[PATCH 3/3] [RFC] Revert "x86: remove the x32 syscall bitmask from syscall_get_nr()"

[Richard Guy Briggs]

This reverts commit 8b4b9f27e57584f3d90e0bb84cf800ad81cfe3a1.
which broke audit and potentially other users of syscall_get_nr() which depend
on that call as named without being overloaded by architecture bits.

This patch along with
	seccomp: give BPF x32 bit when restoring x32 filter
will satisfy other regular users of syscall_get_nr() and syscall_get_arch()
without changing the seccomp interface to BPF.

Cc: Paul Moore <pmoore at redhat.com>
Cc: Eric Paris <eparis at redhat.com>
Cc: Al Viro <aviro at redhat.com>
Cc: Will Drewry <wad at chromium.org>
Cc: H. Peter Anvin <hpa at zytor.com>
Signed-off-by: Richard Guy Briggs <rgb at redhat.com>
Link: http://lkml.kernel.org/r/cover.1405023592.git.rgb@redhat.com
---
 arch/x86/include/asm/syscall.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h
index d58b6be..8c1bb2b 100644
--- a/arch/x86/include/asm/syscall.h
+++ b/arch/x86/include/asm/syscall.h
@@ -30,13 +30,13 @@ extern const sys_call_ptr_t sys_call_table[];
  */
 static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
 {
-	return regs->orig_ax;
+	return regs->orig_ax & __SYSCALL_MASK;
 }
 
 static inline void syscall_rollback(struct task_struct *task,
 				    struct pt_regs *regs)
 {
-	regs->ax = regs->orig_ax;
+	regs->ax = regs->orig_ax & __SYSCALL_MASK;
 }
 
 static inline long syscall_get_error(struct task_struct *task,
-- 
1.7.1