static int validate_hw_breakpoint(struct perf_event *bp)
{
int ret;
ret = arch_validate_hwbkpt_settings(bp);
if (ret)
return ret;
if (arch_check_bp_in_kernelspace(bp)) {
if (bp->attr.exclude_kernel)
return -EINVAL;
/*
* Don't let unprivileged users set a breakpoint in the trap
* path to avoid trap recursion attacks.
*/
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
}
return 0;
}
static int __kprobes hw_breakpoint_handler(struct die_args *args)
{
int cpu, i, rc = NOTIFY_STOP;
struct perf_event *bp;
unsigned int cmf, resume_mask;
cmf = sh_ubc->triggered_mask();
if (unlikely(!cmf))
return NOTIFY_DONE;
resume_mask = sh_ubc->active_mask();
sh_ubc->disable_all();
cpu = get_cpu();
for (i = 0; i < sh_ubc->num_events; i++) {
unsigned long event_mask = (1 << i);
if (likely(!(cmf & event_mask)))
continue;
rcu_read_lock();
bp = per_cpu(bp_per_reg[i], cpu);
if (bp)
rc = NOTIFY_DONE;
sh_ubc->clear_triggered_mask(event_mask);
if (!bp) {
rcu_read_unlock();
break;
}
if (bp->overflow_handler == ptrace_triggered)
resume_mask &= ~(1 << i);
perf_bp_event(bp, args->regs);
if (!arch_check_bp_in_kernelspace(bp)) {
siginfo_t info;
info.si_signo = args->signr;
info.si_errno = notifier_to_errno(rc);
info.si_code = TRAP_HWBKPT;
force_sig_info(args->signr, &info, current);
}
rcu_read_unlock();
}
if (cmf == 0)
rc = NOTIFY_DONE;
sh_ubc->enable_all(resume_mask);
put_cpu();
return rc;
}
/*
* Construct an arch_hw_breakpoint from a perf_event.
*/
static int arch_build_bp_info(struct perf_event *bp)
{
struct arch_hw_breakpoint *info = counter_arch_bp(bp);
/* Type */
switch (bp->attr.bp_type) {
case HW_BREAKPOINT_X:
info->ctrl.type = ARM_BREAKPOINT_EXECUTE;
break;
case HW_BREAKPOINT_R:
info->ctrl.type = ARM_BREAKPOINT_LOAD;
break;
case HW_BREAKPOINT_W:
info->ctrl.type = ARM_BREAKPOINT_STORE;
break;
case HW_BREAKPOINT_RW:
info->ctrl.type = ARM_BREAKPOINT_LOAD | ARM_BREAKPOINT_STORE;
break;
default:
return -EINVAL;
}
/* Len */
switch (bp->attr.bp_len) {
case HW_BREAKPOINT_LEN_1:
info->ctrl.len = ARM_BREAKPOINT_LEN_1;
break;
case HW_BREAKPOINT_LEN_2:
info->ctrl.len = ARM_BREAKPOINT_LEN_2;
break;
case HW_BREAKPOINT_LEN_4:
info->ctrl.len = ARM_BREAKPOINT_LEN_4;
break;
case HW_BREAKPOINT_LEN_8:
info->ctrl.len = ARM_BREAKPOINT_LEN_8;
break;
default:
return -EINVAL;
}
/*
* On AArch64, we only permit breakpoints of length 4, whereas
* AArch32 also requires breakpoints of length 2 for Thumb.
* Watchpoints can be of length 1, 2, 4 or 8 bytes.
*/
if (info->ctrl.type == ARM_BREAKPOINT_EXECUTE) {
if (is_compat_task()) {
if (info->ctrl.len != ARM_BREAKPOINT_LEN_2 &&
info->ctrl.len != ARM_BREAKPOINT_LEN_4)
return -EINVAL;
} else if (info->ctrl.len != ARM_BREAKPOINT_LEN_4) {
/*
* FIXME: Some tools (I'm looking at you perf) assume
* that breakpoints should be sizeof(long). This
* is nonsense. For now, we fix up the parameter
* but we should probably return -EINVAL instead.
*/
info->ctrl.len = ARM_BREAKPOINT_LEN_4;
}
}
/* Address */
info->address = bp->attr.bp_addr;
/*
* Privilege
* Note that we disallow combined EL0/EL1 breakpoints because
* that would complicate the stepping code.
*/
if (arch_check_bp_in_kernelspace(bp))
info->ctrl.privilege = AARCH64_BREAKPOINT_EL1;
else
info->ctrl.privilege = AARCH64_BREAKPOINT_EL0;
/* Enabled? */
info->ctrl.enabled = !bp->attr.disabled;
return 0;
}
static int __kprobes hw_breakpoint_handler(struct die_args *args)
{
int cpu, i, rc = NOTIFY_STOP;
struct perf_event *bp;
unsigned int cmf, resume_mask;
/*
* Do an early return if none of the channels triggered.
*/
cmf = sh_ubc->triggered_mask();
if (unlikely(!cmf))
return NOTIFY_DONE;
/*
* By default, resume all of the active channels.
*/
resume_mask = sh_ubc->active_mask();
/*
* Disable breakpoints during exception handling.
*/
sh_ubc->disable_all();
cpu = get_cpu();
for (i = 0; i < sh_ubc->num_events; i++) {
unsigned long event_mask = (1 << i);
if (likely(!(cmf & event_mask)))
continue;
/*
* The counter may be concurrently released but that can only
* occur from a call_rcu() path. We can then safely fetch
* the breakpoint, use its callback, touch its counter
* while we are in an rcu_read_lock() path.
*/
rcu_read_lock();
bp = per_cpu(bp_per_reg[i], cpu);
if (bp)
rc = NOTIFY_DONE;
/*
* Reset the condition match flag to denote completion of
* exception handling.
*/
sh_ubc->clear_triggered_mask(event_mask);
/*
* bp can be NULL due to concurrent perf counter
* removing.
*/
if (!bp) {
rcu_read_unlock();
break;
}
/*
* Don't restore the channel if the breakpoint is from
* ptrace, as it always operates in one-shot mode.
*/
if (bp->overflow_handler == ptrace_triggered)
resume_mask &= ~(1 << i);
perf_bp_event(bp, args->regs);
/* Deliver the signal to userspace */
if (!arch_check_bp_in_kernelspace(bp)) {
siginfo_t info;
info.si_signo = args->signr;
info.si_errno = notifier_to_errno(rc);
info.si_code = TRAP_HWBKPT;
force_sig_info(args->signr, &info, current);
}
rcu_read_unlock();
}
if (cmf == 0)
rc = NOTIFY_DONE;
sh_ubc->enable_all(resume_mask);
put_cpu();
return rc;
}
