4 files changed, 31 insertions, 4 deletions

diff --git a/arch/x86/include/asm/compat.h b/arch/x86/include/asm/compat.h
index 30d737ef2a42..7938b84e4506 100644
--- a/arch/x86/include/asm/compat.h
+++ b/arch/x86/include/asm/compat.h
@@ -7,6 +7,7 @@
 #include <linux/types.h>
 #include <linux/sched.h>
 #include <asm/user32.h>
+#include <asm/unistd.h>
 
 #define COMPAT_USER_HZ          100
 #define COMPAT_UTS_MACHINE      "i686\0\0"
@@ -212,9 +213,17 @@ static inline void __user *arch_compat_alloc_user_space(long len)
         return (void __user *)regs->sp - len;
 }
 
-static inline int is_compat_task(void)
+static inline bool is_compat_task(void)
 {
-        return current_thread_info()->status & TS_COMPAT;
+#ifdef CONFIG_IA32_EMULATION
+        if (current_thread_info()->status & TS_COMPAT)
+                return true;
+#endif
+#ifdef CONFIG_X86_X32_ABI
+        if (task_pt_regs(current)->orig_ax & __X32_SYSCALL_BIT)
+                return true;
+#endif
+        return false;
 }
 
 #endif /* _ASM_X86_COMPAT_H */
diff --git a/arch/x86/include/asm/syscall.h b/arch/x86/include/asm/syscall.h
index d962e5652a73..386b78686c4d 100644
--- a/arch/x86/include/asm/syscall.h
+++ b/arch/x86/include/asm/syscall.h
@@ -16,6 +16,7 @@
 #include <linux/sched.h>
 #include <linux/err.h>
 #include <asm/asm-offsets.h>    /* For NR_syscalls */
+#include <asm/unistd.h>
 
 extern const unsigned long sys_call_table[];
 
@@ -26,13 +27,13 @@ extern const unsigned long 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,
diff --git a/arch/x86/include/asm/unistd.h b/arch/x86/include/asm/unistd.h
index 7a48a5557470..37cdc9d99bb1 100644
--- a/arch/x86/include/asm/unistd.h
+++ b/arch/x86/include/asm/unistd.h
@@ -5,6 +5,13 @@
 #define __X32_SYSCALL_BIT       0x40000000
 
 #ifdef __KERNEL__
+
+# ifdef CONFIG_X86_X32_ABI
+#  define __SYSCALL_MASK (~(__X32_SYSCALL_BIT))
+# else
+#  define __SYSCALL_MASK (~0)
+# endif
+
 # ifdef CONFIG_X86_32
 
 #  include <asm/unistd_32.h>
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 3fe8239fd8fb..a17b34216971 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -482,7 +482,12 @@ GLOBAL(system_call_after_swapgs)
         testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP-ARGOFFSET)
         jnz tracesys
 system_call_fastpath:
+#if __SYSCALL_MASK == ~0
         cmpq $__NR_syscall_max,%rax
+#else
+        andl $__SYSCALL_MASK,%eax
+        cmpl $__NR_syscall_max,%eax
+#endif
         ja badsys
         movq %r10,%rcx
         call *sys_call_table(,%rax,8)  # XXX:    rip relative
@@ -596,7 +601,12 @@ tracesys:
          */
         LOAD_ARGS ARGOFFSET, 1
         RESTORE_REST
+#if __SYSCALL_MASK == ~0
         cmpq $__NR_syscall_max,%rax
+#else
+        andl $__SYSCALL_MASK,%eax
+        cmpl $__NR_syscall_max,%eax
+#endif
         ja   int_ret_from_sys_call      /* RAX(%rsp) set to -ENOSYS above */
         movq %r10,%rcx  /* fixup for C */
         call *sys_call_table(,%rax,8)