Commit 8fe4908b authored by James Hogan's avatar James Hogan Committed by Ralf Baechle
Browse files

MIPS: tlbex: Avoid unnecessary _PAGE_PRESENT shifts 



Commit c5b36783 ("MIPS: Add support for XPA.") added generation of a
shift by _PAGE_PRESENT_SHIFT in build_pte_present() and
build_pte_writable(), however except for the XPA case this is always
zero making it unnecessary.

Make the shift conditional upon _PAGE_PRESENT_SHIFT being non-zero to
save an instruction in those cases.

Fixes: c5b36783 ("MIPS: Add support for XPA.")
Signed-off-by: default avatarJames Hogan <james.hogan@imgtec.com>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9889/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent a3ae565a

arch/mips/mm/tlbex.c

+17 −6
Original line number Diff line number Diff line
@@ -1608,22 +1608,29 @@ build_pte_present(u32 **p, struct uasm_reloc **r, 
		  int pte, int ptr, int scratch, enum label_id lid)

{

	int t = scratch >= 0 ? scratch : pte;

	int cur = pte;



	if (cpu_has_rixi) {

		if (use_bbit_insns()) {

			uasm_il_bbit0(p, r, pte, ilog2(_PAGE_PRESENT), lid);

			uasm_i_nop(p);

		} else {

			uasm_i_srl(p, t, pte, _PAGE_PRESENT_SHIFT);

			uasm_i_andi(p, t, t, 1);

			if (_PAGE_PRESENT_SHIFT) {

				uasm_i_srl(p, t, cur, _PAGE_PRESENT_SHIFT);

				cur = t;

			}

			uasm_i_andi(p, t, cur, 1);

			uasm_il_beqz(p, r, t, lid);

			if (pte == t)

				/* You lose the SMP race :-(*/

				iPTE_LW(p, pte, ptr);

		}

	} else {

		uasm_i_srl(p, t, pte, _PAGE_PRESENT_SHIFT);

		uasm_i_andi(p, t, t,

		if (_PAGE_PRESENT_SHIFT) {

			uasm_i_srl(p, t, cur, _PAGE_PRESENT_SHIFT);

			cur = t;

		}

		uasm_i_andi(p, t, cur,

			(_PAGE_PRESENT | _PAGE_READ) >> _PAGE_PRESENT_SHIFT);

		uasm_i_xori(p, t, t,

			(_PAGE_PRESENT | _PAGE_READ) >> _PAGE_PRESENT_SHIFT);
@@ -1654,9 +1661,13 @@ build_pte_writable(u32 **p, struct uasm_reloc **r, 
		   enum label_id lid)

{

	int t = scratch >= 0 ? scratch : pte;

	int cur = pte;



	uasm_i_srl(p, t, pte, _PAGE_PRESENT_SHIFT);

	uasm_i_andi(p, t, t,

	if (_PAGE_PRESENT_SHIFT) {

		uasm_i_srl(p, t, cur, _PAGE_PRESENT_SHIFT);

		cur = t;

	}

	uasm_i_andi(p, t, cur,

		    (_PAGE_PRESENT | _PAGE_WRITE) >> _PAGE_PRESENT_SHIFT);

	uasm_i_xori(p, t, t,

		    (_PAGE_PRESENT | _PAGE_WRITE) >> _PAGE_PRESENT_SHIFT);

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