RFR: 8369393: NMT: poison the canaries of malloc header under ASAN build [v2]

[Afshin Zafari]

On Wed, 8 Oct 2025 12:05:56 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Afshin Zafari has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   include sort
>
> src/hotspot/share/nmt/mallocHeader.hpp line 142:
> 
>> 140:       footer_address()[0] = (uint8_t)(v >> 8); footer_address()[1] = (uint8_t)v;
>> 141:     }
>> 142:   #endif
> 
> I'd prefer the following. Then we keep the simple definitions separate and as small as previously.
> 
> ```c++
> #if INCLUDE_ASAN
>   // Insert your defs here.
> #else
>   uint8_t* footer_address() const   { return ((address)this) + sizeof(MallocHeader) + _size; }
>   uint16_t get_footer() const       { return build_footer(footer_address()[0], footer_address()[1]); }
>   void set_footer(uint16_t v)       { footer_address()[0] = (uint8_t)(v >> 8); footer_address()[1] = (uint8_t)v; }
> #endif

Done.

> src/hotspot/share/nmt/mallocHeader.hpp line 191:
> 
>> 189:     inline bool is_poisoned() const { return false; }
>> 190:     inline void set_poisoned(bool poison) { }
>> 191:   #endif
> 
> Please do the same type of separation that I suggested above.

Done.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27685#discussion_r2413737076
PR Review Comment: https://git.openjdk.org/jdk/pull/27685#discussion_r2413736531