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authorPeter Maydell <peter.maydell@linaro.org>2022-05-09 16:54:57 +0100
committerPeter Maydell <peter.maydell@linaro.org>2022-05-19 16:19:02 +0100
commit75662f36e3d11b986456210670719a7837111cd7 (patch)
treec14c771deb155975118d95194173e70a197489ec /docs
parente04bf5a793ee5e7afdda8a1d1af08888fd67a989 (diff)
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target/arm: Implement FEAT_IDST
The Armv8.4 feature FEAT_IDST specifies that exceptions generated by read accesses to the feature ID space should report a syndrome code of 0x18 (EC_SYSTEMREGISTERTRAP) rather than 0x00 (EC_UNCATEGORIZED). The feature ID space is defined to be: op0 == 3, op1 == {0,1,3}, CRn == 0, CRm == {0-7}, op2 == {0-7} In our implementation we might return the EC_UNCATEGORIZED syndrome value for a system register access in four cases: * no reginfo struct in the hashtable * cp_access_ok() fails (ie ri->access doesn't permit the access) * ri->accessfn returns CP_ACCESS_TRAP_UNCATEGORIZED at runtime * ri->type includes ARM_CP_RAISES_EXC, and the readfn raises an UNDEF exception at runtime We have very few regdefs that set ARM_CP_RAISES_EXC, and none of them are in the feature ID space. (In the unlikely event that any are added in future they would need to take care of setting the correct syndrome themselves.) This patch deals with the other three cases, and enables FEAT_IDST for AArch64 -cpu max. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20220509155457.3560724-1-peter.maydell@linaro.org
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-rw-r--r--docs/system/arm/emulation.rst1
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diff --git a/docs/system/arm/emulation.rst b/docs/system/arm/emulation.rst
index 8f25502..3e95bba 100644
--- a/docs/system/arm/emulation.rst
+++ b/docs/system/arm/emulation.rst
@@ -31,6 +31,7 @@ the following architecture extensions:
- FEAT_FlagM2 (Enhancements to flag manipulation instructions)
- FEAT_HPDS (Hierarchical permission disables)
- FEAT_I8MM (AArch64 Int8 matrix multiplication instructions)
+- FEAT_IDST (ID space trap handling)
- FEAT_IESB (Implicit error synchronization event)
- FEAT_JSCVT (JavaScript conversion instructions)
- FEAT_LOR (Limited ordering regions)