From b69fb7699c92f85991672fc144b0adb7c717fbc8 Mon Sep 17 00:00:00 2001
From: David Ahern <david.ahern@oracle.com>
Date: Mon, 15 Jun 2015 16:15:45 -0400
Subject: [PATCH] sparc64: perf: Add sanity checking on addresses in user stack

Processes are getting killed (sigbus or segv) while walking userspace
callchains when using perf. In some instances I have seen ufp = 0x7ff
which does not seem like a proper stack address.

This patch adds a function to run validity checks against the address
before attempting the copy_from_user. The checks are copied from the
x86 version as a start point with the addition of a 4-byte alignment
check.

Signed-off-by: David Ahern <david.ahern@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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