[tip:x86/entry] x86/syscalls: Disallow compat entries for all types of 64-bit syscalls

[tip-bot for Andy Lutomirski]

Commit-ID:  f85a8573ceb225e606fcf38a9320782316f47c71
Gitweb:     https://git.kernel.org/tip/f85a8573ceb225e606fcf38a9320782316f47c71
Author:     Andy Lutomirski <luto@xxxxxxxxxx>
AuthorDate: Wed, 3 Jul 2019 13:34:03 -0700
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Mon, 22 Jul 2019 10:31:22 +0200

x86/syscalls: Disallow compat entries for all types of 64-bit syscalls

A "compat" entry in the syscall tables means to use a different entry on
32-bit and 64-bit builds.

This only makes sense for syscalls that exist in the first place in 32-bit
builds, so disallow it for anything other than i386.

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/4b7565954c5a06530ac01d98cb1592538fd8ae51.1562185330.git.luto@xxxxxxxxxx

---
 arch/x86/entry/syscalls/syscalltbl.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/entry/syscalls/syscalltbl.sh b/arch/x86/entry/syscalls/syscalltbl.sh
index 94fcd1951aca..53c8c1a9adf9 100644
--- a/arch/x86/entry/syscalls/syscalltbl.sh
+++ b/arch/x86/entry/syscalls/syscalltbl.sh
@@ -27,8 +27,8 @@ emit() {
     compat="$4"
     umlentry=""
 
-    if [ "$abi" = "64" -a -n "$compat" ]; then
-	echo "a compat entry for a 64-bit syscall makes no sense" >&2
+    if [ "$abi" != "I386" -a -n "$compat" ]; then
+	echo "a compat entry ($abi: $compat) for a 64-bit syscall makes no sense" >&2
 	exit 1
     fi