mirror of
https://github.com/NationalSecurityAgency/ghidra.git
synced 2025-10-04 18:29:37 +02:00
223 lines
7.1 KiB
C++
223 lines
7.1 KiB
C++
/* ###
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* IP: GHIDRA
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "context.hh"
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#include "slghsymbol.hh"
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#include "translate.hh"
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ParserContext::ParserContext(ContextCache *ccache)
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{
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parsestate = 0;
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contcache = ccache;
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if (ccache != (ContextCache *)0) {
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contextsize = ccache->getDatabase()->getContextSize();
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context = new uintm[ contextsize ];
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}
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else {
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contextsize = 0;
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context = (uintm *)0;
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}
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}
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void ParserContext::initialize(int4 maxstate,int4 maxparam,AddrSpace *spc)
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{
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const_space = spc;
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state.resize(maxstate);
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state[0].parent = (ConstructState *)0;
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for(int4 i=0;i<maxstate;++i)
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state[i].resolve.resize(maxparam);
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base_state = &state[0];
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}
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uintm ParserContext::getInstructionBytes(int4 bytestart,int4 size,uint4 off) const
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{ // Get bytes from the instruction stream into a intm
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// (assuming big endian format)
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off += bytestart;
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if (off >=16)
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throw BadDataError("Instruction is using more than 16 bytes");
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const uint1 *ptr = buf + off;
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uintm res = 0;
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for(int4 i=0;i<size;++i) {
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res <<= 8;
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res |= ptr[i];
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}
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return res;
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}
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uintm ParserContext::getInstructionBits(int4 startbit,int4 size,uint4 off) const
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{
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off += (startbit/8);
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if (off >= 16)
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throw BadDataError("Instruction is using more than 16 bytes");
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const uint1 *ptr = buf + off;
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startbit = startbit % 8;
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int4 bytesize = (startbit+size-1)/8 + 1;
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uintm res = 0;
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for(int4 i=0;i<bytesize;++i) {
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res <<= 8;
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res |= ptr[i];
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}
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res <<= 8*(sizeof(uintm)-bytesize)+startbit; // Move starting bit to highest position
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res >>= 8*sizeof(uintm)-size; // Shift to bottom of intm
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return res;
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}
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uintm ParserContext::getContextBytes(int4 bytestart,int4 size) const
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{ // Get bytes from context into a uintm
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int4 intstart = bytestart / sizeof(uintm);
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uintm res = context[ intstart ];
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int4 byteOffset = bytestart % sizeof(uintm);
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int4 unusedBytes = sizeof(uintm) - size;
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res <<= byteOffset*8;
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res >>= unusedBytes*8;
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int4 remaining = size - sizeof(uintm) + byteOffset;
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if ((remaining > 0)&&(++intstart < contextsize)) { // If we extend beyond boundary of a single uintm
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uintm res2 = context[ intstart ];
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unusedBytes = sizeof(uintm) - remaining;
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res2 >>= unusedBytes * 8;
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res |= res2;
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}
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return res;
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}
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uintm ParserContext::getContextBits(int4 startbit,int4 size) const
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{
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int4 intstart = startbit / (8*sizeof(uintm));
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uintm res = context[ intstart ]; // Get intm containing highest bit
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int4 bitOffset = startbit % (8*sizeof(uintm));
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int4 unusedBits = 8*sizeof(uintm) - size;
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res <<= bitOffset; // Shift startbit to highest position
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res >>= unusedBits;
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int4 remaining = size - 8*sizeof(uintm) + bitOffset;
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if ((remaining > 0) && (++intstart < contextsize)) {
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uintm res2 = context[ intstart ];
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unusedBits = 8*sizeof(uintm) - remaining;
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res2 >>= unusedBits;
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res |= res2;
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}
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return res;
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}
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void ParserContext::addCommit(TripleSymbol *sym,int4 num,uintm mask,bool flow,ConstructState *point)
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{
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contextcommit.push_back(ContextSet());
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ContextSet &set(contextcommit.back());
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set.sym = sym;
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set.point = point; // This is the current state
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set.num = num;
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set.mask = mask;
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set.value = context[num] & mask;
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set.flow = flow;
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}
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void ParserContext::applyCommits(void)
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{
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if (contextcommit.empty()) return;
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ParserWalker walker(this);
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walker.baseState();
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vector<ContextSet>::iterator iter;
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for(iter=contextcommit.begin();iter!=contextcommit.end();++iter) {
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TripleSymbol *sym = (*iter).sym;
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Address commitaddr;
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if (sym->getType() == SleighSymbol::operand_symbol) {
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// The value for an OperandSymbol is probabably already
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// calculated, we just need to find the right
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// tree node of the state
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int4 i = ((OperandSymbol *)sym)->getIndex();
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FixedHandle &h((*iter).point->resolve[i]->hand);
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commitaddr = Address(h.space,h.offset_offset);
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}
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else {
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FixedHandle hand;
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sym->getFixedHandle(hand,walker);
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commitaddr = Address(hand.space,hand.offset_offset);
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}
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if (commitaddr.isConstant()) {
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// If the symbol handed to globalset was a computed value, the getFixedHandle calculation
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// will return a value in the constant space. If this is a case, we explicitly convert the
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// offset into the current address space
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uintb newoff = AddrSpace::addressToByte(commitaddr.getOffset(),addr.getSpace()->getWordSize());
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commitaddr = Address(addr.getSpace(),newoff);
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}
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// Commit context change
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if ((*iter).flow) // The context flows
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contcache->setContext(commitaddr,(*iter).num,(*iter).mask,(*iter).value);
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else { // Set the context so that is doesn't flow
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Address nextaddr = commitaddr + 1;
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if (nextaddr.getOffset() < commitaddr.getOffset())
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contcache->setContext(commitaddr,(*iter).num,(*iter).mask,(*iter).value);
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else
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contcache->setContext(commitaddr,nextaddr,(*iter).num,(*iter).mask,(*iter).value);
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}
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}
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}
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void ParserWalker::setOutOfBandState(Constructor *ct,int4 index,ConstructState *tempstate,const ParserWalker &otherwalker)
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{ // Initialize walker for future calls into getInstructionBytes assuming -ct- is the current position in the walk
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const ConstructState *pt = otherwalker.point;
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int4 curdepth = otherwalker.depth;
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while(pt->ct != ct) {
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if (curdepth <= 0) return;
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curdepth -= 1;
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pt = pt->parent;
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}
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OperandSymbol *sym = ct->getOperand(index);
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int4 i = sym->getOffsetBase();
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// if i<0, i.e. the offset of the operand is constructor relative
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// its possible that the branch corresponding to the operand
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// has not been constructed yet. Context expressions are
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// evaluated BEFORE the constructors branches are created.
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// So we have to construct the offset explicitly.
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if (i<0)
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tempstate->offset = pt->offset + sym->getRelativeOffset();
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else
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tempstate->offset = pt->resolve[index]->offset;
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tempstate->ct = ct;
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tempstate->length = pt->length;
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point = tempstate;
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depth = 0;
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breadcrumb[0] = 0;
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}
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void ParserWalkerChange::calcCurrentLength(int4 length,int4 numopers)
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{ // Calculate the length of the current constructor
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// state assuming all its operands are constructed
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length += point->offset; // Convert relative length to absolute length
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for(int4 i=0;i<numopers;++i) {
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ConstructState *subpoint = point->resolve[i];
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int4 sublength = subpoint->length + subpoint->offset;
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// Since subpoint->offset is an absolute offset
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// (relative to beginning of instruction) sublength
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if (sublength > length) // is absolute and must be compared to absolute length
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length = sublength;
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}
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point->length = length - point->offset; // Convert back to relative length
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}
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