Re: [CFR] Adding a function to rtld-elf.so, how to handle Symbol
--/sv6gJA63ZcCAX3m
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable
On Thu, Jul 17, 2014 at 06:17:41PM -0600, Ian Lepore wrote:
> On Thu, 2014-07-17 at 20:29 +0300, Konstantin Belousov wrote:
> > On Thu, Jul 17, 2014 at 11:09:50AM -0600, Ian Lepore wrote:
> > > On Thu, 2014-07-17 at 03:45 +0300, Konstantin Belousov wrote:
> > > > On Wed, Jul 16, 2014 at 03:23:53PM -0600, Ian Lepore wrote:
> > > [snip]
>=20
> > > I did some looking around and Netbsd, Android, and Risc Os all
> > > implemented this in their dynamic loaders, so that seemed like the way
> > > to go. Android actually puts a function with this __gnu name in its
> > > libc, but all that function does is calls dl_unwind_find_exidx() which
> > > is implemented in their loader.
> > >=20
> > > I've just discovered that the arm unwind support code that will arrive
> > > as part of clang 3.5 appears to assume the Android way of things unle=
ss
> > > __LINUX__ is defined, so maybe it would be good to follow that model
> > > ourselves and add a dl_unwind_find_exidx() stub to libc/gen/dlfcn.c a=
nd
> > > name the new implementation in ld-elf to match.
> > I think that Android/__LINUX__ combination does the right thing, by
> > providing the symbol in libc. A libc implementation does not need any
> > additional service from rtld, except already existing _rtld_addr_phdr().
> >=20
>=20
> Android provides a stub of dl_unwind_find_exidx() in libdl and the
> shared-object implementation in the dynamic linker. What it puts in
> libc is the __gnu_Unwind_Find_exidx() symbol, which just calls through
> to the dl_unwind_find_exidx() implementation in the dynamic linker.
>=20
> That aside, I've reworked my code so it all lives in libc instead of
> rtld, as you suggested. It seems to work fine, and I guess I'm agnostic
> about whether we're exporting a new function from libc versus rtld. It
> seems a bit strange to me to have just one dl_something() function with
> its shared/dynamic implementation in libc, while all the other functions
> with dl-prefix names are implemented in rtld. But not so weird that
> it's a big deal.
The new patch is fine with me. =20
Could you, please, comment why did you decided to export the
dl_unwind_find_exidx alias ? It was absent in the original patch,
and from your description, it seems to be an implementation detail
on Linux.
--/sv6gJA63ZcCAX3m
Content-Type: application/pgp-signature
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2
iQIcBAEBAgAGBQJTyNd/AAoJEJDCuSvBvK1BY3YP/i+0rHyXtv2s6+WUIZIAq7Sx
qt5EhabJT+e934pErTLH4BZPizbRXBjGM7FI8/cr43KsiiM3Dq6p2Y2zupOMk5l8
DrX76pqEdzCB7Nr7NydQuglBw+OAXatJBiN51VMdWC+uO04Gi1+Ne8581fceAG82
rQ79PcXtTmmCrtQQaJvQFuBUKTV3qdc5pdn0Hoso11+OPDWSs0ajmqlgFSgS2X5x
15s8x4uV7qUjWVbD8ksdxs49dPBr8x7wUfRnakBWNv71Gna5isRCSyJQsWjDPCCJ
zKTVxq95fubyEe2LOX72m7xlCqpXB8/Cidy2T+fP/ziFkQvB+pH4xzQGyuC87Qnx
h9ZLaEbHl/n+JToXgyEk10NCVcd8vDL3FktS6p9yNrRlleA7RB33evdgjyUgmjXG
vNApBeridTmwb3E1UhC+SkOKcOwP+6j7Y9+DkHhFelDSeHGCTcMHyIdAtwY3METf
ItBpKH+agIk+8+KI2UiSUjgySFyF4SpnPYTo+F8ZTKwrLxKtt9t+HzIaNwr73FN4
Z4EXqyz23TMv1ije7TU397DAyW4n6eYWm8dIR9DhqJ4zdx2X586Q23YhE57qCO1q
D+nCrcrrX8dDw51YK1P6KH3ILdDhn9LkpO3cZsNtY71mgLxahF7qPOTIBBrnXwBs
QKro600NBsAy/s4/IS1d
=7OX1
-----END PGP SIGNATURE-----
--/sv6gJA63ZcCAX3m--
討論串 (同標題文章)
完整討論串 (本文為第 6 之 11 篇)：