Xtensa fixes for v4.20-rc5

- Fix kernel exception on userspace access to a currently disabled
   coprocessor.
 - Fix coprocessor data saving/restoring in configurations with multiple
   coprocessors.
 - Fix ptrace access to coprocessor data on configurations with multiple
   coprocessors with high alignment requirements.
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Merge tag 'xtensa-20181128' of git://github.com/jcmvbkbc/linux-xtensa

Pull Xtensa fixes from Max Filippov:

 - fix kernel exception on userspace access to a currently disabled
   coprocessor

 - fix coprocessor data saving/restoring in configurations with multiple
   coprocessors

 - fix ptrace access to coprocessor data on configurations with multiple
   coprocessors with high alignment requirements

* tag 'xtensa-20181128' of git://github.com/jcmvbkbc/linux-xtensa:
  xtensa: fix coprocessor part of ptrace_{get,set}xregs
  xtensa: fix coprocessor context offset definitions
  xtensa: enable coprocessors that are being flushed

arch/xtensa/kernel/asm-offsets.c

@@ -94,14 +94,14 @@ int main(void)
 	DEFINE(THREAD_SP, offsetof (struct task_struct, thread.sp));
 	DEFINE(THREAD_CPENABLE, offsetof (struct thread_info, cpenable));
 #if XTENSA_HAVE_COPROCESSORS
-	DEFINE(THREAD_XTREGS_CP0, offsetof (struct thread_info, xtregs_cp));
-	DEFINE(THREAD_XTREGS_CP1, offsetof (struct thread_info, xtregs_cp));
-	DEFINE(THREAD_XTREGS_CP2, offsetof (struct thread_info, xtregs_cp));
-	DEFINE(THREAD_XTREGS_CP3, offsetof (struct thread_info, xtregs_cp));
-	DEFINE(THREAD_XTREGS_CP4, offsetof (struct thread_info, xtregs_cp));
-	DEFINE(THREAD_XTREGS_CP5, offsetof (struct thread_info, xtregs_cp));
-	DEFINE(THREAD_XTREGS_CP6, offsetof (struct thread_info, xtregs_cp));
-	DEFINE(THREAD_XTREGS_CP7, offsetof (struct thread_info, xtregs_cp));
+	DEFINE(THREAD_XTREGS_CP0, offsetof(struct thread_info, xtregs_cp.cp0));
+	DEFINE(THREAD_XTREGS_CP1, offsetof(struct thread_info, xtregs_cp.cp1));
+	DEFINE(THREAD_XTREGS_CP2, offsetof(struct thread_info, xtregs_cp.cp2));
+	DEFINE(THREAD_XTREGS_CP3, offsetof(struct thread_info, xtregs_cp.cp3));
+	DEFINE(THREAD_XTREGS_CP4, offsetof(struct thread_info, xtregs_cp.cp4));
+	DEFINE(THREAD_XTREGS_CP5, offsetof(struct thread_info, xtregs_cp.cp5));
+	DEFINE(THREAD_XTREGS_CP6, offsetof(struct thread_info, xtregs_cp.cp6));
+	DEFINE(THREAD_XTREGS_CP7, offsetof(struct thread_info, xtregs_cp.cp7));
 #endif
 	DEFINE(THREAD_XTREGS_USER, offsetof (struct thread_info, xtregs_user));
 	DEFINE(XTREGS_USER_SIZE, sizeof(xtregs_user_t));

arch/xtensa/kernel/process.c

@@ -94,18 +94,21 @@ void coprocessor_release_all(struct thread_info *ti)
 
 void coprocessor_flush_all(struct thread_info *ti)
 {
-	unsigned long cpenable;
+	unsigned long cpenable, old_cpenable;
 	int i;
 
 	preempt_disable();
 
+	RSR_CPENABLE(old_cpenable);
 	cpenable = ti->cpenable;
+	WSR_CPENABLE(cpenable);
 
 	for (i = 0; i < XCHAL_CP_MAX; i++) {
 		if ((cpenable & 1) != 0 && coprocessor_owner[i] == ti)
 			coprocessor_flush(ti, i);
 		cpenable >>= 1;
 	}
+	WSR_CPENABLE(old_cpenable);
 
 	preempt_enable();
 }

arch/xtensa/kernel/ptrace.c

@@ -127,12 +127,37 @@ static int ptrace_setregs(struct task_struct *child, void __user *uregs)
 }
 
 
+#if XTENSA_HAVE_COPROCESSORS
+#define CP_OFFSETS(cp) \
+	{ \
+		.elf_xtregs_offset = offsetof(elf_xtregs_t, cp), \
+		.ti_offset = offsetof(struct thread_info, xtregs_cp.cp), \
+		.sz = sizeof(xtregs_ ## cp ## _t), \
+	}
+
+static const struct {
+	size_t elf_xtregs_offset;
+	size_t ti_offset;
+	size_t sz;
+} cp_offsets[] = {
+	CP_OFFSETS(cp0),
+	CP_OFFSETS(cp1),
+	CP_OFFSETS(cp2),
+	CP_OFFSETS(cp3),
+	CP_OFFSETS(cp4),
+	CP_OFFSETS(cp5),
+	CP_OFFSETS(cp6),
+	CP_OFFSETS(cp7),
+};
+#endif
+
 static int ptrace_getxregs(struct task_struct *child, void __user *uregs)
 {
 	struct pt_regs *regs = task_pt_regs(child);
 	struct thread_info *ti = task_thread_info(child);
 	elf_xtregs_t __user *xtregs = uregs;
 	int ret = 0;
+	int i __maybe_unused;
 
 	if (!access_ok(VERIFY_WRITE, uregs, sizeof(elf_xtregs_t)))
 		return -EIO;
@@ -140,8 +165,13 @@ static int ptrace_getxregs(struct task_struct *child, void __user *uregs)
 #if XTENSA_HAVE_COPROCESSORS
 	/* Flush all coprocessor registers to memory. */
 	coprocessor_flush_all(ti);
-	ret |= __copy_to_user(&xtregs->cp0, &ti->xtregs_cp,
-			      sizeof(xtregs_coprocessor_t));
+
+	for (i = 0; i < ARRAY_SIZE(cp_offsets); ++i)
+		ret |= __copy_to_user((char __user *)xtregs +
+				      cp_offsets[i].elf_xtregs_offset,
+				      (const char *)ti +
+				      cp_offsets[i].ti_offset,
+				      cp_offsets[i].sz);
 #endif
 	ret |= __copy_to_user(&xtregs->opt, &regs->xtregs_opt,
 			      sizeof(xtregs->opt));
@@ -157,6 +187,7 @@ static int ptrace_setxregs(struct task_struct *child, void __user *uregs)
 	struct pt_regs *regs = task_pt_regs(child);
 	elf_xtregs_t *xtregs = uregs;
 	int ret = 0;
+	int i __maybe_unused;
 
 	if (!access_ok(VERIFY_READ, uregs, sizeof(elf_xtregs_t)))
 		return -EFAULT;
@@ -166,8 +197,11 @@ static int ptrace_setxregs(struct task_struct *child, void __user *uregs)
 	coprocessor_flush_all(ti);
 	coprocessor_release_all(ti);
 
-	ret |= __copy_from_user(&ti->xtregs_cp, &xtregs->cp0,
-				sizeof(xtregs_coprocessor_t));
+	for (i = 0; i < ARRAY_SIZE(cp_offsets); ++i)
+		ret |= __copy_from_user((char *)ti + cp_offsets[i].ti_offset,
+					(const char __user *)xtregs +
+					cp_offsets[i].elf_xtregs_offset,
+					cp_offsets[i].sz);
 #endif
 	ret |= __copy_from_user(&regs->xtregs_opt, &xtregs->opt,
 				sizeof(xtregs->opt));