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.rutl...@arm.com>
Signed-off-by: Will Deacon <will.dea...@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

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