[GIT PULL] more s390 updates for 5.11 merge window

From: Heiko Carstens
Date: Fri Dec 18 2020 - 13:54:07 EST

Hi Linus,

please pull some more small updates for s390. This is mainly to
decouple udelay() and arch_cpu_idle() and simplify both of them,
like I brought it up after the lockdep breakage in 5.10-rc6.

Thanks,
Heiko

The following changes since commit 586592478b1fa8bb8cd6875a9191468e9b1a8b13:

Merge tag 's390-5.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux (2020-12-14 16:22:26 -0800)

are available in the Git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux.git tags/s390-5.11-2

for you to fetch changes up to dfdc6e73cdcf011a04568231132916c6d06b861f:

s390/zcrypt: convert comma to semicolon (2020-12-16 14:55:50 +0100)

----------------------------------------------------------------
- Always initialize kernel stack backchain when entering the kernel, so
that unwinding works properly.

- Fix stack unwinder test case to avoid rare interrupt stack corruption.

- Simplify udelay() and just let it busy loop instead of implementing a
complex logic.

- arch_cpu_idle() cleanup.

- Some other minor improvements.

----------------------------------------------------------------
Heiko Carstens (10):
s390: always clear kernel stack backchain before calling functions
s390: make calls to TRACE_IRQS_OFF/TRACE_IRQS_ON balanced
s390/test_unwind: fix CALL_ON_STACK tests
s390/test_unwind: use timer instead of udelay
s390/delay: simplify udelay
s390/irq: select HAVE_IRQ_EXIT_ON_IRQ_STACK
s390/delay: remove udelay_simple()
s390/idle: merge enabled_wait() and arch_cpu_idle()
s390/idle: remove raw_local_irq_save()/restore() from arch_cpu_idle()
s390/idle: allow arch_cpu_idle() to be kprobed

Zheng Yongjun (1):
s390/zcrypt: convert comma to semicolon

arch/s390/Kconfig | 1 +
arch/s390/include/asm/delay.h | 12 ++---
arch/s390/include/asm/processor.h | 7 ---
arch/s390/kernel/entry.S | 16 +++---
arch/s390/kernel/idle.c | 18 ++-----
arch/s390/kernel/ipl.c | 2 +-
arch/s390/kernel/setup.c | 1 -
arch/s390/lib/delay.c | 105 ++++---------------------------------
arch/s390/lib/test_unwind.c | 31 ++++++-----
drivers/s390/cio/device.c | 2 +-
drivers/s390/crypto/zcrypt_cex2a.c | 2 +-
drivers/s390/crypto/zcrypt_cex4.c | 2 +-
12 files changed, 44 insertions(+), 155 deletions(-)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index a60cc523d810..9e8895cb9ee7 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -153,6 +153,7 @@ config S390
select HAVE_FUTEX_CMPXCHG if FUTEX
select HAVE_GCC_PLUGINS
select HAVE_GENERIC_VDSO
+ select HAVE_IRQ_EXIT_ON_IRQ_STACK
select HAVE_KERNEL_BZIP2
select HAVE_KERNEL_GZIP
select HAVE_KERNEL_LZ4
diff --git a/arch/s390/include/asm/delay.h b/arch/s390/include/asm/delay.h
index 4a08379cd1eb..21a8fe18fe66 100644
--- a/arch/s390/include/asm/delay.h
+++ b/arch/s390/include/asm/delay.h
@@ -13,14 +13,12 @@
#ifndef _S390_DELAY_H
#define _S390_DELAY_H

-void udelay_enable(void);
-void __ndelay(unsigned long long nsecs);
-void __udelay(unsigned long long usecs);
-void udelay_simple(unsigned long long usecs);
+void __ndelay(unsigned long nsecs);
+void __udelay(unsigned long usecs);
void __delay(unsigned long loops);

-#define ndelay(n) __ndelay((unsigned long long) (n))
-#define udelay(n) __udelay((unsigned long long) (n))
-#define mdelay(n) __udelay((unsigned long long) (n) * 1000)
+#define ndelay(n) __ndelay((unsigned long)(n))
+#define udelay(n) __udelay((unsigned long)(n))
+#define mdelay(n) __udelay((unsigned long)(n) * 1000)

#endif /* defined(_S390_DELAY_H) */
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 6b7269f51f83..2058a435add4 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -16,14 +16,12 @@

#define CIF_NOHZ_DELAY 2 /* delay HZ disable for a tick */
#define CIF_FPU 3 /* restore FPU registers */
-#define CIF_IGNORE_IRQ 4 /* ignore interrupt (for udelay) */
#define CIF_ENABLED_WAIT 5 /* in enabled wait state */
#define CIF_MCCK_GUEST 6 /* machine check happening in guest */
#define CIF_DEDICATED_CPU 7 /* this CPU is dedicated */

#define _CIF_NOHZ_DELAY BIT(CIF_NOHZ_DELAY)
#define _CIF_FPU BIT(CIF_FPU)
-#define _CIF_IGNORE_IRQ BIT(CIF_IGNORE_IRQ)
#define _CIF_ENABLED_WAIT BIT(CIF_ENABLED_WAIT)
#define _CIF_MCCK_GUEST BIT(CIF_MCCK_GUEST)
#define _CIF_DEDICATED_CPU BIT(CIF_DEDICATED_CPU)
@@ -292,11 +290,6 @@ static inline unsigned long __rewind_psw(psw_t psw, unsigned long ilc)
return (psw.addr - ilc) & mask;
}

-/*
- * Function to stop a processor until the next interrupt occurs
- */
-void enabled_wait(void);
-
/*
* Function to drop a processor into disabled wait state
*/
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 8bb9ebb71c4b..87e83164c330 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -413,6 +413,7 @@ ENTRY(system_call)
mvc __PT_PSW(16,%r11),__LC_SVC_OLD_PSW
mvc __PT_INT_CODE(4,%r11),__LC_SVC_ILC
stg %r14,__PT_FLAGS(%r11)
+ xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
ENABLE_INTS
.Lsysc_do_svc:
# clear user controlled register to prevent speculative use
@@ -429,7 +430,6 @@ ENTRY(system_call)
jnl .Lsysc_nr_ok
slag %r8,%r1,3
.Lsysc_nr_ok:
- xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
stg %r2,__PT_ORIG_GPR2(%r11)
stg %r7,STACK_FRAME_OVERHEAD(%r15)
lg %r9,0(%r8,%r10) # get system call add.
@@ -698,8 +698,8 @@ ENTRY(pgm_check_handler)
mvc __THREAD_per_address(8,%r14),__LC_PER_ADDRESS
mvc __THREAD_per_cause(2,%r14),__LC_PER_CODE
mvc __THREAD_per_paid(1,%r14),__LC_PER_ACCESS_ID
-6: RESTORE_SM_CLEAR_PER
- xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
+6: xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
+ RESTORE_SM_CLEAR_PER
larl %r1,pgm_check_table
llgh %r10,__PT_INT_CODE+2(%r11)
nill %r10,0x007f
@@ -730,8 +730,8 @@ ENTRY(pgm_check_handler)
# PER event in supervisor state, must be kprobes
#
.Lpgm_kprobe:
- RESTORE_SM_CLEAR_PER
xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
+ RESTORE_SM_CLEAR_PER
lgr %r2,%r11 # pass pointer to pt_regs
brasl %r14,do_per_trap
j .Lpgm_return
@@ -777,10 +777,8 @@ ENTRY(io_int_handler)
.Lio_skip_asce:
mvc __PT_INT_CODE(12,%r11),__LC_SUBCHANNEL_ID
xc __PT_FLAGS(8,%r11),__PT_FLAGS(%r11)
- TSTMSK __LC_CPU_FLAGS,_CIF_IGNORE_IRQ
- jo .Lio_restore
- TRACE_IRQS_OFF
xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
+ TRACE_IRQS_OFF
.Lio_loop:
lgr %r2,%r11 # pass pointer to pt_regs
lghi %r3,IO_INTERRUPT
@@ -965,10 +963,8 @@ ENTRY(ext_int_handler)
mvc __PT_INT_PARM(4,%r11),__LC_EXT_PARAMS
mvc __PT_INT_PARM_LONG(8,%r11),0(%r1)
xc __PT_FLAGS(8,%r11),__PT_FLAGS(%r11)
- TSTMSK __LC_CPU_FLAGS,_CIF_IGNORE_IRQ
- jo .Lio_restore
- TRACE_IRQS_OFF
xc __SF_BACKCHAIN(8,%r15),__SF_BACKCHAIN(%r15)
+ TRACE_IRQS_OFF
lgr %r2,%r11 # pass pointer to pt_regs
lghi %r3,EXT_INTERRUPT
brasl %r14,do_IRQ
diff --git a/arch/s390/kernel/idle.c b/arch/s390/kernel/idle.c
index 2b85096964f8..a5d4d80d6ede 100644
--- a/arch/s390/kernel/idle.c
+++ b/arch/s390/kernel/idle.c
@@ -9,7 +9,6 @@

#include <linux/kernel.h>
#include <linux/kernel_stat.h>
-#include <linux/kprobes.h>
#include <linux/notifier.h>
#include <linux/init.h>
#include <linux/cpu.h>
@@ -21,22 +20,19 @@

static DEFINE_PER_CPU(struct s390_idle_data, s390_idle);

-void enabled_wait(void)
+void arch_cpu_idle(void)
{
struct s390_idle_data *idle = this_cpu_ptr(&s390_idle);
unsigned long long idle_time;
- unsigned long psw_mask, flags;
-
+ unsigned long psw_mask;

/* Wait for external, I/O or machine check interrupt. */
psw_mask = PSW_KERNEL_BITS | PSW_MASK_WAIT | PSW_MASK_DAT |
PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
clear_cpu_flag(CIF_NOHZ_DELAY);

- raw_local_irq_save(flags);
- /* Call the assembler magic in entry.S */
+ /* psw_idle() returns with interrupts disabled. */
psw_idle(idle, psw_mask);
- raw_local_irq_restore(flags);

/* Account time spent with enabled wait psw loaded as idle time. */
raw_write_seqcount_begin(&idle->seqcount);
@@ -46,8 +42,8 @@ void enabled_wait(void)
idle->idle_count++;
account_idle_time(cputime_to_nsecs(idle_time));
raw_write_seqcount_end(&idle->seqcount);
+ raw_local_irq_enable();
}
-NOKPROBE_SYMBOL(enabled_wait);

static ssize_t show_idle_count(struct device *dev,
struct device_attribute *attr, char *buf)
@@ -120,12 +116,6 @@ void arch_cpu_idle_enter(void)
{
}

-void arch_cpu_idle(void)
-{
- enabled_wait();
- raw_local_irq_enable();
-}
-
void arch_cpu_idle_exit(void)
{
}
diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index 98b3aca1de8e..7a21eca498aa 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -1512,7 +1512,7 @@ static void diag308_dump(void *dump_block)
while (1) {
if (diag308(DIAG308_LOAD_NORMAL_DUMP, NULL) != 0x302)
break;
- udelay_simple(USEC_PER_SEC);
+ udelay(USEC_PER_SEC);
}
}

diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 1f16a03be995..1fbed91c73bc 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -335,7 +335,6 @@ int __init arch_early_irq_init(void)
if (!stack)
panic("Couldn't allocate async stack");
S390_lowcore.async_stack = stack + STACK_INIT_OFFSET;
- udelay_enable();
return 0;
}

diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c
index 68d61f2835df..f289afeb3f31 100644
--- a/arch/s390/lib/delay.c
+++ b/arch/s390/lib/delay.c
@@ -19,13 +19,6 @@
#include <asm/div64.h>
#include <asm/idle.h>

-static DEFINE_STATIC_KEY_FALSE(udelay_ready);
-
-void __init udelay_enable(void)
-{
- static_branch_enable(&udelay_ready);
-}
-
void __delay(unsigned long loops)
{
/*
@@ -39,105 +32,25 @@ void __delay(unsigned long loops)
}
EXPORT_SYMBOL(__delay);

-static void __udelay_disabled(unsigned long long usecs)
+static void delay_loop(unsigned long delta)
{
- unsigned long cr0, cr0_new, psw_mask;
- struct s390_idle_data idle;
- u64 end;
+ unsigned long end;

- end = get_tod_clock() + (usecs << 12);
- __ctl_store(cr0, 0, 0);
- cr0_new = cr0 & ~CR0_IRQ_SUBCLASS_MASK;
- cr0_new |= (1UL << (63 - 52)); /* enable clock comparator irq */
- __ctl_load(cr0_new, 0, 0);
- psw_mask = __extract_psw() | PSW_MASK_EXT | PSW_MASK_WAIT;
- set_clock_comparator(end);
- set_cpu_flag(CIF_IGNORE_IRQ);
- psw_idle(&idle, psw_mask);
- trace_hardirqs_off();
- clear_cpu_flag(CIF_IGNORE_IRQ);
- set_clock_comparator(S390_lowcore.clock_comparator);
- __ctl_load(cr0, 0, 0);
+ end = get_tod_clock_monotonic() + delta;
+ while (!tod_after(get_tod_clock_monotonic(), end))
+ cpu_relax();
}

-static void __udelay_enabled(unsigned long long usecs)
+void __udelay(unsigned long usecs)
{
- u64 clock_saved, end;
-
- end = get_tod_clock_fast() + (usecs << 12);
- do {
- clock_saved = 0;
- if (tod_after(S390_lowcore.clock_comparator, end)) {
- clock_saved = local_tick_disable();
- set_clock_comparator(end);
- }
- enabled_wait();
- if (clock_saved)
- local_tick_enable(clock_saved);
- } while (get_tod_clock_fast() < end);
-}
-
-/*
- * Waits for 'usecs' microseconds using the TOD clock comparator.
- */
-void __udelay(unsigned long long usecs)
-{
- unsigned long flags;
-
- if (!static_branch_likely(&udelay_ready)) {
- udelay_simple(usecs);
- return;
- }
-
- preempt_disable();
- local_irq_save(flags);
- if (in_irq()) {
- __udelay_disabled(usecs);
- goto out;
- }
- if (in_softirq()) {
- if (raw_irqs_disabled_flags(flags))
- __udelay_disabled(usecs);
- else
- __udelay_enabled(usecs);
- goto out;
- }
- if (raw_irqs_disabled_flags(flags)) {
- local_bh_disable();
- __udelay_disabled(usecs);
- _local_bh_enable();
- goto out;
- }
- __udelay_enabled(usecs);
-out:
- local_irq_restore(flags);
- preempt_enable();
+ delay_loop(usecs << 12);
}
EXPORT_SYMBOL(__udelay);

-/*
- * Simple udelay variant. To be used on startup and reboot
- * when the interrupt handler isn't working.
- */
-void udelay_simple(unsigned long long usecs)
-{
- u64 end;
-
- end = get_tod_clock_fast() + (usecs << 12);
- while (get_tod_clock_fast() < end)
- cpu_relax();
-}
-
-void __ndelay(unsigned long long nsecs)
+void __ndelay(unsigned long nsecs)
{
- u64 end;
-
nsecs <<= 9;
do_div(nsecs, 125);
- end = get_tod_clock_fast() + nsecs;
- if (nsecs & ~0xfffUL)
- __udelay(nsecs >> 12);
- while (get_tod_clock_fast() < end)
- barrier();
+ delay_loop(nsecs);
}
EXPORT_SYMBOL(__ndelay);
diff --git a/arch/s390/lib/test_unwind.c b/arch/s390/lib/test_unwind.c
index 7c988994931f..dcd8946255be 100644
--- a/arch/s390/lib/test_unwind.c
+++ b/arch/s390/lib/test_unwind.c
@@ -9,12 +9,12 @@
#include <linux/kallsyms.h>
#include <linux/kthread.h>
#include <linux/module.h>
+#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/kprobes.h>
#include <linux/wait.h>
#include <asm/irq.h>
-#include <asm/delay.h>

#define BT_BUF_SIZE (PAGE_SIZE * 4)

@@ -205,12 +205,15 @@ static noinline int unwindme_func3(struct unwindme *u)
/* This function must appear in the backtrace. */
static noinline int unwindme_func2(struct unwindme *u)
{
+ unsigned long flags;
int rc;

if (u->flags & UWM_SWITCH_STACK) {
- preempt_disable();
+ local_irq_save(flags);
+ local_mcck_disable();
rc = CALL_ON_STACK(unwindme_func3, S390_lowcore.nodat_stack, 1, u);
- preempt_enable();
+ local_mcck_enable();
+ local_irq_restore(flags);
return rc;
} else {
return unwindme_func3(u);
@@ -223,31 +226,27 @@ static noinline int unwindme_func1(void *u)
return unwindme_func2((struct unwindme *)u);
}

-static void unwindme_irq_handler(struct ext_code ext_code,
- unsigned int param32,
- unsigned long param64)
+static void unwindme_timer_fn(struct timer_list *unused)
{
struct unwindme *u = READ_ONCE(unwindme);

- if (u && u->task == current) {
+ if (u) {
unwindme = NULL;
u->task = NULL;
u->ret = unwindme_func1(u);
+ complete(&u->task_ready);
}
}

+static struct timer_list unwind_timer;
+
static int test_unwind_irq(struct unwindme *u)
{
- preempt_disable();
- if (register_external_irq(EXT_IRQ_CLK_COMP, unwindme_irq_handler)) {
- pr_info("Couldn't register external interrupt handler");
- return -1;
- }
- u->task = current;
unwindme = u;
- udelay(1);
- unregister_external_irq(EXT_IRQ_CLK_COMP, unwindme_irq_handler);
- preempt_enable();
+ init_completion(&u->task_ready);
+ timer_setup(&unwind_timer, unwindme_timer_fn, 0);
+ mod_timer(&unwind_timer, jiffies + 1);
+ wait_for_completion(&u->task_ready);
return u->ret;
}

diff --git a/drivers/s390/cio/device.c b/drivers/s390/cio/device.c
index e0005a4fc978..9e3c8b4e7fa8 100644
--- a/drivers/s390/cio/device.c
+++ b/drivers/s390/cio/device.c
@@ -1668,7 +1668,7 @@ void ccw_device_wait_idle(struct ccw_device *cdev)
cio_tsch(sch);
if (sch->schib.scsw.cmd.actl == 0)
break;
- udelay_simple(100);
+ udelay(100);
}
}
#endif
diff --git a/drivers/s390/crypto/zcrypt_cex2a.c b/drivers/s390/crypto/zcrypt_cex2a.c
index 226a5612e855..62ceeb7fc125 100644
--- a/drivers/s390/crypto/zcrypt_cex2a.c
+++ b/drivers/s390/crypto/zcrypt_cex2a.c
@@ -175,7 +175,7 @@ static int zcrypt_cex2a_queue_probe(struct ap_device *ap_dev)
atomic_set(&zq->load, 0);
ap_queue_init_state(aq);
ap_queue_init_reply(aq, &zq->reply);
- aq->request_timeout = CEX2A_CLEANUP_TIME,
+ aq->request_timeout = CEX2A_CLEANUP_TIME;
aq->private = zq;
rc = zcrypt_queue_register(zq);
if (rc) {
diff --git a/drivers/s390/crypto/zcrypt_cex4.c b/drivers/s390/crypto/zcrypt_cex4.c
index f5195bca1d85..f4a6d3744241 100644
--- a/drivers/s390/crypto/zcrypt_cex4.c
+++ b/drivers/s390/crypto/zcrypt_cex4.c
@@ -631,7 +631,7 @@ static int zcrypt_cex4_queue_probe(struct ap_device *ap_dev)
atomic_set(&zq->load, 0);
ap_queue_init_state(aq);
ap_queue_init_reply(aq, &zq->reply);
- aq->request_timeout = CEX4_CLEANUP_TIME,
+ aq->request_timeout = CEX4_CLEANUP_TIME;
aq->private = zq;
rc = zcrypt_queue_register(zq);
if (rc) {