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x86/retpoline: Avoid retpolines for built-in __init functions

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(cherry picked from commit 66f793099a)

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
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
[jwang: port to 4.4]
Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
David Woodhouse 2018-02-23 11:42:11 +01:00 committed by Greg Kroah-Hartman
parent 355e059499
commit b98197294b
1 changed files with 8 additions and 1 deletions
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9
include/linux/init.h
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@ -4,6 +4,13 @@
#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
@ -39,7 +46,7 @@
/* These are for everybody (although not all archs will actually
discard it in modules) */
#define __init __section(.init.text) __cold notrace
#define __init __section(.init.text) __cold notrace __noretpoline
#define __initdata __section(.init.data)
#define __initconst __constsection(.init.rodata)
#define __exitdata __section(.exit.data)