[PATCH 1/6] powerpc/64: fix irq replay missing preempt

[PATCH 1/6] powerpc/64: fix irq replay missing preempt

[Nicholas Piggin]

Prior to commit 3282a3da25bd ("powerpc/64: Implement soft interrupt
replay in C"), replayed interrupts returned by the regular interrupt
exit code, which performs preemption in case an interrupt had set
need_resched.

This logic was missed by the conversion. Adding preempt_disable/enable
around the interrupt replay and final irq enable will reschedule if
needed.

Fixes: 3282a3da25bd ("powerpc/64: Implement soft interrupt replay in C")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kernel/irq.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index bf21ebd36190..77019699606a 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -368,6 +368,12 @@ notrace void arch_local_irq_restore(unsigned long mask)
 		}
 	}
 
+	/*
+	 * Disable preempt here, so that the below preempt_enable will
+	 * perform resched if required (a replayed interrupt may set
+	 * need_resched).
+	 */
+	preempt_disable();
 	irq_soft_mask_set(IRQS_ALL_DISABLED);
 	trace_hardirqs_off();
 
@@ -377,6 +383,7 @@ notrace void arch_local_irq_restore(unsigned long mask)
 	trace_hardirqs_on();
 	irq_soft_mask_set(IRQS_ENABLED);
 	__hard_irq_enable();
+	preempt_enable();
 }
 EXPORT_SYMBOL(arch_local_irq_restore);
 
-- 
2.23.0

[PATCH 2/6] powerpc/64: fix irq replay pt_regs->softe value

[Nicholas Piggin]

Replayed interrupts get an "artificial" struct pt_regs constructed to
pass to interrupt handler functions. This did not get the softe field
set correctly, it's as though the interrupt has hit while irqs are
disabled. It should be IRQS_ENABLED.

This is possibly harmless, asynchronous handlers should not be testing
if irqs were disabled, but it might be possible for example some code
is shared with synchronous or NMI handlers, and it makes more sense if
debug output looks at this.

Fixes: 3282a3da25bd ("powerpc/64: Implement soft interrupt replay in C")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kernel/irq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 77019699606a..3fdad9336885 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -214,7 +214,7 @@ void replay_soft_interrupts(void)
 	struct pt_regs regs;
 
 	ppc_save_regs(&regs);
-	regs.softe = IRQS_ALL_DISABLED;
+	regs.softe = IRQS_ENABLED;
 
 again:
 	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
-- 
2.23.0

[PATCH 3/6] powerpc/64e: remove PACA_IRQ_EE_EDGE

[Nicholas Piggin]

This is not used anywhere.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/include/asm/hw_irq.h    |  5 ++---
 arch/powerpc/kernel/exceptions-64e.S |  1 -
 arch/powerpc/kernel/irq.c            | 23 -----------------------
 3 files changed, 2 insertions(+), 27 deletions(-)

diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h
index 35060be09073..50dc35711db3 100644
--- a/arch/powerpc/include/asm/hw_irq.h
+++ b/arch/powerpc/include/asm/hw_irq.h
@@ -25,9 +25,8 @@
 #define PACA_IRQ_DBELL		0x02
 #define PACA_IRQ_EE		0x04
 #define PACA_IRQ_DEC		0x08 /* Or FIT */
-#define PACA_IRQ_EE_EDGE	0x10 /* BookE only */
-#define PACA_IRQ_HMI		0x20
-#define PACA_IRQ_PMI		0x40
+#define PACA_IRQ_HMI		0x10
+#define PACA_IRQ_PMI		0x20
 
 /*
  * Some soft-masked interrupts must be hard masked until they are replayed
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index d9ed79415100..ca444ca82b8d 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -988,7 +988,6 @@ kernel_dbg_exc:
 .endm
 
 masked_interrupt_book3e_0x500:
-	// XXX When adding support for EPR, use PACA_IRQ_EE_EDGE
 	masked_interrupt_book3e PACA_IRQ_EE 1
 
 masked_interrupt_book3e_0x900:
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 3fdad9336885..736a6b56e7d6 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -181,16 +181,6 @@ notrace unsigned int __check_irq_replay(void)
 		return 0x500;
 	}
 
-	/*
-	 * Check if an EPR external interrupt happened this bit is typically
-	 * set if we need to handle another "edge" interrupt from within the
-	 * MPIC "EPR" handler.
-	 */
-	if (happened & PACA_IRQ_EE_EDGE) {
-		local_paca->irq_happened &= ~PACA_IRQ_EE_EDGE;
-		return 0x500;
-	}
-
 	if (happened & PACA_IRQ_DBELL) {
 		local_paca->irq_happened &= ~PACA_IRQ_DBELL;
 		return 0x280;
@@ -270,19 +260,6 @@ void replay_soft_interrupts(void)
 			hard_irq_disable();
 	}
 
-	/*
-	 * Check if an EPR external interrupt happened this bit is typically
-	 * set if we need to handle another "edge" interrupt from within the
-	 * MPIC "EPR" handler.
-	 */
-	if (IS_ENABLED(CONFIG_PPC_BOOK3E) && (happened & PACA_IRQ_EE_EDGE)) {
-		local_paca->irq_happened &= ~PACA_IRQ_EE_EDGE;
-		regs.trap = 0x500;
-		do_IRQ(&regs);
-		if (!(local_paca->irq_happened & PACA_IRQ_HARD_DIS))
-			hard_irq_disable();
-	}
-
 	if (IS_ENABLED(CONFIG_PPC_DOORBELL) && (happened & PACA_IRQ_DBELL)) {
 		local_paca->irq_happened &= ~PACA_IRQ_DBELL;
 		if (IS_ENABLED(CONFIG_PPC_BOOK3E))
-- 
2.23.0

[PATCH 4/6] powerpc/64e: remove 64s specific interrupt soft-mask code

[Nicholas Piggin]

Since the assembly soft-masking code was moved to 64e specific, there
are some 64s specific interrupt types still there. Remove them.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kernel/exceptions-64e.S | 10 ----------
 arch/powerpc/kernel/irq.c            |  2 +-
 2 files changed, 1 insertion(+), 11 deletions(-)

diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index ca444ca82b8d..f579ce46eef2 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -1302,16 +1302,6 @@ fast_exception_return:
 	addi	r3,r1,STACK_FRAME_OVERHEAD;
 	bl	do_IRQ
 	b	ret_from_except
-1:	cmpwi	cr0,r3,0xf00
-	bne	1f
-	addi	r3,r1,STACK_FRAME_OVERHEAD;
-	bl	performance_monitor_exception
-	b	ret_from_except
-1:	cmpwi	cr0,r3,0xe60
-	bne	1f
-	addi	r3,r1,STACK_FRAME_OVERHEAD;
-	bl	handle_hmi_exception
-	b	ret_from_except
 1:	cmpwi	cr0,r3,0x900
 	bne	1f
 	addi	r3,r1,STACK_FRAME_OVERHEAD;
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 736a6b56e7d6..b725509f9073 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -113,7 +113,7 @@ static inline notrace int decrementer_check_overflow(void)
 #ifdef CONFIG_PPC_BOOK3E
 
 /* This is called whenever we are re-enabling interrupts
- * and returns either 0 (nothing to do) or 500/900/280/a00/e80 if
+ * and returns either 0 (nothing to do) or 500/900/280 if
  * there's an EE, DEC or DBELL to generate.
  *
  * This is called in two contexts: From arch_local_irq_restore()
-- 
2.23.0

[PATCH 5/6] powerpc/64: make restore_interrupts 64e only

[Nicholas Piggin]

This is not used by 64s.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kernel/irq.c | 37 +++++++++++++++++++------------------
 1 file changed, 19 insertions(+), 18 deletions(-)

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index b725509f9073..631e6d236c97 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -191,6 +191,25 @@ notrace unsigned int __check_irq_replay(void)
 
 	return 0;
 }
+
+/*
+ * This is specifically called by assembly code to re-enable interrupts
+ * if they are currently disabled. This is typically called before
+ * schedule() or do_signal() when returning to userspace. We do it
+ * in C to avoid the burden of dealing with lockdep etc...
+ *
+ * NOTE: This is called with interrupts hard disabled but not marked
+ * as such in paca->irq_happened, so we need to resync this.
+ */
+void notrace restore_interrupts(void)
+{
+	if (irqs_disabled()) {
+		local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
+		local_irq_enable();
+	} else
+		__hard_irq_enable();
+}
+
 #endif /* CONFIG_PPC_BOOK3E */
 
 void replay_soft_interrupts(void)
@@ -364,24 +383,6 @@ notrace void arch_local_irq_restore(unsigned long mask)
 }
 EXPORT_SYMBOL(arch_local_irq_restore);
 
-/*
- * This is specifically called by assembly code to re-enable interrupts
- * if they are currently disabled. This is typically called before
- * schedule() or do_signal() when returning to userspace. We do it
- * in C to avoid the burden of dealing with lockdep etc...
- *
- * NOTE: This is called with interrupts hard disabled but not marked
- * as such in paca->irq_happened, so we need to resync this.
- */
-void notrace restore_interrupts(void)
-{
-	if (irqs_disabled()) {
-		local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
-		local_irq_enable();
-	} else
-		__hard_irq_enable();
-}
-
 /*
  * This is a helper to use when about to go into idle low-power
  * when the latter has the side effect of re-enabling interrupts
-- 
2.23.0

[PATCH 6/6] powerpc/64: irq replay remove decrementer overflow check

[Nicholas Piggin]

This is an ad-hoc way to catch some cases of decrementer overflow. It
won't catch cases where interrupts were hard disabled before any soft
masked interrupts fired, for example. And it doesn't catch cases that
have overflowed an even number of times.

It's not clear what exactly what problem s being solved here. A lost
timer when we have an IRQ off latency of more than ~4.3 seconds could
be avoided (so long as it's also less than ~8.6s) but this is already
a hard lockup order of magnitude event, and the decrementer will wrap
again and provide a timer interrupt within the same latency magnitdue.

So the test catches some cases of lost decrementers in very exceptional
(buggy) latency event cases, reducing timer interrupt latency in that
case by up to 4.3 seconds. And for large decrementer, it's useless. It
is performed in potentially quite a hot path, reading the TB can be
a noticable overhead.

Perhaps more importantly it allows the clunky MSR[EE] vs
PACA_IRQ_HARD_DIS incoherency to be removed.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kernel/irq.c | 50 +--------------------------------------
 1 file changed, 1 insertion(+), 49 deletions(-)

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index 631e6d236c97..d7162f142f24 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -102,14 +102,6 @@ static inline notrace unsigned long get_irq_happened(void)
 	return happened;
 }
 
-static inline notrace int decrementer_check_overflow(void)
-{
- 	u64 now = get_tb_or_rtc();
-	u64 *next_tb = this_cpu_ptr(&decrementers_next_tb);
- 
-	return now >= *next_tb;
-}
-
 #ifdef CONFIG_PPC_BOOK3E
 
 /* This is called whenever we are re-enabling interrupts
@@ -142,35 +134,6 @@ notrace unsigned int __check_irq_replay(void)
 	trace_hardirqs_on();
 	trace_hardirqs_off();
 
-	/*
-	 * We are always hard disabled here, but PACA_IRQ_HARD_DIS may
-	 * not be set, which means interrupts have only just been hard
-	 * disabled as part of the local_irq_restore or interrupt return
-	 * code. In that case, skip the decrementr check becaus it's
-	 * expensive to read the TB.
-	 *
-	 * HARD_DIS then gets cleared here, but it's reconciled later.
-	 * Either local_irq_disable will replay the interrupt and that
-	 * will reconcile state like other hard interrupts. Or interrupt
-	 * retur will replay the interrupt and in that case it sets
-	 * PACA_IRQ_HARD_DIS by hand (see comments in entry_64.S).
-	 */
-	if (happened & PACA_IRQ_HARD_DIS) {
-		local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS;
-
-		/*
-		 * We may have missed a decrementer interrupt if hard disabled.
-		 * Check the decrementer register in case we had a rollover
-		 * while hard disabled.
-		 */
-		if (!(happened & PACA_IRQ_DEC)) {
-			if (decrementer_check_overflow()) {
-				local_paca->irq_happened |= PACA_IRQ_DEC;
-				happened |= PACA_IRQ_DEC;
-			}
-		}
-	}
-
 	if (happened & PACA_IRQ_DEC) {
 		local_paca->irq_happened &= ~PACA_IRQ_DEC;
 		return 0x900;
@@ -229,18 +192,6 @@ void replay_soft_interrupts(void)
 	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
 		WARN_ON_ONCE(mfmsr() & MSR_EE);
 
-	if (happened & PACA_IRQ_HARD_DIS) {
-		/*
-		 * We may have missed a decrementer interrupt if hard disabled.
-		 * Check the decrementer register in case we had a rollover
-		 * while hard disabled.
-		 */
-		if (!(happened & PACA_IRQ_DEC)) {
-			if (decrementer_check_overflow())
-				happened |= PACA_IRQ_DEC;
-		}
-	}
-
 	/*
 	 * Force the delivery of pending soft-disabled interrupts on PS3.
 	 * Any HV call will have this side effect.
@@ -345,6 +296,7 @@ notrace void arch_local_irq_restore(unsigned long mask)
 		if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
 			WARN_ON_ONCE(!(mfmsr() & MSR_EE));
 		__hard_irq_disable();
+		local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
 	} else {
 		/*
 		 * We should already be hard disabled here. We had bugs
-- 
2.23.0

Re: [PATCH 6/6] powerpc/64: irq replay remove decrementer overflow check

[Michael Ellerman]

Nicholas Piggin <npiggin@gmail.com> writes:
> This is an ad-hoc way to catch some cases of decrementer overflow. It
> won't catch cases where interrupts were hard disabled before any soft
> masked interrupts fired, for example. And it doesn't catch cases that
> have overflowed an even number of times.
>
> It's not clear what exactly what problem s being solved here. A lost
> timer when we have an IRQ off latency of more than ~4.3 seconds could
> be avoided (so long as it's also less than ~8.6s) but this is already
> a hard lockup order of magnitude event, and the decrementer will wrap
> again and provide a timer interrupt within the same latency magnitdue.
>
> So the test catches some cases of lost decrementers in very exceptional
> (buggy) latency event cases, reducing timer interrupt latency in that
> case by up to 4.3 seconds. And for large decrementer, it's useless. It
> is performed in potentially quite a hot path, reading the TB can be
> a noticable overhead.
>
> Perhaps more importantly it allows the clunky MSR[EE] vs
> PACA_IRQ_HARD_DIS incoherency to be removed.
>
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
> ---
>  arch/powerpc/kernel/irq.c | 50 +--------------------------------------
>  1 file changed, 1 insertion(+), 49 deletions(-)

Seems to be unhappy on qemu ppc64e:

  kernel BUG at arch/powerpc/kernel/irq.c:153!

Which is:

notrace unsigned int __check_irq_replay(void)
{
...

	/* There should be nothing left ! */
	BUG_ON(local_paca->irq_happened != 0);

	return 0;
}

Full log below.

cheers


spawn qemu-system-ppc64 -nographic -M ppce500 -cpu e5500 -m 2G -kernel /home/michael/build/adhoc/ci_output/build/corenet64_smp_defconfig@ppc64@korg@10.1.0/uImage -initrd ppc64-novsx-rootfs.cpio.gz -append noreboot
MMU: Supported page sizes
         4 KB as direct
      4096 KB as direct
     16384 KB as direct
     65536 KB as direct
    262144 KB as direct
   1048576 KB as direct
MMU: Book3E HW tablewalk not supported
Linux version 5.9.0-rc2-00187-gf523995cc1ee (linuxppc@e054daee57c9) (powerpc64-linux-gnu-gcc (GCC) 10.1.0, GNU ld (GNU Binutils) 2.34) #1 SMP Fri Sep 18 11:52:25 Australia 2020
Found initrd at 0xc000000005000000:0xc0000000051e9a47
Using QEMU e500 machine description
ioremap() called early from .find_legacy_serial_ports+0x6cc/0x7bc. Use early_ioremap() instead
printk: bootconsole [udbg0] enabled
CPU maps initialized for 1 thread per core
-----------------------------------------------------
phys_mem_size     = 0x80000000
dcache_bsize      = 0x40
icache_bsize      = 0x40
cpu_features      = 0x00000003008001b4
  possible        = 0x00000003009003b6
  always          = 0x00000003008003b4
cpu_user_features = 0xcc008000 0x08000000
mmu_features      = 0x000a0010
firmware_features = 0x0000000000000000
-----------------------------------------------------
qemu_e500_setup_arch()
barrier-nospec: using isync; sync as speculation barrier
Zone ranges:
  DMA      [mem 0x0000000000000000-0x000000007fffffff]
  Normal   empty
Movable zone start for each node
Early memory node ranges
  node   0: [mem 0x0000000000000000-0x000000007fffffff]
Initmem setup node 0 [mem 0x0000000000000000-0x000000007fffffff]
MMU: Allocated 2112 bytes of context maps for 255 contexts
percpu: Embedded 28 pages/cpu s77400 r0 d37288 u1048576
Built 1 zonelists, mobility grouping on.  Total pages: 517120
Kernel command line: noreboot
Dentry cache hash table entries: 262144 (order: 9, 2097152 bytes, linear)
Inode-cache hash table entries: 131072 (order: 8, 1048576 bytes, linear)
mem auto-init: stack:off, heap alloc:off, heap free:off
Memory: 1977432K/2097152K available (12048K kernel code, 2204K rwdata, 3788K rodata, 460K init, 321K bss, 119720K reserved, 0K cma-reserved)
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
rcu: Hierarchical RCU implementation.
rcu:    RCU event tracing is enabled.
rcu:    RCU restricting CPUs from NR_CPUS=24 to nr_cpu_ids=1.
rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies.
rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
NR_IRQS: 512, nr_irqs: 512, preallocated irqs: 16
mpic: Setting up MPIC " OpenPIC  " version 1.2 at fe0040000, max 1 CPUs
mpic: ISU size: 256, shift: 8, mask: ff
mpic: Initializing for 256 sources
random: get_random_u64 called from .start_kernel+0x498/0x70c with crng_init=0
clocksource: timebase: mask: 0xffffffffffffffff max_cycles: 0x5c4093a7d1, max_idle_ns: 440795210635 ns
clocksource: timebase mult[2800000] shift[24] registered
Console: colour dummy device 80x25
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 4096 (order: 3, 32768 bytes, linear)
Mountpoint-cache hash table entries: 4096 (order: 3, 32768 bytes, linear)
e500 family performance monitor hardware support registered
rcu: Hierarchical SRCU implementation.
smp: Bringing up secondary CPUs ...
smp: Brought up 1 node, 1 CPU
devtmpfs: initialized
clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
futex hash table entries: 256 (order: 2, 16384 bytes, linear)
------------[ cut here ]------------
kernel BUG at arch/powerpc/kernel/irq.c:153!
Oops: Exception in kernel mode, sig: 5 [#1]
BE PAGE_SIZE=4K SMP NR_CPUS=24 QEMU e500
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc2-00187-gf523995cc1ee #1
NIP:  c0000000000039d4 LR: c00000000001a634 CTR: c000000000594d00
REGS: c00000007d0df5e0 TRAP: 0700   Not tainted  (5.9.0-rc2-00187-gf523995cc1ee)
MSR:  0000000080021000 <CE,ME>  CR: 28000242  XER: 20000000
IRQMASK: 1
GPR00: 0000000000000001 c00000007d0df870 c0000000011e2200 0000000000000000
GPR04: 0000000000000800 0000000000000000 0000000000000001 c00000000116eec0
GPR08: 0000000000000000 0000000000000001 0000000000000000 0000000000000300
GPR12: 0000000028000242 c000000001263000 c000000000002434 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR24: c00000000110b248 c000000000fd3728 c000000000fc1ef8 c000000000f715f8
GPR28: c0000000010c8700 0000000000000000 0000000000000002 0000000000000001
NIP [c0000000000039d4] .__check_irq_replay+0x24/0x60
LR [c00000000001a634] fast_exception_return+0xe0/0x140
Call Trace:
[c00000007d0df870] [c00000000001a37c] storage_fault_common+0x40/0x44 (unreliable)
--- interrupt: 300 at .__se_sys_futex_time32+0x1fc/0x2c8
    LR = .futex_init+0xbc/0x144
[c00000007d0dfb70] [c000000000f8af88] .futex_init+0x88/0x144 (unreliable)
[c00000007d0dfc10] [c000000000001ed8] .do_one_initcall+0x6c/0x28c
[c00000007d0dfcf0] [c000000000f79258] .kernel_init_freeable+0x298/0x314
[c00000007d0dfda0] [c000000000002450] .kernel_init+0x1c/0x138
[c00000007d0dfe20] [c00000000000082c] .ret_from_kernel_thread+0x58/0x60
Instruction dump:
4bffff64 48bb8a49 60000000 892d067b 71280008 40820028 71280004 40820040
71280002 40820028 3149ffff 7d2a4910 <0b090000> 38600000 4e800020 55290776
---[ end trace 276324e35afb2c5e ]---

Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000005
Rebooting in 180 seconds..
System Halted, OK to tu

Re: [PATCH 1/6] powerpc/64: fix irq replay missing preempt

[Michael Ellerman]

On Tue, 15 Sep 2020 21:46:45 +1000, Nicholas Piggin wrote:
> Prior to commit 3282a3da25bd ("powerpc/64: Implement soft interrupt
> replay in C"), replayed interrupts returned by the regular interrupt
> exit code, which performs preemption in case an interrupt had set
> need_resched.
> 
> This logic was missed by the conversion. Adding preempt_disable/enable
> around the interrupt replay and final irq enable will reschedule if
> needed.

Patches 1-5 applied to powerpc/next.

[1/6] powerpc/64: fix irq replay missing preempt
      https://git.kernel.org/powerpc/c/903fd31d3212ab72d564c68f6cfb5d04db68773e
[2/6] powerpc/64: fix irq replay pt_regs->softe value
      https://git.kernel.org/powerpc/c/2b48e96be2f9f7151197fd25dc41487054bc6f5b
[3/6] powerpc/64e: remove PACA_IRQ_EE_EDGE
      https://git.kernel.org/powerpc/c/012a9a97a8fd6c96d5ec64eb0583220490d95e73
[4/6] powerpc/64e: remove 64s specific interrupt soft-mask code
      https://git.kernel.org/powerpc/c/903dd1ff453e458fc7608ee4df42a6df16d3d1a0
[5/6] powerpc/64: make restore_interrupts 64e only
      https://git.kernel.org/powerpc/c/455575533c7aa294d3c0284d59a77ae9a60c0537

cheers