Hello,
its been some time since I looked at the TLS conventions and I only done
this on ARM.
But I would strongly advise you to implement the function in asm, on ARM
you arent allowed to change any register except the one you return and I
would bet its the same on other architectures.
Norbert
Am 29.01.2014, 08:51 Uhr, schrieb Sebastian Huber
<sebastian.huber@xxxxxxxxxxxxxxxxxx>:
On 2014-01-28 20:15, Ian Lance Taylor wrote:
On Tue, Jan 28, 2014 at 7:49 AM, Sebastian Huber
<sebastian.huber@xxxxxxxxxxxxxxxxxx> wrote:
it seems GCC uses this ColdFire TLS ABI:
https://lists.debian.org/debian-68k/2007/11/msg00071.html
Here we have a function
void *__m68k_read_tp(void)
which must return the thread pointer in register a0.
I have to implement this function. Is there a way to instruct GCC to
return
the value in register a0 instead of d0 or do I have to use assembler to
implement this function?
I believe that on m68k GNU/Linux a function that returns a pointer
will normally return the value in a0.
Ian
The function
void *__m68k_read_tp(void)
{
const Thread_Control *executing = _Thread_Get_executing();
return (char *) executing->Start.tls_area +
_TLS_Get_thread_control_block_area_size((uintptr_t) _TLS_Alignment)
+ 0x7000;
}
translates to
__m68k_read_tp:
move.l #_TLS_Alignment,%d0
moveq #8,%d1
move.l _Per_CPU_Information+18,%a0
cmp.l %d0,%d1
jls .L2
moveq #8,%d0
.L2:
add.l #28672,%d0
add.l 194(%a0),%d0
rts
I use now:
void __m68k_read_tp(void)
{
const Thread_Control *executing = _Thread_Get_executing();
void *tp = (char *) executing->Start.tls_area +
_TLS_Get_thread_control_block_area_size((uintptr_t) _TLS_Alignment)
+ 0x7000;
__asm__ volatile (
"move.l %0, %%a0"
:
: "d" (tp)
);
}
