Patch "parisc/kgdb: add kgdb_roundup() to make kgdb work with idle polling" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    parisc/kgdb: add kgdb_roundup() to make kgdb work with idle polling

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     parisc-kgdb-add-kgdb_roundup-to-make-kgdb-work-with-.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 314dad22e3206eabc97acf04a6f81753d30e0520
Author: Sven Schnelle <svens@xxxxxxxxxxxxxx>
Date:   Fri Oct 15 21:49:23 2021 +0200

    parisc/kgdb: add kgdb_roundup() to make kgdb work with idle polling
    
    [ 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@xxxxxxxxxxxxxx>
    Signed-off-by: Helge Deller <deller@xxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/parisc/kernel/smp.c b/arch/parisc/kernel/smp.c
index e202c37e56af3..9997465c11820 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>
@@ -71,7 +72,10 @@ 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
 };
 
 
@@ -169,7 +173,12 @@ 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);
@@ -225,6 +234,12 @@ 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); }