static inline void vperfctr_handle_overflow(struct task_struct *tsk,
struct vperfctr *perfctr)
{
unsigned int pmc_mask;
siginfo_t si;
sigset_t old_blocked;
pmc_mask = perfctr_cpu_identify_overflow(&perfctr->cpu_state);
if (!pmc_mask) {
printk(KERN_ERR "%s: BUG! pid %d has unidentifiable overflow source\n", __FUNCTION__, tsk->pid);
return;
}
/* suspend a-mode and i-mode PMCs, leaving only TSC on */
/* XXX: some people also want to suspend the TSC */
// we are storing 'cpu_state.cstatus' in 'iresume_cstatus' because
// in vperfctr_resume, we only want to read the status of those
// In the following TSC is resumed and continues to collect the
// stats
// if 'perfctr->iresume_cstatus' is not updated below, vperfctr_iresume() fails
// as it thinks it was spuriously called inspite of absence of i-mode counters.
// vperfctr_iresume() -> ... -> do_vperfctr_iresume() is a different thread of
// execution from vperfctr_resume() -> ... -> vperfctr_iresume() -> __write_control() ->
// ...
perfctr->iresume_cstatus = perfctr->cpu_state.cstatus;
if (perfctr_cstatus_has_tsc(perfctr->iresume_cstatus)) {
perfctr->cpu_state.cstatus = perfctr_mk_cstatus(1, 0, 0);
vperfctr_resume(perfctr);
}
else {
perfctr->cpu_state.cstatus = 0;
}
// the following siginfo_t structure helps the kernel in invoking
// the correct signal handler. Is that right ?
// what's the deal with si_errno? what does it say ? si_code ?
si.si_signo = perfctr->si_signo;
si.si_errno = 0;
si.si_code = SI_PMC_OVF;
si.si_pmc_ovf_mask = pmc_mask;
/* deliver signal without waking up the receiver */
spin_lock_irq(&tsk->sighand->siglock);
old_blocked = tsk->blocked;
sigaddset(&tsk->blocked, si.si_signo);
spin_unlock_irq(&tsk->sighand->siglock);
if (!send_sig_info(si.si_signo, &si, tsk)) {
send_sig(si.si_signo, tsk, 1);
}
spin_lock_irq(&tsk->sighand->siglock);
tsk->blocked = old_blocked;
recalc_sigpending();
spin_unlock_irq(&tsk->sighand->siglock);
}
static void vperfctr_handle_overflow(struct task_struct *tsk,
struct vperfctr *perfctr)
{
unsigned int pmc_mask;
siginfo_t si;
sigset_t old_blocked;
pmc_mask = perfctr_cpu_identify_overflow(&perfctr->cpu_state);
if (!pmc_mask) {
#ifdef CONFIG_PPC64
/* On some hardware (ppc64, in particular) it's
* impossible to control interrupts finely enough to
* eliminate overflows on counters we don't care
* about. So in this case just restart the counters
* and keep going. */
vperfctr_resume(perfctr);
#else
printk(KERN_ERR "%s: BUG! pid %d has unidentifiable overflow source\n",
__FUNCTION__, tsk->id);
#endif
return;
}
perfctr->ireload_needed = 1;
/* suspend a-mode and i-mode PMCs, leaving only TSC on */
/* XXX: some people also want to suspend the TSC */
perfctr->resume_cstatus = perfctr->cpu_state.user.cstatus;
if (perfctr_cstatus_has_tsc(perfctr->resume_cstatus)) {
perfctr->cpu_state.user.cstatus = perfctr_mk_cstatus(1, 0, 0);
vperfctr_resume(perfctr);
} else
perfctr->cpu_state.user.cstatus = 0;
si.si_signo = perfctr->si_signo;
si.si_errno = 0;
si.si_code = SI_PMC_OVF;
si.si_pmc_ovf_mask = pmc_mask;
/* deliver signal without waking up the receiver */
spin_lock_irq(&tsk->sighand->siglock);
old_blocked = tsk->blocked;
sigaddset(&tsk->blocked, si.si_signo);
spin_unlock_irq(&tsk->sighand->siglock);
if (!send_sig_info(si.si_signo, &si, tsk))
send_sig(si.si_signo, tsk, 1);
spin_lock_irq(&tsk->sighand->siglock);
tsk->blocked = old_blocked;
recalc_sigpending();
spin_unlock_irq(&tsk->sighand->siglock);
}
static void vperfctr_handle_overflow(struct task_struct *tsk,
struct vperfctr *perfctr)
{
unsigned int pmc_mask;
siginfo_t si;
sigset_t old_blocked;
pmc_mask = perfctr_cpu_identify_overflow(&perfctr->cpu_state);
if (!pmc_mask) {
printk(KERN_ERR "%s: BUG! pid %d has unidentifiable overflow source\n",
__FUNCTION__, tsk->pid);
return;
}
/* suspend a-mode and i-mode PMCs, leaving only TSC on */
/* XXX: some people also want to suspend the TSC */
perfctr->iresume_cstatus = perfctr->cpu_state.cstatus;
if (perfctr_cstatus_has_tsc(perfctr->iresume_cstatus)) {
perfctr->cpu_state.cstatus = perfctr_mk_cstatus(1, 0, 0);
vperfctr_resume(perfctr);
} else
perfctr->cpu_state.cstatus = 0;
si.si_signo = perfctr->si_signo;
si.si_errno = 0;
si.si_code = SI_PMC_OVF;
si.si_pmc_ovf_mask = pmc_mask;
/* deliver signal without waking up the receiver */
spin_lock_irq(&task_siglock(tsk));
old_blocked = tsk->blocked;
sigaddset(&tsk->blocked, si.si_signo);
spin_unlock_irq(&task_siglock(tsk));
if (!send_sig_info(si.si_signo, &si, tsk))
send_sig(si.si_signo, tsk, 1);
spin_lock_irq(&task_siglock(tsk));
tsk->blocked = old_blocked;
recalc_sigpending();
spin_unlock_irq(&task_siglock(tsk));
}
int perfctr_cpu_update_control(struct perfctr_cpu_state *state, int is_global)
{
int err;
// since we updated the control, we invalidate the cpu id in the state
// so that we can force reload of control registers
clear_isuspend_cpu(state);
state->cstatus = 0;
/* disallow i-mode counters if we cannot catch the interrupts */
if (!(perfctr_info.cpu_features & PERFCTR_FEATURE_PCINT)
&& state->control.nrictrs) {
return -EPERM;
}
err = check_ireset(state);
if (err < 0) {
return err;
}
err = check_control(state); /* may initialise state->cstatus */
if (err < 0) {
return err;
}
// Ok, while the map values and the start values for i-mode counters
// are updated in the above function check_control() and the following
// function setup_imode_start_values(), the 'cstatus' values is set here
// how do u ensure that all i-mode registers are specified beyond a-mode
// registers
state->cstatus |= perfctr_mk_cstatus(state->control.tsc_on,
state->control.nractrs,
state->control.nrictrs);
setup_imode_start_values(state);
return 0;
}
