From 4f8048ee734dab7c463574797b820c0c68c80791 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Thu, 29 Oct 2009 15:04:09 +0100 Subject: [S390] smp: fix prefix handling of offlined cpus Offlined cpus still have valid prefix register contents. Dumpers will store the register contents of a cpu to the location where its prefix register points to. For offlined cpus the area (lowcore) has been freed and the dumper would write the uninteresting contents of the offline cpu to a memory location which might be in use by some other component and destroy valueable information. To fix this set the prefix register of offline cpus to absolute address zero again. This prevents the current dumpers to write to random memory locations. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/smp.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/s390/kernel/smp.c') diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index c932caa5e850..c699ac538c49 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -638,6 +638,8 @@ void __cpu_die(unsigned int cpu) /* Wait until target cpu is down */ while (!cpu_stopped(cpu)) cpu_relax(); + while (signal_processor_p(0, cpu, sigp_set_prefix) == sigp_busy) + udelay(10); smp_free_lowcore(cpu); pr_info("Processor %d stopped\n", cpu); } -- cgit v1.2.2 From f8501ba77d69c88a65e4ebbe03bdc65b1edb0b86 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Thu, 29 Oct 2009 15:04:13 +0100 Subject: [S390] smp: fix sigp stop handling According to the architecture a cpu must not necessarily enter stopped state after completion of a sigp instruction with "stop" order code. So remove the BUG() statement after self sending sigp stop to avoid that it ever gets reached. Also add a sigp busy check to make sure that the order gets delivered. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/smp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/s390/kernel/smp.c') diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index c699ac538c49..c99c45b848e3 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -647,8 +647,8 @@ void __cpu_die(unsigned int cpu) void cpu_die(void) { idle_task_exit(); - signal_processor(smp_processor_id(), sigp_stop); - BUG(); + while (signal_processor(smp_processor_id(), sigp_stop) == sigp_busy) + cpu_relax(); for (;;); } -- cgit v1.2.2 From b3dcf3de8e4d71d79235fc67b6c5def6506c27f8 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Thu, 29 Oct 2009 15:04:14 +0100 Subject: [S390] smp: fix sigp sense handling sigp sense only returns the status of a cpu if it is non zero. If the status of the sensed cpu is all zeros condition code 0 (accpeted) is set and no status bits are returned. The current code however assumes that a status was returned and tests bits in it. This means uninitalized data is accessed with random results. Worst case is that the code that checks if cpu is offline on cpu hotplug assumes that the target cpu is offline while it is still running. This leads potentially to memory corruption since resources that are still needed by the target cpu will be freed and could be resused while still in use. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/smp.c | 1 - 1 file changed, 1 deletion(-) (limited to 'arch/s390/kernel/smp.c') diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index c99c45b848e3..93e52039321b 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -76,7 +76,6 @@ static int cpu_stopped(int cpu) __u32 status; switch (signal_processor_ps(&status, 0, cpu, sigp_sense)) { - case sigp_order_code_accepted: case sigp_status_stored: /* Check for stopped and check stop state */ if (status & 0x50) -- cgit v1.2.2