On March 7, 2019 10:11:52 AM GMT+01:00, Arnd Bergmann <arnd@xxxxxxxx> wrote: >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@xxxxxxxx> >--- > 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: ; > } > } Ugh, it's not pretty but I don't have any objections. :) Acked-by: Christian Brauner <christian@xxxxxxxxxx>
