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Message-Id: <20210524144620.2497249-63-sashal@kernel.org>
Date: Mon, 24 May 2021 10:46:20 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc: Rikard Falkeborn <rikard.falkeborn@...il.com>,
Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
Arnd Bergmann <arnd@...db.de>,
Andy Shevchenko <andy.shevchenko@...il.com>,
Ard Biesheuvel <ardb@...nel.org>,
Yury Norov <yury.norov@...il.com>,
Peter Zijlstra <peterz@...radead.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 5.12 63/63] linux/bits.h: fix compilation error with GENMASK
From: Rikard Falkeborn <rikard.falkeborn@...il.com>
[ Upstream commit f747e6667ebb2ffb8133486c9cd19800d72b0d98 ]
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@...il.com>
Reported-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Acked-by: Arnd Bergmann <arnd@...db.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: Ard Biesheuvel <ardb@...nel.org>
Cc: Yury Norov <yury.norov@...il.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
include/linux/bits.h | 2 +-
include/linux/const.h | 8 ++++++++
include/linux/minmax.h | 10 ++--------
tools/include/linux/bits.h | 2 +-
tools/include/linux/const.h | 8 ++++++++
5 files changed, 20 insertions(+), 10 deletions(-)
diff --git a/include/linux/bits.h b/include/linux/bits.h
index 7f475d59a097..87d112650dfb 100644
--- a/include/linux/bits.h
+++ b/include/linux/bits.h
@@ -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,
diff --git a/include/linux/const.h b/include/linux/const.h
index 81b8aae5a855..435ddd72d2c4 100644
--- a/include/linux/const.h
+++ b/include/linux/const.h
@@ -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@....uni-goettingen.de>
+ */
+#define __is_constexpr(x) \
+ (sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8)))
+
#endif /* _LINUX_CONST_H */
diff --git a/include/linux/minmax.h b/include/linux/minmax.h
index c0f57b0c64d9..5433c08fcc68 100644
--- a/include/linux/minmax.h
+++ b/include/linux/minmax.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@....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))
diff --git a/tools/include/linux/bits.h b/tools/include/linux/bits.h
index 7f475d59a097..87d112650dfb 100644
--- a/tools/include/linux/bits.h
+++ b/tools/include/linux/bits.h
@@ -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,
diff --git a/tools/include/linux/const.h b/tools/include/linux/const.h
index 81b8aae5a855..435ddd72d2c4 100644
--- a/tools/include/linux/const.h
+++ b/tools/include/linux/const.h
@@ -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@....uni-goettingen.de>
+ */
+#define __is_constexpr(x) \
+ (sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8)))
+
#endif /* _LINUX_CONST_H */
--
2.30.2
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