linux-kernel - [RFC PATCH 3/3] signal: Stop special casing TRAP_FIXME and FPE_FIXME in siginfo

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Date:   Sun, 15 Apr 2018 10:59:09 -0500
From:   ebiederm@...ssion.com (Eric W. Biederman)
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Dave Martin <Dave.Martin@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Dmitry V. Levin" <ldv@...linux.org>,
        sparclinux <sparclinux@...r.kernel.org>,
        ppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        <linux-arch@...r.kernel.org>
Subject: [RFC PATCH 3/3] signal: Stop special casing TRAP_FIXME and FPE_FIXME in siginfo_layout

After more experience with the cases where no one the si_code of 0 is
used both as a signal specific si_code, and as SI_USER it appears that
no one cares about the signal specific si_code case and the good
solution is to just fix the architectures by using a different si_code.

In none of the conversations has anyone even suggested that anything
depends on the signal specific redefinition of SI_USER.

There are at least test cases that care when si_code as 0 does not work
as si_user.

So make things simple and keep the generic code from introducing
problems by removing the special casing of TRAP_FIXME and FPE_FIXME.
This will ensure the generic case of sending a signal with kill will
always set SI_USER and work.

The architecture specific, and signal specific overloads that set
si_code to 0 will now have problems with signalfd and the 32bit compat
versions of siginfo copying.  At least until they are fixed.

Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 kernel/signal.c | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/kernel/signal.c b/kernel/signal.c
index d56f4d496c89..fc82d2c0918f 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2835,15 +2835,6 @@ enum siginfo_layout siginfo_layout(int sig, int si_code)
 			layout = SIL_POLL;
 		else if (si_code < 0)
 			layout = SIL_RT;
-		/* Tests to support buggy kernel ABIs */
-#ifdef TRAP_FIXME
-		if ((sig == SIGTRAP) && (si_code == TRAP_FIXME))
-			layout = SIL_FAULT;
-#endif
-#ifdef FPE_FIXME
-		if ((sig == SIGFPE) && (si_code == FPE_FIXME))
-			layout = SIL_FAULT;
-#endif
 	}
 	return layout;
 }
-- 
2.14.1