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arm64: Re-order reserved_ttbr0 in linker script

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Currently one resolves the location of the reserved_ttbr0 for PAN by
taking a positive offset from swapper_pg_dir. In a future patch we wish
to extend the swapper s.t. its size is determined at link time rather
than comile time, rendering SWAPPER_DIR_SIZE unsuitable for such a low
level calculation.

In this patch we re-arrange the order of the linker script s.t. instead
one computes reserved_ttbr0 by subtracting RESERVED_TTBR0_SIZE from
swapper_pg_dir.

Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Steve Capper <steve.capper@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Steve Capper
2018-01-11 10:11:57 +00:00
committed by Catalin Marinas
parent 79e9aa59dc
commit 9dfe4828aa
3 changed files with 8 additions and 9 deletions
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4
arch/arm64/include/asm/uaccess.h
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@@ -108,8 +108,8 @@ static inline void __uaccess_ttbr0_disable(void)
unsigned long ttbr;
ttbr = read_sysreg(ttbr1_el1);
/* reserved_ttbr0 placed at the end of swapper_pg_dir */
write_sysreg(ttbr + SWAPPER_DIR_SIZE, ttbr0_el1);
/* reserved_ttbr0 placed before swapper_pg_dir */
write_sysreg(ttbr - RESERVED_TTBR0_SIZE, ttbr0_el1);
isb();
/* Set reserved ASID */
ttbr &= ~TTBR_ASID_MASK;