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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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8
arch/arm64/include/asm/asm-uaccess.h
View file

@ -13,11 +13,11 @@
*/
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
.macro __uaccess_ttbr0_disable, tmp1
mrs \tmp1, ttbr1_el1 // swapper_pg_dir
add \tmp1, \tmp1, #SWAPPER_DIR_SIZE // reserved_ttbr0 at the end of swapper_pg_dir
msr ttbr0_el1, \tmp1 // set reserved TTBR0_EL1
mrs \tmp1, ttbr1_el1 // swapper_pg_dir
sub \tmp1, \tmp1, #RESERVED_TTBR0_SIZE // reserved_ttbr0 just before swapper_pg_dir
msr ttbr0_el1, \tmp1 // set reserved TTBR0_EL1
isb
sub \tmp1, \tmp1, #SWAPPER_DIR_SIZE
add \tmp1, \tmp1, #RESERVED_TTBR0_SIZE
bic \tmp1, \tmp1, #TTBR_ASID_MASK
msr ttbr1_el1, \tmp1 // set reserved ASID
isb

4
arch/arm64/include/asm/uaccess.h
View file

@ -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;

5
arch/arm64/kernel/vmlinux.lds.S
View file

@ -218,13 +218,12 @@ SECTIONS
. = ALIGN(PAGE_SIZE);
idmap_pg_dir = .;
. += IDMAP_DIR_SIZE;
swapper_pg_dir = .;
. += SWAPPER_DIR_SIZE;
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
reserved_ttbr0 = .;
. += RESERVED_TTBR0_SIZE;
#endif
swapper_pg_dir = .;
. += SWAPPER_DIR_SIZE;
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
tramp_pg_dir = .;