linux-kernel - [PATCH 4.5 023/238] s390/cpumf: add missing lpp magic initialization

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Message-Id: <20160410183457.618205176@linuxfoundation.org>
Date:	Sun, 10 Apr 2016 11:33:20 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Shu Juan Zhang <zhshuj@...ibm.com>,
	Christian Borntraeger <borntraeger@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: [PATCH 4.5 023/238] s390/cpumf: add missing lpp magic initialization

4.5-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Heiko Carstens <heiko.carstens@...ibm.com>

commit 8f100bb1ff27873dd71f636da670e503b9ade3c6 upstream.

Add the missing lpp magic initialization for cpu 0. Without this all
samples on cpu 0 do not have the most significant bit set in the
program parameter field, which we use to distinguish between guest and
host samples if the pid is also 0.

We did initialize the lpp magic in the absolute zero lowcore but
forgot that when switching to the allocated lowcore on cpu 0 only.

Reported-by: Shu Juan Zhang <zhshuj@...ibm.com>
Acked-by: Christian Borntraeger <borntraeger@...ibm.com>
Fixes: e22cf8ca6f75 ("s390/cpumf: rework program parameter setting to detect guest samples")
Signed-off-by: Heiko Carstens <heiko.carstens@...ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/s390/kernel/setup.c |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -327,6 +327,7 @@ static void __init setup_lowcore(void)
 		+ PAGE_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
 	lc->current_task = (unsigned long) init_thread_union.thread_info.task;
 	lc->thread_info = (unsigned long) &init_thread_union;
+	lc->lpp = LPP_MAGIC;
 	lc->machine_flags = S390_lowcore.machine_flags;
 	lc->stfl_fac_list = S390_lowcore.stfl_fac_list;
 	memcpy(lc->stfle_fac_list, S390_lowcore.stfle_fac_list,