In its current form, user_64bit_mode() can only be used when CONFIG_X86_64
is selected. This implies that code built with CONFIG_X86_64=n cannot use
it. If a piece of code needs to be built for both CONFIG_X86_64=y and
CONFIG_X86_64=n and wants to use this function, it needs to wrap it in
an #ifdef/#endif; potentially, in multiple places.

This can be easily avoided with a single #ifdef/#endif pair within
user_64bit_mode() itself.

Suggested-by: Borislav Petkov <>
Cc: Dave Hansen <>
Cc: Adam Buchbinder <>
Cc: Colin Ian King <>
Cc: Lorenzo Stoakes <>
Cc: Qiaowei Ren <>
Cc: Arnaldo Carvalho de Melo <>
Cc: Masami Hiramatsu <>
Cc: Adrian Hunter <>
Cc: Kees Cook <>
Cc: Thomas Garnier <>
Cc: Peter Zijlstra <>
Cc: Borislav Petkov <>
Cc: Dmitry Vyukov <>
Cc: Ravi V. Shankar <>
Signed-off-by: Ricardo Neri <>
 arch/x86/include/asm/ptrace.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/ptrace.h b/arch/x86/include/asm/ptrace.h
index 2b5d686..ea78a84 100644
--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -115,9 +115,9 @@ static inline int v8086_mode(struct pt_regs *regs)
-#ifdef CONFIG_X86_64
 static inline bool user_64bit_mode(struct pt_regs *regs)
+#ifdef CONFIG_X86_64
         * On non-paravirt systems, this is the only long mode CPL 3
@@ -128,8 +128,12 @@ static inline bool user_64bit_mode(struct pt_regs *regs)
        /* Headers are too twisted for this to go in paravirt.h. */
        return regs->cs == __USER_CS || regs->cs == pv_info.extra_user_64bit_cs;
+#else /* !CONFIG_X86_64 */
+       return false;
+#ifdef CONFIG_X86_64
 #define current_user_stack_pointer()   current_pt_regs()->sp
 #define compat_user_stack_pointer()    current_pt_regs()->sp

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