linux-kernel - Re: [linux-next][bisected 1945bc45] build brakes for PowerPC BE configuration on LPAR

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Message-ID: <20170504204112.130d7735@roar.ozlabs.ibm.com>
Date:   Thu, 4 May 2017 20:41:12 +1000
From:   Nicholas Piggin <npiggin@...il.com>
To:     Abdul Haleem <abdhalee@...ux.vnet.ibm.com>
Cc:     linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        mpe <mpe@...erman.id.au>, ego <ego@...ux.vnet.ibm.com>,
        sachinp <sachinp@...ux.vnet.ibm.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        mahesh@...ux.vnet.ibm.com
Subject: Re: [linux-next][bisected 1945bc45] build brakes for PowerPC BE
 configuration on LPAR

On Thu, 04 May 2017 14:54:19 +0530
Abdul Haleem <abdhalee@...ux.vnet.ibm.com> wrote:

> Hi,
> 
> linux-next build fails on BE config with next-20170424 onwards
> 
> the patch https://lkml.org/lkml/2017/4/20/994  fixes a similar issue
> with kvm guest build failure.
> 
> arch/powerpc/kernel/exceptions-64s.S: Assembler messages:
> arch/powerpc/kernel/exceptions-64s.S:395: Error: operand out of range
> (0xffffffffffff8280 is not between 0x0000000000000000 and
> 0x000000000000ffff)
> make[1]: *** [arch/powerpc/kernel/head_64.o] Error 1
> 
> Bisection resulted with the below bad commit.
> 
> commit 1945bc4549e5cb1f9aa873ec29191aa54dc851d
> Author: Nicholas Piggin <npiggin@...il.com>
> Date:   Wed Apr 19 23:05:47 2017 +1000
> 
>     powerpc/64s: Fix POWER9 machine check handler from stop state
> 
>     Reviewed-by: Gautham R. Shenoy <ego@...ux.vnet.ibm.com>
>     Reviewed-by: Mahesh J Salgaonkar <mahesh@...ux.vnet.ibm.com>
>     Signed-off-by: Nicholas Piggin <npiggin@...il.com>
>     Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
> 
>  arch/powerpc/include/asm/reg.h       |  1 +
>  arch/powerpc/kernel/exceptions-64s.S | 79 ++++++++++++++++++++++++++++++++++++++++++++-----------------------------------
>  arch/powerpc/kernel/idle_book3s.S    | 25 +++++++++++++++++++++++++
>  3 files changed, 70 insertions(+), 35 deletions(-)
> 
> the BE configuration file is attached.
> 

Thanks for the report. I wouldn't reproduce it with this config. I
suspect the following patch should fix it, can you test?

powerpc/64s: Fix unnecessary machine check handler relocation branch

Similarly to 2563a70c3b ("powerpc/64s: Remove unnecessary relocation
branch from idle handler"), the machine check handler has a BRANCH_TO
from relocated to relocated code, which is unnecessary.

It has also caused build errors with some toolchains:

  arch/powerpc/kernel/exceptions-64s.S: Assembler messages:
  arch/powerpc/kernel/exceptions-64s.S:395: Error: operand out of range
  (0xffffffffffff8280 is not between 0x0000000000000000 and
  0x000000000000ffff)

Fixes: 1945bc4549 ("powerpc/64s: Fix POWER9 machine check handler from stop state")
Signed-off-by: Nicholas Piggin <npiggin@...il.com>
---
 arch/powerpc/kernel/exceptions-64s.S | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 3840a7700285..ef72065f684c 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -391,9 +391,7 @@ EXC_COMMON_BEGIN(machine_check_handle_early)
 	 */
 	BEGIN_FTR_SECTION
 	rlwinm.	r11,r12,47-31,30,31
-	beq-	4f
-	BRANCH_TO_COMMON(r10, machine_check_idle_common)
-4:
+	bne	machine_check_idle_common
 	END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
 #endif
 
-- 
2.11.0