Commit ef4c5368 authored by Dave Martin's avatar Dave Martin Committed by Russell King
Browse files

ARM: 7031/1: entry: Fix Thumb-2 undef handling for multi-CPU kernels 



When v6 and >=v7 boards are supported in the same kernel, the
__und_usr code currently makes a build-time assumption that Thumb-2
instructions occurring in userspace don't need to be supported.
Strictly speaking this is incorrect.

This patch fixes the above case by doing a run-time check on the
CPU architecture in these cases.  This only affects kernels which
support v6 and >=v7 CPUs together: plain v6 and plain v7 kernels
are unaffected.

Signed-off-by: default avatarDave Martin <dave.martin@linaro.org>
Reviewed-by: default avatarJon Medhurst <tixy@yxit.co.uk>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 85519189

arch/arm/kernel/entry-armv.S

+37 −1
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ 
#include <asm/unwind.h>

#include <asm/unistd.h>

#include <asm/tls.h>

#include <asm/system.h>



#include "entry-header.S"

#include <asm/entry-macro-multi.S>
@@ -439,7 +440,27 @@ __und_usr: 
#endif

	beq	call_fpe

	@ Thumb instruction

#if __LINUX_ARM_ARCH__ >= 7

#if CONFIG_ARM_THUMB && __LINUX_ARM_ARCH__ >= 6 && CONFIG_CPU_V7

/*

 * Thumb-2 instruction handling.  Note that because pre-v6 and >= v6 platforms

 * can never be supported in a single kernel, this code is not applicable at

 * all when __LINUX_ARM_ARCH__ < 6.  This allows simplifying assumptions to be

 * made about .arch directives.

 */

#if __LINUX_ARM_ARCH__ < 7

/* If the target CPU may not be Thumb-2-capable, a run-time check is needed: */

#define NEED_CPU_ARCHITECTURE

	ldr	r5, .LCcpu_architecture

	ldr	r5, [r5]

	cmp	r5, #CPU_ARCH_ARMv7

	blo	__und_usr_unknown

/*

 * The following code won't get run unless the running CPU really is v7, so

 * coding round the lack of ldrht on older arches is pointless.  Temporarily

 * override the assembler target arch with the minimum required instead:

 */

	.arch	armv6t2

#endif

2:

 ARM(	ldrht	r5, [r4], #2	)

 THUMB(	ldrht	r5, [r4]	)
@@ -449,7 +470,16 @@ __und_usr: 
3:	ldrht	r0, [r4]

	add	r2, r2, #2			@ r2 is PC + 2, make it PC + 4

	orr	r0, r0, r5, lsl #16



#if __LINUX_ARM_ARCH__ < 7

/* If the target arch was overridden, change it back: */

#ifdef CONFIG_CPU_32v6K

	.arch	armv6k

#else

	.arch	armv6

#endif

#endif /* __LINUX_ARM_ARCH__ < 7 */

#else /* !(CONFIG_ARM_THUMB && __LINUX_ARM_ARCH__ >= 6 && CONFIG_CPU_V7) */

	b	__und_usr_unknown

#endif

 UNWIND(.fnend		)
@@ -576,6 +606,12 @@ call_fpe: 
	movw_pc	lr				@ CP#14 (Debug)

	movw_pc	lr				@ CP#15 (Control)



#ifdef NEED_CPU_ARCHITECTURE

	.align	2

.LCcpu_architecture:

	.word	__cpu_architecture

#endif



#ifdef CONFIG_NEON

	.align	6

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