ARM: perf: disable the pagefault handler when reading from user space

[pandora-kernel.git] / arch / arm / kernel / perf_event.c

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 4a2db48..3d865f3 100644 (file)
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -778,11 +778,16 @@ user_backtrace(struct frame_tail __user *tail,
               struct perf_callchain_entry *entry)
 {
        struct frame_tail buftail;
+       unsigned long err;
 
-       /* Also check accessibility of one struct frame_tail beyond */
        if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
                return NULL;
-       if (__copy_from_user_inatomic(&buftail, tail, sizeof(buftail)))
+
+       pagefault_disable();
+       err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));
+       pagefault_enable();
+
+       if (err)
                return NULL;
 
        perf_callchain_store(entry, buftail.lr);
@@ -804,6 +809,10 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
 
 
        perf_callchain_store(entry, regs->ARM_pc);
+
+       if (!current->mm)
+               return;
+
        tail = (struct frame_tail __user *)regs->ARM_fp - 1;
 
        while ((entry->nr < PERF_MAX_STACK_DEPTH) &&