Re: [PATCH] man2 : syscall.2 : document syscall calling conventions

[Mike Frysinger <vapier@gentoo.org>]

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On Sunday 07 April 2013 14:48:42 John David Anglin wrote:
> On 7-Apr-13, at 2:39 PM, Mike Frysinger wrote:
> > just to be clear, the only insn you need is:
> > 	ble 0x100(%sr2, %r0);
> > 
> > the kernel docs say sr2 holds the kernel gateway page (so i guess
> > 0x100 is a
> > known offset into that).  the docs don't mention r0 that i can see,
> > so i'm
> > guessing it's one of those "always 0" registers ?
> 
> Yes.  There is also an entry at offset 0xb0 for light-weight-
> syscalls.  Currently,
> this implements an atomic CAS operation used for pthread support.

interesting.  sounds like a poor man's vDSO.  i'll document this the new 
vdso(7) man page.
-mike

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