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arm64: mm: Move ASID from TTBR0 to TTBR1

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In preparation for mapping kernelspace and userspace with different
ASIDs, move the ASID to TTBR1 and update switch_mm to context-switch
TTBR0 via an invalid mapping (the zero page).

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon 2017-08-10 13:19:09 +01:00
parent 376133b7ed
commit 7655abb953
4 changed files with 14 additions and 9 deletions
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7
arch/arm64/include/asm/mmu_context.h
View File

@ -57,6 +57,13 @@ static inline void cpu_set_reserved_ttbr0(void)
isb();
}
static inline void cpu_switch_mm(pgd_t *pgd, struct mm_struct *mm)
{
BUG_ON(pgd == swapper_pg_dir);
cpu_set_reserved_ttbr0();
cpu_do_switch_mm(virt_to_phys(pgd),mm);
}
/*
* TCR.T0SZ value to use when the ID map is active. Usually equals
* TCR_T0SZ(VA_BITS), unless system RAM is positioned very high in

1
arch/arm64/include/asm/pgtable-hwdef.h
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@ -272,6 +272,7 @@
#define TCR_TG1_4K (UL(2) << TCR_TG1_SHIFT)
#define TCR_TG1_64K (UL(3) << TCR_TG1_SHIFT)
#define TCR_A1 (UL(1) << 22)
#define TCR_ASID16 (UL(1) << 36)
#define TCR_TBI0 (UL(1) << 37)
#define TCR_HA (UL(1) << 39)

6
arch/arm64/include/asm/proc-fns.h
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@ -35,12 +35,6 @@ extern u64 cpu_do_resume(phys_addr_t ptr, u64 idmap_ttbr);
#include <asm/memory.h>
#define cpu_switch_mm(pgd,mm) \
do { \
BUG_ON(pgd == swapper_pg_dir); \
cpu_do_switch_mm(virt_to_phys(pgd),mm); \
} while (0)
#endif /* __ASSEMBLY__ */
#endif /* __KERNEL__ */
#endif /* __ASM_PROCFNS_H */

9
arch/arm64/mm/proc.S
View File

@ -139,9 +139,12 @@ ENDPROC(cpu_do_resume)
*/
ENTRY(cpu_do_switch_mm)
pre_ttbr0_update_workaround x0, x2, x3
mrs x2, ttbr1_el1
mmid x1, x1 // get mm->context.id
bfi x0, x1, #48, #16 // set the ASID
msr ttbr0_el1, x0 // set TTBR0
bfi x2, x1, #48, #16 // set the ASID
msr ttbr1_el1, x2 // in TTBR1 (since TCR.A1 is set)
isb
msr ttbr0_el1, x0 // now update TTBR0
isb
post_ttbr0_update_workaround
ret
@ -224,7 +227,7 @@ ENTRY(__cpu_setup)
* both user and kernel.
*/
ldr x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \
TCR_TG_FLAGS | TCR_ASID16 | TCR_TBI0
TCR_TG_FLAGS | TCR_ASID16 | TCR_TBI0 | TCR_A1
tcr_set_idmap_t0sz x10, x9
/*