x86/syscalls: Add syscall entry qualifiers

This will let us specify something like 'sys_xyz/foo' instead of
'sys_xyz' in the syscall table, where the 'foo' qualifier conveys
some extra information to the C code.

The intent is to allow things like sys_execve/ptregs to indicate
that sys_execve() touches pt_regs.

Signed-off-by: Andy Lutomirski <luto@kernel.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: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/2de06e33dce62556b3ec662006fcb295504e296e.1454022279.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 16 insertions, 3 deletions

diff --git a/arch/x86/entry/syscalls/syscalltbl.sh b/arch/x86/entry/syscalls/syscalltbl.sh
index b81479c8c5fb..cd3d3015d7df 100644
--- a/arch/x86/entry/syscalls/syscalltbl.sh
+++ b/arch/x86/entry/syscalls/syscalltbl.sh
@@ -3,6 +3,19 @@
 in="$1"
 out="$2"
 
+syscall_macro() {
+    abi="$1"
+    nr="$2"
+    entry="$3"
+
+    # Entry can be either just a function name or "function/qualifier"
+    real_entry="${entry%%/*}"
+    qualifier="${entry:${#real_entry}}"		# Strip the function name
+    qualifier="${qualifier:1}"			# Strip the slash, if any
+
+    echo "__SYSCALL_${abi}($nr, $real_entry, $qualifier)"
+}
+
 emit() {
     abi="$1"
     nr="$2"
@@ -16,15 +29,15 @@ emit() {
 
     if [ -z "$compat" ]; then
 	if [ -n "$entry" ]; then
-	    echo "__SYSCALL_${abi}($nr, $entry)"
+	    syscall_macro "$abi" "$nr" "$entry"
 	fi
     else
 	echo "#ifdef CONFIG_X86_32"
 	if [ -n "$entry" ]; then
-	    echo "__SYSCALL_${abi}($nr, $entry)"
+	    syscall_macro "$abi" "$nr" "$entry"
 	fi
 	echo "#else"
-	echo "__SYSCALL_${abi}($nr, $compat)"
+	syscall_macro "$abi" "$nr" "$compat"
 	echo "#endif"
     fi
 }