Message ID | 20160923141154.GA970@yury-N73SV |
---|---|
State | New |
Headers | show |
On 23/09/2016 11:11, Yury Norov wrote: > On Fri, Sep 23, 2016 at 10:32:35AM -0300, Adhemerval Zanella wrote: >> >> Indeed, unfortunately tile seems to get its own readahead definition. >> However I think it should not prevent us to use my previous strategy, >> we can follow the SH example for pread (where it adds a dummy argument >> before offset), and do something as: >> >> sysdeps/unix/sysv/linux/tile/readahead.c >> >> #include <sysdep.h> >> >> #ifndef _LP64 >> /* Although tile 32-bit ABI passed 64-bit arguments in even registers, >> readahead interface does not follow this convention. */ >> # undef __ALIGNMENT_ARG >> #endif >> >> #include <sysdeps/unix/sysv/linux/readhead.c> > > Currently it looks like this to me (see below). If you think that separated file > is better than new option - I'm OK with it, but I think it's strange because in > other patches of series you introduce options (if I'm not mistake). I prefer to not add any more __ASSUME macro until it is more general and for this specific case (tile seems the only supported ABI that implements readhead different than usual ABI). > > We also have 2 another implementations - in linux/wordsize-64/syscalls.list > and linux/mips/mips64/n32/syscalls.list. > > I think wordsize-64 is safe to generalize, but I'm worry about mips64. If we'll > choose adding new options and so having a single file, it seems, we'll have to > add another option for mips64/n32, like this: My understanding is mipc64n32 adds it on syscall list to avoid current default Linux implementation where it splits the off64_t (since mips64n32 passes off64_t in only one register afaik). I think it is safe here, since SYSCALL_LL64 for mips64n32 will correctly pass only one argument instead of splitting it. > > #if __ASSUME_READAHEAD_NO_PAIRS > # define SYSCALL_LL64(val) (val) > #endif > > If we choose 3 implementations, we can introduce no option, but have > generic, tile and mips separated versions. > > Yury. > > -- > diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h > index 71ce57a..ba7d745 100644 > --- a/sysdeps/unix/sysv/linux/kernel-features.h > +++ b/sysdeps/unix/sysv/linux/kernel-features.h > @@ -50,6 +50,11 @@ > #define __ASSUME_ST_INO_64_BIT 1 > #endif > > +#ifndef __ASSUME_READAHEAD_ALIGN > +/* readahead() adds padding to registers if this control is enabled. */ > +# define __ASSUME_READAHEAD_ALIGN 1 > +#endif > + > /* The statfs64 syscalls are available in 2.5.74 (but not for alpha). */ > #define __ASSUME_STATFS64 1 > > diff --git a/sysdeps/unix/sysv/linux/readahead.c b/sysdeps/unix/sysv/linux/readahead.c > index 92e5428..eea3142 100644 > --- a/sysdeps/unix/sysv/linux/readahead.c > +++ b/sysdeps/unix/sysv/linux/readahead.c > @@ -23,16 +23,20 @@ > #include <sysdep.h> > #include <sys/syscall.h> > > +#include <kernel-features.h> > > #ifdef __NR_readahead > > +#if !__ASSUME_READAHEAD_ALIGN > +# undef __ALIGNMENT_ARG > +# define __ALIGNMENT_ARG > +#endif > + > ssize_t > __readahead (int fd, off64_t offset, size_t count) > { > - return INLINE_SYSCALL (readahead, 4, fd, > - __LONG_LONG_PAIR ((off_t) (offset >> 32), > - (off_t) (offset & 0xffffffff)), > - count); > + return INLINE_SYSCALL_CALL (readahead, fd, __ALIGNMENT_ARG > + SYSCALL_LL64 (offset)); > } > #else > ssize_t > diff --git a/sysdeps/unix/sysv/linux/tile/kernel-features.h b/sysdeps/unix/sysv/linux/tile/kernel-features.h > index ded0e43..15ad2d3 100644 > --- a/sysdeps/unix/sysv/linux/tile/kernel-features.h > +++ b/sysdeps/unix/sysv/linux/tile/kernel-features.h > @@ -24,4 +24,5 @@ > #ifndef _LP64 > # define __ASSUME_ALIGNED_REGISTER_PAIRS 1 > # define __ASSUME_FADVISE64_64_NO_ALIGN 1 > +# define __ASSUME_READAHEAD_ALIGN 0 > #endif >
On Fri, Sep 23, 2016 at 11:24:32AM -0300, Adhemerval Zanella wrote: > > > On 23/09/2016 11:11, Yury Norov wrote: > > On Fri, Sep 23, 2016 at 10:32:35AM -0300, Adhemerval Zanella wrote: > >> > >> Indeed, unfortunately tile seems to get its own readahead definition. > >> However I think it should not prevent us to use my previous strategy, > >> we can follow the SH example for pread (where it adds a dummy argument > >> before offset), and do something as: > >> > >> sysdeps/unix/sysv/linux/tile/readahead.c > >> > >> #include <sysdep.h> > >> > >> #ifndef _LP64 > >> /* Although tile 32-bit ABI passed 64-bit arguments in even registers, > >> readahead interface does not follow this convention. */ > >> # undef __ALIGNMENT_ARG > >> #endif > >> > >> #include <sysdeps/unix/sysv/linux/readhead.c> > > > > Currently it looks like this to me (see below). If you think that separated file > > is better than new option - I'm OK with it, but I think it's strange because in > > other patches of series you introduce options (if I'm not mistake). > > I prefer to not add any more __ASSUME macro until it is more general > and for this specific case (tile seems the only supported ABI that > implements readhead different than usual ABI). > > > > > We also have 2 another implementations - in linux/wordsize-64/syscalls.list > > and linux/mips/mips64/n32/syscalls.list. > > > > I think wordsize-64 is safe to generalize, but I'm worry about mips64. If we'll > > choose adding new options and so having a single file, it seems, we'll have to > > add another option for mips64/n32, like this: > > My understanding is mipc64n32 adds it on syscall list to avoid current > default Linux implementation where it splits the off64_t (since mips64n32 > passes off64_t in only one register afaik). I think it is safe here, > since SYSCALL_LL64 for mips64n32 will correctly pass only one argument > instead of splitting it. OK. So for v2: - remove arm, mips, wordsize-64, powerpc implementations - generalize linux/readahead.c like below - add tile exception - remove all new __ASSUME If it's correct, I'll send new patch this evening or tomorrow. Yury. > > ssize_t > > __readahead (int fd, off64_t offset, size_t count) > > { > > - return INLINE_SYSCALL (readahead, 4, fd, > > - __LONG_LONG_PAIR ((off_t) (offset >> 32), > > - (off_t) (offset & 0xffffffff)), > > - count); > > + return INLINE_SYSCALL_CALL (readahead, fd, __ALIGNMENT_ARG > > + SYSCALL_LL64 (offset));
On 23/09/2016 12:44, Yury Norov wrote: > On Fri, Sep 23, 2016 at 11:24:32AM -0300, Adhemerval Zanella wrote: >> >> >> On 23/09/2016 11:11, Yury Norov wrote: >>> On Fri, Sep 23, 2016 at 10:32:35AM -0300, Adhemerval Zanella wrote: >>>> >>>> Indeed, unfortunately tile seems to get its own readahead definition. >>>> However I think it should not prevent us to use my previous strategy, >>>> we can follow the SH example for pread (where it adds a dummy argument >>>> before offset), and do something as: >>>> >>>> sysdeps/unix/sysv/linux/tile/readahead.c >>>> >>>> #include <sysdep.h> >>>> >>>> #ifndef _LP64 >>>> /* Although tile 32-bit ABI passed 64-bit arguments in even registers, >>>> readahead interface does not follow this convention. */ >>>> # undef __ALIGNMENT_ARG >>>> #endif >>>> >>>> #include <sysdeps/unix/sysv/linux/readhead.c> >>> >>> Currently it looks like this to me (see below). If you think that separated file >>> is better than new option - I'm OK with it, but I think it's strange because in >>> other patches of series you introduce options (if I'm not mistake). >> >> I prefer to not add any more __ASSUME macro until it is more general >> and for this specific case (tile seems the only supported ABI that >> implements readhead different than usual ABI). >> >>> >>> We also have 2 another implementations - in linux/wordsize-64/syscalls.list >>> and linux/mips/mips64/n32/syscalls.list. >>> >>> I think wordsize-64 is safe to generalize, but I'm worry about mips64. If we'll >>> choose adding new options and so having a single file, it seems, we'll have to >>> add another option for mips64/n32, like this: >> >> My understanding is mipc64n32 adds it on syscall list to avoid current >> default Linux implementation where it splits the off64_t (since mips64n32 >> passes off64_t in only one register afaik). I think it is safe here, >> since SYSCALL_LL64 for mips64n32 will correctly pass only one argument >> instead of splitting it. > > OK. So for v2: > - remove arm, mips, wordsize-64, powerpc implementations > - generalize linux/readahead.c like below > - add tile exception > - remove all new __ASSUME > > If it's correct, I'll send new patch this evening or tomorrow. That would be my recommendation.
diff --git a/sysdeps/unix/sysv/linux/kernel-features.h b/sysdeps/unix/sysv/linux/kernel-features.h index 71ce57a..ba7d745 100644 --- a/sysdeps/unix/sysv/linux/kernel-features.h +++ b/sysdeps/unix/sysv/linux/kernel-features.h @@ -50,6 +50,11 @@ #define __ASSUME_ST_INO_64_BIT 1 #endif +#ifndef __ASSUME_READAHEAD_ALIGN +/* readahead() adds padding to registers if this control is enabled. */ +# define __ASSUME_READAHEAD_ALIGN 1 +#endif + /* The statfs64 syscalls are available in 2.5.74 (but not for alpha). */ #define __ASSUME_STATFS64 1 diff --git a/sysdeps/unix/sysv/linux/readahead.c b/sysdeps/unix/sysv/linux/readahead.c index 92e5428..eea3142 100644 --- a/sysdeps/unix/sysv/linux/readahead.c +++ b/sysdeps/unix/sysv/linux/readahead.c @@ -23,16 +23,20 @@ #include <sysdep.h> #include <sys/syscall.h> +#include <kernel-features.h> #ifdef __NR_readahead +#if !__ASSUME_READAHEAD_ALIGN +# undef __ALIGNMENT_ARG +# define __ALIGNMENT_ARG +#endif + ssize_t __readahead (int fd, off64_t offset, size_t count) { - return INLINE_SYSCALL (readahead, 4, fd, - __LONG_LONG_PAIR ((off_t) (offset >> 32), - (off_t) (offset & 0xffffffff)), - count); + return INLINE_SYSCALL_CALL (readahead, fd, __ALIGNMENT_ARG + SYSCALL_LL64 (offset)); } #else ssize_t diff --git a/sysdeps/unix/sysv/linux/tile/kernel-features.h b/sysdeps/unix/sysv/linux/tile/kernel-features.h index ded0e43..15ad2d3 100644 --- a/sysdeps/unix/sysv/linux/tile/kernel-features.h +++ b/sysdeps/unix/sysv/linux/tile/kernel-features.h @@ -24,4 +24,5 @@ #ifndef _LP64 # define __ASSUME_ALIGNED_REGISTER_PAIRS 1 # define __ASSUME_FADVISE64_64_NO_ALIGN 1 +# define __ASSUME_READAHEAD_ALIGN 0 #endif