| Message ID | 20230721105744.022509272@infradead.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | futex: More futex2 bits | expand |
On Fri, Jul 21, 2023, at 12:22, Peter Zijlstra wrote: > --- a/arch/arm/tools/syscall.tbl > +++ b/arch/arm/tools/syscall.tbl > @@ -465,3 +465,4 @@ > 449 common futex_waitv sys_futex_waitv > 450 common set_mempolicy_home_node sys_set_mempolicy_home_node > 451 common cachestat sys_cachestat > +452 common futex_wake sys_futex_wake This clashes with __NR_fchmodat2 in linux-next, which also wants number 452. > --- a/arch/arm64/include/asm/unistd32.h > +++ b/arch/arm64/include/asm/unistd32.h > @@ -909,6 +909,8 @@ __SYSCALL(__NR_futex_waitv, sys_futex_wa > __SYSCALL(__NR_set_mempolicy_home_node, sys_set_mempolicy_home_node) > #define __NR_cachestat 451 > __SYSCALL(__NR_cachestat, sys_cachestat) > +#define __NR_futex_wake 452 > +__SYSCALL(__NR_futex_wake, sys_futex_wake) > > /* > * Please add new compat syscalls above this comment and update Unfortunately, changing this file still requires updating __NR_compat_syscalls in arch/arm64/include/asm/unistd.h as well. > --- a/kernel/sys_ni.c > +++ b/kernel/sys_ni.c > @@ -87,6 +87,7 @@ COND_SYSCALL_COMPAT(set_robust_list); > COND_SYSCALL(get_robust_list); > COND_SYSCALL_COMPAT(get_robust_list); > COND_SYSCALL(futex_waitv); > +COND_SYSCALL(futex_wake); > COND_SYSCALL(kexec_load); > COND_SYSCALL_COMPAT(kexec_load); > COND_SYSCALL(init_module); This is fine for the moment, but I wonder if we should start making futex mandatory at some point. Right now, sparc32 with CONFIG_SMP cannot support futex because of the lack of atomics in early sparc processors, but sparc32 glibc actually requires futexes and consequently only works on uniprocessor machines, on sparc64 compat mode, or on Leon3 with out of tree patches. Arnd
On Fri, Jul 21, 2023 at 05:41:20PM +0200, Arnd Bergmann wrote: > On Fri, Jul 21, 2023, at 12:22, Peter Zijlstra wrote: > > --- a/arch/arm/tools/syscall.tbl > > +++ b/arch/arm/tools/syscall.tbl > > @@ -465,3 +465,4 @@ > > 449 common futex_waitv sys_futex_waitv > > 450 common set_mempolicy_home_node sys_set_mempolicy_home_node > > 451 common cachestat sys_cachestat > > +452 common futex_wake sys_futex_wake > > This clashes with __NR_fchmodat2 in linux-next, which also wants number 452. Yeah, I fully expected some collisions :/ Unavoidable. > > --- a/arch/arm64/include/asm/unistd32.h > > +++ b/arch/arm64/include/asm/unistd32.h > > @@ -909,6 +909,8 @@ __SYSCALL(__NR_futex_waitv, sys_futex_wa > > __SYSCALL(__NR_set_mempolicy_home_node, sys_set_mempolicy_home_node) > > #define __NR_cachestat 451 > > __SYSCALL(__NR_cachestat, sys_cachestat) > > +#define __NR_futex_wake 452 > > +__SYSCALL(__NR_futex_wake, sys_futex_wake) > > > > /* > > * Please add new compat syscalls above this comment and update > > Unfortunately, changing this file still requires updating __NR_compat_syscalls > in arch/arm64/include/asm/unistd.h as well. Bah I missed that. I'll go fix it up. Thanks! > > --- a/kernel/sys_ni.c > > +++ b/kernel/sys_ni.c > > @@ -87,6 +87,7 @@ COND_SYSCALL_COMPAT(set_robust_list); > > COND_SYSCALL(get_robust_list); > > COND_SYSCALL_COMPAT(get_robust_list); > > COND_SYSCALL(futex_waitv); > > +COND_SYSCALL(futex_wake); > > COND_SYSCALL(kexec_load); > > COND_SYSCALL_COMPAT(kexec_load); > > COND_SYSCALL(init_module); > > This is fine for the moment, but I wonder if we should start making > futex mandatory at some point. Right now, sparc32 with CONFIG_SMP > cannot support futex because of the lack of atomics in early > sparc processors, but sparc32 glibc actually requires futexes > and consequently only works on uniprocessor machines, on sparc64 > compat mode, or on Leon3 with out of tree patches. PARISC is another 'fun' case.
On Fri, Jul 21, 2023, at 20:54, Peter Zijlstra wrote: > On Fri, Jul 21, 2023 at 05:41:20PM +0200, Arnd Bergmann wrote: >> On Fri, Jul 21, 2023, at 12:22, Peter Zijlstra wrote: >> > --- a/kernel/sys_ni.c >> > +++ b/kernel/sys_ni.c >> > @@ -87,6 +87,7 @@ COND_SYSCALL_COMPAT(set_robust_list); >> > COND_SYSCALL(get_robust_list); >> > COND_SYSCALL_COMPAT(get_robust_list); >> > COND_SYSCALL(futex_waitv); >> > +COND_SYSCALL(futex_wake); >> > COND_SYSCALL(kexec_load); >> > COND_SYSCALL_COMPAT(kexec_load); >> > COND_SYSCALL(init_module); >> >> This is fine for the moment, but I wonder if we should start making >> futex mandatory at some point. Right now, sparc32 with CONFIG_SMP >> cannot support futex because of the lack of atomics in early >> sparc processors, but sparc32 glibc actually requires futexes >> and consequently only works on uniprocessor machines, on sparc64 >> compat mode, or on Leon3 with out of tree patches. > > PARISC is another 'fun' case. I had to look up how that works, but as far as I can tell, the parisc code actually has a chance of working, as the userspace atomics go through the light-weight syscall that shares a hashed lock with the actual futex syscall. On sparc32 I think it's worse because userspace assumes that atomic instructions are supported while the kernel assumes they are not. Arnd
On Fri, Jul 21, 2023 at 1:03 PM Peter Zijlstra <peterz@infradead.org> wrote: > To complement sys_futex_waitv() add sys_futex_wake(). This syscall > implements what was previously known as FUTEX_WAKE_BITSET except it > uses 'unsigned long' for the bitmask and takes FUTEX2 flags. > > The 'unsigned long' allows FUTEX2_64 on 64bit platforms. > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > arch/m68k/kernel/syscalls/syscall.tbl | 1 For adding the syscall: Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> For the actual number, you have to take the Big Syscall Lock ;-) Gr{oetje,eeting}s, Geert
--- a/arch/alpha/kernel/syscalls/syscall.tbl +++ b/arch/alpha/kernel/syscalls/syscall.tbl @@ -491,3 +491,4 @@ 559 common futex_waitv sys_futex_waitv 560 common set_mempolicy_home_node sys_ni_syscall 561 common cachestat sys_cachestat +562 common futex_wake sys_futex_wake --- a/arch/arm/tools/syscall.tbl +++ b/arch/arm/tools/syscall.tbl @@ -465,3 +465,4 @@ 449 common futex_waitv sys_futex_waitv 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat +452 common futex_wake sys_futex_wake --- a/arch/arm64/include/asm/unistd32.h +++ b/arch/arm64/include/asm/unistd32.h @@ -909,6 +909,8 @@ __SYSCALL(__NR_futex_waitv, sys_futex_wa __SYSCALL(__NR_set_mempolicy_home_node, sys_set_mempolicy_home_node) #define __NR_cachestat 451 __SYSCALL(__NR_cachestat, sys_cachestat) +#define __NR_futex_wake 452 +__SYSCALL(__NR_futex_wake, sys_futex_wake) /* * Please add new compat syscalls above this comment and update --- a/arch/ia64/kernel/syscalls/syscall.tbl +++ b/arch/ia64/kernel/syscalls/syscall.tbl @@ -372,3 +372,4 @@ 449 common futex_waitv sys_futex_waitv 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat +452 common futex_wake sys_futex_wake --- a/arch/m68k/kernel/syscalls/syscall.tbl +++ b/arch/m68k/kernel/syscalls/syscall.tbl @@ -451,3 +451,4 @@ 449 common futex_waitv sys_futex_waitv 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat +452 common futex_wake sys_futex_wake --- a/arch/microblaze/kernel/syscalls/syscall.tbl +++ b/arch/microblaze/kernel/syscalls/syscall.tbl @@ -457,3 +457,4 @@ 449 common futex_waitv sys_futex_waitv 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat +452 common futex_wake sys_futex_wake --- a/arch/mips/kernel/syscalls/syscall_n32.tbl +++ b/arch/mips/kernel/syscalls/syscall_n32.tbl @@ -390,3 +390,4 @@ 449 n32 futex_waitv sys_futex_waitv 450 n32 set_mempolicy_home_node sys_set_mempolicy_home_node 451 n32 cachestat sys_cachestat +452 n32 futex_wake sys_futex_wake --- a/arch/mips/kernel/syscalls/syscall_n64.tbl +++ b/arch/mips/kernel/syscalls/syscall_n64.tbl @@ -366,3 +366,4 @@ 449 n64 futex_waitv sys_futex_waitv 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 n64 cachestat sys_cachestat +452 n64 futex_wake sys_futex_wake --- a/arch/mips/kernel/syscalls/syscall_o32.tbl +++ b/arch/mips/kernel/syscalls/syscall_o32.tbl @@ -439,3 +439,4 @@ 449 o32 futex_waitv sys_futex_waitv 450 o32 set_mempolicy_home_node sys_set_mempolicy_home_node 451 o32 cachestat sys_cachestat +452 o32 futex_wake sys_futex_wake --- a/arch/parisc/kernel/syscalls/syscall.tbl +++ b/arch/parisc/kernel/syscalls/syscall.tbl @@ -450,3 +450,4 @@ 449 common futex_waitv sys_futex_waitv 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat +452 common futex_wake sys_futex_wake --- a/arch/powerpc/kernel/syscalls/syscall.tbl +++ b/arch/powerpc/kernel/syscalls/syscall.tbl @@ -538,3 +538,4 @@ 449 common futex_waitv sys_futex_waitv 450 nospu set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat +452 common futex_wake sys_futex_wake --- a/arch/s390/kernel/syscalls/syscall.tbl +++ b/arch/s390/kernel/syscalls/syscall.tbl @@ -454,3 +454,4 @@ 449 common futex_waitv sys_futex_waitv sys_futex_waitv 450 common set_mempolicy_home_node sys_set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat sys_cachestat +452 common futex_wake sys_futex_wake sys_futex_wake --- a/arch/sh/kernel/syscalls/syscall.tbl +++ b/arch/sh/kernel/syscalls/syscall.tbl @@ -454,3 +454,4 @@ 449 common futex_waitv sys_futex_waitv 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat +452 common futex_wake sys_futex_wake --- a/arch/sparc/kernel/syscalls/syscall.tbl +++ b/arch/sparc/kernel/syscalls/syscall.tbl @@ -497,3 +497,4 @@ 449 common futex_waitv sys_futex_waitv 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat +452 common futex_wake sys_futex_wake --- a/arch/x86/entry/syscalls/syscall_32.tbl +++ b/arch/x86/entry/syscalls/syscall_32.tbl @@ -456,3 +456,4 @@ 449 i386 futex_waitv sys_futex_waitv 450 i386 set_mempolicy_home_node sys_set_mempolicy_home_node 451 i386 cachestat sys_cachestat +452 i386 futex_wake sys_futex_wake --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -373,6 +373,7 @@ 449 common futex_waitv sys_futex_waitv 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat +452 common futex_wake sys_futex_wake # # Due to a historical design error, certain syscalls are numbered differently --- a/arch/xtensa/kernel/syscalls/syscall.tbl +++ b/arch/xtensa/kernel/syscalls/syscall.tbl @@ -422,3 +422,4 @@ 449 common futex_waitv sys_futex_waitv 450 common set_mempolicy_home_node sys_set_mempolicy_home_node 451 common cachestat sys_cachestat +452 common futex_wake sys_futex_wake --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -563,6 +563,9 @@ asmlinkage long sys_set_robust_list(stru asmlinkage long sys_futex_waitv(struct futex_waitv *waiters, unsigned int nr_futexes, unsigned int flags, struct __kernel_timespec __user *timeout, clockid_t clockid); + +asmlinkage long sys_futex_wake(void __user *uaddr, unsigned long mask, int nr, unsigned int flags); + asmlinkage long sys_nanosleep(struct __kernel_timespec __user *rqtp, struct __kernel_timespec __user *rmtp); asmlinkage long sys_nanosleep_time32(struct old_timespec32 __user *rqtp, --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -816,12 +816,13 @@ __SYSCALL(__NR_process_mrelease, sys_pro __SYSCALL(__NR_futex_waitv, sys_futex_waitv) #define __NR_set_mempolicy_home_node 450 __SYSCALL(__NR_set_mempolicy_home_node, sys_set_mempolicy_home_node) - #define __NR_cachestat 451 __SYSCALL(__NR_cachestat, sys_cachestat) +#define __NR_futex_wake 452 +__SYSCALL(__NR_futex_wake, sys_futex_wake) #undef __NR_syscalls -#define __NR_syscalls 452 +#define __NR_syscalls 453 /* * 32 bit systems traditionally used different --- a/kernel/futex/syscalls.c +++ b/kernel/futex/syscalls.c @@ -306,6 +306,36 @@ SYSCALL_DEFINE5(futex_waitv, struct fute return ret; } +/* + * sys_futex_wake - Wake a number of futexes + * @uaddr: Address of the futex(es) to wake + * @mask: bitmask + * @nr: Number of the futexes to wake + * @flags: FUTEX2 flags + * + * Identical to the traditional FUTEX_WAKE_BITSET op, except it is part of the + * futex2 family of calls. + */ + +SYSCALL_DEFINE4(futex_wake, + void __user *, uaddr, + unsigned long, mask, + int, nr, + unsigned int, flags) +{ + if (flags & ~FUTEX2_MASK) + return -EINVAL; + + flags = futex2_to_flags(flags); + if (!futex_flags_valid(flags)) + return -EINVAL; + + if (!futex_validate_input(flags, mask)) + return -EINVAL; + + return futex_wake(uaddr, flags, nr, mask); +} + #ifdef CONFIG_COMPAT COMPAT_SYSCALL_DEFINE2(set_robust_list, struct compat_robust_list_head __user *, head, --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -87,6 +87,7 @@ COND_SYSCALL_COMPAT(set_robust_list); COND_SYSCALL(get_robust_list); COND_SYSCALL_COMPAT(get_robust_list); COND_SYSCALL(futex_waitv); +COND_SYSCALL(futex_wake); COND_SYSCALL(kexec_load); COND_SYSCALL_COMPAT(kexec_load); COND_SYSCALL(init_module);
To complement sys_futex_waitv() add sys_futex_wake(). This syscall implements what was previously known as FUTEX_WAKE_BITSET except it uses 'unsigned long' for the bitmask and takes FUTEX2 flags. The 'unsigned long' allows FUTEX2_64 on 64bit platforms. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- arch/alpha/kernel/syscalls/syscall.tbl | 1 arch/arm/tools/syscall.tbl | 1 arch/arm64/include/asm/unistd32.h | 2 + arch/ia64/kernel/syscalls/syscall.tbl | 1 arch/m68k/kernel/syscalls/syscall.tbl | 1 arch/microblaze/kernel/syscalls/syscall.tbl | 1 arch/mips/kernel/syscalls/syscall_n32.tbl | 1 arch/mips/kernel/syscalls/syscall_n64.tbl | 1 arch/mips/kernel/syscalls/syscall_o32.tbl | 1 arch/parisc/kernel/syscalls/syscall.tbl | 1 arch/powerpc/kernel/syscalls/syscall.tbl | 1 arch/s390/kernel/syscalls/syscall.tbl | 1 arch/sh/kernel/syscalls/syscall.tbl | 1 arch/sparc/kernel/syscalls/syscall.tbl | 1 arch/x86/entry/syscalls/syscall_32.tbl | 1 arch/x86/entry/syscalls/syscall_64.tbl | 1 arch/xtensa/kernel/syscalls/syscall.tbl | 1 include/linux/syscalls.h | 3 ++ include/uapi/asm-generic/unistd.h | 5 ++-- kernel/futex/syscalls.c | 30 ++++++++++++++++++++++++++++ kernel/sys_ni.c | 1 21 files changed, 55 insertions(+), 2 deletions(-)