3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> 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 <schwidefsky@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/s390/kernel/entry.S | 3 ++- arch/s390/kernel/entry64.S | 5 +++-- 2 files changed, 5 insertions(+), 3 deletions(-) --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -669,7 +669,8 @@ ENTRY(mcck_int_handler) UPDATE_VTIME %r14,%r15,__LC_MCCK_ENTER_TIMER mcck_skip: SWITCH_ASYNC __LC_GPREGS_SAVE_AREA+32,__LC_PANIC_STACK,PAGE_SHIFT - 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) --- a/arch/s390/kernel/entry64.S +++ b/arch/s390/kernel/entry64.S @@ -689,8 +689,9 @@ ENTRY(mcck_int_handler) UPDATE_VTIME %r14,__LC_MCCK_ENTER_TIMER LAST_BREAK %r14 mcck_skip: - 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 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html