How do I write to RAM, beyond the RAM-range specified in the linker script, when caching is enabled?

I am working with the STM32F760I-EVAL board. In the linker script I have specified that the RAM is only 500 x 1024 bytes, even though it really is 512 * 1024 bytes. By doing this I can place variables in the last 12 x 1024 bytes of the RAM that survives a software reset. The problem, as soon as I enable caching using SCB_EnableICache() and SCB_EnableDCache() this trick stops working. It doesn't matter how many volatile modifiers I throw into the code that does the writing into RAM, it just won't work anymore. Can someone please help me?