From: tip-bot for David Woodhouse <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: mingo@kernel.org, tglx@linutronix.de, hpa@zytor.com,
dwmw@amazon.co.uk, linux-kernel@vger.kernel.org
Subject: [tip:x86/pti] x86/retpoline: Avoid retpolines for built-in __init functions
Date: Fri, 2 Feb 2018 03:46:41 -0800 [thread overview]
Message-ID: <tip-66f793099a636862a71c59d4a6ba91387b155e0c@git.kernel.org> (raw)
In-Reply-To: <1517484441-1420-2-git-send-email-dwmw@amazon.co.uk>
Commit-ID: 66f793099a636862a71c59d4a6ba91387b155e0c
Gitweb: https://git.kernel.org/tip/66f793099a636862a71c59d4a6ba91387b155e0c
Author: David Woodhouse <dwmw@amazon.co.uk>
AuthorDate: Thu, 1 Feb 2018 11:27:20 +0000
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 2 Feb 2018 12:28:27 +0100
x86/retpoline: Avoid retpolines for built-in __init functions
There's no point in building init code with retpolines, since it runs before
any potentially hostile userspace does. And before the retpoline is actually
ALTERNATIVEd into place, for much of it.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: karahmed@amazon.de
Cc: peterz@infradead.org
Cc: bp@alien8.de
Link: https://lkml.kernel.org/r/1517484441-1420-2-git-send-email-dwmw@amazon.co.uk
---
include/linux/init.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/include/linux/init.h b/include/linux/init.h
index ea1b311..506a981 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -5,6 +5,13 @@
#include <linux/compiler.h>
#include <linux/types.h>
+/* Built-in __init functions needn't be compiled with retpoline */
+#if defined(RETPOLINE) && !defined(MODULE)
+#define __noretpoline __attribute__((indirect_branch("keep")))
+#else
+#define __noretpoline
+#endif
+
/* These macros are used to mark some functions or
* initialized data (doesn't apply to uninitialized data)
* as `initialization' functions. The kernel can take this
@@ -40,7 +47,7 @@
/* These are for everybody (although not all archs will actually
discard it in modules) */
-#define __init __section(.init.text) __cold __latent_entropy
+#define __init __section(.init.text) __cold __latent_entropy __noretpoline
#define __initdata __section(.init.data)
#define __initconst __section(.init.rodata)
#define __exitdata __section(.exit.data)
next prev parent reply other threads:[~2018-02-02 11:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-01 11:27 [PATCH 0/2] Spectre v2 tweaks David Woodhouse
2018-02-01 11:27 ` [PATCH 1/2] x86/retpoline: No retpolines for built-in __init functions David Woodhouse
2018-02-02 11:46 ` tip-bot for David Woodhouse [this message]
2018-02-01 11:27 ` [PATCH 2/2] x86: Simplify spectre_v2 command line parsing David Woodhouse
2018-02-02 11:47 ` [tip:x86/pti] x86/spectre: " tip-bot for KarimAllah Ahmed
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