Re: armv7-on-aarch64 stuck at urdlck

On 22.07.2024 13:46, Mark Millard wrote:
> On Jul 21, 2024, at 22:59, Michal Meloun <[email protected]> wrote:
> 
>> I don't want to hijack the original thread, so I'm replying in a new one.
>>
>> My tegra track current, has been running 24/7 by building kernel/world and kde5 in a loop for a few years now. But I have never encountered the aforementioned lockup in native armv7.
>>
>> I have seen usermode mutex lockup in arm32 jail on aarch64, but only very rarely (once a month or so) and all my attempts to reproduce it in a more deterministic way have failed. Also, I don't think I've ever seen this with the debug version of libc.
>>
>> Unfortunately I also failed to reproduce given lockup using dlopen_test.c, neither on native armv7 or arm32 jail.
>>
>> Michal Meloun
> 
> What is the output of:
> 
> # readelf -a /libexec/ld-elf.so.1 | grep -E "(^[^ 0-9]|.*_rtld_get_stack_prot)"
> 
> in your armv7 context(s)? Does it include for likes of:
> 
> QUOTE
> Symbol table '.symtab' contains 911 entries:
>   903: 000000000001b9ac    16 FUNC    GLOBAL DEFAULT   11 _rtld_get_stack_prot
> END QUOTE
> `
> vs. not?
> 
> Note that the "debug version of libc" being involved likely means that
> DEBUG_FLAGS was defined. That in turn likely means that strip is not
> being used. In such a case, I expect that the .symtab entry for
> _rtld_get_stack_prot (and more) exists for such a context.
> 
At tis time, I have standard (thus stripped, non-debug) version of 
runtime linker library installed. Thus it have only dynamic relocation 
record for _rtld_get_stack_prot:

root@tegra124:~/dlopen_test # readelf -a /libexec/ld-elf.so.1 | grep -E 
"(^[^ 0-9]|.*_rtld_get_stack_prot)"
ELF Header:
Elf file type is DYN (Shared object file)
Entry point 0x1449c
There are 10 program headers, starting at offset 52
Program Headers:
There are 23 section headers, starting at offset 0x1a448:
Section Headers:
Key to Flags:
Dynamic section at offset 0x19fa4 contains 15 entries:
Relocation section (.rel.dyn):
r_offset r_info   r_type              st_value st_name
Symbol table '.dynsym' contains 27 entries:
      5: 000000000001ba0c    16 FUNC    GLOBAL DEFAULT   12 
_rtld_get_stack_prot@@FBSDprivate_1.0 (11)
Notes at offset 0x00000174 with length 0x00000018:
Histogram for bucket list length (total of 6 buckets):
Histogram for bucket list length (total of 27 buckets):
Version symbol section (.gnu.version):
Version definition section (.gnu.version_d):
Attribute Section: aeabi

------

root@tegra124:~/dlopen_test # ./dlopen_test
root@tegra124:~/dlopen_test #

Michal Meloun




Michal Meloun