linux-kernel - [PATCH] x86, pat: Add comments to cachemode translation tables

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 22 Jul 2015 12:06:11 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	mingo@...nel.org
Cc:	tglx@...utronix.de, peterz@...radead.org, bp@...e.de,
	jbeulich@...e.com, x86@...nel.org, linux-kernel@...r.kernel.org,
	Toshi Kani <toshi.kani@...com>
Subject: [PATCH] x86, pat: Add comments to cachemode translation tables

Add comments to the cachemode translation tables to clarify that
the default values are set as minimal supported mode, which are
necessary to handle WC and WT fallback to UC- when they are not
enabled.

Signed-off-by: Toshi Kani <toshi.kani@...com>
Cc: Jan Beulich <jbeulich@...e.com>
Cc: Borislav Petkov <bp@...e.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
---
Ingo, please replace the patch below with this patch.
https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg937806.html
---
 arch/x86/mm/init.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 8533b46..1d8a83d 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -30,8 +30,11 @@
 /*
  * Tables translating between page_cache_type_t and pte encoding.
  *
- * Minimal supported modes are defined statically, they are modified
- * during bootup if more supported cache modes are available.
+ * The default values are defined statically as minimal supported mode;
+ * WC and WT fall back to UC-.  pat_init() updates these values to support
+ * more cache modes, WC and WT, when it is safe to do so.  See pat_init()
+ * for the details.  Note, __early_ioremap() used during early boot-time
+ * takes pgprot_t (pte encoding) and does not use these tables.
  *
  *   Index into __cachemode2pte_tbl[] is the cachemode.
  *
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/