[PATCHv3] powerpc: ABI change - add HWCAP/HWCAP2/platform info to TCB

[Carlos Eduardo Seo <cseo at linux dot vnet dot ibm dot com>]

Hi

After OâDonell's and Steve's comments (thanks again for the review, btw), I made the following changes to address his concerns (see the original discussion here - https://sourceware.org/ml/libc-alpha/2015-08/msg01138.html):

* Changed the data initialization: the function that processes the data before it can be written into the TCB (init_hwcapinfo) is now called very early in program initialization. In the dynamic linking case, init_hwcapinfo() is called in _dl_sysdep_start() (via DL_PLATFORM_INIT). In the static linking case, it has to be called as early as in __libc_start_main(), since the TLS initialization happens shortly after that, so we use the powerpc-specific libc-start.c file for that. This new procedure eliminates the concurrency issues raised by OâDonell in v2 and it should conform with the design goals Steve mentioned.

* Added a testcase for the static linking case.

* Testcases now cover multithreads.

* Addressed manual issues. It should have only the necessary information now.

* The âinit_hwcapinfoâ symbol is moved to the loader, since it is used mostly by ld code now. But Iâd like to read your comments about where this is most appropriate.

Tested on ppc32, ppc64 and ppc64le, both dynamic and static cases.

Please review.

Thanks,

-- 
Carlos Eduardo Seo
Software Engineer - Linux on Power Toolchain
cseo@linux.vnet.ibm.com

Attachment: 0001-powerpc-Add-hwcap-hwcap2-platform-data-to-TCB.patch
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