From: John David Anglin <dave.anglin@bell.net>
To: Jeff Law <law@redhat.com>, Richard Earnshaw <Richard.Earnshaw@arm.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: [PATCH 00/11] (v2) Mitigation against unsafe data speculation (CVE-2017-5753)
Date: Thu, 02 Aug 2018 20:19:00 -0000 [thread overview]
Message-ID: <1ed6a085-faf7-cfc0-af4a-7d4de8aeab46@bell.net> (raw)
In-Reply-To: <26e2cb56-8a62-8f09-adfc-8d9e7c9fe6ec@redhat.com>
[-- Attachment #1: Type: text/plain, Size: 1372 bytes --]
On 2018-08-02 2:40 PM, Jeff Law wrote:
> It's been eons. I think there's enough building blocks on the PA to
> mount a spectre v1 attack. They've got branch prediction with varying
> degress of speculative execution, caches and user accessable cycle timers.
Yes.
>
> There's varying degrees of out of order execution all the way back in
> the PA7xxx processors (hit-under-miss) to full o-o-o execution in the
> PA8xxx series (including the PA8900 that's in the rp3440).
However, as far as I know, loads and stores are always ordered.
>
> I suspect that given enough time we could figure out why the test didn't
> indicate spectre v1 vulnerability on your system and twiddle it, but
> given it's a dead processor, I doubt it's worth the effort.
Spectre output looks like this:
dave@mx3210:~/meltdown$ ./spectre
Reading 40 bytes:
Reading at malicious_x = 0xffffef10... Unclear: 0xFE='?' score=999Â Â Â
(second best: 0xFC score=999)
Reading at malicious_x = 0xffffef11... Unclear: 0xFC='?' score=999Â Â Â
(second best: 0xFB score=999)
Reading at malicious_x = 0xffffef12... Unclear: 0xFE='?' score=999Â Â Â
(second best: 0xFC score=999)
I don't think there's a suitable barrier. The sync instruction seems
like overkill.
So, I'm going to install attached change after testing is complete.
Dave
--
John David Anglin dave.anglin@bell.net
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Index: config/pa/pa.c
===================================================================
--- config/pa/pa.c (revision 263228)
+++ config/pa/pa.c (working copy)
@@ -428,6 +428,9 @@
#undef TARGET_STARTING_FRAME_OFFSET
#define TARGET_STARTING_FRAME_OFFSET pa_starting_frame_offset
+#undef TARGET_HAVE_SPECULATION_SAFE_VALUE
+#define TARGET_HAVE_SPECULATION_SAFE_VALUE speculation_safe_value_not_needed
+
struct gcc_target targetm = TARGET_INITIALIZER;
\f
/* Parse the -mfixed-range= option string. */
next prev parent reply other threads:[~2018-08-02 20:19 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-09 16:39 [PATCH 0/7] " Richard Earnshaw
2018-07-09 16:39 ` [PATCH 3/7] AArch64 - add speculation barrier Richard Earnshaw
2018-07-09 16:39 ` [PATCH 7/7] AArch64 - use CSDB based sequences if speculation tracking is enabled Richard Earnshaw
2018-07-09 16:39 ` [PATCH 4/7] AArch64 - Add new option -mtrack-speculation Richard Earnshaw
2018-07-09 16:39 ` [PATCH 6/7] AArch64 - new pass to add conditional-branch speculation tracking Richard Earnshaw
2018-07-11 21:01 ` Jeff Law
2018-07-23 14:33 ` Richard Earnshaw (lists)
2018-07-24 21:31 ` Jeff Law
2018-07-09 16:39 ` [PATCH 1/7] Add __builtin_speculation_safe_value Richard Earnshaw
2018-07-23 14:28 ` Richard Earnshaw (lists)
2018-07-24 17:26 ` Richard Biener
2018-07-25 9:49 ` Richard Earnshaw (lists)
2018-07-25 10:36 ` Richard Biener
2018-07-25 12:41 ` Richard Earnshaw (lists)
2018-07-25 13:47 ` Richard Biener
2018-07-26 10:03 ` Richard Earnshaw (lists)
2018-07-26 12:41 ` Richard Biener
2018-07-26 13:06 ` Richard Earnshaw (lists)
2018-07-26 13:13 ` Richard Biener
2018-07-26 23:34 ` Joseph Myers
2018-07-27 0:46 ` Paul Koning
2018-07-27 8:59 ` Richard Earnshaw (lists)
2018-07-27 10:59 ` Joseph Myers
2018-07-25 18:03 ` Richard Earnshaw (lists)
2018-07-26 8:42 ` Richard Biener
2018-07-09 16:39 ` [PATCH 5/7] AArch64 - disable CB[N]Z TB[N]Z when tracking speculation Richard Earnshaw
2018-07-09 16:39 ` [PATCH 2/7] Arm - add speculation_barrier pattern Richard Earnshaw
2018-07-09 23:13 ` [PATCH 0/7] Mitigation against unsafe data speculation (CVE-2017-5753) Jeff Law
2018-07-10 8:49 ` Richard Earnshaw (lists)
2018-07-10 13:48 ` Bill Schmidt
2018-07-10 14:14 ` Richard Earnshaw (lists)
2018-07-10 15:44 ` Jeff Law
2018-07-10 15:42 ` Jeff Law
2018-07-10 16:43 ` Richard Earnshaw (lists)
2018-07-11 20:47 ` Jeff Law
2018-07-11 22:31 ` Richard Earnshaw (lists)
2018-07-10 7:19 ` Richard Biener
2018-07-10 8:39 ` Richard Earnshaw (lists)
2018-07-10 10:10 ` Richard Biener
2018-07-10 10:53 ` Richard Earnshaw (lists)
2018-07-10 11:22 ` Richard Biener
2018-07-10 13:43 ` Richard Earnshaw (lists)
2018-07-10 15:56 ` Jeff Law
2018-07-27 9:38 ` [PATCH 00/11] (v2) " Richard Earnshaw
2018-07-27 9:38 ` [PATCH 04/11] AArch64 - Add new option -mtrack-speculation Richard Earnshaw
2018-07-27 9:38 ` [PATCH 05/11] AArch64 - disable CB[N]Z TB[N]Z when tracking speculation Richard Earnshaw
2018-07-27 9:38 ` [PATCH 08/11] targhooks - provide an alternative hook for targets that never execute speculatively Richard Earnshaw
2018-07-30 13:17 ` Richard Biener
2018-07-27 9:38 ` [PATCH 09/11] pdp11 - example of a port not needing a speculation barrier Richard Earnshaw
2018-07-27 13:27 ` Paul Koning
2018-07-27 15:19 ` Richard Biener
2018-07-27 9:38 ` [PATCH 06/11] AArch64 - new pass to add conditional-branch speculation tracking Richard Earnshaw
2018-07-27 9:38 ` [PATCH 01/11] Add __builtin_speculation_safe_value Richard Earnshaw
2018-07-27 12:11 ` Nathan Sidwell
2018-07-27 12:32 ` Richard Earnshaw (lists)
2018-07-27 12:49 ` Nathan Sidwell
2018-07-27 12:53 ` Richard Earnshaw (lists)
2018-07-30 13:16 ` Richard Biener
2018-07-31 19:25 ` H.J. Lu
2018-07-31 20:51 ` Ian Lance Taylor via gcc-patches
2018-08-01 8:50 ` Richard Earnshaw (lists)
2018-08-01 8:54 ` Jakub Jelinek
2018-08-01 9:25 ` Richard Earnshaw (lists)
2018-07-27 9:38 ` [PATCH 07/11] AArch64 - use CSDB based sequences if speculation tracking is enabled Richard Earnshaw
2018-07-27 9:38 ` [PATCH 10/11] x86 - add speculation_barrier pattern Richard Earnshaw
2018-07-28 8:25 ` Uros Bizjak
2018-07-31 23:15 ` H.J. Lu
2018-07-27 9:38 ` [PATCH 11/11] rs6000 " Richard Earnshaw
2018-07-31 22:01 ` Bill Schmidt
2018-07-31 23:31 ` Segher Boessenkool
2018-07-27 9:38 ` [PATCH 02/11] Arm " Richard Earnshaw
2018-08-06 14:01 ` Christophe Lyon
2018-08-06 15:59 ` Richard Earnshaw (lists)
2018-07-27 9:38 ` [PATCH 03/11] AArch64 - add speculation barrier Richard Earnshaw
2018-07-27 19:49 ` [PATCH 00/11] (v2) Mitigation against unsafe data speculation (CVE-2017-5753) John David Anglin
2018-08-02 18:40 ` Jeff Law
2018-08-02 20:19 ` John David Anglin [this message]
2018-08-03 9:06 ` Richard Earnshaw (lists)
2018-08-06 21:52 ` John David Anglin
2018-08-07 14:05 ` Richard Earnshaw (lists)
2018-08-07 14:56 ` John David Anglin
2018-08-03 17:26 ` Jeff Law
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