Thread (37 messages) 37 messages, 5 authors, 2020-06-24

Re: [PATCH v2 3/6] prctl.2: Add PR_SPEC_DISABLE_NOEXEC for SPECULATION_CTRL prctls

From: Michael Kerrisk (man-pages) <hidden>
Date: 2020-05-28 06:58:04
Also in: linux-arch, linux-man

Hi Dave,

On Wed, 27 May 2020 at 23:18, Dave Martin [off-list ref] wrote:
Add the PR_SPEC_DISABLE_NOEXEC mode added in Linux 5.1
for the PR_SPEC_STORE_BYPASS "misfeature" of
PR_SET_SPECULATION_CTRL and PR_GET_SPECULATION_CTRL.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Thomas Gleixner <redacted>
I had already applied your earlier send of this patch (in a private
branch). I'll push those changes shortly.

Cheers,

Michael
quoted hunk ↗ jump to hunk
---
 man2/prctl.2 | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)
diff --git a/man2/prctl.2 b/man2/prctl.2
index b6fb51c..cab9915 100644
--- a/man2/prctl.2
+++ b/man2/prctl.2
@@ -1187,6 +1187,12 @@ The speculation feature is disabled, mitigation is enabled.
 Same as
 .B PR_SPEC_DISABLE
 but cannot be undone.
+.TP
+.BR PR_SPEC_DISABLE_NOEXEC " (since Linux 5.1)"
+Same as
+.BR PR_SPEC_DISABLE ,
+but but the state will be cleared on
+.BR execve (2).
 .RE
 .IP
 If all bits are 0,
@@ -1251,6 +1257,17 @@ with the same value for
 .I arg2
 will fail with the error
 .BR EPERM .
+.\" commit 71368af9027f18fe5d1c6f372cfdff7e4bde8b48
+.TP
+.BR PR_SPEC_DISABLE_NOEXEC " (since Linux 5.1)"
+Same as
+.BR PR_SPEC_DISABLE ,
+but but the state will be cleared on
+.BR execve (2).
+Currently only supported for
+.I arg2
+equal to
+.B PR_SPEC_STORE_BYPASS.
 .RE
 .IP
 Any unsupported value in
@@ -1899,11 +1916,12 @@ was
 .BR PR_SET_SPECULATION_CTRL
 and
 .IR arg3
-is neither
+is not
 .BR PR_SPEC_ENABLE ,
 .BR PR_SPEC_DISABLE ,
+.BR PR_SPEC_FORCE_DISABLE ,
 nor
-.BR PR_SPEC_FORCE_DISABLE .
+.BR PR_SPEC_DISABLE_NOEXEC .
 .SH VERSIONS
 The
 .BR prctl ()
--
2.1.4

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/

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