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Commit 7655abb9 authored by Will Deacon's avatar Will Deacon
Browse files

arm64: mm: Move ASID from TTBR0 to TTBR1 



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: default avatarMark Rutland <mark.rutland@arm.com>
Tested-by: default avatarLaura Abbott <labbott@redhat.com>
Tested-by: default avatarShanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 376133b7

arch/arm64/include/asm/mmu_context.h

+7 −0
Original line number Diff line number Diff line
@@ -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

arch/arm64/include/asm/pgtable-hwdef.h

+1 −0
Original line number Diff line number Diff line
@@ -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)

arch/arm64/include/asm/proc-fns.h

+0 −6
Original line number Diff line number Diff line
@@ -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 */

arch/arm64/mm/proc.S

+6 −3
Original line number Diff line number Diff line
@@ -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



	/*