The current SPSR updation code as part of the SDEI interrupt handler
code is outdated. This patch replaces the legacy code with a call to
an up-to-date create_spsr()
Change-Id: I1f5fdd41dd14f4b09601310fe881fa3783d7f505
Signed-off-by: Arvind Ram Prakash <arvind.ramprakash@arm.com>
For a feature to be used at lower ELs, EL3 generally needs to disable
the trap so that lower ELs can access the system registers associated
with the feature. Lower ELs generally check ID registers to dynamically
detect if a feature is present (in HW) or not while EL3 Firmware relies
statically on feature build macros to enable a feature.
If a lower EL accesses a system register for a feature that EL3 FW is
unaware of, EL3 traps the access and panics. This happens mostly with
EL2 but sometimes VMs can also cause EL3 panic.
To provide platforms with capability to mitigate this problem, UNDEF
injection support has been introduced which injects a synchronous
exception into the lower EL which is supposed to handle the
synchronous exception.
The current support is only provided for aarch64.
The implementation does the following on encountering sys reg trap
- Get the target EL, which can be either EL2 or EL1
- Update ELR_ELx with ELR_EL3, so that after UNDEF handling in lower EL
control returns to original location.
- ESR_ELx with EC_UNKNOWN
- Update ELR_EL3 with vector address of sync exception handler with
following possible causes
- Current EL with SP0
- Current EL with SPx
- Lower EL using AArch64
- Re-create SPSR_EL3 which will be used to generate PSTATE at ERET
Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: I1b7bf6c043ce7aec1ee4fc1121c389b490b7bfb7
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
