/**
* modify_user_hw_breakpoint - modify a user-space hardware breakpoint
* @bp: the breakpoint structure to modify
* @attr: new breakpoint attributes
* @triggered: callback to trigger when we hit the breakpoint
* @tsk: pointer to 'task_struct' of the process to which the address belongs
*/
int modify_user_hw_breakpoint(struct perf_event *bp, struct perf_event_attr *attr)
{
u64 old_addr = bp->attr.bp_addr;
int old_type = bp->attr.bp_type;
int old_len = bp->attr.bp_len;
int err = 0;
perf_event_disable(bp);
bp->attr.bp_addr = attr->bp_addr;
bp->attr.bp_type = attr->bp_type;
bp->attr.bp_len = attr->bp_len;
if (attr->disabled)
goto end;
err = arch_validate_hwbkpt_settings(bp, bp->ctx->task);
if (!err)
perf_event_enable(bp);
if (err) {
bp->attr.bp_addr = old_addr;
bp->attr.bp_type = old_type;
bp->attr.bp_len = old_len;
if (!bp->attr.disabled)
perf_event_enable(bp);
return err;
}
end:
bp->attr.disabled = attr->disabled;
return 0;
}
int register_perf_hw_breakpoint(struct perf_event *bp)
{
int ret;
ret = reserve_bp_slot(bp);
if (ret)
return ret;
/*
* Ptrace breakpoints can be temporary perf events only
* meant to reserve a slot. In this case, it is created disabled and
* we don't want to check the params right now (as we put a null addr)
* But perf tools create events as disabled and we want to check
* the params for them.
* This is a quick hack that will be removed soon, once we remove
* the tmp breakpoints from ptrace
*/
if (!bp->attr.disabled || !bp->overflow_handler)
ret = arch_validate_hwbkpt_settings(bp, bp->ctx->task);
/* if arch_validate_hwbkpt_settings() fails then release bp slot */
if (ret)
release_bp_slot(bp);
return ret;
}
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;
}
