netdev - Re: [PATCH net-next] sh: add missing fpscr

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: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 2 Apr 2014 09:38:54 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Alexei Starovoitov <ast@...mgrid.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@...esas.com>,
	Daniel Borkmann <dborkman@...hat.com>,
	Paul Mundt <lethal@...ux-sh.org>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Linux-sh list <linux-sh@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] sh: add missing fpscr_values

On Wed, Apr 2, 2014 at 4:54 AM, Alexei Starovoitov <ast@...mgrid.com> wrote:
> GCC on SuperH for the following program:
> int foo(int i)
> {
>         static const void *table[2] = {
>                 [0] = &&label1,
>                 [1] = &&label2,
>         };
>         goto *table[i & 1];
>
>         label1:
>                 return 1;
>         label2:
>                 return 2;
> }
> generates code:
>         mov.l   .L9,r1
>         mov     #1,r0
>         rts
>         lds.l   @r1+,fpscr
> .L9:
>         .long   __fpscr_values+4
>
> so kernel has to provide body of fpscr_values just like glibc does
>
> Fixes: bd4cf0ed331a ("net: filter: rework/optimize internal BPF interpreter's instruction set")
> Reported-by: Fengguang Wu <fengguang.wu@...el.com>
> Signed-off-by: Alexei Starovoitov <ast@...mgrid.com>
> Cc: Daniel Borkmann <dborkman@...hat.com>
> ---
>
> kernel modules can hit the same problem, so export it
>
>  arch/sh/lib/Makefile       |    2 +-
>  arch/sh/lib/fpscr_values.c |    4 ++++
>  2 files changed, 5 insertions(+), 1 deletion(-)
>  create mode 100644 arch/sh/lib/fpscr_values.c
>
> diff --git a/arch/sh/lib/Makefile b/arch/sh/lib/Makefile
> index 3baff31e58cf..0d0c7ae21cfe 100644
> --- a/arch/sh/lib/Makefile
> +++ b/arch/sh/lib/Makefile
> @@ -8,7 +8,7 @@ lib-y  = delay.o memmove.o memchr.o \
>  # Extracted from libgcc
>  obj-y += movmem.o ashldi3.o ashrdi3.o lshrdi3.o \
>          ashlsi3.o ashrsi3.o ashiftrt.o lshrsi3.o \
> -        udiv_qrnnd.o
> +        udiv_qrnnd.o fpscr_values.o
>
>  udivsi3-y                      := udivsi3_i4i-Os.o
>
> diff --git a/arch/sh/lib/fpscr_values.c b/arch/sh/lib/fpscr_values.c
> new file mode 100644
> index 000000000000..58153272aba1
> --- /dev/null
> +++ b/arch/sh/lib/fpscr_values.c
> @@ -0,0 +1,4 @@
> +#include <linux/module.h>
> +
> +long __fpscr_values[2] = { 0L, 0x80000L };
> +EXPORT_SYMBOL(__fpscr_values);

Pardon my ignorance, but according to
http://www.sourceware.org/ml/libc-alpha/2003-06/msg00027.html
__fpscr_values is needed for FPU support only.

The kernel is built with -m4-nofpu. If this option is used, gcc doesn't generate
the reference to __fpscr_values?

Why do we need symbols for userspace FPU support in the kernel?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html