From fded2e508a1d3c26ab477ab3b98f13274d4359ba Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Mon, 13 Jun 2005 20:24:00 +0000 Subject: Optimize R3k TLB Load/Store/Modified handlers, by scheduling delay slots properly and avoiding an unnecessary jump to a jump. Signed-off-by: Ralf Baechle --- arch/mips/mm/tlbex.c | 70 ++++++++++++++++++++++------------------------------ 1 file changed, 30 insertions(+), 40 deletions(-) (limited to 'arch/mips/mm') diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c index 68d24b80053..48546d18a5a 100644 --- a/arch/mips/mm/tlbex.c +++ b/arch/mips/mm/tlbex.c @@ -6,6 +6,7 @@ * Synthesize TLB refill handlers at runtime. * * Copyright (C) 2004,2005 by Thiemo Seufer + * Copyright (C) 2005 Maciej W. Rozycki */ #include @@ -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); -- cgit v1.2.3