linux/arch/mn10300
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
..
boot inflate: refactor inflate malloc code 2008-07-25 10:53:28 -07:00
configs mn10300: update the ASB2303 defconfig 2010-01-11 09:34:10 -08:00
include/asm ptrace: move user_enable_single_step & co prototypes to linux/ptrace.h 2010-03-12 15:52:38 -08:00
kernel Add generic sys_ipc wrapper 2010-03-12 15:52:32 -08:00
lib mn10300: add cc clobbers to asm statements 2010-01-11 09:34:10 -08:00
mm MM: Pass a PTE pointer to update_mmu_cache() rather than the PTE itself 2010-02-20 16:41:46 +00:00
oprofile MN10300: Kill MN10300's own profiling Kconfig 2009-04-09 10:53:16 -07:00
proc-mn103e010 Separate out the proc- and unit-specific header directories from the general 2009-04-10 14:33:48 +01:00
unit-asb2303 mn10300: fix kernel build failures when using gcc-4.x 2009-10-01 16:11:12 -07:00
unit-asb2305 PCI: add pci_bus_for_each_resource(), remove direct bus->resource[] refs 2010-02-23 09:43:31 -08:00
Kconfig MN10300: Add utrace/tracehooks support 2009-06-11 09:02:20 -07:00
Kconfig.debug MN10300: Add built-in testing for misalignment handler 2008-11-12 10:41:17 -08:00
Makefile mn10300: objcopy flags fix 2010-01-11 09:34:09 -08:00