On Thu, May 28, 2026 at 12:53:25PM +0200, Peter Zijlstra wrote: > On Tue, May 26, 2026 at 08:21:48AM -0700, Boqun Feng wrote: > > From: Heiko Carstens <[email protected]> > > > > Convert s390's preempt_count to 64 bit, and change the preempt > > primitives accordingly. > > > > Signed-off-by: Heiko Carstens <[email protected]> > > Signed-off-by: Boqun Feng <[email protected]> > > Link: https://patch.msgid.link/[email protected] > > --- > > arch/s390/Kconfig | 1 + > > arch/s390/include/asm/lowcore.h | 13 +++++++---- > > arch/s390/include/asm/preempt.h | 41 +++++++++++++++------------------ > > 3 files changed, 29 insertions(+), 26 deletions(-) > > > > diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig > > index ecbcbb781e40..cbbca82f8443 100644 > > --- a/arch/s390/Kconfig > > +++ b/arch/s390/Kconfig > > @@ -276,6 +276,7 @@ config S390 > > select PCI_MSI if PCI > > select PCI_MSI_ARCH_FALLBACKS if PCI_MSI > > select PCI_QUIRKS if PCI > > + select HAS_SEPARATE_PREEMPT_RESCHED_BITS > > select SPARSE_IRQ > > select SWIOTLB > > select SYSCTL_EXCEPTION_TRACE > > diff --git a/arch/s390/include/asm/lowcore.h > > b/arch/s390/include/asm/lowcore.h > > index 50ffe75adeb4..0974ab278169 100644 > > --- a/arch/s390/include/asm/lowcore.h > > +++ b/arch/s390/include/asm/lowcore.h > > @@ -160,10 +160,15 @@ struct lowcore { > > /* SMP info area */ > > __u32 cpu_nr; /* 0x03a0 */ > > __u32 softirq_pending; /* 0x03a4 */ > > - __s32 preempt_count; /* 0x03a8 */ > > - __u32 spinlock_lockval; /* 0x03ac */ > > - __u32 spinlock_index; /* 0x03b0 */ > > - __u8 pad_0x03b4[0x03b8-0x03b4]; /* 0x03b4 */ > > + union { > > + struct { > > + __u32 need_resched; /* 0x03a8 */ > > + __u32 count; /* 0x03ac */ > > + } preempt; > > + __u64 preempt_count; /* 0x03a8 */ > > + }; > > I'm a little confused by this union; afaict it isn't actually used.
(TIL: s390 is big endian) In preempt_count() the union is used for reading the lower 32bits in an asm block. Regards, Boqun
