Yes, the cache disabling is quite hacky, as mentionnd in the doc:
"Valgrind disables the cache using some internal
knowledge of the glibc stack cache implementation and by
examining the debug information of the pthread
library. This technique is thus somewhat fragile and might
not work for all glibc versions. This has been successfully
tested with various glibc versions (e.g. 2.11, 2.16, 2.18)
on various platforms."
As you indicate, it looks broken on the more recent glibc version you tried.
Philippe
Indeed. Looks like this:
Author: Florian Weimer <fwei...@redhat.com> 2021-05-10 10:31:41
Committer: Florian Weimer <fwei...@redhat.com> 2021-05-10 10:31:41
Parent: d017b0ab5a181dce4145f3a1b3b27e3341abd201 (elf: Introduce
__tls_pre_init_tp)
Child: ee07b3a7222746fafc5d5cb2163c9609b81615ef (nptl: Simplify the
change_stack_perm calling convention)
Branches: master, remotes/origin/arm/morello/main,
remotes/origin/arm/morello/v1, remotes/origin/arm/morello/v2,
remotes/origin/azanella/bz23960-dirent, remotes/origin/azanella/clang,
remotes/origin/codonell/c-utf8, remotes/origin/codonell/ld-audit,
remotes/origin/fw/localedef-utf8, remotes/origin/maskray/relr,
remotes/origin/maskray/x86-mpx, remotes/origin/master,
remotes/origin/nsz/bug23293, remotes/origin/nsz/bug23293-v5,
remotes/origin/nsz/bug23293-v6, remotes/origin/release/2.34/master,
remotes/origin/release/2.35/master, remotes/origin/release/2.36/master,
remotes/origin/siddhesh/realpath-and-getcwd
Follows: glibc-2.33.9000
Precedes: glibc-2.34
nptl: Move more stack management variables into _rtld_global
Permissions of the cached stacks may have to be updated if an object
is loaded that requires executable stacks, so the dynamic loader
needs to know about these cached stacks.
The move of in_flight_stack and stack_cache_actsize is a
requirement for
merging __reclaim_stacks into the fork implementation in libc.
Tested-by: Carlos O'Donell <car...@redhat.com>
Reviewed-by: Carlos O'Donell <car...@redhat.com>
It looks like "stack_cache_actsize" in libc moved to be
_dl_stack_cache_actsize in ld-linux-x86-64.so.2
A+
Paul
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