linux/arch/h8300
Pavel Emelyanov a8fc927780 sk-filter: Add ability to get socket filter program (v2)
The SO_ATTACH_FILTER option is set only. I propose to add the get
ability by using SO_ATTACH_FILTER in getsockopt. To be less
irritating to eyes the SO_GET_FILTER alias to it is declared. This
ability is required by checkpoint-restore project to be able to
save full state of a socket.

There are two issues with getting filter back.

First, kernel modifies the sock_filter->code on filter load, thus in
order to return the filter element back to user we have to decode it
into user-visible constants. Fortunately the modification in question
is interconvertible.

Second, the BPF_S_ALU_DIV_K code modifies the command argument k to
speed up the run-time division by doing kernel_k = reciprocal(user_k).
Bad news is that different user_k may result in same kernel_k, so we
can't get the original user_k back. Good news is that we don't have
to do it. What we need to is calculate a user2_k so, that

  reciprocal(user2_k) == reciprocal(user_k) == kernel_k

i.e. if it's re-loaded back the compiled again value will be exactly
the same as it was. That said, the user2_k can be calculated like this

  user2_k = reciprocal(kernel_k)

with an exception, that if kernel_k == 0, then user2_k == 1.

The optlen argument is treated like this -- when zero, kernel returns
the amount of sock_fprog elements in filter, otherwise it should be
large enough for the sock_fprog array.

changes since v1:
* Declared SO_GET_FILTER in all arch headers
* Added decode of vlan-tag codes

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2012-11-01 11:17:15 -04:00
..
boot
include sk-filter: Add ability to get socket filter program (v2) 2012-11-01 11:17:15 -04:00
kernel vfs: define struct filename and have getname() return it 2012-10-12 20:14:55 -04:00
lib
mm h8300: use the declarations provided by <asm/sections.h> 2012-06-20 14:39:35 -07:00
platform sections: fix section conflicts in arch/h8300 2012-10-06 03:04:38 +09:00
defconfig
Kconfig Merge branch 'modules-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux 2012-10-14 13:39:34 -07:00
Kconfig.cpu timers: Fixup the Kconfig consolidation fallout 2012-05-21 23:43:46 +02:00
Kconfig.debug
Kconfig.ide
Makefile
README

linux-2.6 for H8/300 README
Yoshinori Sato <ysato@users.sourceforge.jp>

* Supported CPU
H8/300H and H8S

* Supported Target
1.simulator of GDB
  require patches.

2.AE 3068/AE 3069
  more information 
  MICROTRONIQUE <http://www.microtronique.com/>
  Akizuki Denshi Tsusho Ltd. <http://www.akizuki.ne.jp> (Japanese Only)

3.H8MAX 
  see http://ip-sol.jp/h8max/ (Japanese Only)

4.EDOSK2674
  see http://www.eu.renesas.com/products/mpumcu/tool/edk/support/edosk2674.html
      http://www.uclinux.org/pub/uClinux/ports/h8/HITACHI-EDOSK2674-HOWTO
      http://www.azpower.com/H8-uClinux/

* Toolchain Version
gcc-3.1 or higher and patch
see arch/h8300/tools_patch/README
binutils-2.12 or higher
gdb-5.2 or higher
The environment that can compile a h8300-elf binary is necessary.

* Userland Develop environment
used h8300-elf toolchains.
see http://www.uclinux.org/pub/uClinux/ports/h8/

* A few words of thanks
Porting to H8/300 serieses is support of Information-technology Promotion Agency, Japan.
I thank support.
and All developer/user.