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  1. Apr 06, 2009
    • Linus Torvalds's avatar
      Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/drzeus/mmc · 0a053e8c
      Linus Torvalds authored 
      * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/drzeus/mmc: (42 commits)
  atmel-mci: fix sdc_reg typo
  tmio_mmc: add maintainer
  mmc: Add OpenFirmware bindings for SDHCI driver
  sdhci: Add quirk for forcing maximum block size to 2048 bytes
  sdhci: Add quirk for controllers that need IRQ re-init after reset
  sdhci: Add quirk for controllers that need small delays for PIO
  sdhci: Add set_clock callback and a quirk for nonstandard clocks
  sdhci: Add get_{max,timeout}_clock callbacks
  sdhci: Add support for hosts reporting inverted write-protect state
  sdhci: Add support for card-detection polling
  sdhci: Enable only relevant (DMA/PIO) interrupts during transfers
  sdhci: Split card-detection IRQs management from sdhci_init()
  sdhci: Add support for bus-specific IO memory accessors
  mmc_spi: adjust for delayed data token response
  omap_hsmmc: Wait for SDBP
  omap_hsmmc: Fix MMC3 dma
  omap_hsmmc: Disable SDBP at suspend
  omap_hsmmc: Do not prefix slot name
  omap_hsmmc: Allow cover switch to cause rescan
  omap_hsmmc: Add 8-bit bus width mode support
  ...
      0a053e8c
  3. Apr 05, 2009
    • Linus Torvalds's avatar
      Make non-compat preadv/pwritev use native register size · 601cc11d
      Linus Torvalds authored 
      

Instead of always splitting the file offset into 32-bit 'high' and 'low'
parts, just split them into the largest natural word-size - which in C
terms is 'unsigned long'.

This allows 64-bit architectures to avoid the unnecessary 32-bit
shifting and masking for native format (while the compat interfaces will
obviously always have to do it).

This also changes the order of 'high' and 'low' to be "low first".  Why?
Because when we have it like this, the 64-bit system calls now don't use
the "pos_high" argument at all, and it makes more sense for the native
system call to simply match the user-mode prototype.

This results in a much more natural calling convention, and allows the
compiler to generate much more straightforward code.  On x86-64, we now
generate

        testq   %rcx, %rcx      # pos_l
        js      .L122   #,
        movq    %rcx, -48(%rbp) # pos_l, pos

from the C source

        loff_t pos = pos_from_hilo(pos_h, pos_l);
	...
        if (pos < 0)
                return -EINVAL;

and the 'pos_h' register isn't even touched.  It used to generate code
like

        mov     %r8d, %r8d      # pos_low, pos_low
        salq    $32, %rcx       #, tmp71
        movq    %r8, %rax       # pos_low, pos.386
        orq     %rcx, %rax      # tmp71, pos.386
        js      .L122   #,
        movq    %rax, -48(%rbp) # pos.386, pos

which isn't _that_ horrible, but it does show how the natural word size
is just a more sensible interface (same arguments will hold in the user
level glibc wrapper function, of course, so the kernel side is just half
of the equation!)

Note: in all cases the user code wrapper can again be the same. You can
just do

	#define HALF_BITS (sizeof(unsigned long)*4)
	__syscall(PWRITEV, fd, iov, count, offset, (offset >> HALF_BITS) >> HALF_BITS);

or something like that.  That way the user mode wrapper will also be
nicely passing in a zero (it won't actually have to do the shifts, the
compiler will understand what is going on) for the last argument.

And that is a good idea, even if nobody will necessarily ever care: if
we ever do move to a 128-bit lloff_t, this particular system call might
be left alone.  Of course, that will be the least of our worries if we
really ever need to care, so this may not be worth really caring about.

[ Fixed for lost 'loff_t' cast noticed by Andrew Morton ]

Acked-by: default avatarGerd Hoffmann <kraxel@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-api@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ralf Baechle <ralf@linux-mips.org>>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      601cc11d
  5. Apr 04, 2009