULT_FLAG_WRITE : 0);
+        if (unlikely(fault & VM_FAULT_ERROR))
+                return fault;
         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;
-
 check_stack:
         if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
                 goto good_area;
@@ -278,6 +285,18 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
                 if (!user_mode(regs) && !search_exception_tables(regs->ARM_pc))
                         goto no_context;
                 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, tsk);
@@ -289,6 +308,16 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
         if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
                 return 0;
 
+        if (fault & VM_FAULT_OOM) {
+                /*
+                 * 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)
+                 */
+                pagefault_out_of_memory();
+                return 0;
+        }
+
         /*
          * If we are in kernel mode at this point, we
          * have no context to handle this fault with.
@@ -296,16 +325,6 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
         if (!user_mode(regs))
                 goto no_context;
 
-        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.
-                 */
-                printk("VM: killing process %s\n", tsk->comm);
-                do_group_exit(SIGKILL);
-                return 0;
-        }
         if (fault & VM_FAULT_SIGBUS) {
                 /*
                  * We had some memory, but were unable to
@@ -489,10 +508,10 @@ 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",
@@ -505,9 +524,58 @@ do_DataAbort(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
         arm_notify_die("", regs, &info, fsr, 0);
 }
 
+
+static struct fsr_info ifsr_info[] = {
+        { do_bad,               SIGBUS,  0,             "unknown 0"                        },
+        { do_bad,               SIGBUS,  0,             "unknown 1"                        },
+        { do_bad,               SIGBUS,  0,             "debug event"                      },
+        { do_bad,               SIGSEGV, SEGV_ACCERR,   "section access flag fault"        },
+        { do_bad,               SIGBUS,  0,             "unknown 4"                        },
+        { do_translation_fault, SIGSEGV, SEGV_MAPERR,   "section translation fault"        },
+        { do_bad,               SIGSEGV, SEGV_ACCERR,   "page access flag fault"           },
+        { 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,             "unknown 10"                       },
+        { 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"            },
+        { 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,             "unknown 20"                       },
+        { do_bad,               SIGBUS,  0,             "unknown 21"                       },
+        { do_bad,               SIGBUS,  0,             "unknown 22"                       },
+        { do_bad,               SIGBUS,  0,             "unknown 23"                       },
+        { do_bad,               SIGBUS,  0,             "unknown 24"                       },
+        { 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"                       },
+};
+
 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);
 }