RFR: 8367609: serviceability/sa/ClhsdbPmap.java fails when built with Clang [v5]

[Kevin Walls]

On Tue, 16 Sep 2025 08:22:10 GMT, Francesco Andreuzzi <fandreuzzi at openjdk.org> wrote:

>> The problem seems to be in read_lib_segments (ps_core.c), this check is too harsh:
>> 
>> https://github.com/openjdk/jdk/blob/5271448b3a013b2e3edcd619a4a3b975b292dae1/src/jdk.hotspot.agent/linux/native/libsaproc/ps_core.c#L423-L425
>> 
>> In my run, `existing_map->memsz = 0xe24000`, while the rhs in L425 is `0xe23000`. According to the NT_FILE entry, this segment of `libjvm.so` has file offset 0x67f000. It seems that the linker aligned it down according to the page size (0x1000). The offset of the same segment according to `readelf -l libjvm.so` is 0x67fc80. This additional offset should be added to `p_memsz` to obtain the 0xe24000, which we see in the core dump.
>> 
>> I added some files to the ticket for context.
>> 
>> Passes `tier1` and `tier2`.
>
> Francesco Andreuzzi has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - nn
>  - comment and rename

Thanks - does that still have the same problem?
(Do you have the jtreg log from this one, to confirm I was looking at the right address here...)


libjvm second seg:
core:

Type           Offset             VirtAddr           PhysAddr
                 FileSiz            MemSiz              Flags  Align
  LOAD           0x0000000006b23000 0x00007fa9ff881000 0x0000000000000000
                 0x0000000000e23000 0x0000000000e23000  R E    0x1000


libjvm binary:

LOAD           0x0000000000680180 0x0000000000681180 0x0000000000681180
               0x0000000000e226c0 0x0000000000e226c0  R E    0x1000

			 
These figures look like they work, for that check which has been working for gcc builds:

ROUNDUP(existing_map->memsz, page_size) != ROUNDUP(lib_php->p_memsz, page_size)

left: 	core file memsize: 0x0000000000e23000
right: 	lib mem size 0x0000000000e226c0 rounds to 0xe23000
	
Was core 1 different? Looks like a slightly smaller libjvm in that run (mem size was 0e225c0 and the core contained a 0xe24000 size mapping, which was the problem).

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PR Comment: https://git.openjdk.org/jdk/pull/27274#issuecomment-3306693613