This is a note to let you know that I've just added the patch titled
ARC: smp-boot: Decouple Non masters waiting API from jump to entry point
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:
arc-smp-boot-decouple-non-masters-waiting-api-from-jump-to-entry-point.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 16:23:30 CEST 2017
From: Vineet Gupta <vgupta@xxxxxxxxxxxx>
Date: Thu, 12 Jan 2017 14:30:29 -0800
Subject: ARC: smp-boot: Decouple Non masters waiting API from jump to entry point
From: Vineet Gupta <vgupta@xxxxxxxxxxxx>
[ Upstream commit bf02454a741b58682a82c314a9a46bed930ed2f7 ]
For run-on-reset SMP configs, non master cores call a routine which
waits until Master gives it a "go" signal (currently using a shared
mem flag). The same routine then jumps off the well known entry point of
all non Master cores i.e. @first_lines_of_secondary
This patch moves out the last part into one single place in early boot
code.
This is better in terms of absraction (the wait API only waits) and
returns, leaving out the "jump off to" part.
In actual implementation this requires some restructuring of the early
boot code as well as Master now jumps to BSS setup explicitly,
vs. falling thru into it before.
Technically this patch doesn't cause any functional change, it just
moves the ugly #ifdef'ry from assembly code to "C"
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/head.S | 14 +++++++-------
arch/arc/kernel/smp.c | 6 ++++--
2 files changed, 11 insertions(+), 9 deletions(-)
--- a/arch/arc/kernel/head.S
+++ b/arch/arc/kernel/head.S
@@ -71,14 +71,14 @@ ENTRY(stext)
GET_CPU_ID r5
cmp r5, 0
mov.nz r0, r5
-#ifdef CONFIG_ARC_SMP_HALT_ON_RESET
- ; Non-Master can proceed as system would be booted sufficiently
- jnz first_lines_of_secondary
-#else
+ bz .Lmaster_proceed
+
; Non-Masters wait for Master to boot enough and bring them up
- jnz arc_platform_smp_wait_to_boot
-#endif
- ; Master falls thru
+ ; when they resume, tail-call to entry point
+ mov blink, @first_lines_of_secondary
+ j arc_platform_smp_wait_to_boot
+
+.Lmaster_proceed:
#endif
; Clear BSS before updating any globals
--- a/arch/arc/kernel/smp.c
+++ b/arch/arc/kernel/smp.c
@@ -98,14 +98,16 @@ static void arc_default_smp_cpu_kick(int
void arc_platform_smp_wait_to_boot(int cpu)
{
+ /* for halt-on-reset, we've waited already */
+ if (IS_ENABLED(CONFIG_ARC_SMP_HALT_ON_RESET))
+ return;
+
while (wake_flag != cpu)
;
wake_flag = 0;
- __asm__ __volatile__("j @first_lines_of_secondary \n");
}
-
const char *arc_platform_smp_cpuinfo(void)
{
return plat_smp_ops.info ? : "";
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