[PATCH AUTOSEL 5.4 067/330] s390: avoid misusing CALL_ON_STACK for task stack setup

[PATCH AUTOSEL 5.4 067/330] s390: avoid misusing CALL_ON_STACK for task stack setup

[Sasha Levin]

From: Vasily Gorbik <gor@linux.ibm.com>

[ Upstream commit 7bcaad1f9fac889f5fcd1a383acf7e00d006da41 ]

CALL_ON_STACK is intended to be used for temporary stack switching with
potential return to the caller.

When CALL_ON_STACK is misused to switch from nodat stack to task stack
back_chain information would later lead stack unwinder from task stack into
(per cpu) nodat stack which is reused for other purposes. This would
yield confusing unwinding result or errors.

To avoid that introduce CALL_ON_STACK_NORETURN to be used instead. It
makes sure that back_chain is zeroed and unwinder finishes gracefully
ending up at task pt_regs.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/s390/include/asm/stacktrace.h | 11 +++++++++++
 arch/s390/kernel/setup.c           |  9 +--------
 arch/s390/kernel/smp.c             |  2 +-
 3 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/arch/s390/include/asm/stacktrace.h b/arch/s390/include/asm/stacktrace.h
index 0ae4bbf7779c8..3679d224fd3c5 100644
--- a/arch/s390/include/asm/stacktrace.h
+++ b/arch/s390/include/asm/stacktrace.h
@@ -111,4 +111,15 @@ struct stack_frame {
 	r2;								\
 })
 
+#define CALL_ON_STACK_NORETURN(fn, stack)				\
+({									\
+	asm volatile(							\
+		"	la	15,0(%[_stack])\n"			\
+		"	xc	%[_bc](8,15),%[_bc](15)\n"		\
+		"	brasl	14,%[_fn]\n"				\
+		::[_bc] "i" (offsetof(struct stack_frame, back_chain)),	\
+		  [_stack] "a" (stack), [_fn] "X" (fn));		\
+	BUG();								\
+})
+
 #endif /* _ASM_S390_STACKTRACE_H */
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 07b2b61a0289f..82ef081e7448e 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -356,7 +356,6 @@ early_initcall(async_stack_realloc);
 
 void __init arch_call_rest_init(void)
 {
-	struct stack_frame *frame;
 	unsigned long stack;
 
 	stack = stack_alloc();
@@ -369,13 +368,7 @@ void __init arch_call_rest_init(void)
 	set_task_stack_end_magic(current);
 	stack += STACK_INIT_OFFSET;
 	S390_lowcore.kernel_stack = stack;
-	frame = (struct stack_frame *) stack;
-	memset(frame, 0, sizeof(*frame));
-	/* Branch to rest_init on the new stack, never returns */
-	asm volatile(
-		"	la	15,0(%[_frame])\n"
-		"	jg	rest_init\n"
-		: : [_frame] "a" (frame));
+	CALL_ON_STACK_NORETURN(rest_init, stack);
 }
 
 static void __init setup_lowcore_dat_off(void)
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 66bf050d785cf..ad426cc656e56 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -878,7 +878,7 @@ static void __no_sanitize_address smp_start_secondary(void *cpuvoid)
 	S390_lowcore.restart_source = -1UL;
 	__ctl_load(S390_lowcore.cregs_save_area, 0, 15);
 	__load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
-	CALL_ON_STACK(smp_init_secondary, S390_lowcore.kernel_stack, 0);
+	CALL_ON_STACK_NORETURN(smp_init_secondary, S390_lowcore.kernel_stack);
 }
 
 /* Upping and downing of CPUs */
-- 
2.25.1

[PATCH AUTOSEL 5.4 099/330] s390/cpum_sf: Use kzalloc and minor changes

[Sasha Levin]

From: Thomas Richter <tmricht@linux.ibm.com>

[ Upstream commit 32dab6828c42f087439d3e2617dc7283546bd8f7 ]

Use kzalloc() to allocate auxiliary buffer structure initialized
with all zeroes to avoid random value in trace output.

Avoid double access to SBD hardware flags.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/s390/kernel/perf_cpum_sf.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
index 229e1e2f8253a..996e447ead3a6 100644
--- a/arch/s390/kernel/perf_cpum_sf.c
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -1429,8 +1429,8 @@ static int aux_output_begin(struct perf_output_handle *handle,
 		idx = aux->empty_mark + 1;
 		for (i = 0; i < range_scan; i++, idx++) {
 			te = aux_sdb_trailer(aux, idx);
-			te->flags = te->flags & ~SDB_TE_BUFFER_FULL_MASK;
-			te->flags = te->flags & ~SDB_TE_ALERT_REQ_MASK;
+			te->flags &= ~(SDB_TE_BUFFER_FULL_MASK |
+				       SDB_TE_ALERT_REQ_MASK);
 			te->overflow = 0;
 		}
 		/* Save the position of empty SDBs */
@@ -1477,8 +1477,7 @@ static bool aux_set_alert(struct aux_buffer *aux, unsigned long alert_index,
 	te = aux_sdb_trailer(aux, alert_index);
 	do {
 		orig_flags = te->flags;
-		orig_overflow = te->overflow;
-		*overflow = orig_overflow;
+		*overflow = orig_overflow = te->overflow;
 		if (orig_flags & SDB_TE_BUFFER_FULL_MASK) {
 			/*
 			 * SDB is already set by hardware.
@@ -1712,7 +1711,7 @@ static void *aux_buffer_setup(struct perf_event *event, void **pages,
 	}
 
 	/* Allocate aux_buffer struct for the event */
-	aux = kmalloc(sizeof(struct aux_buffer), GFP_KERNEL);
+	aux = kzalloc(sizeof(struct aux_buffer), GFP_KERNEL);
 	if (!aux)
 		goto no_aux;
 	sfb = &aux->sfb;
-- 
2.25.1

[PATCH AUTOSEL 5.4 163/330] s390/irq: replace setup_irq() by request_irq()

[Sasha Levin]

From: afzal mohammed <afzal.mohd.ma@gmail.com>

[ Upstream commit 8719b6d29d2851fa84c4074bb2e5adc022911ab8 ]

request_irq() is preferred over setup_irq(). Invocations of setup_irq()
occur after memory allocators are ready.

Per tglx[1], setup_irq() existed in olden days when allocators were not
ready by the time early interrupts were initialized.

Hence replace setup_irq() by request_irq().

[1] https://lkml.kernel.org/r/alpine.DEB.2.20.1710191609480.1971@nanos

Signed-off-by: afzal mohammed <afzal.mohd.ma@gmail.com>
Message-Id: <20200304005049.5291-1-afzal.mohd.ma@gmail.com>
[heiko.carstens@de.ibm.com: replace pr_err with panic]
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/s390/kernel/irq.c  | 8 ++------
 drivers/s390/cio/airq.c | 8 ++------
 drivers/s390/cio/cio.c  | 8 ++------
 3 files changed, 6 insertions(+), 18 deletions(-)

diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c
index 8371855042dc2..da550cb8b31bd 100644
--- a/arch/s390/kernel/irq.c
+++ b/arch/s390/kernel/irq.c
@@ -294,11 +294,6 @@ static irqreturn_t do_ext_interrupt(int irq, void *dummy)
 	return IRQ_HANDLED;
 }
 
-static struct irqaction external_interrupt = {
-	.name	 = "EXT",
-	.handler = do_ext_interrupt,
-};
-
 void __init init_ext_interrupts(void)
 {
 	int idx;
@@ -308,7 +303,8 @@ void __init init_ext_interrupts(void)
 
 	irq_set_chip_and_handler(EXT_INTERRUPT,
 				 &dummy_irq_chip, handle_percpu_irq);
-	setup_irq(EXT_INTERRUPT, &external_interrupt);
+	if (request_irq(EXT_INTERRUPT, do_ext_interrupt, 0, "EXT", NULL))
+		panic("Failed to register EXT interrupt\n");
 }
 
 static DEFINE_SPINLOCK(irq_subclass_lock);
diff --git a/drivers/s390/cio/airq.c b/drivers/s390/cio/airq.c
index 427b2e24a8cea..cb466ed7eb5ef 100644
--- a/drivers/s390/cio/airq.c
+++ b/drivers/s390/cio/airq.c
@@ -105,16 +105,12 @@ static irqreturn_t do_airq_interrupt(int irq, void *dummy)
 	return IRQ_HANDLED;
 }
 
-static struct irqaction airq_interrupt = {
-	.name	 = "AIO",
-	.handler = do_airq_interrupt,
-};
-
 void __init init_airq_interrupts(void)
 {
 	irq_set_chip_and_handler(THIN_INTERRUPT,
 				 &dummy_irq_chip, handle_percpu_irq);
-	setup_irq(THIN_INTERRUPT, &airq_interrupt);
+	if (request_irq(THIN_INTERRUPT, do_airq_interrupt, 0, "AIO", NULL))
+		panic("Failed to register AIO interrupt\n");
 }
 
 static inline unsigned long iv_size(unsigned long bits)
diff --git a/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index 18f5458f90e8f..6d716db2a46ab 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -563,16 +563,12 @@ static irqreturn_t do_cio_interrupt(int irq, void *dummy)
 	return IRQ_HANDLED;
 }
 
-static struct irqaction io_interrupt = {
-	.name	 = "I/O",
-	.handler = do_cio_interrupt,
-};
-
 void __init init_cio_interrupts(void)
 {
 	irq_set_chip_and_handler(IO_INTERRUPT,
 				 &dummy_irq_chip, handle_percpu_irq);
-	setup_irq(IO_INTERRUPT, &io_interrupt);
+	if (request_irq(IO_INTERRUPT, do_cio_interrupt, 0, "I/O", NULL))
+		panic("Failed to register I/O interrupt\n");
 }
 
 #ifdef CONFIG_CCW_CONSOLE
-- 
2.25.1