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DDR: fix support for DWARF version 5
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Some DWARF forms are used for both signed and unsigned attribute values.
Require callers of getConstValue() to specify how ambiguous forms
should be interpreted.

Signed-off-by: Keith W. Campbell <keithc@ca.ibm.com>
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@keithc-ca
keithc-ca committed Feb 26, 2024
1 parent 1f5293c commit bd9c572
Showing 1 changed file with 46 additions and 15 deletions.
61 changes: 46 additions & 15 deletions ddr/lib/ddr-scanner/dwarf/DwarfScanner.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,7 @@
#include <stack>
#include <utility>

static DDR_RC getConstValue(Dwarf_Debug debug, Dwarf_Attribute attr, const char *attrName, uint64_t *value);
static DDR_RC getConstValue(Dwarf_Debug debug, Dwarf_Attribute attr, const char *attrName, bool assumeSigned, uint64_t *value);

class DwarfVisitor : public TypeVisitor
{
Expand Down Expand Up @@ -235,7 +235,7 @@ DwarfScanner::excludedDie(Dwarf_Die die, bool *dieExcluded)
}

uint64_t declFile = 0;
rc = getConstValue(_debug, attr, "decl_file", &declFile);
rc = getConstValue(_debug, attr, "decl_file", false, &declFile);
dwarf_dealloc(_debug, attr, DW_DLA_ATTR);
if (DDR_RC_OK != rc) {
goto Done;
Expand Down Expand Up @@ -407,7 +407,7 @@ DwarfScanner::getBitField(Dwarf_Die die, size_t *bitField)
goto Done;
}
uint64_t bitSize = 0;
rc = getConstValue(_debug, attr, "bit_size", &bitSize);
rc = getConstValue(_debug, attr, "bit_size", false, &bitSize);
dwarf_dealloc(_debug, attr, DW_DLA_ATTR);
if (DDR_RC_OK != rc) {
goto Done;
Expand Down Expand Up @@ -480,7 +480,7 @@ DwarfScanner::getTypeInfo(Dwarf_Die die, Dwarf_Die *dieOut, string *typeName, Mo
rc = DDR_RC_ERROR;
break;
}
rc = getConstValue(_debug, attr, "upper_bound", &upperBound);
rc = getConstValue(_debug, attr, "upper_bound", false, &upperBound);
dwarf_dealloc(_debug, attr, DW_DLA_ATTR);
if (DDR_RC_OK != rc) {
break;
Expand Down Expand Up @@ -652,7 +652,7 @@ DwarfScanner::getTypeSize(Dwarf_Die die, size_t *typeSize)
rc = DDR_RC_ERROR;
} else {
uint64_t byteSize = 0;
rc = getConstValue(_debug, attr, "byte_size", &byteSize);
rc = getConstValue(_debug, attr, "byte_size", false, &byteSize);
dwarf_dealloc(_debug, attr, DW_DLA_ATTR);
if (DDR_RC_OK == rc) {
*typeSize = (size_t)byteSize;
Expand Down Expand Up @@ -1095,9 +1095,11 @@ DwarfVisitor::visitUnion(UnionUDT *newType) const

/*
* Extract the constant value of the given attribute.
* Some forms are used for both signed and unsigned attributes;
* assumeSigned indicates how ambiguous forms should be handled.
*/
static DDR_RC
getConstValue(Dwarf_Debug debug, Dwarf_Attribute attr, const char *attrName, uint64_t *value)
getConstValue(Dwarf_Debug debug, Dwarf_Attribute attr, const char *attrName, bool assumeSigned, uint64_t *value)
{
DDR_RC rc = DDR_RC_ERROR;
Dwarf_Error error = NULL;
Expand Down Expand Up @@ -1137,23 +1139,52 @@ getConstValue(Dwarf_Debug debug, Dwarf_Attribute attr, const char *attrName, uin
}
dwarf_dealloc(debug, block, DW_DLA_BLOCK);
}
} else if (DW_FORM_sdata == form) {
Dwarf_Signed svalue = 0;

if (DW_DLV_OK == dwarf_formsdata(attr, &svalue, &error)) {
*value = (uint64_t)(int64_t)svalue;
rc = DDR_RC_OK;
} else {
ERRMSG("Getting formudata of %s attribute: %s\n", attrName, dwarf_errmsg(error));
}
} else if (DW_FORM_udata == form) {
Dwarf_Unsigned uvalue = 0;

if (DW_DLV_ERROR == dwarf_formudata(attr, &uvalue, &error)) {
ERRMSG("Getting formudata of %s attribute: %s\n", attrName, dwarf_errmsg(error));
} else {
if (DW_DLV_OK == dwarf_formudata(attr, &uvalue, &error)) {
*value = uvalue;
rc = DDR_RC_OK;
} else {
ERRMSG("Getting formudata of %s attribute: %s\n", attrName, dwarf_errmsg(error));
}
} else {
Dwarf_Signed svalue = 0;
Dwarf_Unsigned uvalue = 0;

if (DW_DLV_ERROR == dwarf_formsdata(attr, &svalue, &error)) {
ERRMSG("Getting formsdata of %s attribute: %s\n", attrName, dwarf_errmsg(error));
/*
* For other forms, e.g. DW_FORM_data{1,2,4,8}, assumeSigned
* indicates whether the value is signed or not by default.
*/
if (assumeSigned) {
if (DW_DLV_OK == dwarf_formsdata(attr, &svalue, &error)) {
*value = (uint64_t)(int64_t)svalue;
rc = DDR_RC_OK;
} else if (DW_DLV_OK == dwarf_formudata(attr, &uvalue, &error)) {
*value = uvalue;
rc = DDR_RC_OK;
} else {
ERRMSG("Getting formsdata of %s attribute: %s\n", attrName, dwarf_errmsg(error));
}
} else {
*value = (uint64_t)(int64_t)svalue;
rc = DDR_RC_OK;
if (DW_DLV_OK == dwarf_formudata(attr, &uvalue, &error)) {
*value = uvalue;
rc = DDR_RC_OK;
} else if (DW_DLV_OK == dwarf_formsdata(attr, &svalue, &error)) {
*value = (uint64_t)(int64_t)svalue;
rc = DDR_RC_OK;
} else {
ERRMSG("Getting formsdata of %s attribute: %s\n", attrName, dwarf_errmsg(error));
}
}
}

Expand Down Expand Up @@ -1201,7 +1232,7 @@ DwarfScanner::addEnumMember(Dwarf_Die die, NamespaceUDT *outerUDT, EnumUDT *newE
goto AddEnumMemberError;
}

rc = getConstValue(_debug, attr, "const_value", &enumValue);
rc = getConstValue(_debug, attr, "const_value", true, &enumValue);
dwarf_dealloc(_debug, attr, DW_DLA_ATTR);

if (DDR_RC_OK == rc) {
Expand Down Expand Up @@ -1426,7 +1457,7 @@ DwarfScanner::addClassField(Dwarf_Die die, ClassType *newClass, const string &fi
newClass->_name.c_str(), fieldName.c_str());
goto FreeAttrThenDone;
}
} else if (DDR_RC_OK == getConstValue(_debug, attr, "offset", &offset64)) {
} else if (DDR_RC_OK == getConstValue(_debug, attr, "offset", false, &offset64)) {
offset = (Dwarf_Unsigned)offset64;
} else {
FreeAttrThenDone:
Expand Down

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