Merge tag 's390-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 updates from Vasily Gorbik:

 - Convert to using the generic entry infrastructure.

 - Add vdso time namespace support.

 - Switch s390 and alpha to 64-bit ino_t. As discussed at

     https://lore.kernel.org/linux-mm/YCV7QiyoweJwvN+m@osiris/

 - Get rid of expensive stck (store clock) usages where possible.
   Utilize cpu alternatives to patch stckf when supported.

 - Make tod_clock usage less error prone by converting it to a union and
   rework code which is using it.

 - Machine check handler fixes and cleanups.

 - Drop couple of minor inline asm optimizations to fix clang build.

 - Default configs changes notably to make libvirt happy.

 - Various changes to rework and improve qdio code.

 - Other small various fixes and improvements all over the code.

* tag 's390-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (68 commits)
  s390/qdio: remove 'merge_pending' mechanism
  s390/qdio: improve handling of PENDING buffers for QEBSM devices
  s390/qdio: rework q->qdio_error indication
  s390/qdio: inline qdio_kick_handler()
  s390/time: remove get_tod_clock_ext()
  s390/crypto: use store_tod_clock_ext()
  s390/hypfs: use store_tod_clock_ext()
  s390/debug: use union tod_clock
  s390/kvm: use union tod_clock
  s390/vdso: use union tod_clock
  s390/time: convert tod_clock_base to union
  s390/time: introduce new store_tod_clock_ext()
  s390/time: rename store_tod_clock_ext() and use union tod_clock
  s390/time: introduce union tod_clock
  s390,alpha: switch to 64-bit ino_t
  s390: split cleanup_sie
  s390: use r13 in cleanup_sie as temp register
  s390: fix kernel asce loading when sie is interrupted
  s390: add stack for machine check handler
  s390: use WRITE_ONCE when re-allocating async stack
  ...

1 files changed, 23 insertions, 7 deletions

diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index bc3ca54edfb4..367bd000f6d1 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -29,6 +29,7 @@
 #include <linux/random.h>
 #include <linux/export.h>
 #include <linux/init_task.h>
+#include <linux/entry-common.h>
 #include <asm/cpu_mf.h>
 #include <asm/io.h>
 #include <asm/processor.h>
@@ -43,9 +44,22 @@
 #include <asm/unwind.h>
 #include "entry.h"
 
-asmlinkage void ret_from_fork(void) asm ("ret_from_fork");
+void ret_from_fork(void) asm("ret_from_fork");
 
-extern void kernel_thread_starter(void);
+void __ret_from_fork(struct task_struct *prev, struct pt_regs *regs)
+{
+	void (*func)(void *arg);
+
+	schedule_tail(prev);
+
+	if (!user_mode(regs)) {
+		/* Kernel thread */
+		func = (void *)regs->gprs[9];
+		func((void *)regs->gprs[10]);
+	}
+	clear_pt_regs_flag(regs, PIF_SYSCALL);
+	syscall_exit_to_user_mode(regs);
+}
 
 void flush_thread(void)
 {
@@ -108,10 +122,12 @@ int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 	p->thread.last_break = 1;
 
 	frame->sf.back_chain = 0;
+	frame->sf.gprs[5] = (unsigned long)frame + sizeof(struct stack_frame);
+	frame->sf.gprs[6] = (unsigned long)p;
 	/* new return point is ret_from_fork */
-	frame->sf.gprs[8] = (unsigned long) ret_from_fork;
+	frame->sf.gprs[8] = (unsigned long)ret_from_fork;
 	/* fake return stack for resume(), don't go back to schedule */
-	frame->sf.gprs[9] = (unsigned long) frame;
+	frame->sf.gprs[9] = (unsigned long)frame;
 
 	/* Store access registers to kernel stack of new process. */
 	if (unlikely(p->flags & PF_KTHREAD)) {
@@ -120,10 +136,10 @@ int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 		frame->childregs.psw.mask = PSW_KERNEL_BITS | PSW_MASK_DAT |
 				PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
 		frame->childregs.psw.addr =
-				(unsigned long) kernel_thread_starter;
+				(unsigned long)__ret_from_fork;
 		frame->childregs.gprs[9] = new_stackp; /* function */
 		frame->childregs.gprs[10] = arg;
-		frame->childregs.gprs[11] = (unsigned long) do_exit;
+		frame->childregs.gprs[11] = (unsigned long)do_exit;
 		frame->childregs.orig_gpr2 = -1;
 
 		return 0;
@@ -153,7 +169,7 @@ int copy_thread(unsigned long clone_flags, unsigned long new_stackp,
 	return 0;
 }
 
-asmlinkage void execve_tail(void)
+void execve_tail(void)
 {
 	current->thread.fpu.fpc = 0;
 	asm volatile("sfpc %0" : : "d" (0));