linux-kernel - [PATCH] powerpc/8xx: set STACK_END_MAGIC earlier on the init

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Message-Id: <54f67bb7ac486c1350f2fa8905cd279f94b9dfb1.1566382841.git.christophe.leroy@c-s.fr>
Date:   Wed, 21 Aug 2019 10:20:51 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH] powerpc/8xx: set STACK_END_MAGIC earlier on the init_stack

Today, the STACK_END_MAGIC is set on init_stack in start_kernel().

To avoid a false 'Thread overran stack, or stack corrupted' message
on early Oopses, setup STACK_END_MAGIC as soon as possible.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 arch/powerpc/kernel/head_8xx.S | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 5ab9178c2347..b8ca5b43e587 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -15,6 +15,7 @@
  */
 
 #include <linux/init.h>
+#include <linux/magic.h>
 #include <asm/processor.h>
 #include <asm/page.h>
 #include <asm/mmu.h>
@@ -741,6 +742,9 @@ start_here:
 	/* stack */
 	lis	r1,init_thread_union@ha
 	addi	r1,r1,init_thread_union@l
+	lis	r0, STACK_END_MAGIC@h
+	ori	r0, r0, STACK_END_MAGIC@l
+	stw	r0, 0(r1)
 	li	r0,0
 	stwu	r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
 
-- 
2.13.3