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The Debugger convinced me to make probeAddr() safe for any 1/2/4-byte read

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This commit is contained in:
Jeff Parsons 2015-11-06 14:00:49 -08:00
commit ef282eee47
2 changed files with 69 additions and 33 deletions
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53
modules/pcjs/lib/debugger.js
View file

@ -2060,10 +2060,7 @@ if (DEBUGGER) {
*/
Debugger.prototype.getWord = function(dbgAddr, fAdvance)
{
if (!dbgAddr.fData32) {
return this.getShort(dbgAddr, fAdvance? 2 : 0);
}
return this.getLong(dbgAddr, fAdvance? 4 : 0);
return dbgAddr.fData32? this.getLong(dbgAddr, fAdvance? 4 : 0) : this.getShort(dbgAddr, fAdvance? 2 : 0);
};
/**
@ -2107,6 +2104,9 @@ if (DEBUGGER) {
/**
* setByte(dbgAddr, b, inc)
*
* WARNING: Be careful with the editing commands that use function, because we don't have a safe
* counterpart to cpu.probeAddr().
*
* @this {Debugger}
* @param {DbgAddr} dbgAddr
* @param {number} b
@ -2125,6 +2125,9 @@ if (DEBUGGER) {
/**
* setShort(dbgAddr, w, inc)
*
* WARNING: Be careful with the editing commands that use function, because we don't have a safe
* counterpart to cpu.probeAddr().
*
* @this {Debugger}
* @param {DbgAddr} dbgAddr
* @param {number} w
@ -3360,7 +3363,7 @@ if (DEBUGGER) {
i += sReplace.length;
continue;
}
$i++;
i++;
}
/*
* Replace every ^XXXX:XXXX, where XXXX:XXXX is a segmented address, with the FCB filename stored at that address.
@ -3856,7 +3859,13 @@ if (DEBUGGER) {
sStopped += " (";
if (this.checksEnabled()) {
sStopped += this.cOpcodes + " opcodes, ";
this.cOpcodes = this.cOpcodesStart = 0;
/*
* $ops displays progress by calculating cOpcodes - cOpcodesStart, so before
* zeroing cOpcodes, we should subtract cOpcodes from cOpcodesStart (since we're
* effectively subtracting cOpcodes from cOpcodes as well).
*/
this.cOpcodesStart -= this.cOpcodes;
this.cOpcodes = 0;
}
sStopped += this.nCycles + " cycles, " + msTotal + " ms, " + nCyclesPerSecond + " hz)";
if (MAXDEBUG && this.chipset) {
@ -6300,7 +6309,7 @@ if (DEBUGGER) {
* Displays information about the given software interrupt (assuming that said interrupt is in progress).
*
* These messages also reset the system variable $ops (by updating cOpcodesStart), to make it easier to see
* how many opcodes were executed since the interrupt "started".
* how many opcodes were executed since these interrupts "started".
*
* @this {Debugger}
* @param {string|undefined} sInt
@ -7151,6 +7160,9 @@ if (DEBUGGER) {
/**
* getCall(dbgAddr, fFar)
*
* Given a possible return address (typically from the stack), look for a matching CALL (or INT) that
* immediately precedes that address.
*
* @this {Debugger}
* @param {DbgAddr} dbgAddr
* @param {boolean} [fFar]
@ -7167,8 +7179,18 @@ if (DEBUGGER) {
dbgAddr.addr = null;
var s = this.getInstruction(dbgAddr);
if (s.indexOf("CALL") > 0 || fFar && s.indexOf("INT") > 0) {
sCall = s;
break;
/*
* Verify that the length of this CALL (or INT), when added to the address of the CALL (or INT),
* matches the original return address. We do this by getting the string index of the opcode bytes,
* subtracting that from the string index of the next space, and dividing that difference by two,
* to yield the length of the CALL (or INT) instruction, in bytes.
*/
var i = s.indexOf(' ');
var j = s.indexOf(' ', i+1);
if (off + (j - i - 1)/2 == offOrig) {
sCall = s;
break;
}
}
}
off--;
@ -7202,7 +7224,7 @@ if (DEBUGGER) {
this.println("stack trace for " + this.toHexAddr(dbgAddrStack));
while (cFrames < nFrames) {
var sCall = null, cTests = 256;
var sCall = null, sCallPrev = null, cTests = 256;
while ((dbgAddrStack.off >>> 0) < (this.cpu.regLSPLimit >>> 0)) {
dbgAddrCall.off = this.getWord(dbgAddrStack, true);
/*
@ -7225,14 +7247,21 @@ if (DEBUGGER) {
break;
}
}
if (!sCall) break;
/*
* The sCallPrev check eliminates duplicate sequential calls, which are usually (but not always)
* indicative of a false positive, in which case the previous call is probably bogus as well, but
* at least we won't duplicate that mistake. Of course, there are always exceptions, recursion
* being one of them, but it's rare that we're debugging recursive code.
*/
if (!sCall || sCall == sCallPrev) break;
var sSymbol = null;
if (sCmd == "ks") {
var a = sCall.match(/[0-9A-F]+$/);
if (a) sSymbol = this.doList(a[0]);
}
sCall = str.pad(sCall, 50) + " ;" + (sSymbol || "stack=" + this.toHexAddr(dbgAddrStack) + " return=" + this.toHexAddr(dbgAddrCall));
sCall = str.pad(sCall, 50) + " ;" + (sSymbol || "stack=" + this.toHexAddr(dbgAddrStack)); // + " return=" + this.toHexAddr(dbgAddrCall));
this.println(sCall);
sCallPrev = sCall;
cFrames++;
}
if (!cFrames) this.println("no return addresses found");

49
modules/pcjs/lib/x86cpu.js
View file

@ -2901,44 +2901,51 @@ X86CPU.prototype.setBinding = function(sHTMLType, sBinding, control)
* functions, like fnFaultMessage(), that must also avoid triggering faults, since they're not part of
* standard CPU operation.
*
* NOTE: If the size parameter is used, then the caller is required to provide a valid size (1, 2 or 4)
* and ensure that the data is contained entirely with the requested block (which we assert below).
* Since originally written, I've also relaxed the requirement that the request be contained entirely
* within a single block; this was never a problem for any size-aligned request, but unfortunately, it
* was difficult for the Debugger to guarantee that every 2 or 4-byte request would be always be word or
* dword-aligned. So now requests that straddle blocks will be broken into smaller probeAddr() requests.
*
* @this {X86CPU}
* @param {number} addr is a linear address
* @param {number} [size] is a length (default is 1)
* @param {number} [size] is a length (default is 1; if specified, must be 1, 2 or 4)
* @param {boolean} [fLinear] (true for linear probe, false for physical; linear is the default)
* @return {number|null} byte (8-bit) value at that address, or null if invalid
* @return {number|null} value at the specified address, or null if invalid
*/
X86CPU.prototype.probeAddr = function(addr, size, fLinear)
{
var aBlocks = fLinear === false? this.aBusBlocks : this.aMemBlocks;
var aBlocks = (fLinear === false? this.aBusBlocks : this.aMemBlocks);
var block = aBlocks[(addr & this.nMemMask) >>> this.nBlockShift];
if (block && block.type == Memory.TYPE.UNPAGED) {
block = this.mapPageBlock(addr, false, true);
}
if (block && block.type == Memory.TYPE.UNPAGED) block = this.mapPageBlock(addr, false, true);
if (block) {
var off = addr & this.nBlockLimit;
/*
* TODO: We actually hit this assert in rare cases where the Debugger is disassembling
* an instruction straddling a page boundary that also references a short or long operand.
* The best solution is to change the Debugger's getShort(), getLong(), etc, functions to
* use getByte() internally, which in turn will never call probeAddr() with a size > 1.
*/
this.assert(off + (size || 1) <= this.nBlockSize);
switch(size) {
default:
if (!size || size == 1) {
return block.readByteDirect(off, addr);
case 2:
return block.readShortDirect(off, addr);
case 4:
return block.readLongDirect(off, addr);
}
if (size == 2) {
if (off < this.nBlockLimit) {
return block.readShortDirect(off, addr);
}
return block.readByteDirect(off, addr) | (this.probeAddr(addr + 1, 1, fLinear) << 8);
}
if (size == 4) {
if (off < this.nBlockLimit - 2) {
return block.readLongDirect(off, addr);
}
if (off == this.nBlockLimit - 1) {
return block.readShortDirect(off, addr) | (this.probeAddr(addr + 2, 2, fLinear) << 16);
}
return block.readByteDirect(off, addr) | (this.probeAddr(addr + 1, 1, fLinear) << 8) | (this.probeAddr(addr + 2, 1, fLinear) << 16) | (this.probeAddr(addr + 3, 1, fLinear) << 24);
}
}
/*
* Since the Bus component initializes all unused portions of physical address space with an empty
* block, we have also written mapPageBlock() to return an empty block (memEmpty) whenever there is
* no valid mapping. So if we ever end up here, this may represent a hole that needs plugging.
*
* It's also possible the caller passed a bogus parameter, such as an invalid size (must be 1, 2 or 4).
*/
this.assert(false);
return null;