From 1f474646fdc36b457606bbcd6a3592e6cbd31ac4 Mon Sep 17 00:00:00 2001
From: "David S. Miller" <davem@davemloft.net>
Date: Fri, 19 Feb 2010 15:19:52 -0800
Subject: [PATCH] sparc64: Fix sun4u execute bit check in TSB I-TLB load.
Thanks to testcase and report from Brad Spengler:
--------------------
#include <stdio.h>
typedef int (* _wee)(void);
int main(void)
{
char buf[8] = { '\x81', '\xc7', '\xe0', '\x08', '\x81', '\xe8',
'\x00', '\x00' };
_wee wee;
printf("%p\n", &buf);
wee = (_wee)&buf;
wee();
return 0;
}
--------------------
TSB I-tlb load code tries to use andcc to check the _PAGE_EXEC_4U bit,
but that's bit 12 so it gets sign extended all the way up to bit 63
and the test nearly always passes as a result.
Use sethi to fix the bug.
Signed-off-by: David S. Miller <davem@davemloft.net>
---
arch/sparc/kernel/tsb.S | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/sparc/kernel/tsb.S b/arch/sparc/kernel/tsb.S
index 8c91d9b29a2f2..db15d123f0544 100644
--- a/arch/sparc/kernel/tsb.S
+++ b/arch/sparc/kernel/tsb.S
@@ -191,10 +191,12 @@ tsb_dtlb_load:
tsb_itlb_load:
/* Executable bit must be set. */
-661: andcc %g5, _PAGE_EXEC_4U, %g0
- .section .sun4v_1insn_patch, "ax"
+661: sethi %hi(_PAGE_EXEC_4U), %g4
+ andcc %g5, %g4, %g0
+ .section .sun4v_2insn_patch, "ax"
.word 661b
andcc %g5, _PAGE_EXEC_4V, %g0
+ nop
.previous
be,pn %xcc, tsb_do_fault