linux-kernel - [PATCH 12/14] arm64: Check for selected granule support

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Date:	Thu, 13 Aug 2015 12:34:02 +0100
From:	"Suzuki K. Poulose" <suzuki.poulose@....com>
To:	linux-arm-kernel@...ts.infradead.org
Cc:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	kvmarm@...ts.cs.columbia.edu, catalin.marinas@....com,
	will.deacon@....com, mark.rutland@....com, marc.zyngier@....com,
	"Suzuki K. Poulose" <suzuki.poulose@....com>
Subject: [PATCH 12/14] arm64: Check for selected granule support

From: "Suzuki K. Poulose" <suzuki.poulose@....com>

Ensure that the selected page size is supported by the
CPU(s).

Cc: Mark Rutland <mark.rutland@....com>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will.deacon@....com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@....com>
---
 arch/arm64/include/asm/sysreg.h |    6 ++++++
 arch/arm64/kernel/head.S        |   24 +++++++++++++++++++++++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index a7f3d4b..e01d323 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -87,4 +87,10 @@ static inline void config_sctlr_el1(u32 clear, u32 set)
 }
 #endif
 
+#define ID_AA64MMFR0_TGran4_SHIFT	28
+#define ID_AA64MMFR0_TGran64_SHIFT	24
+
+#define ID_AA64MMFR0_TGran4_ENABLED	0x0
+#define ID_AA64MMFR0_TGran64_ENABLED	0x0
+
 #endif	/* __ASM_SYSREG_H */
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 01b8e58..0cb04db 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -31,10 +31,11 @@
 #include <asm/cputype.h>
 #include <asm/kernel-pgtable.h>
 #include <asm/memory.h>
-#include <asm/thread_info.h>
 #include <asm/pgtable-hwdef.h>
 #include <asm/pgtable.h>
 #include <asm/page.h>
+#include <asm/sysreg.h>
+#include <asm/thread_info.h>
 #include <asm/virt.h>
 
 #define __PHYS_OFFSET	(KERNEL_START - TEXT_OFFSET)
@@ -606,9 +607,25 @@ ENDPROC(__secondary_switched)
  *  x27 = *virtual* address to jump to upon completion
  *
  * other registers depend on the function called upon completion
+ * Checks if the selected granule size is supported by the CPU.
  */
+#if	defined(CONFIG_ARM64_64K_PAGES)
+
+#define ID_AA64MMFR0_TGran_SHIFT	ID_AA64MMFR0_TGran64_SHIFT
+#define ID_AA64MMFR0_TGran_ENABLED	ID_AA64MMFR0_TGran64_ENABLED
+
+#else
+
+#define ID_AA64MMFR0_TGran_SHIFT	ID_AA64MMFR0_TGran4_SHIFT
+#define ID_AA64MMFR0_TGran_ENABLED	ID_AA64MMFR0_TGran4_ENABLED
+
+#endif
 	.section	".idmap.text", "ax"
 __enable_mmu:
+	mrs	x1, ID_AA64MMFR0_EL1
+	ubfx	x2, x1, #ID_AA64MMFR0_TGran_SHIFT, 4
+	cmp	x2, #ID_AA64MMFR0_TGran_ENABLED
+	b.ne	__no_granule_support
 	ldr	x5, =vectors
 	msr	vbar_el1, x5
 	msr	ttbr0_el1, x25			// load TTBR0
@@ -626,3 +643,8 @@ __enable_mmu:
 	isb
 	br	x27
 ENDPROC(__enable_mmu)
+
+__no_granule_support:
+	wfe
+	b __no_granule_support
+ENDPROC(__no_granule_support)
-- 
1.7.9.5

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