From: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
To: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: linux-modules@vger.kernel.org
Subject: Re: [PATCH v2] testsuite: also wrap gettid in syscall()
Date: Mon, 8 Jan 2018 13:31:46 -0800 [thread overview]
Message-ID: <20180108213146.GA8638@cmdeoliv-mobl2.jf.intel.com> (raw)
In-Reply-To: <20180108212829.14484-1-lucas.demarchi@intel.com>
+1
On Mon, Jan 08, 2018 at 01:28:29PM -0800, Lucas De Marchi wrote:
> Not a perfect solution for overriding syscall(), but at least
> it makes the testsuite to pass in a modified nsswitch.conf (one that has
> a module which calls syscall() to get the thread id).
> ---
>
> v2:
> - Check nextlib_syscall rather than nextlib to avoid races in
> multithreaded programs
> - Add error message in case we fail to get symbol
>
> testsuite/init_module.c | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/testsuite/init_module.c b/testsuite/init_module.c
> index 199186b..c70147e 100644
> --- a/testsuite/init_module.c
> +++ b/testsuite/init_module.c
> @@ -355,6 +355,26 @@ TS_EXPORT long int syscall(long int __sysno, ...)
> return ret;
> }
>
> + if (__sysno == __NR_gettid) {
> + static void *nextlib = NULL;
> + static long (*nextlib_syscall)(long number, ...);
> +
> + if (nextlib_syscall == NULL) {
> +#ifdef RTLD_NEXT
> + nextlib = RTLD_NEXT;
> +#else
> + nextlib = dlopen("libc.so.6", RTLD_LAZY);
> +#endif
> + nextlib_syscall = dlsym(nextlib, "syscall");
> + if (nextlib_syscall == NULL) {
> + fprintf(stderr, "FIXME FIXME FIXME: libc is missing syscall symbol\n");
> + abort();
> + }
> + }
> +
> + return nextlib_syscall(__NR_gettid);
> + }
> +
> /*
> * FIXME: no way to call the libc function due since this is a
> * variadic argument function and we don't have a vsyscall() variant
> --
> 2.14.3
>
next prev parent reply other threads:[~2018-01-08 21:31 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-08 16:27 [PATCH] testsuite: also wrap gettid in syscall() Lucas De Marchi
2018-01-08 21:28 ` [PATCH v2] " Lucas De Marchi
2018-01-08 21:31 ` Caio Marcelo de Oliveira Filho [this message]
2018-01-08 21:55 ` Lucas De Marchi
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