On Wed, 6 Feb 2008, Greg KH wrote:
> On Tue, Jan 22, 2008 at 03:19:33PM -0500, Chuck Ebbert wrote:
> > On 01/22/2008 07:35 AM, Thomas Gleixner wrote:
> > >
> > > That's a long standing bug in both the PI futex and the standard futex
> > > code. Needs to go to stable as well.
> > >
> >
> > Here's the 2.6.23 version:
> >
> >
> > Subject: x86: fix missing exception entry for SMP alternatives in futex
> > macros
> > From: Thomas Gleixner <[EMAIL PROTECTED]>
>
> I don't see this in Linus's tree, am I just missing it? Do you have a
> git commit id?
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=9d55b9923a1b7ea8193b8875c57ec940dc2ff027
I did a simpler version by just replacing LOCK_PREFIX with lock. The
reason is, that we would need a separate implementation for
__futex_atomic_op1() as well, due to:
case FUTEX_OP_ADD:
__futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
And it's not really worth the trouble.
Backport to 2.6.24 and 2.6.23 attached.
Thanks,
tglxSubject: x86: replace LOCK_PREFIX in futex.h
From: Thomas Gleixner <[EMAIL PROTECTED]>
Date: Thu, 07 Feb 2008 13:05:19 +0100
The exception fixup for the futex macros __futex_atomic_op1/2 and
futex_atomic_cmpxchg_inatomic() is missing an entry when the lock
prefix is replaced by a NOP via SMP alternatives.
Chuck Ebert tracked this down from the information provided in:
https://bugzilla.redhat.com/show_bug.cgi?id=429412
A possible solution would be to add another fixup after the
LOCK_PREFIX, so both the LOCK and NOP case have their own entry in the
exception table, but it's not really worth the trouble.
Simply replace LOCK_PREFIX with lock and keep those untouched by SMP
alternatives.
Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
Index: linux-2.6.23/include/asm-i386/futex.h
===================================================================
--- linux-2.6.23.orig/include/asm-i386/futex.h 2008-02-07 13:08:03.000000000
+0100
+++ linux-2.6.23/include/asm-i386/futex.h 2008-02-07 13:09:39.000000000
+0100
@@ -28,7 +28,7 @@
"1: movl %2, %0\n\
movl %0, %3\n" \
insn "\n" \
-"2: " LOCK_PREFIX "cmpxchgl %3, %2\n\
+"2: lock cmpxchgl %3, %2\n\
jnz 1b\n\
3: .section .fixup,\"ax\"\n\
4: mov %5, %1\n\
@@ -68,7 +68,7 @@ futex_atomic_op_inuser (int encoded_op,
#endif
switch (op) {
case FUTEX_OP_ADD:
- __futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret,
+ __futex_atomic_op1("lock xaddl %0, %2", ret,
oldval, uaddr, oparg);
break;
case FUTEX_OP_OR:
@@ -111,7 +111,7 @@ futex_atomic_cmpxchg_inatomic(int __user
return -EFAULT;
__asm__ __volatile__(
- "1: " LOCK_PREFIX "cmpxchgl %3, %1 \n"
+ "1: lock cmpxchgl %3, %1 \n"
"2: .section .fixup, \"ax\" \n"
"3: mov %2, %0 \n"
Index: linux-2.6.23/include/asm-x86_64/futex.h
===================================================================
--- linux-2.6.23.orig/include/asm-x86_64/futex.h 2008-02-07
13:08:03.000000000 +0100
+++ linux-2.6.23/include/asm-x86_64/futex.h 2008-02-07 13:09:39.000000000
+0100
@@ -27,7 +27,7 @@
"1: movl %2, %0\n\
movl %0, %3\n" \
insn "\n" \
-"2: " LOCK_PREFIX "cmpxchgl %3, %2\n\
+"2: "lock cmpxchgl %3, %2\n\
jnz 1b\n\
3: .section .fixup,\"ax\"\n\
4: mov %5, %1\n\
@@ -62,7 +62,7 @@ futex_atomic_op_inuser (int encoded_op,
__futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
break;
case FUTEX_OP_ADD:
- __futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
+ __futex_atomic_op1("lock xaddl %0, %2", ret, oldval,
uaddr, oparg);
break;
case FUTEX_OP_OR:
@@ -101,7 +101,7 @@ futex_atomic_cmpxchg_inatomic(int __user
return -EFAULT;
__asm__ __volatile__(
- "1: " LOCK_PREFIX "cmpxchgl %3, %1 \n"
+ "1: lock cmpxchgl %3, %1 \n"
"2: .section .fixup, \"ax\" \n"
"3: mov %2, %0 \n"
Subject: x86: replace LOCK_PREFIX in futex.h
From: Thomas Gleixner <[EMAIL PROTECTED]>
Date: Thu, 07 Feb 2008 13:06:02 +0100
The exception fixup for the futex macros __futex_atomic_op1/2 and
futex_atomic_cmpxchg_inatomic() is missing an entry when the lock
prefix is replaced by a NOP via SMP alternatives.
Chuck Ebert tracked this down from the information provided in:
https://bugzilla.redhat.com/show_bug.cgi?id=429412
A possible solution would be to add another fixup after the
LOCK_PREFIX, so both the LOCK and NOP case have their own entry in the
exception table, but it's not really worth the trouble.
Simply replace LOCK_PREFIX with lock and keep those untouched by SMP
alternatives.
Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
Index: linux-2.6.24/include/asm-x86/futex_32.h
===================================================================
--- linux-2.6.24.orig/include/asm-x86/futex_32.h 2008-02-07
13:05:39.000000000 +0100
+++ linux-2.6.24/include/asm-x86/futex_32.h 2008-02-07 13:07:20.000000000
+0100
@@ -28,7 +28,7 @@
"1: movl %2, %0\n\
movl %0, %3\n" \
insn "\n" \
-"2: " LOCK_PREFIX "cmpxchgl %3, %2\n\
+"2: lock cmpxchgl %3, %2\n\
jnz 1b\n\
3: .section .fixup,\"ax\"\n\
4: mov %5, %1\n\
@@ -68,7 +68,7 @@ futex_atomic_op_inuser (int encoded_op,
#endif
switch (op) {
case FUTEX_OP_ADD:
- __futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret,
+ __futex_atomic_op1("lock xaddl %0, %2", ret,
oldval, uaddr, oparg);
break;
case FUTEX_OP_OR:
@@ -111,7 +111,7 @@ futex_atomic_cmpxchg_inatomic(int __user
return -EFAULT;
__asm__ __volatile__(
- "1: " LOCK_PREFIX "cmpxchgl %3, %1 \n"
+ "1: lock cmpxchgl %3, %1 \n"
"2: .section .fixup, \"ax\" \n"
"3: mov %2, %0 \n"
Index: linux-2.6.24/include/asm-x86/futex_64.h
===================================================================
--- linux-2.6.24.orig/include/asm-x86/futex_64.h 2008-02-07
13:05:39.000000000 +0100
+++ linux-2.6.24/include/asm-x86/futex_64.h 2008-02-07 13:06:45.000000000
+0100
@@ -27,7 +27,7 @@
"1: movl %2, %0\n\
movl %0, %3\n" \
insn "\n" \
-"2: " LOCK_PREFIX "cmpxchgl %3, %2\n\
+"2: "lock cmpxchgl %3, %2\n\
jnz 1b\n\
3: .section .fixup,\"ax\"\n\
4: mov %5, %1\n\
@@ -62,7 +62,7 @@ futex_atomic_op_inuser (int encoded_op,
__futex_atomic_op1("xchgl %0, %2", ret, oldval, uaddr, oparg);
break;
case FUTEX_OP_ADD:
- __futex_atomic_op1(LOCK_PREFIX "xaddl %0, %2", ret, oldval,
+ __futex_atomic_op1("lock xaddl %0, %2", ret, oldval,
uaddr, oparg);
break;
case FUTEX_OP_OR:
@@ -101,7 +101,7 @@ futex_atomic_cmpxchg_inatomic(int __user
return -EFAULT;
__asm__ __volatile__(
- "1: " LOCK_PREFIX "cmpxchgl %3, %1 \n"
+ "1: lock cmpxchgl %3, %1 \n"
"2: .section .fixup, \"ax\" \n"
"3: mov %2, %0 \n"
