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

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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: Dave Martin <dave.martin@linaro.org>
Reviewed-by: Jon Medhurst <tixy@yxit.co.uk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Dave Martin 2011-08-19 18:00:08 +01:00 committed by Russell King
parent 85519189df
commit ef4c53687e
1 changed files with 37 additions and 1 deletions
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38
arch/arm/kernel/entry-armv.S
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@ -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