+
+/*
+ * Determine which stack to use..
+ */
+static unsigned long align_sigframe(unsigned long sp)
+{
+#ifdef CONFIG_X86_32
+ /*
+ * Align the stack pointer according to the i386 ABI,
+ * i.e. so that on function entry ((sp + 4) & 15) == 0.
+ */
+ sp = ((sp + 4) & -16ul) - 4;
+#else /* !CONFIG_X86_32 */
+ sp = round_down(sp, 16) - 8;
+#endif
+ return sp;
+}
+
+static inline void __user *
+get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
+ void __user **fpstate)
+{
+ /* Default to using normal stack */
+ unsigned long sp = regs->sp;
+ int onsigstack = on_sig_stack(sp);
+
+#ifdef CONFIG_X86_64
+ /* redzone */
+ sp -= 128;
+#endif /* CONFIG_X86_64 */
+
+ if (!onsigstack) {
+ /* This is the X/Open sanctioned signal stack switching. */
+ if (ka->sa.sa_flags & SA_ONSTACK) {
+ if (current->sas_ss_size)
+ sp = current->sas_ss_sp + current->sas_ss_size;
+ } else {
+#ifdef CONFIG_X86_32
+ /* This is the legacy signal stack switching. */
+ if ((regs->ss & 0xffff) != __USER_DS &&
+ !(ka->sa.sa_flags & SA_RESTORER) &&
+ ka->sa.sa_restorer)
+ sp = (unsigned long) ka->sa.sa_restorer;
+#endif /* CONFIG_X86_32 */
+ }
+ }
+
+ if (used_math()) {
+ sp -= sig_xstate_size;
+#ifdef CONFIG_X86_64
+ sp = round_down(sp, 64);
+#endif /* CONFIG_X86_64 */
+ *fpstate = (void __user *)sp;
+ }
+
+ sp = align_sigframe(sp - frame_size);
+
+ /*
+ * If we are on the alternate signal stack and would overflow it, don't.
+ * Return an always-bogus address instead so we will die with SIGSEGV.
+ */
+ if (onsigstack && !likely(on_sig_stack(sp)))
+ return (void __user *)-1L;
+
+ /* save i387 state */
+ if (used_math() && save_i387_xstate(*fpstate) < 0)
+ return (void __user *)-1L;
+
+ return (void __user *)sp;
+}
+