I'm not going to sit and debug your asm, but you're doing something
wrong because this works.
Here's some 32-bit functions I wrote a while back for a project, it
should help you figure out whats going on.
void
unsetTF(void)
{
__asm__ __volatile__(
"pushf \n"
"mov $0x100, %eax \n"
"not %eax \n"
"andl (%esp), %eax \n"
"popf \n"
);
}
void
setTF(void)
{
__asm__ __volatile__(
"pushf \n"
"orl $0x100, (%esp) \n"
"popf "
);
return;
}
unsigned int
isTFset(void)
{
unsigned int retval;
__asm__ __volatile__(
"xor %%eax, %%eax \n"
"pushf \n"
"pop %%eax \n"
"and $0x100, %%eax \n"
: "=a" (retval)
);
return retval;
}
On Dec 5, 2007 11:19 AM, ninjaboy <n0b0dyn1nj4@xxxxxxxxx> wrote:
> 2007/12/5, Rene Herman <rene.herman@xxxxxxxxxxxx>:
>
> > On 05-12-07 15:23, ninjaboy wrote:
> >
> > > why if i put TF in my prog and install an handler to SIGTRAP the
> > > handler is not caught?
> >
> > Works for me.
> >
> > Rene.
> >
> > /* gcc -W -Wall -o sigtrap sigtrap.c */
> >
> > #include <stdlib.h>
> > #include <stdio.h>
> > #include <signal.h>
> >
> > volatile sig_atomic_t trap;
> >
> > void sigtrap(int signum __attribute__((unused)))
> > {
> > trap = 1;
> > }
> >
> > int main(void)
> > {
> > struct sigaction sa;
> >
> > sa.sa_handler = sigtrap;
> > sigemptyset(&sa.sa_mask);
> > sa.sa_flags = 0;
> >
> > if (sigaction(SIGTRAP, &sa, NULL) < 0) {
> > perror("could not install handler");
> > return EXIT_FAILURE;
> > }
> >
> > asm("int3");
> >
> > printf("trap = %d\n", (int)trap);
> > return EXIT_SUCCESS;
> > }
> >
> >
> Ehm... int3 works for me too, the TF doesn't work.
>
> pushf
> xor %rax, %rax
> pop %rax
> orq $0x100, %rax
> pushq %rax
> popf
>
> the trap released here doesn't exec my handler.
>
>
> --
> noone is alone.
>
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>
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