| Message ID | 20231211094414.8078-5-parri.andrea@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | membarrier: riscv: Core serializing command | expand |
On 2023-12-11 04:44, Andrea Parri wrote: > Architectures supporting the "private expedited" membarrier command must > select the Kconfig to use the command. Document status and requirements > for each architecture in a single file under Documentation/features. Sorry for being vague in my suggestion: I did not intend to make it optional (not ARCH_HAS_MEMBARRIER), but rather just to have a central place where this would be documented. I'm not sure where in Documentation this should land though ? Thanks, Mathieu > > Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> > Signed-off-by: Andrea Parri <parri.andrea@gmail.com> > --- > The TODOs in the arch-support table below should really be interpreted > as "I'm not sure/haven't checked" (the respective arch maintainers will > be able to verify and amend such information). > > Based on the following inline comment in __schedule(): > > /* > * The membarrier system call requires each architecture > * to have a full memory barrier after updating > * rq->curr, before returning to user-space. > * > * Here are the schemes providing that barrier on the > * various architectures: > * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC, > * RISC-V. switch_mm() relies on membarrier_arch_switch_mm() > * on PowerPC and on RISC-V. > * - finish_lock_switch() for weakly-ordered > * architectures where spin_unlock is a full barrier, > * - switch_to() for arm64 (weakly-ordered, spin_unlock > * is a RELEASE barrier), > */ > > .../sched/membarrier/arch-support.txt | 50 +++++++++++++++++++ > MAINTAINERS | 1 + > arch/alpha/Kconfig | 1 + > arch/arc/Kconfig | 1 + > arch/arm/Kconfig | 1 + > arch/arm64/Kconfig | 1 + > arch/hexagon/Kconfig | 1 + > arch/mips/Kconfig | 1 + > arch/powerpc/Kconfig | 1 + > arch/riscv/Kconfig | 1 + > arch/s390/Kconfig | 1 + > arch/sparc/Kconfig | 1 + > arch/x86/Kconfig | 1 + > init/Kconfig | 3 ++ > kernel/sched/core.c | 4 +- > kernel/sched/membarrier.c | 15 +++++- > 16 files changed, 80 insertions(+), 4 deletions(-) > create mode 100644 Documentation/features/sched/membarrier/arch-support.txt > > diff --git a/Documentation/features/sched/membarrier/arch-support.txt b/Documentation/features/sched/membarrier/arch-support.txt > new file mode 100644 > index 0000000000000..95e65195e47c2 > --- /dev/null > +++ b/Documentation/features/sched/membarrier/arch-support.txt > @@ -0,0 +1,50 @@ > +# > +# Feature name: membarrier > +# Kconfig: ARCH_HAS_MEMBARRIER > +# description: arch supports MEMBARRIER_CMD_PRIVATE_EXPEDITED > +# > +# Architecture requirements > +# > +# The membarrier() system call requires each architecture to have a full memory > +# barrier after updating rq->curr, before returning to user-space. > +# > +# Here are the schemes providing that barrier on the various architectures: > +# > +# * alpha/arc/arm/hexagon/mips > +# > +# We rely on the full barrier implied by spin_unlock() in finish_lock_switch(). > +# > +# * arm64 > +# > +# We rely on the full barrier implied by switch_to(). > +# > +# * powerpc/riscv/s390/sparc/x86 > +# > +# We rely on the full barrier implied by switch_mm(), if mm isn't NULL; we rely > +# on the full barrier implied by mmdrop(), otherwise. > +# > + ----------------------- > + | arch |status| > + ----------------------- > + | alpha: | ok | > + | arc: | ok | > + | arm: | ok | > + | arm64: | ok | > + | csky: | TODO | > + | hexagon: | ok | > + | loongarch: | TODO | > + | m68k: | TODO | > + | microblaze: | TODO | > + | mips: | ok | > + | nios2: | TODO | > + | openrisc: | TODO | > + | parisc: | TODO | > + | powerpc: | ok | > + | riscv: | ok | > + | s390: | ok | > + | sh: | TODO | > + | sparc: | ok | > + | um: | TODO | > + | x86: | ok | > + | xtensa: | TODO | > + ----------------------- > diff --git a/MAINTAINERS b/MAINTAINERS > index f6f1fdc76cf46..c5a053605cbc4 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -13807,6 +13807,7 @@ M: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> > M: "Paul E. McKenney" <paulmck@kernel.org> > L: linux-kernel@vger.kernel.org > S: Supported > +F: Documentation/features/sched/membarrier*/ > F: arch/*/include/asm/membarrier.h > F: arch/*/include/asm/sync_core.h > F: include/uapi/linux/membarrier.h > diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig > index d6968d090d49a..f98d6cba0bd9a 100644 > --- a/arch/alpha/Kconfig > +++ b/arch/alpha/Kconfig > @@ -24,6 +24,7 @@ config ALPHA > select GENERIC_IRQ_SHOW > select ARCH_WANT_IPC_PARSE_VERSION > select ARCH_HAVE_NMI_SAFE_CMPXCHG > + select ARCH_HAS_MEMBARRIER > select AUDIT_ARCH > select GENERIC_CPU_VULNERABILITIES > select GENERIC_SMP_IDLE_THREAD > diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig > index 3162db540ee96..1d8a6ba98ae33 100644 > --- a/arch/arc/Kconfig > +++ b/arch/arc/Kconfig > @@ -9,6 +9,7 @@ config ARC > select ARCH_HAS_CACHE_LINE_SIZE > select ARCH_HAS_DEBUG_VM_PGTABLE > select ARCH_HAS_DMA_PREP_COHERENT > + select ARCH_HAS_MEMBARRIER > select ARCH_HAS_PTE_SPECIAL > select ARCH_HAS_SETUP_DMA_OPS > select ARCH_HAS_SYNC_DMA_FOR_CPU > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index f8567e95f98be..700d1d9ff2f8b 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -14,6 +14,7 @@ config ARM > select ARCH_HAS_FORTIFY_SOURCE > select ARCH_HAS_KEEPINITRD > select ARCH_HAS_KCOV > + select ARCH_HAS_MEMBARRIER > select ARCH_HAS_MEMBARRIER_SYNC_CORE > select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE > select ARCH_HAS_PTE_SPECIAL if ARM_LPAE > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 7b071a00425d2..d21788e6920f6 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -31,6 +31,7 @@ config ARM64 > select ARCH_HAS_GIGANTIC_PAGE > select ARCH_HAS_KCOV > select ARCH_HAS_KEEPINITRD > + select ARCH_HAS_MEMBARRIER > select ARCH_HAS_MEMBARRIER_SYNC_CORE > select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS > select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE > diff --git a/arch/hexagon/Kconfig b/arch/hexagon/Kconfig > index a880ee067d2ec..c2b2713c01bbd 100644 > --- a/arch/hexagon/Kconfig > +++ b/arch/hexagon/Kconfig > @@ -5,6 +5,7 @@ comment "Linux Kernel Configuration for Hexagon" > config HEXAGON > def_bool y > select ARCH_32BIT_OFF_T > + select ARCH_HAS_MEMBARRIER > select ARCH_HAS_SYNC_DMA_FOR_DEVICE > select ARCH_NO_PREEMPT > select DMA_GLOBAL_POOL > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig > index 797ae590ebdba..4b65e73e34c16 100644 > --- a/arch/mips/Kconfig > +++ b/arch/mips/Kconfig > @@ -16,6 +16,7 @@ config MIPS > select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST > select ARCH_HAS_UBSAN_SANITIZE_ALL > select ARCH_HAS_GCOV_PROFILE_ALL > + select ARCH_HAS_MEMBARRIER > select ARCH_KEEP_MEMBLOCK > select ARCH_USE_BUILTIN_BSWAP > select ARCH_USE_CMPXCHG_LOCKREF if 64BIT > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > index 6f105ee4f3cf5..c13980eac3585 100644 > --- a/arch/powerpc/Kconfig > +++ b/arch/powerpc/Kconfig > @@ -137,6 +137,7 @@ config PPC > select ARCH_HAS_GCOV_PROFILE_ALL > select ARCH_HAS_HUGEPD if HUGETLB_PAGE > select ARCH_HAS_KCOV > + select ARCH_HAS_MEMBARRIER > select ARCH_HAS_MEMBARRIER_CALLBACKS > select ARCH_HAS_MEMBARRIER_SYNC_CORE > select ARCH_HAS_MEMREMAP_COMPAT_ALIGN if PPC_64S_HASH_MMU > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index db7b1acd943e4..fd4c6a74ebd61 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -27,6 +27,7 @@ config RISCV > select ARCH_HAS_GCOV_PROFILE_ALL > select ARCH_HAS_GIGANTIC_PAGE > select ARCH_HAS_KCOV > + select ARCH_HAS_MEMBARRIER > select ARCH_HAS_MEMBARRIER_CALLBACKS > select ARCH_HAS_MEMBARRIER_SYNC_CORE > select ARCH_HAS_MMIOWB > diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig > index 3bec98d20283b..2e044d424fd4a 100644 > --- a/arch/s390/Kconfig > +++ b/arch/s390/Kconfig > @@ -72,6 +72,7 @@ config S390 > select ARCH_HAS_GCOV_PROFILE_ALL > select ARCH_HAS_GIGANTIC_PAGE > select ARCH_HAS_KCOV > + select ARCH_HAS_MEMBARRIER > select ARCH_HAS_MEMBARRIER_SYNC_CORE > select ARCH_HAS_MEM_ENCRYPT > select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS > diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig > index 49849790e66dc..40eb179c2416a 100644 > --- a/arch/sparc/Kconfig > +++ b/arch/sparc/Kconfig > @@ -30,6 +30,7 @@ config SPARC > select RTC_SYSTOHC > select HAVE_ARCH_JUMP_LABEL if SPARC64 > select GENERIC_IRQ_SHOW > + select ARCH_HAS_MEMBARRIER > select ARCH_WANT_IPC_PARSE_VERSION > select GENERIC_PCI_IOMAP > select HAS_IOPORT > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index 3762f41bb0929..83f63e00312ee 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -82,6 +82,7 @@ config X86 > select ARCH_HAS_GCOV_PROFILE_ALL > select ARCH_HAS_KCOV if X86_64 > select ARCH_HAS_MEM_ENCRYPT > + select ARCH_HAS_MEMBARRIER > select ARCH_HAS_MEMBARRIER_SYNC_CORE > select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS > select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE > diff --git a/init/Kconfig b/init/Kconfig > index 87daf50838f02..8114404b52b91 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1742,6 +1742,9 @@ config KALLSYMS_BASE_RELATIVE > > # syscall, maps, verifier > > +config ARCH_HAS_MEMBARRIER > + bool > + > config ARCH_HAS_MEMBARRIER_CALLBACKS > bool > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 711dc753f7216..dff1c6df337f9 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -6673,8 +6673,8 @@ static void __sched notrace __schedule(unsigned int sched_mode) > * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC, > * RISC-V. switch_mm() relies on membarrier_arch_switch_mm() > * on PowerPC and on RISC-V. > - * - finish_lock_switch() for weakly-ordered > - * architectures where spin_unlock is a full barrier, > + * - finish_lock_switch() for alpha, arc, arm, hexagon, mips > + * where spin_unlock is a full barrier, > * - switch_to() for arm64 (weakly-ordered, spin_unlock > * is a RELEASE barrier), > */ > diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c > index 58f801e013988..248a38c9b261c 100644 > --- a/kernel/sched/membarrier.c > +++ b/kernel/sched/membarrier.c > @@ -137,6 +137,14 @@ > * Bitmask made from a "or" of all commands within enum membarrier_cmd, > * except MEMBARRIER_CMD_QUERY. > */ > +#ifdef CONFIG_ARCH_HAS_MEMBARRIER > +#define MEMBARRIER_PRIVATE_EXPEDITED_BITMASK \ > + (MEMBARRIER_CMD_PRIVATE_EXPEDITED \ > + | MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED) > +#else > +#define MEMBARRIER_PRIVATE_EXPEDITED_BITMASK 0 > +#endif > + > #ifdef CONFIG_ARCH_HAS_MEMBARRIER_SYNC_CORE > #define MEMBARRIER_PRIVATE_EXPEDITED_SYNC_CORE_BITMASK \ > (MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE \ > @@ -156,8 +164,7 @@ > #define MEMBARRIER_CMD_BITMASK \ > (MEMBARRIER_CMD_GLOBAL | MEMBARRIER_CMD_GLOBAL_EXPEDITED \ > | MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED \ > - | MEMBARRIER_CMD_PRIVATE_EXPEDITED \ > - | MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED \ > + | MEMBARRIER_PRIVATE_EXPEDITED_BITMASK \ > | MEMBARRIER_PRIVATE_EXPEDITED_SYNC_CORE_BITMASK \ > | MEMBARRIER_PRIVATE_EXPEDITED_RSEQ_BITMASK \ > | MEMBARRIER_CMD_GET_REGISTRATIONS) > @@ -329,6 +336,8 @@ static int membarrier_private_expedited(int flags, int cpu_id) > return -EPERM; > ipi_func = ipi_rseq; > } else { > + if (!IS_ENABLED(CONFIG_ARCH_HAS_MEMBARRIER)) > + return -EINVAL; > WARN_ON_ONCE(flags); > if (!(atomic_read(&mm->membarrier_state) & > MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY)) > @@ -519,6 +528,8 @@ static int membarrier_register_private_expedited(int flags) > ready_state = > MEMBARRIER_STATE_PRIVATE_EXPEDITED_RSEQ_READY; > } else { > + if (!IS_ENABLED(CONFIG_ARCH_HAS_MEMBARRIER)) > + return -EINVAL; > WARN_ON_ONCE(flags); > } >
On Mon, Dec 11, 2023 at 08:34:21AM -0500, Mathieu Desnoyers wrote: > On 2023-12-11 04:44, Andrea Parri wrote: > > Architectures supporting the "private expedited" membarrier command must > > select the Kconfig to use the command. Document status and requirements > > for each architecture in a single file under Documentation/features. > > Sorry for being vague in my suggestion: I did not intend to make it > optional (not ARCH_HAS_MEMBARRIER), but rather just to have a central > place where this would be documented. I see. > I'm not sure where in Documentation this should land though ? Not sure, perhaps a section in (a new) Documentation/scheduler/membarrier.rst? Andrea
On 2023-12-11 11:53, Andrea Parri wrote: > On Mon, Dec 11, 2023 at 08:34:21AM -0500, Mathieu Desnoyers wrote: >> On 2023-12-11 04:44, Andrea Parri wrote: >>> Architectures supporting the "private expedited" membarrier command must >>> select the Kconfig to use the command. Document status and requirements >>> for each architecture in a single file under Documentation/features. >> >> Sorry for being vague in my suggestion: I did not intend to make it >> optional (not ARCH_HAS_MEMBARRIER), but rather just to have a central >> place where this would be documented. > > I see. > > >> I'm not sure where in Documentation this should land though ? > > Not sure, perhaps a section in (a new) Documentation/scheduler/membarrier.rst? Yes, it makes sense. Thanks! Mathieu > > Andrea
diff --git a/Documentation/features/sched/membarrier/arch-support.txt b/Documentation/features/sched/membarrier/arch-support.txt new file mode 100644 index 0000000000000..95e65195e47c2 --- /dev/null +++ b/Documentation/features/sched/membarrier/arch-support.txt @@ -0,0 +1,50 @@ +# +# Feature name: membarrier +# Kconfig: ARCH_HAS_MEMBARRIER +# description: arch supports MEMBARRIER_CMD_PRIVATE_EXPEDITED +# +# Architecture requirements +# +# The membarrier() system call requires each architecture to have a full memory +# barrier after updating rq->curr, before returning to user-space. +# +# Here are the schemes providing that barrier on the various architectures: +# +# * alpha/arc/arm/hexagon/mips +# +# We rely on the full barrier implied by spin_unlock() in finish_lock_switch(). +# +# * arm64 +# +# We rely on the full barrier implied by switch_to(). +# +# * powerpc/riscv/s390/sparc/x86 +# +# We rely on the full barrier implied by switch_mm(), if mm isn't NULL; we rely +# on the full barrier implied by mmdrop(), otherwise. +# + ----------------------- + | arch |status| + ----------------------- + | alpha: | ok | + | arc: | ok | + | arm: | ok | + | arm64: | ok | + | csky: | TODO | + | hexagon: | ok | + | loongarch: | TODO | + | m68k: | TODO | + | microblaze: | TODO | + | mips: | ok | + | nios2: | TODO | + | openrisc: | TODO | + | parisc: | TODO | + | powerpc: | ok | + | riscv: | ok | + | s390: | ok | + | sh: | TODO | + | sparc: | ok | + | um: | TODO | + | x86: | ok | + | xtensa: | TODO | + ----------------------- diff --git a/MAINTAINERS b/MAINTAINERS index f6f1fdc76cf46..c5a053605cbc4 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -13807,6 +13807,7 @@ M: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> M: "Paul E. McKenney" <paulmck@kernel.org> L: linux-kernel@vger.kernel.org S: Supported +F: Documentation/features/sched/membarrier*/ F: arch/*/include/asm/membarrier.h F: arch/*/include/asm/sync_core.h F: include/uapi/linux/membarrier.h diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index d6968d090d49a..f98d6cba0bd9a 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -24,6 +24,7 @@ config ALPHA select GENERIC_IRQ_SHOW select ARCH_WANT_IPC_PARSE_VERSION select ARCH_HAVE_NMI_SAFE_CMPXCHG + select ARCH_HAS_MEMBARRIER select AUDIT_ARCH select GENERIC_CPU_VULNERABILITIES select GENERIC_SMP_IDLE_THREAD diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig index 3162db540ee96..1d8a6ba98ae33 100644 --- a/arch/arc/Kconfig +++ b/arch/arc/Kconfig @@ -9,6 +9,7 @@ config ARC select ARCH_HAS_CACHE_LINE_SIZE select ARCH_HAS_DEBUG_VM_PGTABLE select ARCH_HAS_DMA_PREP_COHERENT + select ARCH_HAS_MEMBARRIER select ARCH_HAS_PTE_SPECIAL select ARCH_HAS_SETUP_DMA_OPS select ARCH_HAS_SYNC_DMA_FOR_CPU diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index f8567e95f98be..700d1d9ff2f8b 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -14,6 +14,7 @@ config ARM select ARCH_HAS_FORTIFY_SOURCE select ARCH_HAS_KEEPINITRD select ARCH_HAS_KCOV + select ARCH_HAS_MEMBARRIER select ARCH_HAS_MEMBARRIER_SYNC_CORE select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE select ARCH_HAS_PTE_SPECIAL if ARM_LPAE diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 7b071a00425d2..d21788e6920f6 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -31,6 +31,7 @@ config ARM64 select ARCH_HAS_GIGANTIC_PAGE select ARCH_HAS_KCOV select ARCH_HAS_KEEPINITRD + select ARCH_HAS_MEMBARRIER select ARCH_HAS_MEMBARRIER_SYNC_CORE select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE diff --git a/arch/hexagon/Kconfig b/arch/hexagon/Kconfig index a880ee067d2ec..c2b2713c01bbd 100644 --- a/arch/hexagon/Kconfig +++ b/arch/hexagon/Kconfig @@ -5,6 +5,7 @@ comment "Linux Kernel Configuration for Hexagon" config HEXAGON def_bool y select ARCH_32BIT_OFF_T + select ARCH_HAS_MEMBARRIER select ARCH_HAS_SYNC_DMA_FOR_DEVICE select ARCH_NO_PREEMPT select DMA_GLOBAL_POOL diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 797ae590ebdba..4b65e73e34c16 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -16,6 +16,7 @@ config MIPS select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST select ARCH_HAS_UBSAN_SANITIZE_ALL select ARCH_HAS_GCOV_PROFILE_ALL + select ARCH_HAS_MEMBARRIER select ARCH_KEEP_MEMBLOCK select ARCH_USE_BUILTIN_BSWAP select ARCH_USE_CMPXCHG_LOCKREF if 64BIT diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 6f105ee4f3cf5..c13980eac3585 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -137,6 +137,7 @@ config PPC select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_HAS_HUGEPD if HUGETLB_PAGE select ARCH_HAS_KCOV + select ARCH_HAS_MEMBARRIER select ARCH_HAS_MEMBARRIER_CALLBACKS select ARCH_HAS_MEMBARRIER_SYNC_CORE select ARCH_HAS_MEMREMAP_COMPAT_ALIGN if PPC_64S_HASH_MMU diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index db7b1acd943e4..fd4c6a74ebd61 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -27,6 +27,7 @@ config RISCV select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_HAS_GIGANTIC_PAGE select ARCH_HAS_KCOV + select ARCH_HAS_MEMBARRIER select ARCH_HAS_MEMBARRIER_CALLBACKS select ARCH_HAS_MEMBARRIER_SYNC_CORE select ARCH_HAS_MMIOWB diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 3bec98d20283b..2e044d424fd4a 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -72,6 +72,7 @@ config S390 select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_HAS_GIGANTIC_PAGE select ARCH_HAS_KCOV + select ARCH_HAS_MEMBARRIER select ARCH_HAS_MEMBARRIER_SYNC_CORE select ARCH_HAS_MEM_ENCRYPT select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig index 49849790e66dc..40eb179c2416a 100644 --- a/arch/sparc/Kconfig +++ b/arch/sparc/Kconfig @@ -30,6 +30,7 @@ config SPARC select RTC_SYSTOHC select HAVE_ARCH_JUMP_LABEL if SPARC64 select GENERIC_IRQ_SHOW + select ARCH_HAS_MEMBARRIER select ARCH_WANT_IPC_PARSE_VERSION select GENERIC_PCI_IOMAP select HAS_IOPORT diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 3762f41bb0929..83f63e00312ee 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -82,6 +82,7 @@ config X86 select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_HAS_KCOV if X86_64 select ARCH_HAS_MEM_ENCRYPT + select ARCH_HAS_MEMBARRIER select ARCH_HAS_MEMBARRIER_SYNC_CORE select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE diff --git a/init/Kconfig b/init/Kconfig index 87daf50838f02..8114404b52b91 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1742,6 +1742,9 @@ config KALLSYMS_BASE_RELATIVE # syscall, maps, verifier +config ARCH_HAS_MEMBARRIER + bool + config ARCH_HAS_MEMBARRIER_CALLBACKS bool diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 711dc753f7216..dff1c6df337f9 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6673,8 +6673,8 @@ static void __sched notrace __schedule(unsigned int sched_mode) * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC, * RISC-V. switch_mm() relies on membarrier_arch_switch_mm() * on PowerPC and on RISC-V. - * - finish_lock_switch() for weakly-ordered - * architectures where spin_unlock is a full barrier, + * - finish_lock_switch() for alpha, arc, arm, hexagon, mips + * where spin_unlock is a full barrier, * - switch_to() for arm64 (weakly-ordered, spin_unlock * is a RELEASE barrier), */ diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c index 58f801e013988..248a38c9b261c 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -137,6 +137,14 @@ * Bitmask made from a "or" of all commands within enum membarrier_cmd, * except MEMBARRIER_CMD_QUERY. */ +#ifdef CONFIG_ARCH_HAS_MEMBARRIER +#define MEMBARRIER_PRIVATE_EXPEDITED_BITMASK \ + (MEMBARRIER_CMD_PRIVATE_EXPEDITED \ + | MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED) +#else +#define MEMBARRIER_PRIVATE_EXPEDITED_BITMASK 0 +#endif + #ifdef CONFIG_ARCH_HAS_MEMBARRIER_SYNC_CORE #define MEMBARRIER_PRIVATE_EXPEDITED_SYNC_CORE_BITMASK \ (MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE \ @@ -156,8 +164,7 @@ #define MEMBARRIER_CMD_BITMASK \ (MEMBARRIER_CMD_GLOBAL | MEMBARRIER_CMD_GLOBAL_EXPEDITED \ | MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED \ - | MEMBARRIER_CMD_PRIVATE_EXPEDITED \ - | MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED \ + | MEMBARRIER_PRIVATE_EXPEDITED_BITMASK \ | MEMBARRIER_PRIVATE_EXPEDITED_SYNC_CORE_BITMASK \ | MEMBARRIER_PRIVATE_EXPEDITED_RSEQ_BITMASK \ | MEMBARRIER_CMD_GET_REGISTRATIONS) @@ -329,6 +336,8 @@ static int membarrier_private_expedited(int flags, int cpu_id) return -EPERM; ipi_func = ipi_rseq; } else { + if (!IS_ENABLED(CONFIG_ARCH_HAS_MEMBARRIER)) + return -EINVAL; WARN_ON_ONCE(flags); if (!(atomic_read(&mm->membarrier_state) & MEMBARRIER_STATE_PRIVATE_EXPEDITED_READY)) @@ -519,6 +528,8 @@ static int membarrier_register_private_expedited(int flags) ready_state = MEMBARRIER_STATE_PRIVATE_EXPEDITED_RSEQ_READY; } else { + if (!IS_ENABLED(CONFIG_ARCH_HAS_MEMBARRIER)) + return -EINVAL; WARN_ON_ONCE(flags); }
Architectures supporting the "private expedited" membarrier command must select the Kconfig to use the command. Document status and requirements for each architecture in a single file under Documentation/features. Suggested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Andrea Parri <parri.andrea@gmail.com> --- The TODOs in the arch-support table below should really be interpreted as "I'm not sure/haven't checked" (the respective arch maintainers will be able to verify and amend such information). Based on the following inline comment in __schedule(): /* * The membarrier system call requires each architecture * to have a full memory barrier after updating * rq->curr, before returning to user-space. * * Here are the schemes providing that barrier on the * various architectures: * - mm ? switch_mm() : mmdrop() for x86, s390, sparc, PowerPC, * RISC-V. switch_mm() relies on membarrier_arch_switch_mm() * on PowerPC and on RISC-V. * - finish_lock_switch() for weakly-ordered * architectures where spin_unlock is a full barrier, * - switch_to() for arm64 (weakly-ordered, spin_unlock * is a RELEASE barrier), */ .../sched/membarrier/arch-support.txt | 50 +++++++++++++++++++ MAINTAINERS | 1 + arch/alpha/Kconfig | 1 + arch/arc/Kconfig | 1 + arch/arm/Kconfig | 1 + arch/arm64/Kconfig | 1 + arch/hexagon/Kconfig | 1 + arch/mips/Kconfig | 1 + arch/powerpc/Kconfig | 1 + arch/riscv/Kconfig | 1 + arch/s390/Kconfig | 1 + arch/sparc/Kconfig | 1 + arch/x86/Kconfig | 1 + init/Kconfig | 3 ++ kernel/sched/core.c | 4 +- kernel/sched/membarrier.c | 15 +++++- 16 files changed, 80 insertions(+), 4 deletions(-) create mode 100644 Documentation/features/sched/membarrier/arch-support.txt