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Commit 424e5994 authored by Dave Martin's avatar Dave Martin Committed by Marc Zyngier
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ARM: zImage/virt: hyp mode entry support for the zImage loader 



The zImage loader needs to turn on the MMU in order to take
advantage of caching while decompressing the zImage.  Running this
in hyp mode would require the LPAE pagetable format to be
supported; to avoid this complexity, this patch switches out of hyp
mode, and returns back to hyp mode just before booting the kernel.

This implementation assumes that the Hyp mode view of memory and the
PL1 view of memory are coherent, providing that the MMU and caches
are off in both, as required by the boot protocol.  The zImage
decompression code must drain the write buffer on completion anyway, and
entry into Hyp mode should flush any prefetch buffer, avoiding hazards
associated with local write buffers and the pipeline.

Signed-off-by: default avatarDave Martin <dave.martin@linaro.org>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
parent 80c59daf

arch/arm/boot/compressed/.gitignore

+1 −0
Original line number Diff line number Diff line 
ashldi3.S

font.c

lib1funcs.S

hyp-stub.S

piggy.gzip

piggy.lzo

piggy.lzma

arch/arm/boot/compressed/Makefile

+8 −1
Original line number Diff line number Diff line
@@ -30,6 +30,10 @@ FONTC = $(srctree)/drivers/video/console/font_acorn_8x8.c 
OBJS		+= string.o

CFLAGS_string.o	:= -Os



ifeq ($(CONFIG_ARM_VIRT_EXT),y)

OBJS		+= hyp-stub.o

endif



#

# Architecture dependencies

#
@@ -126,7 +130,7 @@ KBUILD_CFLAGS = $(subst -pg, , $(ORIG_CFLAGS)) 
endif



ccflags-y := -fpic -fno-builtin -I$(obj)

asflags-y := -Wa,-march=all

asflags-y := -Wa,-march=all -DZIMAGE



# Supply kernel BSS size to the decompressor via a linker symbol.

KBSS_SZ = $(shell $(CROSS_COMPILE)size $(obj)/../../../../vmlinux | \
@@ -198,3 +202,6 @@ $(obj)/font.c: $(FONTC) 


$(obj)/vmlinux.lds: $(obj)/vmlinux.lds.in arch/arm/boot/Makefile $(KCONFIG_CONFIG)

	@sed "$(SEDFLAGS)" < $< > $@



$(obj)/hyp-stub.S: $(srctree)/arch/$(SRCARCH)/kernel/hyp-stub.S

	$(call cmd,shipped)

arch/arm/boot/compressed/head.S

+64 −7
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
 * published by the Free Software Foundation.

 */

#include <linux/linkage.h>

#include <asm/assembler.h>



/*

 * Debugging stuff
@@ -132,7 +133,12 @@ start: 
		.word	start			@ absolute load/run zImage address

		.word	_edata			@ zImage end address

 THUMB(		.thumb			)

1:		mov	r7, r1			@ save architecture ID

1:

		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 __ARM_ARCH_2__
@@ -148,9 +154,9 @@ start: 
 ARM(		swi	0x123456	)	@ angel_SWI_ARM

 THUMB(		svc	0xab		)	@ angel_SWI_THUMB

not_angel:

		mrs	r2, cpsr		@ turn off interrupts to

		orr	r2, r2, #0xc0		@ prevent angel from running

		msr	cpsr_c, r2

		safe_svcmode_maskall r0

		msr	spsr_cxsf, r9		@ Save the CPU boot mode in

						@ SPSR

#else

		teqp	pc, #0x0c000003		@ turn off interrupts

#endif
@@ -350,6 +356,20 @@ dtb_check_done: 
		adr	r5, restart

		bic	r5, r5, #31



/* Relocate the hyp vector base if necessary */

#ifdef CONFIG_ARM_VIRT_EXT

		mrs	r0, spsr

		and	r0, r0, #MODE_MASK

		cmp	r0, #HYP_MODE

		bne	1f



		bl	__hyp_get_vectors

		sub	r0, r0, r5

		add	r0, r0, r10

		bl	__hyp_set_vectors

1:

#endif



		sub	r9, r6, r5		@ size to copy

		add	r9, r9, #31		@ rounded up to a multiple

		bic	r9, r9, #31		@ ... of 32 bytes
@@ -458,11 +478,29 @@ not_relocated: mov r0, #0 
		bl	decompress_kernel

		bl	cache_clean_flush

		bl	cache_off

		mov	r0, #0			@ must be zero

		mov	r1, r7			@ restore architecture number

		mov	r2, r8			@ restore atags pointer

 ARM(		mov	pc, r4	)		@ call kernel

 THUMB(		bx	r4	)		@ entry point is always ARM



#ifdef CONFIG_ARM_VIRT_EXT

		mrs	r0, spsr		@ Get saved CPU boot mode

		and	r0, r0, #MODE_MASK

		cmp	r0, #HYP_MODE		@ if not booted in HYP mode...

		bne	__enter_kernel		@ boot kernel directly



		adr	r12, .L__hyp_reentry_vectors_offset

		ldr	r0, [r12]

		add	r0, r0, r12



		bl	__hyp_set_vectors

		__HVC(0)			@ otherwise bounce to hyp mode



		b	.			@ should never be reached



		.align	2

.L__hyp_reentry_vectors_offset:	.long	__hyp_reentry_vectors - .

#else

		b	__enter_kernel

#endif



		.align	2

		.type	LC0, #object
@@ -1191,6 +1229,25 @@ memdump: mov r12, r0 
#endif



		.ltorg



#ifdef CONFIG_ARM_VIRT_EXT

.align 5

__hyp_reentry_vectors:

		W(b)	.			@ reset

		W(b)	.			@ undef

		W(b)	.			@ svc

		W(b)	.			@ pabort

		W(b)	.			@ dabort

		W(b)	__enter_kernel		@ hyp

		W(b)	.			@ irq

		W(b)	.			@ fiq

#endif /* CONFIG_ARM_VIRT_EXT */



__enter_kernel:

		mov	r0, #0			@ must be 0

 ARM(		mov	pc, r4	)		@ call kernel

 THUMB(		bx	r4	)		@ entry point is always ARM



reloc_code_end:



		.align

arch/arm/kernel/hyp-stub.S

+18 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <asm/assembler.h>

#include <asm/virt.h>



#ifndef ZIMAGE

/*

 * For the kernel proper, we need to find out the CPU boot mode long after

 * boot, so we need to store it in a writable variable.
@@ -59,6 +60,21 @@ ENTRY(__boot_cpu_mode) 
	strne	r7, [r5, r6]		@ record what happened and give up

	.endm



#else	/* ZIMAGE */



	.macro	store_primary_cpu_mode	reg1:req, reg2:req, reg3:req

	.endm



/*

 * The zImage loader only runs on one CPU, so we don't bother with mult-CPU

 * consistency checking:

 */

	.macro	compare_cpu_mode_with_primary mode, reg1, reg2, reg3

	cmp	\mode, \mode

	.endm



#endif /* ZIMAGE */



/*

 * Hypervisor stub installation functions.

 *
@@ -174,9 +190,11 @@ ENTRY(__hyp_set_vectors) 
	bx	lr

ENDPROC(__hyp_set_vectors)



#ifndef ZIMAGE

.align 2

.L__boot_cpu_mode_offset:

	.long	__boot_cpu_mode - .

#endif



.align 5

__hyp_stub_vectors: