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authorStas Sergeev <stsp@list.ru>2016-04-14 23:20:04 +0300
committerIngo Molnar <mingo@kernel.org>2016-05-03 09:37:59 +0300
commit2a74213838104a41588d86fd5e8d344972891ace (patch)
treea9cbd4a76cf96295bc943567fbd575af908c5974 /include/uapi/linux/signal.h
parent407bc16ad1769f5cb8ad9555611cb198187ef4cd (diff)
downloadlinux-2a74213838104a41588d86fd5e8d344972891ace.tar.xz
signals/sigaltstack: Implement SS_AUTODISARM flag
This patch implements the SS_AUTODISARM flag that can be OR-ed with SS_ONSTACK when forming ss_flags. When this flag is set, sigaltstack will be disabled when entering the signal handler; more precisely, after saving sas to uc_stack. When leaving the signal handler, the sigaltstack is restored by uc_stack. When this flag is used, it is safe to switch from sighandler with swapcontext(). Without this flag, the subsequent signal will corrupt the state of the switched-away sighandler. To detect the support of this functionality, one can do: err = sigaltstack(SS_DISABLE | SS_AUTODISARM); if (err && errno == EINVAL) unsupported(); Signed-off-by: Stas Sergeev <stsp@list.ru> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Aleksa Sarai <cyphar@cyphar.com> Cc: Amanieu d'Antras <amanieu@gmail.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Heinrich Schuchardt <xypron.glpk@gmx.de> Cc: Jason Low <jason.low2@hp.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Moore <pmoore@redhat.com> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Richard Weinberger <richard@nod.at> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Shuah Khan <shuahkh@osg.samsung.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vladimir Davydov <vdavydov@parallels.com> Cc: linux-api@vger.kernel.org Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/1460665206-13646-4-git-send-email-stsp@list.ru Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/uapi/linux/signal.h')
-rw-r--r--include/uapi/linux/signal.h4
1 files changed, 3 insertions, 1 deletions
diff --git a/include/uapi/linux/signal.h b/include/uapi/linux/signal.h
index 7c73165d11ce..738826048af2 100644
--- a/include/uapi/linux/signal.h
+++ b/include/uapi/linux/signal.h
@@ -7,7 +7,9 @@
#define SS_ONSTACK 1
#define SS_DISABLE 2
+/* bit-flags */
+#define SS_AUTODISARM (1 << 4) /* disable sas during sighandling */
/* mask for all SS_xxx flags */
-#define SS_FLAG_BITS 0
+#define SS_FLAG_BITS SS_AUTODISARM
#endif /* _UAPI_LINUX_SIGNAL_H */