target/arm: Always set FAR to a known unknown value for debug exceptions
For debug exceptions due to breakpoints or the BKPT instruction which are taken to AArch32, the Fault Address Register is architecturally UNKNOWN. We were using that as license to simply not set env->exception.vaddress, but this isn't correct, because it will expose to the guest whatever old value was in that field when arm_cpu_do_interrupt_aarch32() writes it to the guest IFSR. That old value might be a FAR for a previous guest EL2 or secure exception, in which case we shouldn't show it to an EL1 or non-secure exception handler. It might also be a non-deterministic value, which is bad for record-and-replay. Clear env->exception.vaddress before taking breakpoint debug exceptions, to avoid this minor information leak. Signed-off-by: NPeter Maydell <peter.maydell@linaro.org> Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org> Message-id: 20180320134114.30418-5-peter.maydell@linaro.org
Showing
想要评论请 注册 或 登录