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Re: missing data cache flush for signal trampoline on fork

To: linux-mips@linux-mips.org
Subject: Re: missing data cache flush for signal trampoline on fork
From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Date: Wed, 28 Sep 2005 20:57:58 +0900 (JST)
Cc: ralf@linux-mips.org
In-reply-to: <20050928.203429.02302175.nemoto@toshiba-tops.co.jp>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20050928.203429.02302175.nemoto@toshiba-tops.co.jp>
Sender: linux-mips-bounce@linux-mips.org
>>>>> On Wed, 28 Sep 2005 20:34:29 +0900 (JST), Atsushi Nemoto 
>>>>> <anemo@mba.ocn.ne.jp> said:
anemo> If I used indexed-flush for executable page in
anemo> flush_cache_page(), the problem disappear.  Is this a right
anemo> fix?

Sorry, this would corrupt cpu_has_ic_fills_f_dc case.  Revised.

diff -u linux-mips/arch/mips/mm/c-r4k.c linux/arch/mips/mm/c-r4k.c
--- linux-mips/arch/mips/mm/c-r4k.c     2005-09-22 10:38:23.000000000 +0900
+++ linux/arch/mips/mm/c-r4k.c  2005-09-28 20:55:55.000000000 +0900
@@ -409,8 +409,9 @@
         * for every cache flush operation.  So we do indexed flushes
         * in that case, which doesn't overly flush the cache too much.
         */
-       if ((mm == current->active_mm) && (pte_val(*ptep) & _PAGE_VALID)) {
-               if (cpu_has_dc_aliases || (exec && !cpu_has_ic_fills_f_dc)) {
+       if ((mm == current->active_mm) && (pte_val(*ptep) & _PAGE_VALID) &&
+           !(exec && !cpu_has_ic_fills_f_dc)) {
+               if (cpu_has_dc_aliases) {
                        r4k_blast_dcache_page(page);
                        if (exec && !cpu_icache_snoops_remote_store)
                                r4k_blast_scache_page(page);
diff -u linux-mips/arch/mips/mm/c-tx39.c linux/arch/mips/mm/c-tx39.c
--- linux-mips/arch/mips/mm/c-tx39.c    2005-09-05 10:16:59.000000000 +0900
+++ linux/arch/mips/mm/c-tx39.c 2005-09-28 18:51:43.000000000 +0900
@@ -213,12 +213,10 @@
         * for every cache flush operation.  So we do indexed flushes
         * in that case, which doesn't overly flush the cache too much.
         */
-       if ((mm == current->active_mm) && (pte_val(*ptep) & _PAGE_VALID)) {
-               if (cpu_has_dc_aliases || exec)
+       if ((mm == current->active_mm) && (pte_val(*ptep) & _PAGE_VALID) &&
+           !exec) {
+               if (cpu_has_dc_aliases)
                        tx39_blast_dcache_page(page);
-               if (exec)
-                       tx39_blast_icache_page(page);
-
                return;
        }
 

---
Atsushi Nemoto

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