[RFC PATCH v2 01/14] m68k: Call timer_interrupt() with interrupts disabled

From: Finn Thain
Date: Sun Nov 18 2018 - 20:23:13 EST

Some platforms execute their timer handler with the interrupt priority
level below 6. That means the handler could be interrupted by another
driver and this could lead to re-entry of the timer core.

Avoid this by use of local_irq_save/restore for timer interrupt dispatch.
This provides mutual exclusion around the timer interrupt flag access
which is needed later in this series for the clocksource coversion.

Reported-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1811131407120.2697@xxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx>
---
I've only checked 680x0 MMU platforms for this issue.
---
arch/m68k/amiga/cia.c | 10 ++++++++++
arch/m68k/atari/ataints.c | 4 ++--
arch/m68k/atari/time.c | 15 ++++++++++++++-
arch/m68k/bvme6000/config.c | 18 +++++++++---------
arch/m68k/hp300/time.c | 10 ++++++++--
arch/m68k/mac/via.c | 17 +++++++++++++++++
arch/m68k/mvme147/config.c | 18 ++++++++++--------
arch/m68k/mvme16x/config.c | 19 ++++++++++---------
arch/m68k/q40/q40ints.c | 7 ++++++-
arch/m68k/sun3/sun3ints.c | 3 +++
arch/m68k/sun3x/time.c | 16 ++++++++++------
11 files changed, 99 insertions(+), 38 deletions(-)

diff --git a/arch/m68k/amiga/cia.c b/arch/m68k/amiga/cia.c
index 2081b8cd5591..b65665160711 100644
--- a/arch/m68k/amiga/cia.c
+++ b/arch/m68k/amiga/cia.c
@@ -88,10 +88,20 @@ static irqreturn_t cia_handler(int irq, void *dev_id)
struct ciabase *base = dev_id;
int mach_irq;
unsigned char ints;
+ unsigned long flags;

+ /* Interrupts get disabled while the timer irq flag is cleared and
+ * the timer interrupt serviced.
+ */
+ local_irq_save(flags);
mach_irq = base->cia_irq;
ints = cia_set_irq(base, CIA_ICR_ALL);
amiga_custom.intreq = base->int_mask;
+ if (ints & 1) {
+ generic_handle_irq(mach_irq);
+ mach_irq++, ints >>= 1;
+ }
+ local_irq_restore(flags);
for (; ints; mach_irq++, ints >>= 1) {
if (ints & 1)
generic_handle_irq(mach_irq);
diff --git a/arch/m68k/atari/ataints.c b/arch/m68k/atari/ataints.c
index 3d2b63bedf05..56f02ea2c248 100644
--- a/arch/m68k/atari/ataints.c
+++ b/arch/m68k/atari/ataints.c
@@ -142,7 +142,7 @@ struct mfptimerbase {
.name = "MFP Timer D"
};

-static irqreturn_t mfptimer_handler(int irq, void *dev_id)
+static irqreturn_t mfp_timer_d_handler(int irq, void *dev_id)
{
struct mfptimerbase *base = dev_id;
int mach_irq;
@@ -344,7 +344,7 @@ void __init atari_init_IRQ(void)
st_mfp.tim_ct_cd = (st_mfp.tim_ct_cd & 0xf0) | 0x6;

/* request timer D dispatch handler */
- if (request_irq(IRQ_MFP_TIMD, mfptimer_handler, IRQF_SHARED,
+ if (request_irq(IRQ_MFP_TIMD, mfp_timer_d_handler, IRQF_SHARED,
stmfp_base.name, &stmfp_base))
pr_err("Couldn't register %s interrupt\n", stmfp_base.name);

diff --git a/arch/m68k/atari/time.c b/arch/m68k/atari/time.c
index 9cca64286464..fafa20f75ab9 100644
--- a/arch/m68k/atari/time.c
+++ b/arch/m68k/atari/time.c
@@ -24,6 +24,18 @@
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL_GPL(rtc_lock);

+static irqreturn_t mfp_timer_c_handler(int irq, void *dev_id)
+{
+ irq_handler_t timer_routine = dev_id;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ timer_routine(0, NULL);
+ local_irq_restore(flags);
+
+ return IRQ_HANDLED;
+}
+
void __init
atari_sched_init(irq_handler_t timer_routine)
{
@@ -32,7 +44,8 @@ atari_sched_init(irq_handler_t timer_routine)
/* start timer C, div = 1:100 */
st_mfp.tim_ct_cd = (st_mfp.tim_ct_cd & 15) | 0x60;
/* install interrupt service routine for MFP Timer C */
- if (request_irq(IRQ_MFP_TIMC, timer_routine, 0, "timer", timer_routine))
+ if (request_irq(IRQ_MFP_TIMC, mfp_timer_c_handler, 0, "timer",
+ timer_routine))
pr_err("Couldn't register timer interrupt\n");
}

diff --git a/arch/m68k/bvme6000/config.c b/arch/m68k/bvme6000/config.c
index 143ee9fa3893..d1de3cb1f8fe 100644
--- a/arch/m68k/bvme6000/config.c
+++ b/arch/m68k/bvme6000/config.c
@@ -44,11 +44,6 @@ extern int bvme6000_hwclk (int, struct rtc_time *);
extern void bvme6000_reset (void);
void bvme6000_set_vectors (void);

-/* Save tick handler routine pointer, will point to xtime_update() in
- * kernel/timer/timekeeping.c, called via bvme6000_process_int() */
-
-static irq_handler_t tick_handler;
-

int __init bvme6000_parse_bootinfo(const struct bi_record *bi)
{
@@ -157,12 +152,18 @@ irqreturn_t bvme6000_abort_int (int irq, void *dev_id)

static irqreturn_t bvme6000_timer_int (int irq, void *dev_id)
{
+ irq_handler_t timer_routine = dev_id;
+ unsigned long flags;
volatile RtcPtr_t rtc = (RtcPtr_t)BVME_RTC_BASE;
- unsigned char msr = rtc->msr & 0xc0;
+ unsigned char msr;

+ local_irq_save(flags);
+ msr = rtc->msr & 0xc0;
rtc->msr = msr | 0x20; /* Ack the interrupt */
+ timer_routine(0, NULL);
+ local_irq_restore(flags);

- return tick_handler(irq, dev_id);
+ return IRQ_HANDLED;
}

/*
@@ -181,9 +182,8 @@ void bvme6000_sched_init (irq_handler_t timer_routine)

rtc->msr = 0; /* Ensure timer registers accessible */

- tick_handler = timer_routine;
if (request_irq(BVME_IRQ_RTC, bvme6000_timer_int, 0,
- "timer", bvme6000_timer_int))
+ "timer", timer_routine))
panic ("Couldn't register timer int");

rtc->t1cr_omr = 0x04; /* Mode 2, ext clk */
diff --git a/arch/m68k/hp300/time.c b/arch/m68k/hp300/time.c
index 289d928a46cb..d30b03ea93a2 100644
--- a/arch/m68k/hp300/time.c
+++ b/arch/m68k/hp300/time.c
@@ -38,13 +38,19 @@

static irqreturn_t hp300_tick(int irq, void *dev_id)
{
+ irq_handler_t timer_routine = dev_id;
+ unsigned long flags;
unsigned long tmp;
- irq_handler_t vector = dev_id;
+
+ local_irq_save(flags);
in_8(CLOCKBASE + CLKSR);
asm volatile ("movpw %1@(5),%0" : "=d" (tmp) : "a" (CLOCKBASE));
+ timer_routine(0, NULL);
+ local_irq_restore(flags);
+
/* Turn off the network and SCSI leds */
blinken_leds(0, 0xe0);
- return vector(irq, NULL);
+ return IRQ_HANDLED;
}

u32 hp300_gettimeoffset(void)
diff --git a/arch/m68k/mac/via.c b/arch/m68k/mac/via.c
index e4facff0c1f3..2ab85b6eb4fe 100644
--- a/arch/m68k/mac/via.c
+++ b/arch/m68k/mac/via.c
@@ -436,6 +436,8 @@ void via_nubus_irq_shutdown(int irq)
* via6522.c :-), disable/pending masks added.
*/

+#define VIA_TIMER_1_INT BIT(6)
+
void via1_irq(struct irq_desc *desc)
{
int irq_num;
@@ -445,6 +447,21 @@ void via1_irq(struct irq_desc *desc)
if (!events)
return;

+ irq_num = IRQ_MAC_TIMER_1;
+ irq_bit = VIA_TIMER_1_INT;
+ if (events & irq_bit) {
+ unsigned long flags;
+
+ local_irq_save(flags);
+ via1[vIFR] = irq_bit;
+ generic_handle_irq(IRQ_MAC_TIMER_1);
+ local_irq_restore(flags);
+
+ events &= ~irq_bit;
+ if (!events)
+ return;
+ }
+
irq_num = VIA1_SOURCE_BASE;
irq_bit = 1;
do {
diff --git a/arch/m68k/mvme147/config.c b/arch/m68k/mvme147/config.c
index adea549d240e..93c68d2b8e0e 100644
--- a/arch/m68k/mvme147/config.c
+++ b/arch/m68k/mvme147/config.c
@@ -45,11 +45,6 @@ extern void mvme147_reset (void);

static int bcd2int (unsigned char b);

-/* Save tick handler routine pointer, will point to xtime_update() in
- * kernel/time/timekeeping.c, called via mvme147_process_int() */
-
-irq_handler_t tick_handler;
-

int __init mvme147_parse_bootinfo(const struct bi_record *bi)
{
@@ -104,16 +99,23 @@ void __init config_mvme147(void)

static irqreturn_t mvme147_timer_int (int irq, void *dev_id)
{
+ irq_handler_t timer_routine = dev_id;
+ unsigned long flags;
+
+ local_irq_save(flags);
m147_pcc->t1_int_cntrl = PCC_TIMER_INT_CLR;
m147_pcc->t1_int_cntrl = PCC_INT_ENAB|PCC_LEVEL_TIMER1;
- return tick_handler(irq, dev_id);
+ timer_routine(0, NULL);
+ local_irq_restore(flags);
+
+ return IRQ_HANDLED;
}


void mvme147_sched_init (irq_handler_t timer_routine)
{
- tick_handler = timer_routine;
- if (request_irq(PCC_IRQ_TIMER1, mvme147_timer_int, 0, "timer 1", NULL))
+ if (request_irq(PCC_IRQ_TIMER1, mvme147_timer_int, 0, "timer 1",
+ timer_routine))
pr_err("Couldn't register timer interrupt\n");

/* Init the clock with a value */
diff --git a/arch/m68k/mvme16x/config.c b/arch/m68k/mvme16x/config.c
index 6ee36a5b528d..4e6229856396 100644
--- a/arch/m68k/mvme16x/config.c
+++ b/arch/m68k/mvme16x/config.c
@@ -50,11 +50,6 @@ extern void mvme16x_reset (void);

int bcd2int (unsigned char b);

-/* Save tick handler routine pointer, will point to xtime_update() in
- * kernel/time/timekeeping.c, called via mvme16x_process_int() */
-
-static irq_handler_t tick_handler;
-

unsigned short mvme16x_config;
EXPORT_SYMBOL(mvme16x_config);
@@ -352,8 +347,15 @@ static irqreturn_t mvme16x_abort_int (int irq, void *dev_id)

static irqreturn_t mvme16x_timer_int (int irq, void *dev_id)
{
- *(volatile unsigned char *)0xfff4201b |= 8;
- return tick_handler(irq, dev_id);
+ irq_handler_t timer_routine = dev_id;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ *(volatile unsigned char *)0xfff4201b |= 8;
+ timer_routine(0, NULL);
+ local_irq_restore(flags);
+
+ return IRQ_HANDLED;
}

void mvme16x_sched_init (irq_handler_t timer_routine)
@@ -361,14 +363,13 @@ void mvme16x_sched_init (irq_handler_t timer_routine)
uint16_t brdno = be16_to_cpu(mvme_bdid.brdno);
int irq;

- tick_handler = timer_routine;
/* Using PCCchip2 or MC2 chip tick timer 1 */
*(volatile unsigned long *)0xfff42008 = 0;
*(volatile unsigned long *)0xfff42004 = 10000; /* 10ms */
*(volatile unsigned char *)0xfff42017 |= 3;
*(volatile unsigned char *)0xfff4201b = 0x16;
if (request_irq(MVME16x_IRQ_TIMER, mvme16x_timer_int, 0,
- "timer", mvme16x_timer_int))
+ "timer", timer_routine))
panic ("Couldn't register timer int");

if (brdno == 0x0162 || brdno == 0x172)
diff --git a/arch/m68k/q40/q40ints.c b/arch/m68k/q40/q40ints.c
index 3e7603202977..ea339c2d47d1 100644
--- a/arch/m68k/q40/q40ints.c
+++ b/arch/m68k/q40/q40ints.c
@@ -139,8 +139,13 @@ static irqreturn_t q40_timer_int (int irq, void * dev)
*DAC_RIGHT=sval;
}

- if (!ql_ticks)
+ if (!ql_ticks) {
+ unsigned long flags;
+
+ local_irq_save(flags);
q40_timer_routine(irq, dev);
+ local_irq_restore(flags);
+ }
return IRQ_HANDLED;
}

diff --git a/arch/m68k/sun3/sun3ints.c b/arch/m68k/sun3/sun3ints.c
index 6bbca30c9188..a5824abb4a39 100644
--- a/arch/m68k/sun3/sun3ints.c
+++ b/arch/m68k/sun3/sun3ints.c
@@ -61,8 +61,10 @@ static irqreturn_t sun3_int7(int irq, void *dev_id)

static irqreturn_t sun3_int5(int irq, void *dev_id)
{
+ unsigned long flags;
unsigned int cnt;

+ local_irq_save(flags);
#ifdef CONFIG_SUN3
intersil_clear();
#endif
@@ -76,6 +78,7 @@ static irqreturn_t sun3_int5(int irq, void *dev_id)
cnt = kstat_irqs_cpu(irq, 0);
if (!(cnt % 20))
sun3_leds(led_pattern[cnt % 160 / 20]);
+ local_irq_restore(flags);
return IRQ_HANDLED;
}

diff --git a/arch/m68k/sun3x/time.c b/arch/m68k/sun3x/time.c
index 047e2bcee3d7..3c8a86d08508 100644
--- a/arch/m68k/sun3x/time.c
+++ b/arch/m68k/sun3x/time.c
@@ -80,15 +80,19 @@ u32 sun3x_gettimeoffset(void)
}

#if 0
-static void sun3x_timer_tick(int irq, void *dev_id, struct pt_regs *regs)
+static irqreturn_t sun3x_timer_tick(int irq, void *dev_id)
{
- void (*vector)(int, void *, struct pt_regs *) = dev_id;
+ irq_handler_t timer_routine = dev_id;
+ unsigned long flags;

- /* Clear the pending interrupt - pulse the enable line low */
- disable_irq(5);
- enable_irq(5);
+ local_irq_save(flags);
+ /* Clear the pending interrupt - pulse the enable line low */
+ disable_irq(5);
+ enable_irq(5);
+ timer_routine(0, NULL);
+ local_irq_restore(flags);

- vector(irq, NULL, regs);
+ return IRQ_HANDLED;
}
#endif

--
2.18.1