kernel_optimize_test/arch
Dan Williams ec6347bb43 x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}()
In reaction to a proposal to introduce a memcpy_mcsafe_fast()
implementation Linus points out that memcpy_mcsafe() is poorly named
relative to communicating the scope of the interface. Specifically what
addresses are valid to pass as source, destination, and what faults /
exceptions are handled.

Of particular concern is that even though x86 might be able to handle
the semantics of copy_mc_to_user() with its common copy_user_generic()
implementation other archs likely need / want an explicit path for this
case:

  On Fri, May 1, 2020 at 11:28 AM Linus Torvalds <torvalds@linux-foundation.org> wrote:
  >
  > On Thu, Apr 30, 2020 at 6:21 PM Dan Williams <dan.j.williams@intel.com> wrote:
  > >
  > > However now I see that copy_user_generic() works for the wrong reason.
  > > It works because the exception on the source address due to poison
  > > looks no different than a write fault on the user address to the
  > > caller, it's still just a short copy. So it makes copy_to_user() work
  > > for the wrong reason relative to the name.
  >
  > Right.
  >
  > And it won't work that way on other architectures. On x86, we have a
  > generic function that can take faults on either side, and we use it
  > for both cases (and for the "in_user" case too), but that's an
  > artifact of the architecture oddity.
  >
  > In fact, it's probably wrong even on x86 - because it can hide bugs -
  > but writing those things is painful enough that everybody prefers
  > having just one function.

Replace a single top-level memcpy_mcsafe() with either
copy_mc_to_user(), or copy_mc_to_kernel().

Introduce an x86 copy_mc_fragile() name as the rename for the
low-level x86 implementation formerly named memcpy_mcsafe(). It is used
as the slow / careful backend that is supplanted by a fast
copy_mc_generic() in a follow-on patch.

One side-effect of this reorganization is that separating copy_mc_64.S
to its own file means that perf no longer needs to track dependencies
for its memcpy_64.S benchmarks.

 [ bp: Massage a bit. ]

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: <stable@vger.kernel.org>
Link: http://lore.kernel.org/r/CAHk-=wjSqtXAqfUJxFtWNwmguFASTgB0dz1dT3V-78Quiezqbg@mail.gmail.com
Link: https://lkml.kernel.org/r/160195561680.2163339.11574962055305783722.stgit@dwillia2-desk3.amr.corp.intel.com
2020-10-06 11:18:04 +02:00
..
alpha iomap: constify ioreadX() iomem argument (as in generic implementation) 2020-08-14 19:56:57 -07:00
arc mm/gup: remove task_struct pointer for all gup code 2020-08-12 10:58:04 -07:00
arm all arch: remove system call sys_sysctl 2020-08-14 19:56:56 -07:00
arm64 all arch: remove system call sys_sysctl 2020-08-14 19:56:56 -07:00
c6x Merge branch 'work.regset' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-08-07 09:29:25 -07:00
csky mm/csky: use general page fault accounting 2020-08-12 10:58:03 -07:00
h8300 uaccess: remove segment_eq 2020-08-12 10:57:58 -07:00
hexagon mm/hexagon: use general page fault accounting 2020-08-12 10:58:03 -07:00
ia64 all arch: remove system call sys_sysctl 2020-08-14 19:56:56 -07:00
m68k Cleanup, SECCOMP_FILTER support, message printing fixes, and other 2020-08-15 18:50:32 -07:00
microblaze all arch: remove system call sys_sysctl 2020-08-14 19:56:56 -07:00
mips all arch: remove system call sys_sysctl 2020-08-14 19:56:56 -07:00
nds32 mm/nds32: use general page fault accounting 2020-08-12 10:58:03 -07:00
nios2 mm/nios2: use general page fault accounting 2020-08-12 10:58:03 -07:00
openrisc OpenRISC updates for 5.9 2020-08-14 14:04:53 -07:00
parisc parisc: fix PMD pages allocation by restoring pmd_alloc_one() 2020-08-16 10:53:13 -07:00
powerpc x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}() 2020-10-06 11:18:04 +02:00
riscv A RISC-V Fix for 5.9 2020-08-15 18:54:42 -07:00
s390 all arch: remove system call sys_sysctl 2020-08-14 19:56:56 -07:00
sh Cleanup, SECCOMP_FILTER support, message printing fixes, and other 2020-08-15 18:50:32 -07:00
sparc all arch: remove system call sys_sysctl 2020-08-14 19:56:56 -07:00
um Cleanup, SECCOMP_FILTER support, message printing fixes, and other 2020-08-15 18:50:32 -07:00
x86 x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}() 2020-10-06 11:18:04 +02:00
xtensa all arch: remove system call sys_sysctl 2020-08-14 19:56:56 -07:00
.gitignore
Kconfig A set oftimekeeping/VDSO updates: 2020-08-14 14:26:08 -07:00