MIPS: Fix minimum alignment requirement of IRQ stack

mpredfearn · ralfbaechle · commit 5fdc66e04620 · 2017-07-11T14:13:06.000+02:00
Commit db8466c ("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. Fix IRQ_STACK_START such that it leaves space for the dummy stack frame (containing interrupted task kernel stack pointer) while also meeting minimum alignment requirements. Fixes: db8466c ("MIPS: IRQ Stack: Unwind IRQ stack onto task stack") Reported-by: Darius Ivanauskas <dasilt@yahoo.com> Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Jason A. Donenfeld <jason@zx2c4.com> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/16760/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/asm/irq.h b/arch/mips/include/asm/irq.h
@@ -18,7 +18,7 @@
 #include <irq.h>
 
 #define IRQ_STACK_SIZE			THREAD_SIZE
-#define IRQ_STACK_START			(IRQ_STACK_SIZE - sizeof(unsigned long))
+#define IRQ_STACK_START			(IRQ_STACK_SIZE - 16)
 
 extern void *irq_stack[NR_CPUS];
 
