From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
PARISC has a hope based mechanism to restore consoles in case of a HPMC
(machine check exception) which is scattered over several places.
Move it into one place to make further changes simpler and add comments.
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
Reviewed-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
---
arch/parisc/include/asm/pdc.h | 2 +-
arch/parisc/kernel/pdc_cons.c | 38 ++++++++++++++++++++++++++++-------
arch/parisc/kernel/traps.c | 17 +++++-----------
3 files changed, 37 insertions(+), 20 deletions(-)
diff --git a/arch/parisc/include/asm/pdc.h b/arch/parisc/include/asm/pdc.h
index b643092d4b98..12bffd8a5d05 100644
--- a/arch/parisc/include/asm/pdc.h
+++ b/arch/parisc/include/asm/pdc.h
@@ -20,7 +20,7 @@ extern unsigned long parisc_pat_pdc_cap; /* PDC capabilities (PAT) */
#define PDC_TYPE_SNAKE 2 /* Doesn't support SYSTEM_MAP */
void pdc_console_init(void); /* in pdc_console.c */
-void pdc_console_restart(void);
+void pdc_console_restart(bool hpmc);
void setup_pdc(void); /* in inventory.c */
diff --git a/arch/parisc/kernel/pdc_cons.c b/arch/parisc/kernel/pdc_cons.c
index 2661cdd256ae..9a0c0932d2f9 100644
--- a/arch/parisc/kernel/pdc_cons.c
+++ b/arch/parisc/kernel/pdc_cons.c
@@ -237,20 +237,44 @@ void __init pdc_console_init(void)
/*
- * Used for emergencies. Currently only used if an HPMC occurs. If an
- * HPMC occurs, it is possible that the current console may not be
- * properly initialised after the PDC IO reset. This routine unregisters
- * all of the current consoles, reinitializes the pdc console and
- * registers it.
+ * <Historical comments>
+ *
+ * Used for emergencies.
+ *
+ * - If an HPMC occurs, it is possible that the current console may not be
+ * properly initialised after the PDC IO reset. This routine unregisters
+ * all of the current consoles, reinitializes the pdc console and registers
+ * it.
+ *
+ * - Maybe the kernel hasn't booted very far yet and hasn't been able
+ * to initialize the serial or STI console. In that case we should
+ * re-enable the pdc console, so that the user will be able to
+ * identify the problem.
+ *
+ * </Historical comments>
+ *
+ * The above is all wishful thinking:
+ *
+ * - Invoking [un]register_console() from exception contexts is obviously
+ * unsafe.
+ *
+ * - If the HPMC left the machine in unpleasant state and the pdc console
+ * was already initialized, but later removed due to CON_BOOT then this
+ * will do nothing.
+ *
+ * Pretend that any of the below works in the same way as we pretend that
+ * any of PARISC works.
*/
-
-void pdc_console_restart(void)
+void pdc_console_restart(bool hpmc)
{
struct console *console;
if (pdc_console_initialized)
return;
+ if (!hpmc && console_drivers)
+ return;
+
/* If we've already seen the output, don't bother to print it again */
if (console_drivers != NULL)
pdc_cons.flags &= ~CON_PRINTBUFFER;
diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c
index b78f1b9d45c1..81e23f589d3d 100644
--- a/arch/parisc/kernel/traps.c
+++ b/arch/parisc/kernel/traps.c
@@ -235,17 +235,12 @@ void die_if_kernel(char *str, struct pt_regs *regs, long err)
" (__)\\ )\\/\\\n"
" U ||----w |\n"
" || ||\n");
-
+
/* unlock the pdc lock if necessary */
pdc_emergency_unlock();
- /* maybe the kernel hasn't booted very far yet and hasn't been able
- * to initialize the serial or STI console. In that case we should
- * re-enable the pdc console, so that the user will be able to
- * identify the problem. */
- if (!console_drivers)
- pdc_console_restart();
-
+ pdc_console_restart(false);
+
if (err)
printk(KERN_CRIT "%s (pid %d): %s (code %ld)\n",
current->comm, task_pid_nr(current), str, err);
@@ -429,9 +424,7 @@ void parisc_terminate(char *msg, struct pt_regs *regs, int code, unsigned long o
/* unlock the pdc lock if necessary */
pdc_emergency_unlock();
- /* restart pdc console if necessary */
- if (!console_drivers)
- pdc_console_restart();
+ pdc_console_restart(false);
/* Not all paths will gutter the processor... */
switch(code){
@@ -483,7 +476,7 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
int si_code;
if (code == 1)
- pdc_console_restart(); /* switch back to pdc if HPMC */
+ pdc_console_restart(true); /* switch back to pdc if HPMC */
else if (!irqs_disabled_flags(regs->gr[0]))
local_irq_enable();
--
2.30.2
