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Message-Id: <20190307091218.2343836-1-arnd@arndb.de>
Date: Thu, 7 Mar 2019 10:11:52 +0100
From: Arnd Bergmann <arnd@...db.de>
To: linux-kernel@...r.kernel.org
Cc: Nick Desaulniers <ndesaulniers@...gle.com>,
Oleg Nesterov <oleg@...hat.com>,
"Eric W . Biederman" <ebiederm@...ssion.com>,
Alexander Viro <viro@...iv.linux.org.uk>,
linux-arch@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
Ralf Baechle <ralf@...ux-mips.org>,
Paul Burton <paul.burton@...s.com>,
James Hogan <jhogan@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Deepa Dinamani <deepa.kernel@...il.com>,
Christian Brauner <christian@...uner.io>,
"Gustavo A. R. Silva" <gustavo@...eddedor.com>,
linux-mips@...r.kernel.org
Subject: [PATCH] signal: fix building with clang
clang warns about the sigset_t manipulating functions (sigaddset, sigdelset,
sigisemptyset, ...) because it performs semantic analysis before discarding
dead code, unlike gcc that does this in the reverse order.
The result is a long list of warnings like:
In file included from arch/arm64/include/asm/ftrace.h:21:
include/linux/compat.h:489:10: error: array index 3 is past the end of the array (which contains 2 elements) [-Werror,-Warray-bounds]
case 2: v.sig[3] = (set->sig[1] >> 32); v.sig[2] = set->sig[1];
^ ~
include/linux/compat.h:138:2: note: array 'sig' declared here
compat_sigset_word sig[_COMPAT_NSIG_WORDS];
^
include/linux/compat.h:489:42: error: array index 2 is past the end of the array (which contains 2 elements) [-Werror,-Warray-bounds]
case 2: v.sig[3] = (set->sig[1] >> 32); v.sig[2] = set->sig[1];
^ ~
include/linux/compat.h:138:2: note: array 'sig' declared here
compat_sigset_word sig[_COMPAT_NSIG_WORDS];
^
As a (rather ugly) workaround, I turn the nice switch()/case statements
into preprocessor conditionals, and where that is not possible, use the
'%' operator to modify the warning case into an operation that clang
will not warn about. Since that only matters for dead code, the actual
behavior does not change.
Link: https://bugs.llvm.org/show_bug.cgi?id=38789
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
arch/mips/include/uapi/asm/signal.h | 3 +-
include/linux/signal.h | 72 ++++++++++++++---------------
2 files changed, 37 insertions(+), 38 deletions(-)
diff --git a/arch/mips/include/uapi/asm/signal.h b/arch/mips/include/uapi/asm/signal.h
index 53104b10aae2..8e71a2f778f7 100644
--- a/arch/mips/include/uapi/asm/signal.h
+++ b/arch/mips/include/uapi/asm/signal.h
@@ -11,9 +11,10 @@
#define _UAPI_ASM_SIGNAL_H
#include <linux/types.h>
+#include <asm/bitsperlong.h>
#define _NSIG 128
-#define _NSIG_BPW (sizeof(unsigned long) * 8)
+#define _NSIG_BPW __BITS_PER_LONG
#define _NSIG_WORDS (_NSIG / _NSIG_BPW)
typedef struct {
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 9702016734b1..b967d502ab61 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -82,35 +82,33 @@ static inline int sigismember(sigset_t *set, int _sig)
static inline int sigisemptyset(sigset_t *set)
{
- switch (_NSIG_WORDS) {
- case 4:
- return (set->sig[3] | set->sig[2] |
- set->sig[1] | set->sig[0]) == 0;
- case 2:
- return (set->sig[1] | set->sig[0]) == 0;
- case 1:
- return set->sig[0] == 0;
- default:
- BUILD_BUG();
- return 0;
- }
+#if _NSIG_WORDS == 4
+ return (set->sig[3] | set->sig[2] |
+ set->sig[1] | set->sig[0]) == 0;
+#elif _NSIG_WORDS == 2
+ return (set->sig[1] | set->sig[0]) == 0;
+#elif _NSIG_WORDS == 1
+ return set->sig[0] == 0;
+#else
+ BUILD_BUG();
+#endif
}
static inline int sigequalsets(const sigset_t *set1, const sigset_t *set2)
{
- switch (_NSIG_WORDS) {
- case 4:
- return (set1->sig[3] == set2->sig[3]) &&
- (set1->sig[2] == set2->sig[2]) &&
- (set1->sig[1] == set2->sig[1]) &&
- (set1->sig[0] == set2->sig[0]);
- case 2:
- return (set1->sig[1] == set2->sig[1]) &&
- (set1->sig[0] == set2->sig[0]);
- case 1:
- return set1->sig[0] == set2->sig[0];
- }
+#if _NSIG_WORDS == 4
+ return (set1->sig[3] == set2->sig[3]) &&
+ (set1->sig[2] == set2->sig[2]) &&
+ (set1->sig[1] == set2->sig[1]) &&
+ (set1->sig[0] == set2->sig[0]);
+#elif _NSIG_WORDS == 2
+ return (set1->sig[1] == set2->sig[1]) &&
+ (set1->sig[0] == set2->sig[0]);
+#elif _NSIG_WORDS == 1
+ return set1->sig[0] == set2->sig[0];
+#else
return 0;
+#endif
}
#define sigmask(sig) (1UL << ((sig) - 1))
@@ -125,14 +123,14 @@ static inline void name(sigset_t *r, const sigset_t *a, const sigset_t *b) \
\
switch (_NSIG_WORDS) { \
case 4: \
- a3 = a->sig[3]; a2 = a->sig[2]; \
- b3 = b->sig[3]; b2 = b->sig[2]; \
- r->sig[3] = op(a3, b3); \
- r->sig[2] = op(a2, b2); \
+ a3 = a->sig[3%_NSIG_WORDS]; a2 = a->sig[2%_NSIG_WORDS]; \
+ b3 = b->sig[3%_NSIG_WORDS]; b2 = b->sig[2%_NSIG_WORDS]; \
+ r->sig[3%_NSIG_WORDS] = op(a3, b3); \
+ r->sig[2%_NSIG_WORDS] = op(a2, b2); \
/* fall through */ \
case 2: \
- a1 = a->sig[1]; b1 = b->sig[1]; \
- r->sig[1] = op(a1, b1); \
+ a1 = a->sig[1%_NSIG_WORDS]; b1 = b->sig[1%_NSIG_WORDS]; \
+ r->sig[1%_NSIG_WORDS] = op(a1, b1); \
/* fall through */ \
case 1: \
a0 = a->sig[0]; b0 = b->sig[0]; \
@@ -161,10 +159,10 @@ _SIG_SET_BINOP(sigandnsets, _sig_andn)
static inline void name(sigset_t *set) \
{ \
switch (_NSIG_WORDS) { \
- case 4: set->sig[3] = op(set->sig[3]); \
- set->sig[2] = op(set->sig[2]); \
+ case 4: set->sig[3%_NSIG_WORDS] = op(set->sig[3%_NSIG_WORDS]); \
+ set->sig[2%_NSIG_WORDS] = op(set->sig[2%_NSIG_WORDS]); \
/* fall through */ \
- case 2: set->sig[1] = op(set->sig[1]); \
+ case 2: set->sig[1%_NSIG_WORDS] = op(set->sig[1%_NSIG_WORDS]); \
/* fall through */ \
case 1: set->sig[0] = op(set->sig[0]); \
break; \
@@ -185,7 +183,7 @@ static inline void sigemptyset(sigset_t *set)
default:
memset(set, 0, sizeof(sigset_t));
break;
- case 2: set->sig[1] = 0;
+ case 2: set->sig[1%_NSIG_WORDS] = 0;
/* fall through */
case 1: set->sig[0] = 0;
break;
@@ -198,7 +196,7 @@ static inline void sigfillset(sigset_t *set)
default:
memset(set, -1, sizeof(sigset_t));
break;
- case 2: set->sig[1] = -1;
+ case 2: set->sig[1%_NSIG_WORDS] = -1;
/* fall through */
case 1: set->sig[0] = -1;
break;
@@ -229,7 +227,7 @@ static inline void siginitset(sigset_t *set, unsigned long mask)
default:
memset(&set->sig[1], 0, sizeof(long)*(_NSIG_WORDS-1));
break;
- case 2: set->sig[1] = 0;
+ case 2: set->sig[1%_NSIG_WORDS] = 0;
case 1: ;
}
}
@@ -241,7 +239,7 @@ static inline void siginitsetinv(sigset_t *set, unsigned long mask)
default:
memset(&set->sig[1], -1, sizeof(long)*(_NSIG_WORDS-1));
break;
- case 2: set->sig[1] = -1;
+ case 2: set->sig[1%_NSIG_WORDS] = -1;
case 1: ;
}
}
--
2.20.0
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