This is a note to let you know that I've just added the patch titled
powerpc: Don't select HAVE_IRQ_EXIT_ON_IRQ_STACK
to the 5.17-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-don-t-select-have_irq_exit_on_irq_stack.patch
and it can be found in the queue-5.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1346d00e1bdfd4067f92bc14e8a6131a01de4190 Mon Sep 17 00:00:00 2001
From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Date: Wed, 25 May 2022 13:26:39 +1000
Subject: powerpc: Don't select HAVE_IRQ_EXIT_ON_IRQ_STACK
From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
commit 1346d00e1bdfd4067f92bc14e8a6131a01de4190 upstream.
The HAVE_IRQ_EXIT_ON_IRQ_STACK option tells generic code that irq_exit()
is called while still running on the hard irq stack (hardirq_ctx[] in
the powerpc code).
Selecting the option means the generic code will *not* switch to the
softirq stack before running softirqs, because the code is already
running on the (mostly empty) hard irq stack.
But since commit 1b1b6a6f4cc0 ("powerpc: handle irq_enter/irq_exit in
interrupt handler wrappers"), irq_exit() is now called on the regular task
stack, not the hard irq stack.
That's because previously irq_exit() was called in __do_irq() which is
run on the hard irq stack, but now it is called in
interrupt_async_exit_prepare() which is called from do_irq() constructed
by the wrapper macro, which is after the switch back to the task stack.
So drop HAVE_IRQ_EXIT_ON_IRQ_STACK from the Kconfig. This will mean an
extra stack switch when processing some interrupts, but should
significantly reduce the likelihood of stack overflow.
It also means the softirq stack will be used for running softirqs from
other interrupts that don't use the hard irq stack, eg. timer interrupts.
Fixes: 1b1b6a6f4cc0 ("powerpc: handle irq_enter/irq_exit in interrupt handler wrappers")
Cc: stable@xxxxxxxxxxxxxxx # v5.12+
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220525032639.1947280-1-mpe@xxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/Kconfig | 1 -
1 file changed, 1 deletion(-)
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -211,7 +211,6 @@ config PPC
select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI && !HAVE_HARDLOCKUP_DETECTOR_ARCH
select HAVE_HW_BREAKPOINT if PERF_EVENTS && (PPC_BOOK3S || PPC_8xx)
select HAVE_IOREMAP_PROT
- select HAVE_IRQ_EXIT_ON_IRQ_STACK
select HAVE_IRQ_TIME_ACCOUNTING
select HAVE_KERNEL_GZIP
select HAVE_KERNEL_LZMA if DEFAULT_UIMAGE
Patches currently in stable-queue which might be from mpe@xxxxxxxxxxxxxx are
queue-5.17/powerpc-don-t-select-have_irq_exit_on_irq_stack.patch
queue-5.17/powerpc-kasan-force-thread-size-increase-with-kasan.patch
queue-5.17/powerpc-32-fix-overread-overwrite-of-thread_struct-via-ptrace.patch
