Merge tag 's390-5.14-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull more s390 updates from Vasily Gorbik:

 - Fix preempt_count initialization.

 - Rework call_on_stack() macro to add proper type handling and avoid
   possible register corruption.

 - More error prone "register asm" removal and fixes.

 - Fix syscall restarting when multiple signals are coming in. This adds
   minimalistic trampolines to vdso so we can return from signal without
   using the stack which requires pgm check handler hacks when NX is
   enabled.

 - Remove HAVE_IRQ_EXIT_ON_IRQ_STACK since this is no longer true after
   switch to generic entry.

 - Fix protected virtualization secure storage access exception
   handling.

 - Make machine check C handler always enter with DAT enabled and move
   register validation to C code.

 - Fix tinyconfig boot problem by avoiding MONITOR CALL without
   CONFIG_BUG.

 - Increase asm symbols alignment to 16 to make it consistent with
   compilers.

 - Enable concurrent access to the CPU Measurement Counter Facility.

 - Add support for dynamic AP bus size limit and rework ap_dqap to deal
   with messages greater than recv buffer.

* tag 's390-5.14-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (41 commits)
  s390: preempt: Fix preempt_count initialization
  s390/linkage: increase asm symbols alignment to 16
  s390: rename CALL_ON_STACK_NORETURN() to call_on_stack_noreturn()
  s390: add type checking to CALL_ON_STACK_NORETURN() macro
  s390: remove old CALL_ON_STACK() macro
  s390/softirq: use call_on_stack() macro
  s390/lib: use call_on_stack() macro
  s390/smp: use call_on_stack() macro
  s390/kexec: use call_on_stack() macro
  s390/irq: use call_on_stack() macro
  s390/mm: use call_on_stack() macro
  s390: introduce proper type handling call_on_stack() macro
  s390/irq: simplify on_async_stack()
  s390/irq: inline do_softirq_own_stack()
  s390/irq: simplify do_softirq_own_stack()
  s390/ap: get rid of register asm in ap_dqap()
  s390: rename PIF_SYSCALL_RESTART to PIF_EXECVE_PGSTE_RESTART
  s390: move restart of execve() syscall
  s390/signal: remove sigreturn on stack
  s390/signal: switch to using vdso for sigreturn and syscall restart
  ...

1 files changed, 26 insertions, 23 deletions

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index 8ae3dc5783fd..e33c43b38afe 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -285,26 +285,6 @@ static noinline void do_sigbus(struct pt_regs *regs)
 			(void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK));
 }
 
-static noinline int signal_return(struct pt_regs *regs)
-{
-	u16 instruction;
-	int rc;
-
-	rc = __get_user(instruction, (u16 __user *) regs->psw.addr);
-	if (rc)
-		return rc;
-	if (instruction == 0x0a77) {
-		set_pt_regs_flag(regs, PIF_SYSCALL);
-		regs->int_code = 0x00040077;
-		return 0;
-	} else if (instruction == 0x0aad) {
-		set_pt_regs_flag(regs, PIF_SYSCALL);
-		regs->int_code = 0x000400ad;
-		return 0;
-	}
-	return -EACCES;
-}
-
 static noinline void do_fault_error(struct pt_regs *regs, int access,
 					vm_fault_t fault)
 {
@@ -312,9 +292,6 @@ static noinline void do_fault_error(struct pt_regs *regs, int access,
 
 	switch (fault) {
 	case VM_FAULT_BADACCESS:
-		if (access == VM_EXEC && signal_return(regs) == 0)
-			break;
-		fallthrough;
 	case VM_FAULT_BADMAP:
 		/* Bad memory access. Check if it is kernel or user space. */
 		if (user_mode(regs)) {
@@ -792,6 +769,32 @@ void do_secure_storage_access(struct pt_regs *regs)
 	struct page *page;
 	int rc;
 
+	/*
+	 * bit 61 tells us if the address is valid, if it's not we
+	 * have a major problem and should stop the kernel or send a
+	 * SIGSEGV to the process. Unfortunately bit 61 is not
+	 * reliable without the misc UV feature so we need to check
+	 * for that as well.
+	 */
+	if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) &&
+	    !test_bit_inv(61, &regs->int_parm_long)) {
+		/*
+		 * When this happens, userspace did something that it
+		 * was not supposed to do, e.g. branching into secure
+		 * memory. Trigger a segmentation fault.
+		 */
+		if (user_mode(regs)) {
+			send_sig(SIGSEGV, current, 0);
+			return;
+		}
+
+		/*
+		 * The kernel should never run into this case and we
+		 * have no way out of this situation.
+		 */
+		panic("Unexpected PGM 0x3d with TEID bit 61=0");
+	}
+
 	switch (get_fault_type(regs)) {
 	case USER_FAULT:
 		mm = current->mm;