Hi All,
Pardon my naive question, I am newbe in x86 (32bit) architecture and I
got hard time to find info on x86 procedure convention with GCC.
The doc I found so far say that with __attribute__((fastcall)) it is
possible to pass up to 2 long into regs ecx, edx.
Yet looking at linux kernel code I got this on a piece of code.
disass crash_kexec
0xc049a8c0 crash_kexec:
....
0x00000000c049a922 movl kexec_crash_image,%eax
0x00000000c049a927 calll machine_kexec
The C code shows
void crash_kexec(struct pt_regs *regs)
{...
machine_kexec(kexec_crash_image);
}
and machine_kexec() prolog shows
0xc042c2a0 machine_kexec:
0x00000000c042c2a0 pushl %ebp
0x00000000c042c2a1 pushl %edi
0x00000000c042c2a2 pushl %esi
0x00000000c042c2a3 pushl %ebx
0x00000000c042c2a4 movl %eax,%ebx
0x00000000c042c2a6 subl $0x2c,%esp
With a save of eax (suposedly args0) into a callee save.
So my question, does GCC under some circumstance does pass args0 into rax ?
Thanx in advance
Cheers,
Phi
