Re: [Xen-devel] Ping: [PATCH v2] build: provide option to disambiguate symbol names

[Jürgen Groß <jgross@xxxxxxxx>]

On 20.11.19 17:30, Jan Beulich wrote:
> On 08.11.2019 12:18, Jan Beulich wrote:
> > The .file assembler directives generated by the compiler do not include
> > any path components (gcc) or just the ones specified on the command line
> > (clang, at least version 5), and hence multiple identically named source
> > files (in different directories) may produce identically named static
> > symbols (in their kallsyms representation). The binary diffing algorithm
> > used by xen-livepatch, however, depends on having unique symbols.
> >
> > Make the ENFORCE_UNIQUE_SYMBOLS Kconfig option control the (build)
> > behavior, and if enabled use objcopy to prepend the (relative to the
> > xen/ subdirectory) path to the compiler invoked STT_FILE symbols. Note
> > that this build option is made no longer depend on LIVEPATCH, but merely
> > defaults to its setting now.
> >
> > Conditionalize explicit .file directive insertion in C files where it
> > exists just to disambiguate names in a less generic manner; note that
> > at the same time the redundant emission of STT_FILE symbols gets
> > suppressed for clang. Assembler files as well as multiply compiled C
> > ones using __OBJECT_FILE__ are left alone for the time being.
> >
> > Since we now expect there not to be any duplicates anymore, also don't
> > force the selection of the option to 'n' anymore in allrandom.config.
> > Similarly COVERAGE no longer suppresses duplicate symbol warnings if
> > enforcement is in effect, which in turn allows
> > SUPPRESS_DUPLICATE_SYMBOL_WARNINGS to simply depend on
> > !ENFORCE_UNIQUE_SYMBOLS.
> >
> > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> I've got acks from Konrad and Wei, but still need an x86 and a release
> one here. Andrew? Or alternatively - Jürgen, would you rather not see
> this go in anymore?
In case the needed x86 Ack is coming in before RC3 I'm fine to give my
Release-ack, but I'm hesitant to take it later.


Juergen

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel