The definitive document is here: http://www.akkadia.org/drepper/tls.pdf
I just had a look through and I guess it probably is a bug. Technically
the code in DLYDRendezvous::GetThreadInfo() should query not only the
location, but also the size of modid (using the same API), and then
later issue the appropriately-sized read.
It's not really "wrong" for little-endian systems right now, unless you
have 4 billion modules loaded.
Steve Pucci wrote:
Hi all,
I'm trying to determine if some code in DynamicLoaderPOSIXDYLD is
correct and I could use some confirmation:
The code in question reads the module id of a module as part of
finding the TLS block associated with that module, by determining its
location and then reading with a hardcoded 32-bit unsigned read. (The
code in question is
source/Plugins/DynamicLoader/POSIX-DYLD/DynamicLoaderPOSIXDYLD.cpp, in
DynamicLoaderPOSIXDYLD::GetThreadLocalData).
I've read http://dev.gentoo.org/~dberkholz/articles/toolchain/tls.pdf
<http://dev.gentoo.org/%7Edberkholz/articles/toolchain/tls.pdf> ,
which describes a number of architectures and in all cases the value
seems to be either size_t or "unsigned long int". Thus the code
appears to be wrong in at least some cases, in that it should be
reading 64 bits when debugging 64-bit runtimes. The code presumably
works today for 64-bit LSB (little-endian) systems (which is most of
the 64-bit Linuxes) because it's reading the right 32-bits out of the
64-bit location.
But I'm not 100% sure, because
* I'm not sure that the referenced pdf is definitive
* I don't have an MSB 64-bit system to test on to verify that it's a bug.
Can anyone with any familiarity with this issue comment on this?
Thanks,
Steve
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