This patch introduces support to handle traps from lower ELs for
IMPDEF system register accesses. The actual support is left to the
platforms to implement.
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
Change-Id: I623d5c432b4ce4328b68f238c15b1c83df97c1e5
When a platform decides to use FEAT_RNG_TRAP, every RNDR or RNDRSS read
will trap into EL3. The platform can then emulate those instructions, by
either executing the real CPU instructions, potentially conditioning the
results, or use rate-limiting or filtering to protect the hardware
entropy pool. Another possiblitiy would be to use some platform specific
TRNG device to get entropy and returning this.
To demonstrate platform specific usage, add a demo implementation for the
FVP: It will execute the actual CPU instruction and just return the
result. This should serve as reference code to implement platform specific
policies.
We change the definition of read_rndr() and read_rndrrs() to use the
alternative sysreg encoding, so that all assemblers can handle that.
Add documentation about the new platform specific RNG handler function.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Change-Id: Ibce817b3b06ad20129d15531b81402e3cc3e9a9e
At the moment we only handle SMC traps from lower ELs, but ignore any
other synchronous traps and just panic.
To cope with system register traps, which we might need to emulate,
introduce a C function to handle those traps, and wire that up in the
exception handler to be called.
We provide a dispatcher function (in C), that will call platform
specific implementation for certain (classes of) system registers.
For now this is empty.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Change-Id: If147bcb49472eb02791498700300926afbcf75ff
