linux-kernel - [PATCH] MIPS: Fix minimum alignment requirement of IRQ stack

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Message-ID: <1499439432-29847-1-git-send-email-matt.redfearn@imgtec.com>
Date:   Fri, 7 Jul 2017 15:57:12 +0100
From:   Matt Redfearn <matt.redfearn@...tec.com>
To:     Ralf Baechle <ralf@...ux-mips.org>
CC:     <linux-mips@...ux-mips.org>,
        Matt Redfearn <matt.redfearn@...tec.com>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        <linux-kernel@...r.kernel.org>, Aaron Tomlin <atomlin@...hat.com>,
        "Jason A. Donenfeld" <jason@...c4.com>
Subject: [PATCH] MIPS: Fix minimum alignment requirement of IRQ stack

Commit db8466c581cc ("MIPS: IRQ Stack: Unwind IRQ stack onto task
stack") erroneously set the initial stack pointer of the IRQ stack to a
value with a 4 byte alignment. The MIPS32 ABI requires that the minimum
stack alignment is 8 byte, and the MIPS64 ABIs(n32/n64) require 16 byte
minimum alignment. Use the ALMASK stack pointer mask to align the stack
as appropriate for the kernel build.

Fixes: db8466c581cc ("MIPS: IRQ Stack: Unwind IRQ stack onto task stack")
Reported-by: Darius Ivanauskas <dasilt@...oo.com>
Suggested-by: James Hogan <james.hogan@...tec.com>
Signed-off-by: Matt Redfearn <matt.redfearn@...tec.com>

---

 arch/mips/include/asm/irq.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/mips/include/asm/irq.h b/arch/mips/include/asm/irq.h
index ddd1c918103b..ac66a2de091a 100644
--- a/arch/mips/include/asm/irq.h
+++ b/arch/mips/include/asm/irq.h
@@ -9,6 +9,7 @@
 #ifndef _ASM_IRQ_H
 #define _ASM_IRQ_H
 
+#include <asm/asm.h>
 #include <linux/linkage.h>
 #include <linux/smp.h>
 #include <linux/irqdomain.h>
@@ -17,8 +18,8 @@
 
 #include <irq.h>
 
-#define IRQ_STACK_SIZE			THREAD_SIZE
-#define IRQ_STACK_START			(IRQ_STACK_SIZE - sizeof(unsigned long))
+#define IRQ_STACK_SIZE	THREAD_SIZE
+#define IRQ_STACK_START	((IRQ_STACK_SIZE - sizeof(unsigned long)) & ALMASK)
 
 extern void *irq_stack[NR_CPUS];
 
-- 
2.7.4