[lkml]   [2010]   [Nov]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: gcc 4.5.1 / as miscompiling drivers/char/i8k.c ?
    On 11/15/2010 05:04 PM, Linus Torvalds wrote:
    > On Mon, Nov 15, 2010 at 3:16 AM, Jakub Jelinek <> wrote:
    >> I don't see any problems on the assembly level. i8k_smm is
    >> not inlined in this case and checks all 3 conditions.
    > If it really is related to gcc not understanding that "*regs" has
    > changed due to the memory being an automatic variable, and passing in
    > "regs" itself as a pointer to that automatic variable together with
    > the "memory" clobber not being sufficient, than I think it's the lack
    > of inlining that will automatically hide the bug.
    > (Side note: and I think this does show how much of a gcc bug it is not
    > to consider "memory" together with passing in a pointer to an asm to
    > always be a clobber).
    > Because if it isn't inlined, then "regs" will be seen a a real pointer
    > to some external memory (the caller) rather than being optimized to
    > just be the auto structure on the stack. Because *mem is auto only
    > within the context of the caller.
    > Which actually points to a possible simpler:
    > - remove the "+m" since it adds too much register pressure
    > - mark the i8k_smm() as "noinline" instead.
    > Quite frankly, I'd hate to add even more crud to that inline asm (to
    > save/restore the registers manually). It's already not the prettiest
    > thing around.
    > So does the attached patch work for everybody?
    > Linus

    Hmm, that doesn't work.

    [ Not sure if you read to whole thread but initial workaround was to
    change the asm(..) to asm volatile(..) which did work. ]


     \ /
      Last update: 2010-11-15 18:45    [W:0.026 / U:10.976 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site