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NOTES.md

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Security Notes

  • Both cores start out of reset without valid stacks
    • core 0 will set a preboot secure stack and enter C code
    • core 1 will wait and do handshake wiht no stack until it is given a secure stack to use
  • Question: do we now need to pause core1? I guess not, because if it is running it can itself reset ACCESSCTRL
  • Question: Clang? No - it crashes in link with our mixed arm6/arm8

OLD

Multiple function tables

For speed we don't want to have to NS wrap functions. However for something like memcpy (anything which accesses memory), we must do so potentially duplicate: If we just use the NS version then it would not be able to access secure memory.

  • Common ARM Secure
  • Common ARM NS
  • Common RISCV

Flash writing

Current thought is to use security attributes

SECURITY REMINDERS

  • don't forget that non secure IRQ can preempt secure code and change NS data.