1 files changed, 11 insertions, 15 deletions

diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 206996c1669d..71820c42b6ce 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -93,8 +93,15 @@ int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
                 COPY(r15);
 #endif /* CONFIG_X86_64 */
 
+#ifdef CONFIG_X86_32
                 COPY_SEG_CPL3(cs);
                 COPY_SEG_CPL3(ss);
+#else /* !CONFIG_X86_32 */
+                /* Kernel saves and restores only the CS segment register on signals,
+                 * which is the bare minimum needed to allow mixed 32/64-bit code.
+                 * App's signal handler can save/restore other segments if needed. */
+                COPY_SEG_CPL3(cs);
+#endif /* CONFIG_X86_32 */
 
                 get_user_ex(tmpflags, &sc->flags);
                 regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
@@ -154,9 +161,8 @@ int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate,
 #else /* !CONFIG_X86_32 */
                 put_user_ex(regs->flags, &sc->flags);
                 put_user_ex(regs->cs, &sc->cs);
-                put_user_ex(0, &sc->__pad2);
-                put_user_ex(0, &sc->__pad1);
-                put_user_ex(regs->ss, &sc->ss);
+                put_user_ex(0, &sc->gs);
+                put_user_ex(0, &sc->fs);
 #endif /* CONFIG_X86_32 */
 
                 put_user_ex(fpstate, &sc->fpstate);
@@ -451,19 +457,9 @@ static int __setup_rt_frame(int sig, struct ksignal *ksig,
 
         regs->sp = (unsigned long)frame;
 
-        /*
-         * Set up the CS and SS registers to run signal handlers in
-         * 64-bit mode, even if the handler happens to be interrupting
-         * 32-bit or 16-bit code.
-         *
-         * SS is subtle.  In 64-bit mode, we don't need any particular
-         * SS descriptor, but we do need SS to be valid.  It's possible
-         * that the old SS is entirely bogus -- this can happen if the
-         * signal we're trying to deliver is #GP or #SS caused by a bad
-         * SS value.
-         */
+        /* Set up the CS register to run signal handlers in 64-bit mode,
+           even if the handler happens to be interrupting 32-bit code. */
         regs->cs = __USER_CS;
-        regs->ss = __USER_DS;
 
         return 0;
 }