xmon can be entered via sreset NMI (from a management sreset, or an
NMI IPI), which can interrupt OPAL. xmon will then issue OPAL calls
to read and write the console, which re-enter OPAL and will destroy
the OPAL stack. So xmon must not attempt to recover in this case.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
--
Skiboot at the moment will spew messages about re-entrant call
detected and things will go bad from there. I have some patches
for it that allow a few calls through that allow the console to
work from xmon, obviously still not recoverable.
---
arch/powerpc/include/asm/opal.h | 2 ++
arch/powerpc/platforms/powernv/opal.c | 5 +++++
arch/powerpc/xmon/xmon.c | 14 ++++++++++++++
3 files changed, 21 insertions(+)
diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index 12e70fb58700..b7efd9b0c720 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -27,6 +27,8 @@ extern struct kobject *opal_kobj;
/* /ibm,opal */
extern struct device_node *opal_node;
+bool in_opal_text(u64 address);
+
/* API functions */
int64_t opal_invalid_call(void);
int64_t opal_npu_destroy_context(uint64_t phb_id, uint64_t pid, uint64_t bdf);
diff --git a/arch/powerpc/platforms/powernv/opal.c
b/arch/powerpc/platforms/powernv/opal.c
index c15182765ff5..88627b59ea2e 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -64,6 +64,11 @@ static struct atomic_notifier_head
opal_msg_notifier_head[OPAL_MSG_TYPE_MAX];
static uint32_t opal_heartbeat;
static struct task_struct *kopald_tsk;
+bool in_opal_text(u64 address)
+{
+ return (address >= opal.base && address < opal.base + opal.size);
+}
+
void opal_configure_cores(void)
{
u64 reinit_flags = 0;
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 82e1a3ee6e0f..482709933c46 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -510,6 +510,20 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
xmon_fault_jmp[cpu] = recurse_jmp;
+ if (firmware_has_feature(FW_FEATURE_OPAL)) {
+ if (in_opal_text(regs->nip)) {
+ printf("WARNING: cpu 0x%x stopped in OPAL, cannot
recover\n", cpu);
+ regs->msr &= ~MSR_RI;
+ /*
+ * It should be possible to return to OPAL if we
+ * didn't do anything else here, but xmon makes
+ * re-entrant OPAL calls to print console, which will
+ * trash the OPAL stack. So we have to mark ourselves
+ * as non-recoverable here.
+ */
+ }
+ }
+
bp = NULL;
if ((regs->msr & (MSR_IR|MSR_PR|MSR_64BIT)) == (MSR_IR|MSR_64BIT))
bp = at_breakpoint(regs->nip);
--
2.16.1
