Hi.
While I was debugging kexec/kdump, I have a question about the mca
handler. I cited the related hunks below. Could you please clarify them?
On mca the firmware saves non-banked and banked general registers
and the most of ar registers must be unchanged.
However before ia64_os_mca_proc_state_dump saves such registers,
the cited hunks unconditionally overwrite ar.k[36] so that
they are destroyed. Am I missing anything?
changeset: 12447:2afdc0066df6
user: awilliam@xxxxxxxxxxx
date: Sun Oct 29 09:27:11 2006 -0700
files: xen/arch/ia64/linux-xen/mca_asm.S
description:
[IA64] MCA support - Add percpu data physical addr mca_asm.S
Signed-off-by: Yutaka Ezaki <yutaka.ezaki@xxxxxxxxxxxxxx>
Signed-off-by: Masaki Kanno <kanno.masaki@xxxxxxxxxxxxxx>
Signed-off-by: Kazuhiro Suzuki <kaz@xxxxxxxxxxxxxx>
...
...
@@ -132,7 +153,40 @@
.text
.align 16
-#ifndef XEN
+#ifdef XEN
+/*
+ * void set_per_cpu_data(void)
+ * {
+ * int i;
+ * for (i = 0; i < 64; i++) {
+ * if (ia64_mca_tlb_list[i].cr_lid == ia64_getreg(_IA64_REG_CR_LID)) {
+ * ia64_set_kr(IA64_KR_PER_CPU_DATA, ia64_mca_tlb_list[i].percpu_paddr);
+ * return;
+ * }
+ * }
+ * while(1); // Endless loop on error
+ * }
+ */
+#define SET_PER_CPU_DATA() \
+ LOAD_PHYSICAL(p0,r2,ia64_mca_tlb_list);; \
+ mov r7 = r0; \
+ mov r6 = r0;; \
+ adds r3 = IA64_MCA_PERCPU_OFFSET, r2; \
+1: add r4 = r6, r2; \
+ mov r5=cr.lid;; \
+ adds r7 = 1, r7; \
+ ld8 r4 = [r4];; \
+ cmp.ne p6, p7 = r5, r4; \
+ cmp4.lt p8, p9 = NR_CPUS-1, r7; \
+(p7) br.cond.dpnt 3f; \
+ adds r6 = 16, r6; \
+(p9) br.cond.sptk 1b; \
+2: br 2b;; /* Endless loop on error */ \
+3: add r4 = r6, r3;; \
+ ld8 r4 = [r4];; \
+ mov ar.k3=r4
+#endif /* XEN */
+
...
@@ -235,6 +327,9 @@
cmp.ne p6,p0=r4,r0
(p6) br ia64_os_mca_spin
+#ifdef XEN
+ SET_PER_CPU_DATA();;
+#endif
// Save the SAL to OS MCA handoff state as defined
// by SAL SPEC 3.0
// NOTE : The order in which the state gets saved
@@ -250,7 +345,19 @@
ia64_os_mca_done_dump:
+#ifdef XEN
+ // Set current to ar.k6
+ GET_THIS_PADDR(r2,cpu_kr);;
+ add r2=IA64_KR_CURRENT_OFFSET,r2;;
+ ld8 r2=[r2];;
+ mov ar.k6=r2;;
+
+ GET_THIS_PADDR(r2,ia64_sal_to_os_handoff_state_addr);;
+ ld8 r2=[r2];;
+ adds r16=56,r2
+#else
LOAD_PHYSICAL(p0,r16,ia64_sal_to_os_handoff_state+56)
+#endif
;;
ld8 r18=[r16] // Get processor state parameter on existing PA
LE_CHECK.
;;
...
@@ -874,12 +1003,6 @@
br ia64_os_mca_done_restore;;
//EndStub/////////////////////////////////////////////////////////////////////
/
-#else
-ia64_os_mca_dispatch:
-1:
- br.sptk 1b
-ia64_os_mca_dispatch_end:
-#endif /* !XEN */
// ok, the issue here is that we need to save state information so
@@ -911,6 +1034,15 @@
GLOBAL_ENTRY(ia64_monarch_init_handler)
.prologue
+#ifdef XEN /* Need in ia64_monarch_init_handler? */
+ SET_PER_CPU_DATA();;
+
+ // Set current to ar.k6
+ GET_THIS_PADDR(r2,cpu_kr);;
+ add r2=IA64_KR_CURRENT_OFFSET,r2;;
+ ld8 r2=[r2];;
+ mov ar.k6=r2;;
+#endif
// stash the information the SAL passed to os
SAL_TO_OS_MCA_HANDOFF_STATE_SAVE(r2)
;;
--
yamahata
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