if (!success) {
panic("Tried to execute unmapped address %#x.\n", vaddr);
} else {
- Addr alignedVaddr = p->pTable->pageAlign(vaddr);
- tc->getITBPtr()->insert(alignedVaddr, 0 /*partition id*/,
- p->_pid /*context id*/, false, entry.pte);
+ Addr alignedvaddr = p->pTable->pageAlign(vaddr);
+
+ // Grab fields used during instruction translation to figure out
+ // which context to use.
+ uint64_t tlbdata = tc->readMiscRegNoEffect(MISCREG_TLB_DATA);
+
+ // Inside a VM, a real address is the address that guest OS would
+ // interpret to be a physical address. To map to the physical address,
+ // it still needs to undergo a translation. The instruction
+ // translation code in the SPARC ITLB code assumes that the context is
+ // zero (kernel-level) if real addressing is being used.
+ bool is_real_address = !bits(tlbdata, 4);
+
+ // The SPARC ITLB code assumes that traps are executed in context
+ // zero so we carry that assumption through here.
+ bool trapped = bits(tlbdata, 18, 16) > 0;
+
+ // The primary context acts as a PASID. It allows the MMU to
+ // distinguish between virtual addresses that would alias to the
+ // same physical address (if two or more processes shared the same
+ // virtual address mapping).
+ int primary_context = bits(tlbdata, 47, 32);
+
+ // The partition id distinguishes between virtualized environments.
+ int const partition_id = 0;
+
+ // Given the assumptions in the translateInst code in the SPARC ITLB,
+ // the logic works out to the following for the context.
+ int context_id = (is_real_address || trapped) ? 0 : primary_context;
+
+ // Insert the TLB entry.
+ // The entry specifying whether the address is "real" is set to
+ // false for syscall emulation mode regardless of whether the
+ // address is real in preceding code. Not sure sure that this is
+ // correct, but also not sure if it matters at all.
+ tc->getITBPtr()->insert(alignedvaddr, partition_id, context_id,
+ false, entry.pte);
}
}
if (!success) {
panic("Tried to access unmapped address %#x.\n", vaddr);
} else {
- Addr alignedVaddr = p->pTable->pageAlign(vaddr);
- tc->getDTBPtr()->insert(alignedVaddr, 0 /*partition id*/,
- p->_pid /*context id*/, false, entry.pte);
+ Addr alignedvaddr = p->pTable->pageAlign(vaddr);
+
+ // Grab fields used during data translation to figure out
+ // which context to use.
+ uint64_t tlbdata = tc->readMiscRegNoEffect(MISCREG_TLB_DATA);
+
+ // The primary context acts as a PASID. It allows the MMU to
+ // distinguish between virtual addresses that would alias to the
+ // same physical address (if two or more processes shared the same
+ // virtual address mapping). There's a secondary context used in the
+ // DTLB translation code, but it should __probably__ be zero for
+ // syscall emulation code. (The secondary context is used by Solaris
+ // to allow kernel privilege code to access user space code:
+ // [ISBN 0-13-022496-0]:PG199.)
+ int primary_context = bits(tlbdata, 47, 32);
+
+ // "Hyper-Privileged Mode" is in use. There are three main modes of
+ // operation for Sparc: Hyper-Privileged Mode, Privileged Mode, and
+ // User Mode.
+ int hpriv = bits(tlbdata, 0);
+
+ // Reset, Error and Debug state is in use. Something horrible has
+ // happened or the system is operating in Reset Mode.
+ int red = bits(tlbdata, 1);
+
+ // Inside a VM, a real address is the address that guest OS would
+ // interpret to be a physical address. To map to the physical address,
+ // it still needs to undergo a translation. The instruction
+ // translation code in the SPARC ITLB code assumes that the context is
+ // zero (kernel-level) if real addressing is being used.
+ int is_real_address = !bits(tlbdata, 5);
+
+ // Grab the address space identifier register from the thread context.
+ // XXX: Inspecting how setMiscReg and setMiscRegNoEffect behave for
+ // MISCREG_ASI causes me to think that the ASI register implementation
+ // might be bugged. The NoEffect variant changes the ASI register
+ // value in the architectural state while the normal variant changes
+ // the context field in the thread context's currently decoded request
+ // but does not directly affect the ASI register value in the
+ // architectural state. The ASI values and the context field in the
+ // request packet seem to have completely different uses.
+ MiscReg reg_asi = tc->readMiscRegNoEffect(MISCREG_ASI);
+ ASI asi = static_cast<ASI>(reg_asi);
+
+ // The SPARC DTLB code assumes that traps are executed in context
+ // zero if the asi value is ASI_IMPLICIT (which is 0x0). There's also
+ // an assumption that the nucleus address space is being used, but
+ // the context is the relevant issue since we need to pass it to TLB.
+ bool trapped = bits(tlbdata, 18, 16) > 0;
+
+ // Given the assumptions in the translateData code in the SPARC DTLB,
+ // the logic works out to the following for the context.
+ int context_id = ((!hpriv && !red && is_real_address) ||
+ asiIsReal(asi) ||
+ (trapped && asi == ASI_IMPLICIT))
+ ? 0 : primary_context;
+
+ // The partition id distinguishes between virtualized environments.
+ int const partition_id = 0;
+
+ // Insert the TLB entry.
+ // The entry specifying whether the address is "real" is set to
+ // false for syscall emulation mode regardless of whether the
+ // address is real in preceding code. Not sure sure that this is
+ // correct, but also not sure if it matters at all.
+ tc->getDTBPtr()->insert(alignedvaddr, partition_id, context_id,
+ false, entry.pte);
}
}
projects / gem5.git / commitdiff