scontext
Supervisor Context
This optional register is only accessible in S/HS-mode, VS-mode, M-mode and Debug Mode.
Accessibility of this CSR is controlled by mstateen0[57] and hstateen0[57] in the
Smstateen extension. Enabling scontext can be a security risk in a virtualized system
with a hypervisor that does not swap scontext.
Attributes
Defining Extension |
allOf: * Sdtrig, version >= Sdtrig@1.0.0 * S, version >= S@1.11.0 |
|---|---|
CSR Address |
0x5a8 |
Length |
* 32 when (priv_mode() == PrivilegeMode::M && CSR[misa].MXL == 0) |
(priv_mode() == PrivilegeMode::S && CSR[mstatus].SXL == %%) |
|
(priv_mode() == PrivilegeMode::VS && CSR[hstatus].VSXL == %%) * 64 when (priv_mode() == PrivilegeMode::M && CSR[misa].MXL == 1) |
|
(priv_mode() == PrivilegeMode::S && CSR[mstatus].SXL == %%) |
|
(priv_mode() == PrivilegeMode::VS && CSR[hstatus].VSXL == %%) |
|
Privilege Mode |
S |
Format
This CSR format changes dynamically.
Software write
This CSR may store a value that is different from what software attempts to write.
When a software write occurs (e.g., through csrrw), the following determines the written value:
DATA = # check if mstateen0 or hstateen0 is clear
if (implemented?(ExtensionName::Smstateen) && ((CSR[mstateen0].CONTEXT != 0) || (CSR[hstateen0].CONTEXT != 0))) {
unimplemented_csr($encoding);
}
# enforce width of SCONTEXT
Bits<32> scontext_value = csr_value.DATA & ((32'1 << DBG_SCONTEXT_WIDTH) - 1);
return scontext_value;
Software read
This CSR may return a value that is different from what is stored in hardware.
if (implemented?(ExtensionName::Smstateen) && mstateen0.CONTEXT != 0) || (hstateen0.CONTEXT != 0) {
unimplemented_csr($encoding);
}