On 2015-02-16 14:49, Mark Rutland wrote:
On Mon, Feb 16, 2015 at 12:54:48PM +0000, Jan Kiszka wrote:
From: Ian Campbell ijc@hellion.org.uk
These registers can be used to prevent non-secure world from accessing a megabyte aligned region of RAM, use them to protect the u-boot secure monitor code.
What happens if the CPU tried to read this memory from the non-secure world? If the OS has it mapped then the CPU could perform speculative reads at any point in time.
If that can raise an abort then the OS needs to not map the region.
I take it U-Boot uses a secure mapping for the region (which I believe should avoid the mismatched attributes issue I mentioned in my other reply).
What I can contribute to this are kernel messages due to a misconfiguration of our hypervisor Jailhouse (while Linux was still trying to boot it):
[ 61.896860] tegra-mc 70019000.memory-controller: mpcorew: write @0x00000000fff00040: Security violation (TrustZone violation) [ 61.896888] tegra-mc 70019000.memory-controller: mpcorew: write @0x00000000fff2d340: Security violation (TrustZone violation)
So it seems that Linux is receiving a violation report here when trying to access the memory.
Jan