Hi,
This is a patch related to this discussion.
http://www.spinics.net/lists/linux-ia64/msg07605.html
When INIT is sent, ip/psr/pfs register is stored to the I-resources
(iip/ipsr/ifs registers), and they are copied in the min-state save
area(pmsa_{iip,ipsr,ifs}).
Therefore, in creating pt_regs at ia64_mca_modify_original_stack(),
cr_{iip,ipsr,ifs} should be derived from pmsa_{iip,ipsr,ifs}. But
current code copies pmsa_{xip,xpsr,xfs} to cr_{iip,ipsr,ifs}
when PSR.ic is 0.
finish_pt_regs(struct pt_regs *regs, const pal_min_state_area_t *ms,
unsigned long *nat)
{
(snip)
if (ia64_psr(regs)->ic) {
regs->cr_iip = ms->pmsa_iip;
regs->cr_ipsr = ms->pmsa_ipsr;
regs->cr_ifs = ms->pmsa_ifs;
} else {
regs->cr_iip = ms->pmsa_xip;
regs->cr_ipsr = ms->pmsa_xpsr;
regs->cr_ifs = ms->pmsa_xfs;
}
It's ok when PSR.ic is not 0. But when PSR.ic is 0, this could be
a problem when we investigate kernel as the value of regs->cr_iip does
not point to where INIT really interrupted.
At first I tried to change finish_pt_regs() so that it uses always
pmsa_{iip,ipsr,ifs} for cr_{iip,ipsr,ifs}, but Keith Owens pointed out
it could cause another problem if I change it.
>The only problem I can think of is an MCA/INIT
>arriving while code like SAVE_MIN or SAVE_REST is executing. Back
>tracing at that point using pmsa_iip is going to be a problem, you have
>no idea what state the registers or stack are in.
I confirmed he was right, so I decided to keep it as-is and to
save pmsa_{iip,ipsr,ifs} to ia64_sal_os_state for debugging.
An attached patch is just adding new members into ia64_sal_os_state to
save pmsa_{iip,ipsr,ifs}.
Any comments would be appreciated.
Thanks,
Takao Indoh
Signed-off-by: Takao Indoh <indou.takao@xxxxxxxxxxxxxx>
---
arch/ia64/include/asm/mca.h | 5 +++++
arch/ia64/kernel/mca.c | 11 ++++++++---
2 files changed, 13 insertions(+), 3 deletions(-)
diff -Nurp linux-2.6-ia64.org/arch/ia64/include/asm/mca.h linux-2.6-ia64/arch/ia64/include/asm/mca.h
--- linux-2.6-ia64.org/arch/ia64/include/asm/mca.h 2009-11-09 17:32:21.000000000 -0500
+++ linux-2.6-ia64/arch/ia64/include/asm/mca.h 2009-11-09 17:34:41.000000000 -0500
@@ -106,6 +106,11 @@ struct ia64_sal_os_state {
unsigned long os_status; /* OS status to SAL, enum below */
unsigned long context; /* 0 if return to same context
1 if return to new context */
+
+ /* I-resources */
+ unsigned long iip;
+ unsigned long ipsr;
+ unsigned long ifs;
};
enum {
diff -Nurp linux-2.6-ia64.org/arch/ia64/kernel/mca.c linux-2.6-ia64/arch/ia64/kernel/mca.c
--- linux-2.6-ia64.org/arch/ia64/kernel/mca.c 2009-11-09 17:32:21.000000000 -0500
+++ linux-2.6-ia64/arch/ia64/kernel/mca.c 2009-11-09 17:34:41.000000000 -0500
@@ -888,9 +888,10 @@ ia64_mca_modify_comm(const struct task_s
}
static void
-finish_pt_regs(struct pt_regs *regs, const pal_min_state_area_t *ms,
+finish_pt_regs(struct pt_regs *regs, struct ia64_sal_os_state *sos,
unsigned long *nat)
{
+ const pal_min_state_area_t *ms = sos->pal_min_state;
const u64 *bank;
/* If ipsr.ic then use pmsa_{iip,ipsr,ifs}, else use
@@ -904,6 +905,10 @@ finish_pt_regs(struct pt_regs *regs, con
regs->cr_iip = ms->pmsa_xip;
regs->cr_ipsr = ms->pmsa_xpsr;
regs->cr_ifs = ms->pmsa_xfs;
+
+ sos->iip = ms->pmsa_iip;
+ sos->ipsr = ms->pmsa_ipsr;
+ sos->ifs = ms->pmsa_ifs;
}
regs->pr = ms->pmsa_pr;
regs->b0 = ms->pmsa_br0;
@@ -1079,7 +1084,7 @@ ia64_mca_modify_original_stack(struct pt
memcpy(old_regs, regs, sizeof(*regs));
old_regs->loadrs = loadrs;
old_unat = old_regs->ar_unat;
- finish_pt_regs(old_regs, ms, &old_unat);
+ finish_pt_regs(old_regs, sos, &old_unat);
/* Next stack a struct switch_stack. mca_asm.S built a partial
* switch_stack, copy it and fill in the blanks using pt_regs and
@@ -1150,7 +1155,7 @@ no_mod:
mprintk(KERN_INFO "cpu %d, %s %s, original stack not modified\n",
smp_processor_id(), type, msg);
old_unat = regs->ar_unat;
- finish_pt_regs(regs, ms, &old_unat);
+ finish_pt_regs(regs, sos, &old_unat);
return previous_current;
}
--
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