lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Fri, 24 Sep 2021 14:34:56 +1000
From:   Alistair Francis <alistair23@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     André Almeida <andrealmeid@...labora.com>,
        Alistair Francis <alistair.francis@...nsource.wdc.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>, linux-perf-users@...r.kernel.org,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Mark Rutland <mark.rutland@....com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Davidlohr Bueso <dave@...olabs.net>,
        Darren Hart <dvhart@...radead.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Atish Patra <atish.patra@....com>,
        Alistair Francis <alistair.francis@....com>
Subject: Re: [PATCH v3 2/2] perf bench: Add support for 32-bit systems with
 64-bit time_t

On Tue, Sep 21, 2021 at 6:08 PM Arnd Bergmann <arnd@...db.de> wrote:
>
> On Tue, Sep 21, 2021 at 12:47 AM André Almeida
> <andrealmeid@...labora.com> wrote:
> >
> > #if defined(__i386__) || __TIMESIZE == 32
> > # define NR_gettime64 __NR_clock_gettime64
> > #else
> > # define NR_gettime64 __NR_clock_gettime
> > #endif
> >
> > struct timespec64 {
> >         long long tv_sec;       /* seconds */
> >         long long tv_nsec;      /* nanoseconds */
> > };
> >
> > int gettime64(clock_t clockid, struct timespec64 *tv)
> > {
> >         return syscall(NR_gettime64, clockid, tv);
> > }
> >
> > Then we can just use &timeout at __NR_futex_time64 for 32bit arch and at
> > __NR_futex for 64bit arch.
>
> This is still broken when you disable CONFIG_COMPAT_32BIT_TIME,
> which disables all system calls that take time32 arguments.
>
> > This might be a simpler solution to the problem that you are facing but
> > I'm not entirely sure. Also, futex's selftests do use the timeout
> > argument and I think that they also won't compile in 32-bit RISC-V, so
> > maybe we can start from there so we can actually test the timeout
> > argument and check if it's working.
>
> I would love to see the wrapper that Alistair wrote as part of some kernel
> uapi header provided to user space. futex is used by tons of applications,
> and we never had a library abstraction for it, so everyone has to do these
> by hand, and they all get them slightly wrong in different ways.
>
> We normally don't do this in kernel headers, but I think the benefits
> would be far greater compared to today's situation.

I'm happy to prepare a patch, if others are on board with it being accepted.

Alistair

>
>       Arnd

Powered by blists - more mailing lists