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Commit 0c8ea531 authored by Will Deacon's avatar Will Deacon
Browse files

arm64: mm: Allocate ASIDs in pairs 



In preparation for separate kernel/user ASIDs, allocate them in pairs
for each mm_struct. The bottom bit distinguishes the two: if it is set,
then the ASID will map only userspace.

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 27a921e7

arch/arm64/include/asm/mmu.h

+1 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#define __ASM_MMU_H



#define MMCF_AARCH32	0x1	/* mm context flag for AArch32 executables */

#define USER_ASID_FLAG	(UL(1) << 48)



typedef struct {

	atomic64_t	id;

arch/arm64/mm/context.c

+17 −8
Original line number Diff line number Diff line
@@ -39,7 +39,16 @@ static cpumask_t tlb_flush_pending; 


#define ASID_MASK		(~GENMASK(asid_bits - 1, 0))

#define ASID_FIRST_VERSION	(1UL << asid_bits)

#define NUM_USER_ASIDS		ASID_FIRST_VERSION



#ifdef CONFIG_UNMAP_KERNEL_AT_EL0

#define NUM_USER_ASIDS		(ASID_FIRST_VERSION >> 1)

#define asid2idx(asid)		(((asid) & ~ASID_MASK) >> 1)

#define idx2asid(idx)		(((idx) << 1) & ~ASID_MASK)

#else

#define NUM_USER_ASIDS		(ASID_FIRST_VERSION)

#define asid2idx(asid)		((asid) & ~ASID_MASK)

#define idx2asid(idx)		asid2idx(idx)

#endif



/* Get the ASIDBits supported by the current CPU */

static u32 get_cpu_asid_bits(void)
@@ -98,7 +107,7 @@ static void flush_context(unsigned int cpu) 
		 */

		if (asid == 0)

			asid = per_cpu(reserved_asids, i);

		__set_bit(asid & ~ASID_MASK, asid_map);

		__set_bit(asid2idx(asid), asid_map);

		per_cpu(reserved_asids, i) = asid;

	}
@@ -153,16 +162,16 @@ static u64 new_context(struct mm_struct *mm, unsigned int cpu) 
		 * We had a valid ASID in a previous life, so try to re-use

		 * it if possible.

		 */

		asid &= ~ASID_MASK;

		if (!__test_and_set_bit(asid, asid_map))

		if (!__test_and_set_bit(asid2idx(asid), asid_map))

			return newasid;

	}



	/*

	 * Allocate a free ASID. If we can't find one, take a note of the

	 * currently active ASIDs and mark the TLBs as requiring flushes.

	 * We always count from ASID #1, as we use ASID #0 when setting a

	 * reserved TTBR0 for the init_mm.

	 * currently active ASIDs and mark the TLBs as requiring flushes.  We

	 * always count from ASID #2 (index 1), as we use ASID #0 when setting

	 * a reserved TTBR0 for the init_mm and we allocate ASIDs in even/odd

	 * pairs.

	 */

	asid = find_next_zero_bit(asid_map, NUM_USER_ASIDS, cur_idx);

	if (asid != NUM_USER_ASIDS)
@@ -179,7 +188,7 @@ static u64 new_context(struct mm_struct *mm, unsigned int cpu) 
set_asid:

	__set_bit(asid, asid_map);

	cur_idx = asid;

	return asid | generation;

	return idx2asid(asid) | generation;

}



void check_and_switch_context(struct mm_struct *mm, unsigned int cpu)