Patchwork [3.5.y.z,extended,stable] Patch "s390: critical section cleanup vs. machine checks" has been added to staging queue

mail settings
Submitter Luis Henriques
Date March 20, 2013, 10:43 a.m.
Message ID <>
Download mbox | patch
Permalink /patch/229319/
State New
Headers show


Luis Henriques - March 20, 2013, 10:43 a.m.
This is a note to let you know that I have just added a patch titled

    s390: critical section cleanup vs. machine checks

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



From 3f24baf25d0ddadb54fe9cff8be7de1c6226d783 Mon Sep 17 00:00:00 2001
From: Martin Schwidefsky <>
Date: Thu, 28 Feb 2013 16:28:41 +0100
Subject: [PATCH] s390: critical section cleanup vs. machine checks

commit 6551fbdfd8b85d1ab5822ac98abb4fb449bcfae0 upstream.

The current machine check code uses the registers stored by the machine
in the lowcore at __LC_GPREGS_SAVE_AREA as the registers of the interrupted
context. The registers 0-7 of a user process can get clobbered if a machine
checks interrupts the execution of a critical section in entry[64].S.

The reason is that the critical section cleanup code may need to modify
the PSW and the registers for the previous context to get to the end of a
critical section. If registers 0-7 have to be replaced the relevant copy
will be in the registers, which invalidates the copy in the lowcore. The
machine check handler needs to explicitly store registers 0-7 to the stack.

Signed-off-by: Martin Schwidefsky <>
Luis Henriques <>
 arch/s390/kernel/entry.S   | 3 ++-
 arch/s390/kernel/entry64.S | 5 +++--
 2 files changed, 5 insertions(+), 3 deletions(-)



diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 1ae93b5..b48e939 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -670,7 +670,8 @@  ENTRY(mcck_int_handler)
-	mvc	__PT_R0(64,%r11),__LC_GPREGS_SAVE_AREA
+	stm	%r0,%r7,__PT_R0(%r11)
+	mvc	__PT_R8(32,%r11),__LC_GPREGS_SAVE_AREA+32
 	stm	%r8,%r9,__PT_PSW(%r11)
 	xc	__SF_BACKCHAIN(4,%r15),__SF_BACKCHAIN(%r15)
 	l	%r1,BASED(.Ldo_machine_check)
diff --git a/arch/s390/kernel/entry64.S b/arch/s390/kernel/entry64.S
index 229fe1d..db8d885 100644
--- a/arch/s390/kernel/entry64.S
+++ b/arch/s390/kernel/entry64.S
@@ -697,8 +697,9 @@  ENTRY(mcck_int_handler)
-	lghi	%r14,__LC_GPREGS_SAVE_AREA
-	mvc	__PT_R0(128,%r11),0(%r14)
+	lghi	%r14,__LC_GPREGS_SAVE_AREA+64
+	stmg	%r0,%r7,__PT_R0(%r11)
+	mvc	__PT_R8(64,%r11),0(%r14)
 	stmg	%r8,%r9,__PT_PSW(%r11)
 	xc	__SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
 	lgr	%r2,%r11		# pass pointer to pt_regs