Memory layout

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Userspace

The userspace virtual address space has 38 bits. It seems that when the IPC protocol was designed, it was only 36 bits leading to a weird encoding format.

There are several regions maintained by the kernel, each one starting at the upper bits bit37-21 randomized:

  • Main binary region.
  • Heap region.
  • Stack mapping region, available from SVC#svcGetInfo.

For the stack mapping region, the userland randomizes a page-offset where to start inside the region. This adds some additional entropy.

Binaries mapped by RO seems to be mapped randomly everywhere in the entire address space.