unicorn/qemu/target
Peter Maydell c6041bf94b
target/arm: Avoid bogus NSACR traps on M-profile without Security Extension
In Arm v8.0 M-profile CPUs without the Security Extension and also in
v7M CPUs, there is no NSACR register. However, the code we have to handle
the FPU does not always check whether the ARM_FEATURE_M_SECURITY bit
is set before testing whether env->v7m.nsacr permits access to the
FPU. This means that for a CPU with an FPU but without the Security
Extension we would always take a bogus fault when trying to stack
the FPU registers on an exception entry.

We could fix this by adding extra feature bit checks for all uses,
but it is simpler to just make the internal value of nsacr 0xcff
("all non-secure accesses allowed"), since this is not guest
visible when the Security Extension is not present. This allows
us to continue to follow the Arm ARM pseudocode which takes a
similar approach. (In particular, in the v8.1 Arm ARM the register
is documented as reading as 0xcff in this configuration.)

Fixes: https://bugs.launchpad.net/qemu/+bug/1838475

Backports commit 02ac2f7f613b47f6a5b397b20ab0e6b2e7fb89fa from qemu
2019-08-08 19:56:56 -04:00
..
arm target/arm: Avoid bogus NSACR traps on M-profile without Security Extension 2019-08-08 19:56:56 -04:00
i386 i386: Fix Snowridge CPU model name and features 2019-08-08 19:52:23 -04:00
m68k m68k comments break patch submission due to being incorrectly formatted 2019-08-08 14:26:45 -04:00
mips target/mips: Fix emulation of MSA pack instructions on big endian hosts 2019-08-08 19:51:34 -04:00
riscv RISC-V: Clear load reservations on context switch and SC 2019-08-08 17:15:45 -04:00
sparc cpu: Introduce CPUNegativeOffsetState 2019-06-13 15:08:25 -04:00