From 72640d880350165c3a7b8f2e4fb4bf852ea7b606 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Mon, 21 Jan 2013 17:23:26 +0000 Subject: [PATCH] powerpc/pasemi: Fix crash on reboot commit f96972f2dc "kernel/sys.c: call disable_nonboot_cpus() in kernel_restart()" added a call to disable_nonboot_cpus() on kernel_restart(), which tries to shutdown all the CPUs except the first one. The issue with the PA Semi, is that it does not support CPU hotplug. When the call is made to __cpu_down(), it calls the notifiers CPU_DOWN_PREPARE, and then tries to take the CPU down. One of the notifiers to the CPU hotplug code, is the cpufreq. The DOWN_PREPARE will call __cpufreq_remove_dev() which calls cpufreq_driver->exit. The PA Semi exit handler unmaps regions of I/O that is used by an interrupt that goes off constantly (system_reset_common, but it goes off during normal system operations too). I'm not sure exactly what this interrupt does. Running a simple function trace, you can see it goes off quite a bit: # tracer: function # # TASK-PID CPU# TIMESTAMP FUNCTION # | | | | | -0 [001] 1558.859363: .pasemi_system_reset_exception <-.system_reset_exception -0 [000] 1558.860112: .pasemi_system_reset_exception <-.system_reset_exception -0 [000] 1558.861109: .pasemi_system_reset_exception <-.system_reset_exception -0 [001] 1558.861361: .pasemi_system_reset_exception <-.system_reset_exception -0 [000] 1558.861437: .pasemi_system_reset_exception <-.system_reset_exception When the region is unmapped, the system crashes with: Disabling non-boot CPUs ... Error taking CPU1 down: -38 Unable to handle kernel paging request for data at address 0xd0000800903a0100 Faulting instruction address: 0xc000000000055fcc Oops: Kernel access of bad area, sig: 11 [#1] PREEMPT SMP NR_CPUS=64 NUMA PA Semi PWRficient Modules linked in: shpchp NIP: c000000000055fcc LR: c000000000055fb4 CTR: c0000000000df1fc REGS: c0000000012175d0 TRAP: 0300 Not tainted (3.8.0-rc4-test-dirty) MSR: 9000000000009032 CR: 24000088 XER: 00000000 SOFTE: 0 DAR: d0000800903a0100, DSISR: 42000000 TASK = c0000000010e9008[0] 'swapper/0' THREAD: c000000001214000 CPU: 0 GPR00: d0000800903a0000 c000000001217850 c0000000012167e0 0000000000000000 GPR04: 0000000000000000 0000000000000724 0000000000000724 0000000000000000 GPR08: 0000000000000000 0000000000000000 0000000000000001 0000000000a70000 GPR12: 0000000024000080 c00000000fff0000 ffffffffffffffff 000000003ffffae0 GPR16: ffffffffffffffff 0000000000a21198 0000000000000060 0000000000000000 GPR20: 00000000008fdd35 0000000000a21258 000000003ffffaf0 0000000000000417 GPR24: 0000000000a226d0 c000000000000000 0000000000000000 0000000000000000 GPR28: c00000000138b358 0000000000000000 c000000001144818 d0000800903a0100 NIP [c000000000055fcc] .set_astate+0x5c/0xa4 LR [c000000000055fb4] .set_astate+0x44/0xa4 Call Trace: [c000000001217850] [c000000000055fb4] .set_astate+0x44/0xa4 (unreliable) [c0000000012178f0] [c00000000005647c] .restore_astate+0x2c/0x34 [c000000001217980] [c000000000054668] .pasemi_system_reset_exception+0x6c/0x88 [c000000001217a00] [c000000000019ef0] .system_reset_exception+0x48/0x84 [c000000001217a80] [c000000000001e40] system_reset_common+0x140/0x180 Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/platforms/pasemi/cpufreq.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/powerpc/platforms/pasemi/cpufreq.c b/arch/powerpc/platforms/pasemi/cpufreq.c index 95d00173029f..890f30e70f98 100644 --- a/arch/powerpc/platforms/pasemi/cpufreq.c +++ b/arch/powerpc/platforms/pasemi/cpufreq.c @@ -236,6 +236,13 @@ out: static int pas_cpufreq_cpu_exit(struct cpufreq_policy *policy) { + /* + * We don't support CPU hotplug. Don't unmap after the system + * has already made it to a running state. + */ + if (system_state != SYSTEM_BOOTING) + return 0; + if (sdcasr_mapbase) iounmap(sdcasr_mapbase); if (sdcpwr_mapbase)