1 files changed, 22 insertions, 8 deletions

diff --git a/arch/x86/kernel/signal_64.c b/arch/x86/kernel/signal_64.c
index 827179c5b32a..ccb2a4560c2d 100644
--- a/arch/x86/kernel/signal_64.c
+++ b/arch/x86/kernel/signal_64.c
@@ -285,14 +285,6 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
            even if the handler happens to be interrupting 32-bit code. */
         regs->cs = __USER_CS;
 
-        /* This, by contrast, has nothing to do with segment registers -
-           see include/asm-x86_64/uaccess.h for details. */
-        set_fs(USER_DS);
-
-        regs->flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_DF);
-        if (test_thread_flag(TIF_SINGLESTEP))
-                ptrace_notify(SIGTRAP);
-
         return 0;
 
 give_sigsegv:
@@ -380,6 +372,28 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 
         if (ret == 0) {
+                /*
+                 * This has nothing to do with segment registers,
+                 * despite the name.  This magic affects uaccess.h
+                 * macros' behavior.  Reset it to the normal setting.
+                 */
+                set_fs(USER_DS);
+
+                /*
+                 * Clear the direction flag as per the ABI for function entry.
+                 */
+                regs->flags &= ~X86_EFLAGS_DF;
+
+                /*
+                 * Clear TF when entering the signal handler, but
+                 * notify any tracer that was single-stepping it.
+                 * The tracer may want to single-step inside the
+                 * handler too.
+                 */
+                regs->flags &= ~X86_EFLAGS_TF;
+                if (test_thread_flag(TIF_SINGLESTEP))
+                        ptrace_notify(SIGTRAP);
+
                 spin_lock_irq(&current->sighand->siglock);
                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
                 if (!(ka->sa.sa_flags & SA_NODEFER))