Merge tag 's390-5.12-6' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 fixes from Heiko Carstens:

 - fix incorrect dereference of the ext_params2 external interrupt
   parameter, which leads to an instant kernel crash if a pfault
   interrupt occurs.

 - add forgotten stack unwinder support, and fix memory leak for the
   new machine check handler stack.

 - fix inline assembly register clobbering due to KASAN code
   instrumentation.

* tag 's390-5.12-6' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/setup: use memblock_free_late() to free old stack
  s390/irq: fix reading of ext_params2 field from lowcore
  s390/unwind: add machine check handler stack
  s390/cpcmd: fix inline assembly register clobbering

5 files changed, 18 insertions, 5 deletions

diff --git a/arch/s390/include/asm/stacktrace.h b/arch/s390/include/asm/stacktrace.h
index ee056f4a4fa306..2b543163d90a02 100644
--- a/arch/s390/include/asm/stacktrace.h
+++ b/arch/s390/include/asm/stacktrace.h
@@ -12,6 +12,7 @@ enum stack_type {
 	STACK_TYPE_IRQ,
 	STACK_TYPE_NODAT,
 	STACK_TYPE_RESTART,
+	STACK_TYPE_MCCK,
 };
 
 struct stack_info {
diff --git a/arch/s390/kernel/cpcmd.c b/arch/s390/kernel/cpcmd.c
index af013b4244d346..2da0273597989b 100644
--- a/arch/s390/kernel/cpcmd.c
+++ b/arch/s390/kernel/cpcmd.c
@@ -37,10 +37,12 @@ static int diag8_noresponse(int cmdlen)
 
 static int diag8_response(int cmdlen, char *response, int *rlen)
 {
+	unsigned long _cmdlen = cmdlen | 0x40000000L;
+	unsigned long _rlen = *rlen;
 	register unsigned long reg2 asm ("2") = (addr_t) cpcmd_buf;
 	register unsigned long reg3 asm ("3") = (addr_t) response;
-	register unsigned long reg4 asm ("4") = cmdlen | 0x40000000L;
-	register unsigned long reg5 asm ("5") = *rlen;
+	register unsigned long reg4 asm ("4") = _cmdlen;
+	register unsigned long reg5 asm ("5") = _rlen;
 
 	asm volatile(
 		"	diag	%2,%0,0x8\n"
diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
index 0dc4b258b98d51..db1bc00229caf2 100644
--- a/arch/s390/kernel/dumpstack.c
+++ b/arch/s390/kernel/dumpstack.c
@@ -79,6 +79,15 @@ static bool in_nodat_stack(unsigned long sp, struct stack_info *info)
 	return in_stack(sp, info, STACK_TYPE_NODAT, top - THREAD_SIZE, top);
 }
 
+static bool in_mcck_stack(unsigned long sp, struct stack_info *info)
+{
+	unsigned long frame_size, top;
+
+	frame_size = STACK_FRAME_OVERHEAD + sizeof(struct pt_regs);
+	top = S390_lowcore.mcck_stack + frame_size;
+	return in_stack(sp, info, STACK_TYPE_MCCK, top - THREAD_SIZE, top);
+}
+
 static bool in_restart_stack(unsigned long sp, struct stack_info *info)
 {
 	unsigned long frame_size, top;
@@ -108,7 +117,8 @@ int get_stack_info(unsigned long sp, struct task_struct *task,
 	/* Check per-cpu stacks */
 	if (!in_irq_stack(sp, info) &&
 	    !in_nodat_stack(sp, info) &&
-	    !in_restart_stack(sp, info))
+	    !in_restart_stack(sp, info) &&
+	    !in_mcck_stack(sp, info))
 		goto unknown;
 
 recursion_check:
diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c
index 601c2179133847..714269e10eec54 100644
--- a/arch/s390/kernel/irq.c
+++ b/arch/s390/kernel/irq.c
@@ -174,7 +174,7 @@ void noinstr do_ext_irq(struct pt_regs *regs)
 
 	memcpy(&regs->int_code, &S390_lowcore.ext_cpu_addr, 4);
 	regs->int_parm = S390_lowcore.ext_params;
-	regs->int_parm_long = *(unsigned long *)S390_lowcore.ext_params2;
+	regs->int_parm_long = S390_lowcore.ext_params2;
 
 	from_idle = !user_mode(regs) && regs->psw.addr == (unsigned long)psw_idle_exit;
 	if (from_idle)
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 60da976eee6ff4..72134f9f6ff527 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -354,7 +354,7 @@ static int __init stack_realloc(void)
 	if (!new)
 		panic("Couldn't allocate machine check stack");
 	WRITE_ONCE(S390_lowcore.mcck_stack, new + STACK_INIT_OFFSET);
-	memblock_free(old, THREAD_SIZE);
+	memblock_free_late(old, THREAD_SIZE);
 	return 0;
 }
 early_initcall(stack_realloc);