On Mon, 26 Aug 2024 22:25:34 GMT, Alex Menkov <[email protected]> wrote:
>> On Windows SA agent gets a class vtable from symbols, exported from jvm.dll
>> (it exports symbols like "??_7" + type + "@@6B@").
>> But symbol lookup function first requests WinDbg about the symbol.
>> Sometimes WinDbg routine IDebugSymbols::GetOffsetByName() returns offset for
>> both class and class pointer types. Returned offsets correspond to symbols
>> like "jvm!class_name::`vftable'".
>> The behavior is intermittent, I was not able to find what is the reason.
>> The fix adds workaround for the case - if GetOffsetByName succeeded, we
>> check if corresponding symbol contains requested one.
>> So it returns expected offset for non-vtable symbols like
>> "MaxJNILocalCapacity" (GetOffsetByName returns offset for
>> "jvm!MaxJNILocalCapacity"), but returns 0 for vtlb lookup.
>>
>> Additionally added check for results of
>> IDebugSymbols::SetImagePath/SetSymbolPath
>>
>> Testing: tier1,tier2,hs-tier5-svc
>
> Alex Menkov has updated the pull request incrementally with one additional
> commit since the last revision:
>
> use SYMBOL_BUFSIZE
src/jdk.hotspot.agent/windows/native/libsaproc/sawindbg.cpp line 867:
> 865: char buf[SYMBOL_BUFSIZE];
> 866: memset(buf, 0, sizeof(buf));
> 867: if (ptrIDebugSymbols->GetNameByOffset(offset, buf, sizeof(buf), 0,
> &disp) == S_OK) {
Nit: Extra space before `S_OK`.
-------------
PR Review Comment: https://git.openjdk.org/jdk/pull/20684#discussion_r1735332182
