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Commit fded2e50 authored by Maciej W. Rozycki's avatar Maciej W. Rozycki Committed by Ralf Baechle
Browse files

Optimize R3k TLB Load/Store/Modified handlers, by scheduling 


delay slots properly and avoiding an unnecessary jump to a jump.

Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent d925c262

arch/mips/mm/tlbex.c

+30 −40
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
 * Synthesize TLB refill handlers at runtime.

 *

 * Copyright (C) 2004,2005 by Thiemo Seufer

 * Copyright (C) 2005  Maciej W. Rozycki

 */



#include <stdarg.h>
@@ -410,7 +411,6 @@ enum label_id { 
	label_nopage_tlbm,

	label_smp_pgtable_change,

	label_r3000_write_probe_fail,

	label_r3000_write_probe_ok

};



struct label {
@@ -443,7 +443,6 @@ L_LA(_nopage_tlbs) 
L_LA(_nopage_tlbm)

L_LA(_smp_pgtable_change)

L_LA(_r3000_write_probe_fail)

L_LA(_r3000_write_probe_ok)



/* convenience macros for instructions */

#ifdef CONFIG_64BIT
@@ -1414,34 +1413,41 @@ build_pte_modifiable(u32 **p, struct label **l, struct reloc **r, 
 * R3000 style TLB load/store/modify handlers.

 */



/* This places the pte in the page table at PTR into ENTRYLO0. */

/*

 * This places the pte into ENTRYLO0 and writes it with tlbwi.

 * Then it returns.

 */

static void __init

build_r3000_pte_reload(u32 **p, unsigned int ptr)

build_r3000_pte_reload_tlbwi(u32 **p, unsigned int pte, unsigned int tmp)

{

	i_lw(p, ptr, 0, ptr);

	i_nop(p); /* load delay */

	i_mtc0(p, ptr, C0_ENTRYLO0);

	i_nop(p); /* cp0 delay */

	i_mtc0(p, pte, C0_ENTRYLO0); /* cp0 delay */

	i_mfc0(p, tmp, C0_EPC); /* cp0 delay */

	i_tlbwi(p);

	i_jr(p, tmp);

	i_rfe(p); /* branch delay */

}



/*

 * The index register may have the probe fail bit set,

 * because we would trap on access kseg2, i.e. without refill.

 * This places the pte into ENTRYLO0 and writes it with tlbwi

 * or tlbwr as appropriate.  This is because the index register

 * may have the probe fail bit set as a result of a trap on a

 * kseg2 access, i.e. without refill.  Then it returns.

 */

static void __init

build_r3000_tlb_write(u32 **p, struct label **l, struct reloc **r,

		      unsigned int tmp)

build_r3000_tlb_reload_write(u32 **p, struct label **l, struct reloc **r,

			     unsigned int pte, unsigned int tmp)

{

	i_mfc0(p, tmp, C0_INDEX);

	i_nop(p); /* cp0 delay */

	il_bltz(p, r, tmp, label_r3000_write_probe_fail);

	i_nop(p); /* branch delay */

	i_tlbwi(p);

	il_b(p, r, label_r3000_write_probe_ok);

	i_nop(p); /* branch delay */

	i_mtc0(p, pte, C0_ENTRYLO0); /* cp0 delay */

	il_bltz(p, r, tmp, label_r3000_write_probe_fail); /* cp0 delay */

	i_mfc0(p, tmp, C0_EPC); /* branch delay */

	i_tlbwi(p); /* cp0 delay */

	i_jr(p, tmp);

	i_rfe(p); /* branch delay */

	l_r3000_write_probe_fail(l, *p);

	i_tlbwr(p);

	l_r3000_write_probe_ok(l, *p);

	i_tlbwr(p); /* cp0 delay */

	i_jr(p, tmp);

	i_rfe(p); /* branch delay */

}



static void __init
@@ -1461,17 +1467,7 @@ build_r3000_tlbchange_handler_head(u32 **p, unsigned int pte, 
	i_andi(p, pte, pte, 0xffc); /* load delay */

	i_addu(p, ptr, ptr, pte);

	i_lw(p, pte, 0, ptr);

	i_nop(p); /* load delay */

	i_tlbp(p);

}



static void __init

build_r3000_tlbchange_handler_tail(u32 **p, unsigned int tmp)

{

	i_mfc0(p, tmp, C0_EPC);

	i_nop(p); /* cp0 delay */

	i_jr(p, tmp);

	i_rfe(p); /* branch delay */

	i_tlbp(p); /* load delay */

}



static void __init build_r3000_tlb_load_handler(void)
@@ -1488,9 +1484,7 @@ static void __init build_r3000_tlb_load_handler(void) 
	build_pte_present(&p, &l, &r, K0, K1, label_nopage_tlbl);

	i_nop(&p); /* load delay */

	build_make_valid(&p, &r, K0, K1);

	build_r3000_pte_reload(&p, K1);

	build_r3000_tlb_write(&p, &l, &r, K0);

	build_r3000_tlbchange_handler_tail(&p, K0);

	build_r3000_tlb_reload_write(&p, &l, &r, K0, K1);



	l_nopage_tlbl(&l, p);

	i_j(&p, (unsigned long)tlb_do_page_fault_0 & 0x0fffffff);
@@ -1530,9 +1524,7 @@ static void __init build_r3000_tlb_store_handler(void) 
	build_pte_writable(&p, &l, &r, K0, K1, label_nopage_tlbs);

	i_nop(&p); /* load delay */

	build_make_write(&p, &r, K0, K1);

	build_r3000_pte_reload(&p, K1);

	build_r3000_tlb_write(&p, &l, &r, K0);

	build_r3000_tlbchange_handler_tail(&p, K0);

	build_r3000_tlb_reload_write(&p, &l, &r, K0, K1);



	l_nopage_tlbs(&l, p);

	i_j(&p, (unsigned long)tlb_do_page_fault_1 & 0x0fffffff);
@@ -1572,9 +1564,7 @@ static void __init build_r3000_tlb_modify_handler(void) 
	build_pte_modifiable(&p, &l, &r, K0, K1, label_nopage_tlbm);

	i_nop(&p); /* load delay */

	build_make_write(&p, &r, K0, K1);

	build_r3000_pte_reload(&p, K1);

	i_tlbwi(&p);

	build_r3000_tlbchange_handler_tail(&p, K0);

	build_r3000_pte_reload_tlbwi(&p, K0, K1);



	l_nopage_tlbm(&l, p);

	i_j(&p, (unsigned long)tlb_do_page_fault_1 & 0x0fffffff);