David Miller [off-list ref] writes:

From: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
Date: Fri, 30 Jun 2017 07:39:01 -0500

quoted

diff --git a/arch/sparc/include/uapi/asm/siginfo.h b/arch/sparc/include/uapi/asm/siginfo.h
index 2d9b79ccaa50..6bc5c677e92f 100644
--- a/arch/sparc/include/uapi/asm/siginfo.h
+++ b/arch/sparc/include/uapi/asm/siginfo.h

@@ -17,6 +17,11 @@
 #define SI_NOINFO	32767		/* no information in siginfo_t */
 
 /*
+ * SIGFPE si_codes
+ */
+#define FPE_FIXME	(__SI_FAULT|0)	/* Broken dup of SI_USER */
+
+/*
  * SIGEMT si_codes
  */
 #define EMT_TAGOVF	(__SI_FAULT|1)	/* tag overflow */

It's one thing to say FIXME in a comment in a kernel local header or
C file.

It's quite another to put this into the name of a macro which has
visibility in the global user compilation namespace.

I don't think you should really do that.

Good point.

Sigh.   It almost fits because we did do something off in the uapi
exported to userspace and we don't have a header file definition for
that case.

Still.  At this point arch/sparc/include/asm/siginfo.h is
a better fit for that definition.

I will respin and fix that.

I wish I knew what would make a better default floating point si_code on
sparc.  Using 0 aka SI_USER is doesn't fit at all.  Sigh.

Unfortunately I don't know the architecture well enough to even guess
what is going on in do_fpe_common when when no bits in fsr are set.

Any suggests for a better fix than just documenting that linux does
something weird and ill advised here?

Eric