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

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

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Maciej W. Rozycki 2005-06-13 20:24:00 +00:00 committed by Ralf Baechle
parent d925c262dd
commit fded2e508a
1 changed files with 30 additions and 40 deletions
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70
arch/mips/mm/tlbex.c
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@ -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);