On Tuesday 02 April 2013 02:54:39 Michael Kerrisk (man-pages) wrote:
> On Mon, Apr 1, 2013 at 12:32 PM, Mike Frysinger wrote:
> > On Monday 01 April 2013 05:29:11 Michael Kerrisk (man-pages) wrote:
> >> On Mon, Apr 1, 2013 at 10:29 AM, Mike Frysinger wrote:
> >> > on a related topic, would it be useful to document the exact calling
> >> > convention for architecture system calls ? from time to time, i need
> >> > to reference this, and i inevitably turn to a variety of sources to
> >> > dig up the answer (the kernel itself, or strace, or qemu, or glibc,
> >> > or uClibc, or lss, or other random places). i would find it handy to
> >> > have all of these in a single location.
> >>
> >> Sounds like it would be useful to have that documented. Would you have
> >> a chance to write patches for that?
> >
> > should we do it in syscall(2) ? or a dedicated man page ?
>
> It's a little hard to say until I see the shape of what comes. Can you
> provide a rough per-syscall example or two of what you expect to
> document? (Don't write too concrete a patch yet, until I can get a
> handle on what you intend.)
this renders nicely i think. it shows most of the stuff i'm interested in.
might be useful to add a dedicated section covering the clobbers in the
future.
-mike
--- a/man2/syscall.2
+++ b/man2/syscall.2
@@ -79,6 +79,35 @@ and an error code is stored in
.BR syscall ()
first appeared in
4BSD.
+.SS Architecture calling conventions
+Every architecture has its own way of invoking & passing arguments to the
+kernel.
+Note that the instruction listed below might not be the fastest or best way to
+transition to the kernel, so you might have to refer to the VDSO.
+Also note that this doesn't cover the entire calling convention -- some
+architectures may indiscriminately clobber other registers not listed here.
+.if t \{\
+.ft CW
+\}
+.TS
+l l l l l l l l l l l.
+arch/ABI insn NR ret arg1 arg2 arg3 arg4 arg5 arg6 arg7
+_
+arm/OABI swi NR; - a1 a1 a2 a3 a4 v1 v2 v3
+arm/EABI swi 0x0; r7 r1 r1 r2 r3 r4 r5 r6 r7
+bfin excpt 0x0; P0 R0 R0 R1 R2 R3 R4 R5 -
+i386 int $0x80; eax eax ebx ecx edx esi edi ebp -
+ia64 break 0x100000; r15 r10/r8 r11 r9 r10 r14 r15 r13 -
+.\" not sure about insn or NR
+.\" parisc ble 0x100(%%sr2, %%r0); - r28 r26 r25 r24 r23 r22 r21 -
+sparc/32 t 0x10; g1 o0 o0 o1 o2 o3 o4 o5 -
+sparc/64 t 0x6d; g1 o0 o0 o1 o2 o3 o4 o5 -
+x86_64 syscall; rax rax rdi rsi rdx r10 r8 r9 -
+.TE
+.if t \{\
+.in
+.ft P
+\}
.SS Architecture-specific requirements
Each architecture ABI has its own requirements on how
system call arguments are passed to the kernel.
Attachment:
signature.asc
Description: This is a digitally signed message part.
