mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 10:49:33 +00:00
linux/bits.h: fix compilation error with GENMASK
[ Upstream commit f747e6667e
]
GENMASK() has an input check which uses __builtin_choose_expr() to
enable a compile time sanity check of its inputs if they are known at
compile time.
However, it turns out that __builtin_constant_p() does not always return
a compile time constant [0]. It was thought this problem was fixed with
gcc 4.9 [1], but apparently this is not the case [2].
Switch to use __is_constexpr() instead which always returns a compile time
constant, regardless of its inputs.
Link: https://lore.kernel.org/lkml/42b4342b-aefc-a16a-0d43-9f9c0d63ba7a@rasmusvillemoes.dk [0]
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19449 [1]
Link: https://lore.kernel.org/lkml/1ac7bbc2-45d9-26ed-0b33-bf382b8d858b@I-love.SAKURA.ne.jp [2]
Link: https://lkml.kernel.org/r/20210511203716.117010-1-rikard.falkeborn@gmail.com
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Yury Norov <yury.norov@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
parent
b0f5d4891e
commit
1354ec8408
5 changed files with 20 additions and 10 deletions
|
@ -22,7 +22,7 @@
|
|||
#include <linux/build_bug.h>
|
||||
#define GENMASK_INPUT_CHECK(h, l) \
|
||||
(BUILD_BUG_ON_ZERO(__builtin_choose_expr( \
|
||||
__builtin_constant_p((l) > (h)), (l) > (h), 0)))
|
||||
__is_constexpr((l) > (h)), (l) > (h), 0)))
|
||||
#else
|
||||
/*
|
||||
* BUILD_BUG_ON_ZERO is not available in h files included from asm files,
|
||||
|
|
|
@ -3,4 +3,12 @@
|
|||
|
||||
#include <vdso/const.h>
|
||||
|
||||
/*
|
||||
* This returns a constant expression while determining if an argument is
|
||||
* a constant expression, most importantly without evaluating the argument.
|
||||
* Glory to Martin Uecker <Martin.Uecker@med.uni-goettingen.de>
|
||||
*/
|
||||
#define __is_constexpr(x) \
|
||||
(sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8)))
|
||||
|
||||
#endif /* _LINUX_CONST_H */
|
||||
|
|
|
@ -2,6 +2,8 @@
|
|||
#ifndef _LINUX_MINMAX_H
|
||||
#define _LINUX_MINMAX_H
|
||||
|
||||
#include <linux/const.h>
|
||||
|
||||
/*
|
||||
* min()/max()/clamp() macros must accomplish three things:
|
||||
*
|
||||
|
@ -17,14 +19,6 @@
|
|||
#define __typecheck(x, y) \
|
||||
(!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
|
||||
|
||||
/*
|
||||
* This returns a constant expression while determining if an argument is
|
||||
* a constant expression, most importantly without evaluating the argument.
|
||||
* Glory to Martin Uecker <Martin.Uecker@med.uni-goettingen.de>
|
||||
*/
|
||||
#define __is_constexpr(x) \
|
||||
(sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8)))
|
||||
|
||||
#define __no_side_effects(x, y) \
|
||||
(__is_constexpr(x) && __is_constexpr(y))
|
||||
|
||||
|
|
|
@ -22,7 +22,7 @@
|
|||
#include <linux/build_bug.h>
|
||||
#define GENMASK_INPUT_CHECK(h, l) \
|
||||
(BUILD_BUG_ON_ZERO(__builtin_choose_expr( \
|
||||
__builtin_constant_p((l) > (h)), (l) > (h), 0)))
|
||||
__is_constexpr((l) > (h)), (l) > (h), 0)))
|
||||
#else
|
||||
/*
|
||||
* BUILD_BUG_ON_ZERO is not available in h files included from asm files,
|
||||
|
|
|
@ -3,4 +3,12 @@
|
|||
|
||||
#include <vdso/const.h>
|
||||
|
||||
/*
|
||||
* This returns a constant expression while determining if an argument is
|
||||
* a constant expression, most importantly without evaluating the argument.
|
||||
* Glory to Martin Uecker <Martin.Uecker@med.uni-goettingen.de>
|
||||
*/
|
||||
#define __is_constexpr(x) \
|
||||
(sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8)))
|
||||
|
||||
#endif /* _LINUX_CONST_H */
|
||||
|
|
Loading…
Reference in a new issue