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: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Dave Martin 2012-02-10 18:07:07 -08:00 committed by Marc Zyngier
parent 80c59dafb1
commit 424e5994e6
4 changed files with 91 additions and 8 deletions

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@ -1,6 +1,7 @@
ashldi3.S
font.c
lib1funcs.S
hyp-stub.S
piggy.gzip
piggy.lzo
piggy.lzma

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@ -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)

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@ -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

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@ -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: