[PATCH 3/7] ARM: zImage/virt: hyp mode entry support for the zImage loader
Marc Zyngier
marc.zyngier at arm.com
Sat Aug 11 07:04:33 EDT 2012
From: Dave Martin <dave.martin at linaro.org>
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 at linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
arch/arm/boot/compressed/.gitignore | 1 +
arch/arm/boot/compressed/Makefile | 9 ++++-
arch/arm/boot/compressed/head.S | 71 +++++++++++++++++++++++++++++++---
arch/arm/kernel/hyp-stub.S | 18 +++++++++
4 files changed, 91 insertions(+), 8 deletions(-)
diff --git a/arch/arm/boot/compressed/.gitignore b/arch/arm/boot/compressed/.gitignore
index d0d441c..f79a08e 100644
--- a/arch/arm/boot/compressed/.gitignore
+++ b/arch/arm/boot/compressed/.gitignore
@@ -1,6 +1,7 @@
ashldi3.S
font.c
lib1funcs.S
+hyp-stub.S
piggy.gzip
piggy.lzo
piggy.lzma
diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index bb26756..a517153 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -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)
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index b8c64b8..0749a61 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -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
diff --git a/arch/arm/kernel/hyp-stub.S b/arch/arm/kernel/hyp-stub.S
index 2d529d6..4ff46fa 100644
--- a/arch/arm/kernel/hyp-stub.S
+++ b/arch/arm/kernel/hyp-stub.S
@@ -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.
*
@@ -169,9 +185,11 @@ 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:
--
1.7.8.6
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