On 18/04/2023 17:46, folkert wrote:
The 2 calls it does are:
print_char:
movb (%esi), %al
movb %al, buffer
movl $4, %eax
movl $1, %ebx
movl $buffer, %ecx
movl $1, %edx
int $0x80
ret
exit:
movl $1, %eax
movl $0, %ebx
int $0x80
Valgrind can't run just any executable binary. It has quite a lot of
hard coded limitations that correspont (mostly) to what compilers and
link editors will produce. So if you use assembler and use opcodes not
normally generated by compilers then it won't work.
The code that handles this is
case 0xCD: /* INT imm8 */
d64 = getUChar(delta); delta++;
/* Handle int $0xD2 (Solaris fasttrap syscalls). */
if (d64 == 0xD2) {
jmp_lit(dres, Ijk_Sys_int210, guest_RIP_bbstart + delta);
vassert(dres->whatNext == Dis_StopHere);
DIP("int $0xD2\n");
return delta;
}
goto decode_failure;
So int 0x80 results in a decode error.
Can you use syscall?
A+
Paul
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