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Provide accessibility control of xcontext CSRs through stateen0[57] CSR #1550

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Provide accessibility control of xcontext CSRs through stateen0[57] CSR #1550

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bd45f59
Implement mstateen0[57] for hcontext and scontext
YenHaoChen Dec 22, 2023
a93755f
Disallow accessing mcontext if mstateen0[57] is 0
YenHaoChen Dec 25, 2023
546cc85
Implement mscontext CSR
YenHaoChen Dec 22, 2023
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57 changes: 57 additions & 0 deletions riscv/csrs.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1127,6 +1127,22 @@ void counter_proxy_csr_t::verify_permissions(insn_t insn, bool write) const {
}
}

context_proxy_csr_t::context_proxy_csr_t(processor_t* const proc, const reg_t addr, csr_t_p delegate):
proxy_csr_t(proc, addr, delegate) {
}

void context_proxy_csr_t::verify_permissions(insn_t insn, bool write) const {
if (proc->extension_enabled(EXT_SMSTATEEN)) {
if ((state->prv < PRV_M) && !(state->mstateen[0]->read() & MSTATEEN0_HCONTEXT))
throw trap_illegal_instruction(insn.bits());

if (state->v && !(state->hstateen[0]->read() & HSTATEEN0_SCONTEXT))
throw trap_virtual_instruction(insn.bits());
}

proxy_csr_t::verify_permissions(insn, write);
}

mevent_csr_t::mevent_csr_t(processor_t* const proc, const reg_t addr):
basic_csr_t(proc, addr, 0) {
}
Expand Down Expand Up @@ -1252,6 +1268,31 @@ void debug_mode_csr_t::verify_permissions(insn_t insn, bool write) const {
throw trap_illegal_instruction(insn.bits());
}

mscontext_csr_t::mscontext_csr_t(processor_t* const proc, const reg_t addr, csr_t_p delegate):
proxy_csr_t(proc, addr, delegate) {
}

void mscontext_csr_t::verify_permissions(insn_t insn, bool write) const {
if (proc->extension_enabled(EXT_SMSTATEEN)) {
if ((state->prv < PRV_M) && !(state->mstateen[0]->read() & MSTATEEN0_HCONTEXT))
throw trap_illegal_instruction(insn.bits());

if (state->v && !(state->hstateen[0]->read() & HSTATEEN0_SCONTEXT))
throw trap_virtual_instruction(insn.bits());
}

// Address of mscontext does not conform to the CSR conventions, i.e., csr_priv == PRV_S
if (!proc->extension_enabled('S'))
throw trap_illegal_instruction(insn.bits());

unsigned priv = state->prv == PRV_S && !state->v ? PRV_HS : state->prv;
if (priv < PRV_S) {
if (state->v)
throw trap_virtual_instruction(insn.bits());
throw trap_illegal_instruction(insn.bits());
}
}

dpc_csr_t::dpc_csr_t(processor_t* const proc, const reg_t addr):
epc_csr_t(proc, addr) {
}
Expand Down Expand Up @@ -1614,6 +1655,22 @@ void jvt_csr_t::verify_permissions(insn_t insn, bool write) const {
}
}

context_csr_t::context_csr_t(processor_t* const proc, const reg_t addr, const reg_t mask, const reg_t init):
masked_csr_t(proc, addr, mask, init) {
}

void context_csr_t::verify_permissions(insn_t insn, bool write) const {
if (proc->extension_enabled(EXT_SMSTATEEN)) {
if ((state->prv < PRV_M) && !(state->mstateen[0]->read() & MSTATEEN0_HCONTEXT))
throw trap_illegal_instruction(insn.bits());

if (state->v && !(state->hstateen[0]->read() & HSTATEEN0_SCONTEXT))
throw trap_virtual_instruction(insn.bits());
}

basic_csr_t::verify_permissions(insn, write);
}

virtualized_indirect_csr_t::virtualized_indirect_csr_t(processor_t* const proc, csr_t_p orig, csr_t_p virt):
virtualized_csr_t(proc, orig, virt) {
}
Expand Down
18 changes: 18 additions & 0 deletions riscv/csrs.h
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Original file line number Diff line number Diff line change
Expand Up @@ -588,6 +588,12 @@ class counter_proxy_csr_t: public proxy_csr_t {
bool myenable(csr_t_p counteren) const noexcept;
};

class context_proxy_csr_t: public proxy_csr_t {
public:
context_proxy_csr_t(processor_t* const proc, const reg_t addr, csr_t_p delegate);
virtual void verify_permissions(insn_t insn, bool write) const override;
};

class mevent_csr_t: public basic_csr_t {
public:
mevent_csr_t(processor_t* const proc, const reg_t addr);
Expand Down Expand Up @@ -664,6 +670,12 @@ class debug_mode_csr_t: public basic_csr_t {
virtual void verify_permissions(insn_t insn, bool write) const override;
};

class mscontext_csr_t: public proxy_csr_t {
public:
mscontext_csr_t(processor_t* const proc, const reg_t addr, csr_t_p delegate);
virtual void verify_permissions(insn_t insn, bool write) const override;
};

class dpc_csr_t: public epc_csr_t {
public:
dpc_csr_t(processor_t* const proc, const reg_t addr);
Expand Down Expand Up @@ -808,6 +820,12 @@ class jvt_csr_t: public basic_csr_t {
virtual void verify_permissions(insn_t insn, bool write) const override;
};

class context_csr_t: public masked_csr_t {
public:
context_csr_t(processor_t* const proc, const reg_t addr, const reg_t mask, const reg_t init);
virtual void verify_permissions(insn_t insn, bool write) const override;
};

// Sscsrind registers needs permissions checked
// (the original virtualized_csr_t does not call verify_permission of the underlying CSRs)
class virtualized_indirect_csr_t: public virtualized_csr_t {
Expand Down
9 changes: 5 additions & 4 deletions riscv/processor.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -418,10 +418,11 @@ void state_t::reset(processor_t* const proc, reg_t max_isa)
csrmap[CSR_TINFO] = std::make_shared<const_csr_t>(proc, CSR_TINFO, 0);
}
unsigned scontext_length = (xlen == 32 ? 16 : 34); // debug spec suggests 16-bit for RV32 and 34-bit for RV64
csrmap[CSR_SCONTEXT] = scontext = std::make_shared<masked_csr_t>(proc, CSR_SCONTEXT, (reg_t(1) << scontext_length) - 1, 0);
csrmap[CSR_SCONTEXT] = scontext = std::make_shared<context_csr_t>(proc, CSR_SCONTEXT, (reg_t(1) << scontext_length) - 1, 0);
unsigned hcontext_length = (xlen == 32 ? 6 : 13) + (proc->extension_enabled('H') ? 1 : 0); // debug spec suggest 7-bit (6-bit) for RV32 and 14-bit (13-bit) for RV64 with (without) H extension
csrmap[CSR_HCONTEXT] = std::make_shared<masked_csr_t>(proc, CSR_HCONTEXT, (reg_t(1) << hcontext_length) - 1, 0);
csrmap[CSR_MCONTEXT] = mcontext = std::make_shared<proxy_csr_t>(proc, CSR_MCONTEXT, csrmap[CSR_HCONTEXT]);
csrmap[CSR_HCONTEXT] = std::make_shared<context_csr_t>(proc, CSR_HCONTEXT, (reg_t(1) << hcontext_length) - 1, 0);
csrmap[CSR_MCONTEXT] = mcontext = std::make_shared<context_proxy_csr_t>(proc, CSR_MCONTEXT, csrmap[CSR_HCONTEXT]);
csrmap[CSR_MSCONTEXT] = std::make_shared<mscontext_csr_t>(proc, CSR_MSCONTEXT, scontext);
debug_mode = false;
single_step = STEP_NONE;

Expand Down Expand Up @@ -482,7 +483,7 @@ void state_t::reset(processor_t* const proc, reg_t max_isa)
const reg_t sstateen0_mask = (proc->extension_enabled(EXT_ZFINX) ? SSTATEEN0_FCSR : 0) |
(proc->extension_enabled(EXT_ZCMT) ? SSTATEEN0_JVT : 0) |
SSTATEEN0_CS;
const reg_t hstateen0_mask = sstateen0_mask | HSTATEEN0_SENVCFG | HSTATEEN_SSTATEEN;
const reg_t hstateen0_mask = sstateen0_mask | HSTATEEN0_SCONTEXT | HSTATEEN0_SENVCFG | HSTATEEN_SSTATEEN;
const reg_t mstateen0_mask = hstateen0_mask;
for (int i = 0; i < 4; i++) {
const reg_t mstateen_mask = i == 0 ? mstateen0_mask : MSTATEEN_HSTATEEN;
Expand Down
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