This is a note to let you know that I've just added the patch titled
ARCv2: smp-boot: wake_flag polling by non-Masters needs to be uncached
to the 4.9-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:
arcv2-smp-boot-wake_flag-polling-by-non-masters-needs-to-be-uncached.patch
and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Jun 15 16:35:05 CEST 2017
From: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Date: Tue, 21 Jun 2016 14:24:33 +0530
Subject: ARCv2: smp-boot: wake_flag polling by non-Masters needs to be uncached
From: Vineet Gupta <vgupta@xxxxxxxxxxxx>
[ Upstream commit 78f824d4312a8944f5340c6b161bba3bf2c81096 ]
This is needed on HS38 cores, for setting up IO-Coherency aperture properly
The polling could perturb the caches and coherecy fabric which could be
wrong in the small window when Master is setting up IOC aperture etc
in arc_cache_init()
We do it only for ARCv2 based builds to not affect EZChip ARCompact
based platform.
Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arc/kernel/smp.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
--- a/arch/arc/kernel/smp.c
+++ b/arch/arc/kernel/smp.c
@@ -90,10 +90,23 @@ void __init smp_cpus_done(unsigned int m
*/
static volatile int wake_flag;
+#ifdef CONFIG_ISA_ARCOMPACT
+
+#define __boot_read(f) f
+#define __boot_write(f, v) f = v
+
+#else
+
+#define __boot_read(f) arc_read_uncached_32(&f)
+#define __boot_write(f, v) arc_write_uncached_32(&f, v)
+
+#endif
+
static void arc_default_smp_cpu_kick(int cpu, unsigned long pc)
{
BUG_ON(cpu == 0);
- wake_flag = cpu;
+
+ __boot_write(wake_flag, cpu);
}
void arc_platform_smp_wait_to_boot(int cpu)
@@ -102,10 +115,10 @@ void arc_platform_smp_wait_to_boot(int c
if (IS_ENABLED(CONFIG_ARC_SMP_HALT_ON_RESET))
return;
- while (wake_flag != cpu)
+ while (__boot_read(wake_flag) != cpu)
;
- wake_flag = 0;
+ __boot_write(wake_flag, 0);
}
const char *arc_platform_smp_cpuinfo(void)
Patches currently in stable-queue which might be from vgupta@xxxxxxxxxxxx are
queue-4.9/arc-smp-boot-decouple-non-masters-waiting-api-from-jump-to-entry-point.patch
queue-4.9/arcv2-smp-boot-wake_flag-polling-by-non-masters-needs-to-be-uncached.patch