On 24-Apr-2002 Kenneth Culver wrote:
>> Brandon S Allbery KF8NH writes:
>> > On Wed, 2002-04-24 at 10:41, Andrew Gallatin wrote:
>> > > Maybe the argument isn't where you expect it to be, but is there.
>> > > Can you make a test program which calls mmap2 with its 6th arg as
>> > > something unique like 0xdeadbeef? Then print out (in hex :) the
>> > > trapframe
>> > > from the linux prepsyscall routine & see if you can find the deadbeef.
>> > My recollection is that beyond 5 arguments, a pointer to the remaining
>> > ones is passed. (But my recollection may be wrong and I don't wish to
>> > subject myself to the source cesspool at the moment....)
>> I think that's how it used to work. Apparently, they've changed it
>> recently and they now pass 6 args in registers. Eg, in the linux
>> kernel sources, old_mmap() fetches its args via copy_from_user(),
>> whereas the newer sys_mmap2() doesn't.
> Yep, according to the docs and source code I looked at in the linux
> kernel, the sixth arg is in the ebp register. I've looked all over the
> FreeBSD kernel and the linux emulator for the place that actually sets
> these, and unfortunately, due to my lack of asm coding knowledge, I can't
> find anything.
libc sets it before it enters the kernel. Then on kernel entry we save ebp
in the trapframe.
John Baldwin <[EMAIL PROTECTED]> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!" - http://www.FreeBSD.org/
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