From 941091024ef0f2f7e09eb81201d293ac18833cc8 Mon Sep 17 00:00:00 2001
From: Franck Bui-Huu <fbuihuu@gmail.com>
Date: Thu, 19 Jul 2007 14:04:21 +0200
Subject: [PATCH] [MIPS] User stack pointer randomisation

Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
---
 arch/mips/kernel/process.c | 14 ++++++++++++++
 include/asm-mips/system.h  |  2 +-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 8f4cf27c7157..bd05f5a927ea 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -25,7 +25,9 @@
 #include <linux/init.h>
 #include <linux/completion.h>
 #include <linux/kallsyms.h>
+#include <linux/random.h>
 
+#include <asm/asm.h>
 #include <asm/bootinfo.h>
 #include <asm/cpu.h>
 #include <asm/dsp.h>
@@ -460,3 +462,15 @@ unsigned long get_wchan(struct task_struct *task)
 out:
 	return pc;
 }
+
+/*
+ * Don't forget that the stack pointer must be aligned on a 8 bytes
+ * boundary for 32-bits ABI and 16 bytes for 64-bits ABI.
+ */
+unsigned long arch_align_stack(unsigned long sp)
+{
+	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
+		sp -= get_random_int() & ~PAGE_MASK;
+
+	return sp & ALMASK;
+}
diff --git a/include/asm-mips/system.h b/include/asm-mips/system.h
index eba2e3da9abe..8d0b1cd4a45e 100644
--- a/include/asm-mips/system.h
+++ b/include/asm-mips/system.h
@@ -470,6 +470,6 @@ extern int stop_a_enabled;
  */
 #define __ARCH_WANT_UNLOCKED_CTXSW
 
-#define arch_align_stack(x) (x)
+extern unsigned long arch_align_stack(unsigned long sp);
 
 #endif /* _ASM_SYSTEM_H */