[PATCHv4 09/12] arm64: Check for selected granule support

[Suzuki K. Poulose]

Ensure that the selected page size is supported by the CPU(s). If it doesn't
park it.

Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@xxxxxxx>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Tested-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
 arch/arm64/include/asm/sysreg.h |   20 ++++++++++++++++++++
 arch/arm64/kernel/head.S        |   17 +++++++++++++++--
 2 files changed, 35 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index a7f3d4b..d59cb23 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -44,6 +44,26 @@
 #define SET_PSTATE_PAN(x) __inst_arm(0xd5000000 | REG_PSTATE_PAN_IMM |\
 				     (!!x)<<8 | 0x1f)
 
+
+#define ID_AA64MMFR0_TGRAN4_SHIFT	28
+#define ID_AA64MMFR0_TGRAN64_SHIFT	24
+#define ID_AA64MMFR0_TGRAN16_SHIFT	20
+
+#define ID_AA64MMFR0_TGRAN4_NI		0xf
+#define ID_AA64MMFR0_TGRAN4_SUPPORTED	0x0
+#define ID_AA64MMFR0_TGRAN64_NI		0xf
+#define ID_AA64MMFR0_TGRAN64_SUPPORTED	0x0
+#define ID_AA64MMFR0_TGRAN16_NI		0x0
+#define ID_AA64MMFR0_TGRAN16_SUPPORTED	0x1
+
+#if defined(CONFIG_ARM64_4K_PAGES)
+#define ID_AA64MMFR0_TGRAN_SHIFT	ID_AA64MMFR0_TGRAN4_SHIFT
+#define ID_AA64MMFR0_TGRAN_SUPPORTED	ID_AA64MMFR0_TGRAN4_SUPPORTED
+#elif defined(CONFIG_ARM64_64K_PAGES)
+#define ID_AA64MMFR0_TGRAN_SHIFT	ID_AA64MMFR0_TGRAN64_SHIFT
+#define ID_AA64MMFR0_TGRAN_SUPPORTED	ID_AA64MMFR0_TGRAN64_SUPPORTED
+#endif
+
 #ifdef __ASSEMBLY__
 
 	.irp	num,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index 7ace955..514c1cc 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)
@@ -613,10 +614,17 @@ ENDPROC(__secondary_switched)
  *  x0  = SCTLR_EL1 value for turning on the MMU.
  *  x27 = *virtual* address to jump to upon completion
  *
- * other registers depend on the function called upon completion
+ * Other registers depend on the function called upon completion.
+ *
+ * Checks if the selected granule size is supported by the CPU.
+ * If it isn't, park the CPU
  */
 	.section	".idmap.text", "ax"
 __enable_mmu:
+	mrs	x1, ID_AA64MMFR0_EL1
+	ubfx	x2, x1, #ID_AA64MMFR0_TGRAN_SHIFT, 4
+	cmp	x2, #ID_AA64MMFR0_TGRAN_SUPPORTED
+	b.ne	__no_granule_support
 	ldr	x5, =vectors
 	msr	vbar_el1, x5
 	msr	ttbr0_el1, x25			// load TTBR0
@@ -634,3 +642,8 @@ __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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