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From: Dave Martin <Dave.Martin@arm.com>
To: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: linux-arch@vger.kernel.org, linux-man@vger.kernel.org,
	Thomas Gleixner <tglx@linutronix.de>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 2/6] prctl.2: Add PR_SPEC_INDIRECT_BRANCH for SPECULATION_CTRL prctls
Date: Wed, 27 May 2020 22:17:34 +0100	[thread overview]
Message-ID: <1590614258-24728-3-git-send-email-Dave.Martin@arm.com> (raw)
In-Reply-To: <1590614258-24728-1-git-send-email-Dave.Martin@arm.com>

Add the PR_SPEC_INDIRECT_BRANCH "misfeature" added in Linux 4.20
for PR_SET_SPECULATION_CTRL and PR_GET_SPECULATION_CTRL.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
 man2/prctl.2 | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/man2/prctl.2 b/man2/prctl.2
index dc99218..b6fb51c 100644
--- a/man2/prctl.2
+++ b/man2/prctl.2
@@ -1213,11 +1213,20 @@ arguments must be specified as 0; otherwise the call fails with the error
 .\" commit 356e4bfff2c5489e016fdb925adbf12a1e3950ee
 Sets the state of the speculation misfeature specified in
 .IR arg2 .
-Currently, the only permitted value for this argument is
+Currently, this argument must be one of:
+.RS
+.TP
 .B PR_SPEC_STORE_BYPASS
-(otherwise the call fails with the error
+speculative store bypass control, or
+.\" commit 9137bb27e60e554dab694eafa4cca241fa3a694f
+.TP
+.BR PR_SPEC_INDIRECT_BRANCH " (since Linux 4.20)"
+indirect branch speculation control.
+.RE
+.IP
+(Otherwise the call fails with the error
 .BR ENODEV ).
-This setting is a per-thread attribute.
+These settings are per-thread attributes.
 The
 .IR arg3
 argument is used to hand in the control value,
@@ -1235,13 +1244,16 @@ Same as
 .BR PR_SPEC_DISABLE ,
 but cannot be undone.
 A subsequent
-.B
-prctl(..., PR_SPEC_ENABLE)
+.BR prctl (\c
+.IR arg2 ,
+.BR PR_SPEC_ENABLE )
+with the same value for
+.I arg2
 will fail with the error
 .BR EPERM .
 .RE
 .IP
-Any other value in
+Any unsupported value in
 .IR arg3
 will result in the call failing with the error
 .BR ERANGE .
-- 
2.1.4


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  parent reply	other threads:[~2020-05-27 21:18 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-27 21:17 [PATCH v2 0/6] prctl.2 man page updates for Linux 5.6 Dave Martin
2020-05-27 21:17 ` [PATCH v2 1/6] prctl.2: ffix use literal hyphens when referencing kernel docs Dave Martin
2020-05-28  6:05   ` Michael Kerrisk (man-pages)
2020-05-27 21:17 ` Dave Martin [this message]
2020-05-28  7:01   ` [PATCH v2 2/6] prctl.2: Add PR_SPEC_INDIRECT_BRANCH for SPECULATION_CTRL prctls Michael Kerrisk (man-pages)
2020-06-01 13:51     ` Dave Martin
2020-06-09 11:00       ` Michael Kerrisk (man-pages)
2020-05-27 21:17 ` [PATCH v2 3/6] prctl.2: Add PR_SPEC_DISABLE_NOEXEC " Dave Martin
2020-05-28  6:57   ` Michael Kerrisk (man-pages)
2020-05-28 13:45   ` Waiman Long
2020-05-27 21:17 ` [PATCH v2 4/6] prctl.2: Add SVE prctls (arm64) Dave Martin
2020-06-09  9:57   ` Will Deacon
2020-06-09 14:11     ` Dave Martin
2020-06-09 14:49       ` Will Deacon
2020-06-10  9:44         ` Dave Martin
2020-06-10 10:16           ` Will Deacon
2020-06-10 12:48             ` Dave Martin
2020-06-09 11:39   ` Michael Kerrisk (man-pages)
2020-06-10  9:45     ` Dave Martin
2020-05-27 21:17 ` [PATCH v2 5/6] prctl.2: Add PR_PAC_RESET_KEYS (arm64) Dave Martin
2020-06-09 10:02   ` Will Deacon
2020-06-09 11:03     ` Michael Kerrisk (man-pages)
2020-06-09 11:36   ` Michael Kerrisk (man-pages)
2020-06-09 14:16     ` Dave Martin
2020-06-09 18:11       ` Michael Kerrisk (man-pages)
2020-05-27 21:17 ` [RFC PATCH v2 6/6] prctl.2: Add tagged address ABI control prctls (arm64) Dave Martin
2020-06-09 11:04   ` Michael Kerrisk (man-pages)
2020-06-09 13:38     ` Will Deacon
2020-06-09 17:22   ` Catalin Marinas
2020-06-10 10:06     ` Dave Martin
2020-06-10 15:26       ` Catalin Marinas
2020-06-10 16:42         ` Dave Martin
2020-06-10 17:42           ` Catalin Marinas
2020-06-15 14:51             ` Dave Martin
2020-06-24  9:54               ` Michael Kerrisk (man-pages)
2020-06-24 10:29                 ` Dave Martin
2020-05-28  7:11 ` [PATCH v2 0/6] prctl.2 man page updates for Linux 5.6 Michael Kerrisk (man-pages)

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