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authorDave Martin <dave.martin@linaro.org>2011-08-19 18:00:08 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-10-17 09:12:41 +0100
commitef4c53687e0adf5409896c4fa688b15f8d4dc0c0 (patch)
treed5f472200e98e4863f1b34c8308f719ffc87f606 /arch/arm/kernel/entry-armv.S
parent85519189df91c8aa9c368de0bdcfd7812200e614 (diff)
downloadlinux-ef4c53687e0adf5409896c4fa688b15f8d4dc0c0.tar.gz
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: 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>
Diffstat (limited to 'arch/arm/kernel/entry-armv.S')
-rw-r--r--arch/arm/kernel/entry-armv.S38
1 files changed, 37 insertions, 1 deletions
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index b7236d400ae..9ad50c4208a 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -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