Re: [PATCH v2 2/6] prctl.2: Add PR_SPEC_INDIRECT_BRANCH for SPECULATION_CTRL prctls
From: Michael Kerrisk (man-pages) <hidden>
Date: 2020-05-28 07:02:18
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_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 <redacted> Cc: Thomas Gleixner <redacted>
I had also applied this patch from the email you sent earlier. I've pushed those changes to master now. Thanks, Michael
quoted hunk ↗ jump to hunk
--- 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
-- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel