Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Ingo Molnar:
 "This tree includes:

   - an FPU related crash fix

   - a ptrace fix (with matching testcase in tools/testing/selftests/)

   - an x86 Kconfig DMA-config defaults tweak to better avoid
     non-working drivers"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  config: Enable NEED_DMA_MAP_STATE by default when SWIOTLB is selected
  x86/fpu: Load xsave pointer *after* initialization
  x86/ptrace: Fix the TIF_FORCED_TF logic in handle_signal()
  x86, selftests: Add single_step_syscall test

3 files changed, 18 insertions, 14 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d43e7e1c784b..937812b8e0b9 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -178,7 +178,7 @@ config SBUS
 
 config NEED_DMA_MAP_STATE
         def_bool y
-        depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG
+        depends on X86_64 || INTEL_IOMMU || DMA_API_DEBUG || SWIOTLB
 
 config NEED_SG_DMA_LENGTH
         def_bool y
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 367f39d35e9c..009183276bb7 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -341,7 +341,7 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
                 unsigned int pos, unsigned int count,
                 void *kbuf, void __user *ubuf)
 {
-        struct xsave_struct *xsave = &target->thread.fpu.state->xsave;
+        struct xsave_struct *xsave;
         int ret;
 
         if (!cpu_has_xsave)
@@ -351,6 +351,8 @@ int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
         if (ret)
                 return ret;
 
+        xsave = &target->thread.fpu.state->xsave;
+
         /*
          * Copy the 48bytes defined by the software first into the xstate
          * memory layout in the thread struct, so that we can copy the entire
@@ -369,7 +371,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
                   unsigned int pos, unsigned int count,
                   const void *kbuf, const void __user *ubuf)
 {
-        struct xsave_struct *xsave = &target->thread.fpu.state->xsave;
+        struct xsave_struct *xsave;
         int ret;
 
         if (!cpu_has_xsave)
@@ -379,6 +381,8 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
         if (ret)
                 return ret;
 
+        xsave = &target->thread.fpu.state->xsave;
+
         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
         /*
          * mxcsr reserved bits must be masked to zero for security reasons.
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index f9804080ccb3..1ea14fd53933 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -616,7 +616,8 @@ setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
 static void
 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 {
-        bool failed;
+        bool stepping, failed;
+
         /* Are we from a system call? */
         if (syscall_get_nr(current, regs) >= 0) {
                 /* If so, check system call restarting.. */
@@ -640,12 +641,13 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs)
         }
 
         /*
-         * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
-         * flag so that register information in the sigcontext is correct.
+         * If TF is set due to a debugger (TIF_FORCED_TF), clear TF now
+         * so that register information in the sigcontext is correct and
+         * then notify the tracer before entering the signal handler.
          */
-        if (unlikely(regs->flags & X86_EFLAGS_TF) &&
-            likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
-                regs->flags &= ~X86_EFLAGS_TF;
+        stepping = test_thread_flag(TIF_SINGLESTEP);
+        if (stepping)
+                user_disable_single_step(current);
 
         failed = (setup_rt_frame(ksig, regs) < 0);
         if (!failed) {
@@ -656,10 +658,8 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs)
                  * it might disable possible debug exception from the
                  * signal handler.
                  *
-                 * 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.
+                 * Clear TF for the case when it wasn't set by debugger to
+                 * avoid the recursive send_sigtrap() in SIGTRAP handler.
                  */
                 regs->flags &= ~(X86_EFLAGS_DF|X86_EFLAGS_RF|X86_EFLAGS_TF);
                 /*
@@ -668,7 +668,7 @@ handle_signal(struct ksignal *ksig, struct pt_regs *regs)
                 if (used_math())
                         fpu_reset_state(current);
         }
-        signal_setup_done(failed, ksig, test_thread_flag(TIF_SINGLESTEP));
+        signal_setup_done(failed, ksig, stepping);
 }
 
 #ifdef CONFIG_X86_32