The FP status register allows for 6 traps to be masked. One of them,

the denormal/unnormal trap, is not a standard IEEE trap. We did
not exclude it from being returned by fpgetmask(), nor did we make
sure that fpsetmask() didn't clobber it. Since the non-IEEE trap
is not part of fp_except_t, users of ifpgetmask()/fpsetmask() would
be confronted with unexpected behaviour, one of which is a SIGFPE
for denormal/unnormal FP results.

This commit makes sure that we don't leak the denormal/unnormal mask
bit in fp_except_t and also that we don't clobber it.

2 files changed, 3 insertions, 3 deletions

diff --git a/lib/libc/ia64/gen/fpgetmask.c b/lib/libc/ia64/gen/fpgetmask.c
index 2c4cadf..ac166e2 100644
--- a/lib/libc/ia64/gen/fpgetmask.c
+++ b/lib/libc/ia64/gen/fpgetmask.c
@@ -36,5 +36,5 @@ fpgetmask(void)
 	u_int64_t fpsr;
 
 	__asm __volatile("mov %0=ar.fpsr" : "=r" (fpsr));
-	return (~fpsr & 0x3f);
+	return (~fpsr & 0x3d);
 }
diff --git a/lib/libc/ia64/gen/fpsetmask.c b/lib/libc/ia64/gen/fpsetmask.c
index be4d8b4..d959dc6 100644
--- a/lib/libc/ia64/gen/fpsetmask.c
+++ b/lib/libc/ia64/gen/fpsetmask.c
@@ -37,8 +37,8 @@ fpsetmask(fp_except_t mask)
 	u_int64_t oldmask;
 
 	__asm __volatile("mov %0=ar.fpsr" : "=r" (fpsr));
-	oldmask = ~fpsr & 0x3f;
-	fpsr = (fpsr & ~0x3f) | (~mask & 0x3f);
+	oldmask = ~fpsr & 0x3d;
+	fpsr = (fpsr & ~0x3d) | (~mask & 0x3d);
 	__asm __volatile("mov ar.fpsr=%0" :: "r" (fpsr));
 	return (oldmask);
 }