Adam Zhang wrote:
Hi Oliver,
Yes. the code was running on Linux. Thank you very much for the
correction.
You are right. i just check the AMD64 ABI
(http://www.x86-64.org/documentation.html) that Solaris conforms to.
Because the parameter I need transfer is char array, it needs to be
put in the stack during the calling.
Hi Adam,
My version of test.c could work on both x86 32bit and 64bit platforms.
It's not necessary to have a amd64 specific version, because Solaris x64
kernel also support running 32bit application.
If you really want to try it, maybe you can use following registers
passing parameters:
%eax -> systcall number
%rdi -> first parameters
%rsi -> first parameters
%rdx -> first parameters
But do you know where i can find the x86 ABI that Solaris uses?
You might need to look into below document:
http://www.sco.com/developers/devspecs/abi386-4.pdf
Oliver Yang wrote:
Oliver Yang wrote:
Adam Zhang wrote:
Hi all,
i just write an independent write function in assembly language to
write a string to stderr.
But the code doesn't work on Solaris.
It seems you are using Gcc inline asm which will generate a system
call by issuing "int 0x91".
But you should know, doesn't like Linux, on 32bit x86, Solaris
passes parameters via stack by "push" instead of using registers.
That means, you should besides using %eax as syscall number, you
should push necessary parameters into stack before issuing "int 0x91".
Hi Adam,
Sorry for my poor English. :-[
I have checked your code, I think you inline ASM code are learned
from Linux, not Solaris. In your code, you are trying to pass
parameters by registers before issuing int 0x91:
%eax: 0x4 -> syscall number %ebx: 0x2 --> fd
%ecx buf address
%edx: int size
But actually, on Solaris x86 32bit kernel, except syscall number
should be passed by %eax, other parameters should be passed by
pushing them in stack, please refer to following code:
# /usr/sfw/bin/gcc test.c
# ./a.out
hello
# cat test.c
void write_stderr ( char * buf, int n )
{
int block[2];
block[0] = (int) buf;
block[1] = n;
__asm__ volatile (
"pushl %%ebx\n"
"movl %0, %%ebx\n"
"pushl %%ebx\n"
"movl $4, %%eax\n"
"push 4(%%ebx)\n"
"push 0(%%ebx)\n"
"push $2\n"
"push %%esp\n"
"int $0x91\n"
"addl $3,%%esp\n"
"movl %%eax, 0(%%ebx)\n"
"popl %%ebx\n"
: /*wr*/
: /*rd*/ "g" (block)
: /*trash*/ "eax", "edi", "ecx", "edx", "memory", "cc"
);
}
int main()
{
char s[]="hello\n";
write_stderr(s, sizeof(s) );
return 0;
}
Another thing is, you should run your program on Solaris Nevada,
because you used "int 0x91".
You could use mdb debug your program by setting break point before
int 0x91, check whether you provide right parameters in stack and
%eax.
Below is the code:
void write_stderr ( char * buf, int n )
{
int block[2];
block[0] = (int) buf;
block[1] = n;
__asm__ volatile (
"pushl %%ebx\n" "movl %0, %%ebx\n"
"pushl %%ebx\n" "movl 0(%%ebx), %%ecx\n"
"movl 4(%%ebx), %%edx\n"
"movl $4, %%eax\n" "movl $2, %%ebx\n"
"int $0x91\n" "popl %%ebx\n" "movl
%%eax, 0(%%ebx)\n"
"popl %%ebx\n" : /*wr*/
: /*rd*/ "g" (block)
: /*trash*/ "eax", "edi", "ecx", "edx", "memory", "cc"
);
}
Does anyone know where i am wrong?
Thank you!
Regards,
adam
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--
Cheers,
----------------------------------------------------------------------
Oliver Yang | [EMAIL PROTECTED] | x82229 | Work from office
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