From 4f8048ee734dab7c463574797b820c0c68c80791 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Thu, 29 Oct 2009 15:04:09 +0100 Subject: [PATCH] [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(+) diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index c932caa..c699ac5 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); } -- 2.7.4