From 07a6a4ae827b54cec4c1b1d92bed1cc9176b45ec Mon Sep 17 00:00:00 2001 From: Hidetoshi Seto <[seto.hidetoshi@jp.fujitsu.com]> Date: Thu, 6 Aug 2009 14:51:56 -0700 Subject: [IA64] kexec: Make INIT safe while transition to kdump/kexec kernel Summary: Asserting INIT on the beginning of kdump/kexec kernel will result in unexpected behavior because INIT handler for previous kernel is invoked on new kernel. Description: In panic situation, we can receive INIT while kernel transition, i.e. from beginning of panic to bootstrap of kdump kernel. Since we initialize registers on leave from current kernel, no longer monarch/slave handlers of current kernel in virtual mode are called safely. (In fact system goes hang as far as I confirmed) How to Reproduce: Start kdump # echo c > /proc/sysrq-trigger Then assert INIT while kdump kernel is booting, before new INIT handler for kdump kernel is registered. Expected(Desirable) result: kdump kernel boots without any problem, crashdump retrieved Actual result: INIT handler for previous kernel is invoked on kdump kernel => panic, hang etc. (unexpected) Proposed fix: We can unregister these init handlers from SAL before jumping into new kernel, however then the INIT will fallback to default behavior, result in warmboot by SAL (according to the SAL specification) and we cannot retrieve the crashdump. Therefore this patch introduces a NOP init handler and register it to SAL before leave from current kernel, to start kdump safely by preventing INITs from entering virtual mode and resulting in warmboot. On the other hand, in case of kexec that not for kdump, it also has same problem with INIT while kernel transition. This patch handles this case differently, because for kexec unregistering handlers will be preferred than registering NOP handler, since the situation "no handlers registered" is usual state for kernel's entry. Signed-off-by: Hidetoshi Seto Cc: Vivek Goyal Cc: Haren Myneni Cc: kexec@lists.infradead.org Acked-by: Fenghua Yu Signed-off-by: Tony Luck --- arch/ia64/include/asm/mca.h | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/ia64/include') diff --git a/arch/ia64/include/asm/mca.h b/arch/ia64/include/asm/mca.h index cb0952f5183..c171cdf0a78 100644 --- a/arch/ia64/include/asm/mca.h +++ b/arch/ia64/include/asm/mca.h @@ -145,6 +145,7 @@ extern void ia64_mca_ucmc_handler(struct pt_regs *, struct ia64_sal_os_state *); extern void ia64_init_handler(struct pt_regs *, struct switch_stack *, struct ia64_sal_os_state *); +extern void ia64_os_init_on_kdump(void); extern void ia64_monarch_init_handler(void); extern void ia64_slave_init_handler(void); extern void ia64_mca_cmc_vector_setup(void); -- cgit v1.2.3