[PATCH v3 19/20] arm64: mm: Introduce TTBR_ASID_MASK for getting at the ASID in the TTBR

Will Deacon
2017-12-06T12:37:46Z

There are now a handful of open-coded masks to extract the ASID from a
TTBR value, so introduce a TTBR_ASID_MASK and use that instead.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/arm64/include/asm/asm-uaccess.h | 3 ++-
arch/arm64/include/asm/mmu.h | 1 +
arch/arm64/include/asm/uaccess.h | 4 ++--
arch/arm64/kernel/entry.S | 2 +-
4 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h
index 21b8cf304028..f4f234b6155e 100644
--- a/arch/arm64/include/asm/asm-uaccess.h
+++ b/arch/arm64/include/asm/asm-uaccess.h
@@ -4,6 +4,7 @@

#include <asm/alternative.h>
#include <asm/kernel-pgtable.h>
+#include <asm/mmu.h>
#include <asm/sysreg.h>
#include <asm/assembler.h>

@@ -17,7 +18,7 @@
msr ttbr0_el1, \tmp1 // set reserved TTBR0_EL1
isb
sub \tmp1, \tmp1, #SWAPPER_DIR_SIZE
- bic \tmp1, \tmp1, #(0xffff << 48)
+ bic \tmp1, \tmp1, #TTBR_ASID_MASK
msr ttbr1_el1, \tmp1 // set reserved ASID
isb
.endm
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
index da6f12e40714..6f7bdb89817f 100644
--- a/arch/arm64/include/asm/mmu.h
+++ b/arch/arm64/include/asm/mmu.h
@@ -18,6 +18,7 @@

#define MMCF_AARCH32 0x1 /* mm context flag for AArch32 executables */
#define USER_ASID_FLAG (UL(1) << 48)
+#define TTBR_ASID_MASK (UL(0xffff) << 48)

#ifndef __ASSEMBLY__

diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 750a3b76a01c..6eadf55ebaf0 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -112,7 +112,7 @@ static inline void __uaccess_ttbr0_disable(void)
write_sysreg(ttbr + SWAPPER_DIR_SIZE, ttbr0_el1);
isb();
/* Set reserved ASID */
- ttbr &= ~(0xffffUL << 48);
+ ttbr &= ~TTBR_ASID_MASK;
write_sysreg(ttbr, ttbr1_el1);
isb();
}
@@ -131,7 +131,7 @@ static inline void __uaccess_ttbr0_enable(void)

/* Restore active ASID */
ttbr1 = read_sysreg(ttbr1_el1);
- ttbr1 |= ttbr0 & (0xffffUL << 48);
+ ttbr1 |= ttbr0 & TTBR_ASID_MASK;
write_sysreg(ttbr1, ttbr1_el1);
isb();

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 5d51bdbb2131..3eabcb194c87 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -205,7 +205,7 @@ alternative_else_nop_endif

.if \el != 0
mrs x21, ttbr1_el1
- tst x21, #0xffff << 48 // Check for the reserved ASID
+ tst x21, #TTBR_ASID_MASK // Check for the reserved ASID
orr x23, x23, #PSR_PAN_BIT // Set the emulated PAN in the saved SPSR
b.eq 1f // TTBR0 access already disabled
and x23, x23, #~PSR_PAN_BIT // Clear the emulated PAN in the saved SPSR
--
2.1.4