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-rw-r--r--arch/arm/boot/compressed/head.S52
1 files changed, 45 insertions, 7 deletions
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index c41a793b519c..2c45b5709fa4 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -10,8 +10,11 @@
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
+#include <asm/v7m.h>
+
+ AR_CLASS( .arch armv7-a )
+ M_CLASS( .arch armv7-m )
- .arch armv7-a
/*
* Debugging stuff
*
@@ -114,7 +117,12 @@
* sort out different calling conventions
*/
.align
- .arm @ Always enter in ARM state
+ /*
+ * Always enter in ARM state for CPUs that support the ARM ISA.
+ * As of today (2014) that's exactly the members of the A and R
+ * classes.
+ */
+ AR_CLASS( .arm )
start:
.type start,#function
.rept 7
@@ -132,14 +140,15 @@ start:
THUMB( .thumb )
1:
- ARM_BE8( setend be ) @ go BE8 if compiled for BE8
- mrs r9, cpsr
+ ARM_BE8( setend be ) @ go BE8 if compiled for BE8
+ AR_CLASS( mrs r9, cpsr )
#ifdef CONFIG_ARM_VIRT_EXT
bl __hyp_stub_install @ get into SVC mode, reversibly
#endif
mov r7, r1 @ save architecture ID
mov r8, r2 @ save atags pointer
+#ifndef CONFIG_CPU_V7M
/*
* Booting from Angel - need to enter SVC mode and disable
* FIQs/IRQs (numeric definitions from angel arm.h source).
@@ -155,6 +164,7 @@ not_angel:
safe_svcmode_maskall r0
msr spsr_cxsf, r9 @ Save the CPU boot mode in
@ SPSR
+#endif
/*
* Note that some cache flushing and other stuff may
* be needed here - is there an Angel SWI call for this?
@@ -168,9 +178,26 @@ not_angel:
.text
#ifdef CONFIG_AUTO_ZRELADDR
- @ determine final kernel image address
+ /*
+ * Find the start of physical memory. As we are executing
+ * without the MMU on, we are in the physical address space.
+ * We just need to get rid of any offset by aligning the
+ * address.
+ *
+ * This alignment is a balance between the requirements of
+ * different platforms - we have chosen 128MB to allow
+ * platforms which align the start of their physical memory
+ * to 128MB to use this feature, while allowing the zImage
+ * to be placed within the first 128MB of memory on other
+ * platforms. Increasing the alignment means we place
+ * stricter alignment requirements on the start of physical
+ * memory, but relaxing it means that we break people who
+ * are already placing their zImage in (eg) the top 64MB
+ * of this range.
+ */
mov r4, pc
and r4, r4, #0xf8000000
+ /* Determine final kernel image address. */
add r4, r4, #TEXT_OFFSET
#else
ldr r4, =zreladdr
@@ -810,6 +837,16 @@ __common_mmu_cache_on:
call_cache_fn: adr r12, proc_types
#ifdef CONFIG_CPU_CP15
mrc p15, 0, r9, c0, c0 @ get processor ID
+#elif defined(CONFIG_CPU_V7M)
+ /*
+ * On v7-M the processor id is located in the V7M_SCB_CPUID
+ * register, but as cache handling is IMPLEMENTATION DEFINED on
+ * v7-M (if existant at all) we just return early here.
+ * If V7M_SCB_CPUID were used the cpu ID functions (i.e.
+ * __armv7_mmu_cache_{on,off,flush}) would be selected which
+ * use cp15 registers that are not implemented on v7-M.
+ */
+ bx lr
#else
ldr r9, =CONFIG_PROCESSOR_ID
#endif
@@ -1310,8 +1347,9 @@ __hyp_reentry_vectors:
__enter_kernel:
mov r0, #0 @ must be 0
- ARM( mov pc, r4 ) @ call kernel
- THUMB( bx r4 ) @ entry point is always ARM
+ ARM( mov pc, r4 ) @ call kernel
+ M_CLASS( add r4, r4, #1 ) @ enter in Thumb mode for M class
+ THUMB( bx r4 ) @ entry point is always ARM for A/R classes
reloc_code_end: