The right of election of a surviving spouse and the rights of the surviving spouse to the homestead, exempt property, and family allowance, or any of them, may be waived, wholly or partially, after marriage, by a written contract, agreement, or waiver signed by the party waiving after fair disclosure. Unless it provides to the contrary, a waiver of “all rights,” or equivalent language, in the property or estate of a spouse is a waiver only of the right to the elective share. Any waiver prior to marriage must be made pursuant to section 519.11.