[PATCH 5.14 334/849] parisc/kgdb: add kgdb_roundup() to make kgdb work with idle polling

Greg Kroah-Hartman
2021-11-15T22:52:22Z

From: Sven Schnelle <svens@stackframe.org>

[ Upstream commit 66e29fcda1824f0427966fbee2bd2c85bf362c82 ]

With idle polling, IPIs are not sent when a CPU idle, but queued
and run later from do_idle(). The default kgdb_call_nmi_hook()
implementation gets the pointer to struct pt_regs from get_irq_reqs(),
which doesn't work in that case because it was not called from the
IPI interrupt handler. Fix it by defining our own kgdb_roundup()
function which sents an IPI_ENTER_KGDB. When that IPI is received
on the target CPU kgdb_nmicallback() is called.

Signed-off-by: Sven Schnelle <svens@stackframe.org>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/parisc/kernel/smp.c | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/parisc/kernel/smp.c b/arch/parisc/kernel/smp.c
index 1405b603b91b6..cf92ece20b757 100644
--- a/arch/parisc/kernel/smp.c
+++ b/arch/parisc/kernel/smp.c
@@ -29,6 +29,7 @@
#include <linux/bitops.h>
#include <linux/ftrace.h>
#include <linux/cpu.h>
+#include <linux/kgdb.h>

#include <linux/atomic.h>
#include <asm/current.h>
@@ -69,7 +70,10 @@ enum ipi_message_type {
IPI_CALL_FUNC,
IPI_CPU_START,
IPI_CPU_STOP,
- IPI_CPU_TEST
+ IPI_CPU_TEST,
+#ifdef CONFIG_KGDB
+ IPI_ENTER_KGDB,
+#endif
};

@@ -167,7 +171,12 @@ ipi_interrupt(int irq, void *dev_id)
case IPI_CPU_TEST:
smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
break;
-
+#ifdef CONFIG_KGDB
+ case IPI_ENTER_KGDB:
+ smp_debug(100, KERN_DEBUG "CPU%d ENTER_KGDB\n", this_cpu);
+ kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
+ break;
+#endif
default:
printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
this_cpu, which);
@@ -226,6 +235,12 @@ send_IPI_allbutself(enum ipi_message_type op)
}
}

+#ifdef CONFIG_KGDB
+void kgdb_roundup_cpus(void)
+{
+ send_IPI_allbutself(IPI_ENTER_KGDB);
+}
+#endif

inline void
smp_send_stop(void) { send_IPI_allbutself(IPI_CPU_STOP); }
--
2.33.0