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authorHidetoshi Seto <[seto.hidetoshi@jp.fujitsu.com]>2009-08-06 14:51:56 -0700
committerTony Luck <tony.luck@intel.com>2009-09-14 16:18:02 -0700
commit07a6a4ae827b54cec4c1b1d92bed1cc9176b45ec (patch)
tree2be2a4a567e0fbd672cac86ebd06d4411e583e67 /arch/ia64/kernel
parent4295ab34883d2070b1145e14f4619478e9788807 (diff)
[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 <seto.hidetoshi@jp.fujitsu.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Haren Myneni <hbabu@us.ibm.com> Cc: kexec@lists.infradead.org Acked-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'arch/ia64/kernel')
-rw-r--r--arch/ia64/kernel/machine_kexec.c12
-rw-r--r--arch/ia64/kernel/mca_asm.S20
2 files changed, 32 insertions, 0 deletions
diff --git a/arch/ia64/kernel/machine_kexec.c b/arch/ia64/kernel/machine_kexec.c
index 0823de1f6eb..571d66373e0 100644
--- a/arch/ia64/kernel/machine_kexec.c
+++ b/arch/ia64/kernel/machine_kexec.c
@@ -24,6 +24,8 @@
#include <asm/delay.h>
#include <asm/meminit.h>
#include <asm/processor.h>
+#include <asm/sal.h>
+#include <asm/mca.h>
typedef NORET_TYPE void (*relocate_new_kernel_t)(
unsigned long indirection_page,
@@ -85,11 +87,21 @@ static void ia64_machine_kexec(struct unw_frame_info *info, void *arg)
void *pal_addr = efi_get_pal_addr();
unsigned long code_addr = (unsigned long)page_address(image->control_code_page);
int ii;
+ u64 fp, gp;
+ ia64_fptr_t *init_handler = (ia64_fptr_t *)ia64_os_init_on_kdump;
BUG_ON(!image);
if (image->type == KEXEC_TYPE_CRASH) {
crash_save_this_cpu();
current->thread.ksp = (__u64)info->sw - 16;
+
+ /* Register noop init handler */
+ fp = ia64_tpa(init_handler->fp);
+ gp = ia64_tpa(ia64_getreg(_IA64_REG_GP));
+ ia64_sal_set_vectors(SAL_VECTOR_OS_INIT, fp, gp, 0, fp, gp, 0);
+ } else {
+ /* Unregister init handlers of current kernel */
+ ia64_sal_set_vectors(SAL_VECTOR_OS_INIT, 0, 0, 0, 0, 0, 0);
}
/* Interrupts aren't acceptable while we reboot */
diff --git a/arch/ia64/kernel/mca_asm.S b/arch/ia64/kernel/mca_asm.S
index 8d2eabe3119..7461d2573d4 100644
--- a/arch/ia64/kernel/mca_asm.S
+++ b/arch/ia64/kernel/mca_asm.S
@@ -40,6 +40,7 @@
.global ia64_do_tlb_purge
.global ia64_os_mca_dispatch
+ .global ia64_os_init_on_kdump
.global ia64_os_init_dispatch_monarch
.global ia64_os_init_dispatch_slave
@@ -299,6 +300,25 @@ END(ia64_os_mca_virtual_begin)
//StartMain////////////////////////////////////////////////////////////////////
//
+// NOP init handler for kdump. In panic situation, we may receive INIT
+// while kernel transition. Since we initialize registers on leave from
+// current kernel, no longer monarch/slave handlers of current kernel in
+// virtual mode are called safely.
+// We can unregister these init handlers from SAL, however then the INIT
+// will result in warmboot by SAL and we cannot retrieve the crashdump.
+// Therefore register this NOP function to SAL, to prevent entering virtual
+// mode and resulting warmboot by SAL.
+//
+ia64_os_init_on_kdump:
+ mov r8=r0 // IA64_INIT_RESUME
+ mov r9=r10 // SAL_GP
+ mov r22=r17 // *minstate
+ ;;
+ mov r10=r0 // return to same context
+ mov b0=r12 // SAL_CHECK return address
+ br b0
+
+//
// SAL to OS entry point for INIT on all processors. This has been defined for
// registration purposes with SAL as a part of ia64_mca_init. Monarch and
// slave INIT have identical processing, except for the value of the