kernel_optimize_test/arch/sh/include
Christoph Hellwig dacbe41f77 ptrace: move user_enable_single_step & co prototypes to linux/ptrace.h
While in theory user_enable_single_step/user_disable_single_step/
user_enable_blockstep could also be provided as an inline or macro there's
no good reason to do so, and having the prototype in one places keeps code
size and confusion down.

Roland said:

  The original thought there was that user_enable_single_step() et al
  might well be only an instruction or three on a sane machine (as if we
  have any of those!), and since there is only one call site inlining
  would be beneficial.  But I agree that there is no strong reason to care
  about inlining it.

  As to the arch changes, there is only one thought I'd add to the
  record.  It was always my thinking that for an arch where
  PTRACE_SINGLESTEP does text-modifying breakpoint insertion,
  user_enable_single_step() should not be provided.  That is,
  arch_has_single_step()=>true means that there is an arch facility with
  "pure" semantics that does not have any unexpected side effects.
  Inserting a breakpoint might do very unexpected strange things in
  multi-threaded situations.  Aside from that, it is a peculiar side
  effect that user_{enable,disable}_single_step() should cause COW
  de-sharing of text pages and so forth.  For PTRACE_SINGLESTEP, all these
  peculiarities are the status quo ante for that arch, so having
  arch_ptrace() itself do those is one thing.  But for building other
  things in the future, it is nicer to have a uniform "pure" semantics
  that arch-independent code can expect.

  OTOH, all such arch issues are really up to the arch maintainer.  As
  of today, there is nothing but ptrace using user_enable_single_step() et
  al so it's a distinction without a practical difference.  If/when there
  are other facilities that use user_enable_single_step() and might care,
  the affected arch's can revisit the question when someone cares about
  the quality of the arch support for said new facility.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-03-12 15:52:38 -08:00
..
asm ptrace: move user_enable_single_step & co prototypes to linux/ptrace.h 2010-03-12 15:52:38 -08:00
cpu-common/cpu
cpu-sh2/cpu sh: Mass ctrl_in/outX to __raw_read/writeX conversion. 2010-01-26 12:58:40 +09:00
cpu-sh2a/cpu
cpu-sh3/cpu dmaengine: shdma: separate DMA headers. 2010-03-02 11:09:04 +09:00
cpu-sh4/cpu sh: merge sh7722 and sh7724 DMA register definitions 2010-03-02 11:10:52 +09:00
cpu-sh5/cpu
mach-common/mach sh: Mass ctrl_in/outX to __raw_read/writeX conversion. 2010-01-26 12:58:40 +09:00
mach-dreamcast/mach sh: mach-dreamcast: Convert to sparseirq. 2010-02-02 18:01:55 +09:00
mach-ecovec24/mach sh: mach-ecovec24: Remove un-defined settings for VPU 2009-12-04 13:42:34 +09:00
mach-kfr2r09/mach sh: LCDC start_transfer() for the KFR2R09 board 2009-12-09 12:40:45 +09:00
mach-landisk/mach
mach-migor/mach sh: audio support for the sh7722 Migo-R board 2010-03-02 11:08:54 +09:00
mach-sdk7786/mach sh: mach-sdk7786: Probe system FPGA area mapping. 2010-01-20 18:25:19 +09:00
mach-se/mach sh: mach-se: Convert SE7343 FPGA to dynamic IRQ allocation. 2010-01-12 13:37:04 +09:00
mach-sh03/mach