Re: svn commit: r368789 - head/libexec/rtld-elf/rtld-libc
On 12/19/20 8:27 PM, Ryan Libby wrote: > On Sat, Dec 19, 2020 at 7:23 PM John Baldwin wrote: >> >> On 12/19/20 12:38 AM, Ryan Libby wrote: >>> Author: rlibby >>> Date: Sat Dec 19 08:38:31 2020 >>> New Revision: 368789 >>> URL: https://svnweb.freebsd.org/changeset/base/368789 >>> >>> Log: >>> rtld-elf: link udivmoddi4 from compiler_rt >>> >>> This fixes the gcc9 build of rtld-elf32 on amd64, which needed an >>> implementation of udivmoddi4. >>> >>> rtld-elf uses certain functions normally found in libc, and so it >>> includes certain files from libc in its own build. It has two >>> mechanisms to include files from libc: one that rebuilds source files in >>> the rtld-elf environment, and one that extracts object files from a >>> purpose-built no-SSP PIC archive. >>> >>> In addition to libc functions, rtld-elf may need to link functions >>> normally found in libcompiler_rt (formerly libgcc). Now, add an ability >>> to rebuild libcompiler_rt source files in the rtld-elf environment. We >>> don't yet have a need for an object file extraction mechanism. >>> >>> libcompiler_rt could also supply udivdi3 and umoddi3, but leave them >>> alone for now. >>> >>> Reviewed by:arichardson, kib >>> Sponsored by: Dell EMC Isilon >>> Differential Revision: https://reviews.freebsd.org/D27665 >> >> Hmm, I had just linked against libcompiler_rt directly as we do on arm: >> >> https://reviews.freebsd.org/D26199 >> >> It was stuck waiting for review feedback. >> >> Given libcompiler_rt is a static archive, we could probably safely link >> against it directly unlike libc where we have to pick specific object >> files. >> >> -- >> John Baldwin > > Sorry, I wasn't aware of your review. Do you want this backed out? No. I do have other patches you can see in that review stack that might be relevant for GCC 9. Some of them I should push as they've been reviewed, but not all of them are ok'd I think. > I did see the arm path. I think it is not quite right, because > libcompiler_rt is compiled with -fstack-protector-strong, which is not > compatible with rtld. However, it will work in practice if stack > protection doesn't actually get used on any linked function. Hmm, ok. I think it's fine to use the current approach then, and perhaps fix arm to match it and keep SSP out of rtld. -- John Baldwin ___ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
Re: svn commit: r368789 - head/libexec/rtld-elf/rtld-libc
On Sat, Dec 19, 2020 at 08:27:31PM -0800, Ryan Libby wrote: > On a tangent, it might be neat to split out an rtld_bootstrap > (everything through init_rtld()) so that only the bootstrap code needs > to be compiled and linked with no-SSP. I looked at this some but I > figured there might not be appetite for a bunch of reorganization of > rtld just to enable SSP. Anyway the bootstrap code would still need > these particular libcompiler_rt functions to be no-SSP, as they get used > in the printf procedure, which I am guessing the bootstrap may need. Just my opinion. SSP is not too useful itself, and I believe it is useless in rtld, simply due to what rtld typically executes (matching static strings). Rototiling early rtld stages to get another bullet on the list of doubtful features should not be done. ___ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
Re: svn commit: r368789 - head/libexec/rtld-elf/rtld-libc
On Sat, Dec 19, 2020 at 7:23 PM John Baldwin wrote: > > On 12/19/20 12:38 AM, Ryan Libby wrote: > > Author: rlibby > > Date: Sat Dec 19 08:38:31 2020 > > New Revision: 368789 > > URL: https://svnweb.freebsd.org/changeset/base/368789 > > > > Log: > > rtld-elf: link udivmoddi4 from compiler_rt > > > > This fixes the gcc9 build of rtld-elf32 on amd64, which needed an > > implementation of udivmoddi4. > > > > rtld-elf uses certain functions normally found in libc, and so it > > includes certain files from libc in its own build. It has two > > mechanisms to include files from libc: one that rebuilds source files in > > the rtld-elf environment, and one that extracts object files from a > > purpose-built no-SSP PIC archive. > > > > In addition to libc functions, rtld-elf may need to link functions > > normally found in libcompiler_rt (formerly libgcc). Now, add an ability > > to rebuild libcompiler_rt source files in the rtld-elf environment. We > > don't yet have a need for an object file extraction mechanism. > > > > libcompiler_rt could also supply udivdi3 and umoddi3, but leave them > > alone for now. > > > > Reviewed by:arichardson, kib > > Sponsored by: Dell EMC Isilon > > Differential Revision: https://reviews.freebsd.org/D27665 > > Hmm, I had just linked against libcompiler_rt directly as we do on arm: > > https://reviews.freebsd.org/D26199 > > It was stuck waiting for review feedback. > > Given libcompiler_rt is a static archive, we could probably safely link > against it directly unlike libc where we have to pick specific object > files. > > -- > John Baldwin Sorry, I wasn't aware of your review. Do you want this backed out? I did see the arm path. I think it is not quite right, because libcompiler_rt is compiled with -fstack-protector-strong, which is not compatible with rtld. However, it will work in practice if stack protection doesn't actually get used on any linked function. We could build a special libcompiler_rt with no stack protection like we do just for rtld with libc, but since we'd only want this no-SSP library for rtld, that's not much different from just rebuilding its source files in rtld. In addition, by rebuilding specific files we avoid overlinking--although that may not be a big deal (?), and there may be other cleaner ways to avoid that (?). On a tangent, it might be neat to split out an rtld_bootstrap (everything through init_rtld()) so that only the bootstrap code needs to be compiled and linked with no-SSP. I looked at this some but I figured there might not be appetite for a bunch of reorganization of rtld just to enable SSP. Anyway the bootstrap code would still need these particular libcompiler_rt functions to be no-SSP, as they get used in the printf procedure, which I am guessing the bootstrap may need. Ryan ___ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
Re: svn commit: r368789 - head/libexec/rtld-elf/rtld-libc
On 12/19/20 12:38 AM, Ryan Libby wrote: > Author: rlibby > Date: Sat Dec 19 08:38:31 2020 > New Revision: 368789 > URL: https://svnweb.freebsd.org/changeset/base/368789 > > Log: > rtld-elf: link udivmoddi4 from compiler_rt > > This fixes the gcc9 build of rtld-elf32 on amd64, which needed an > implementation of udivmoddi4. > > rtld-elf uses certain functions normally found in libc, and so it > includes certain files from libc in its own build. It has two > mechanisms to include files from libc: one that rebuilds source files in > the rtld-elf environment, and one that extracts object files from a > purpose-built no-SSP PIC archive. > > In addition to libc functions, rtld-elf may need to link functions > normally found in libcompiler_rt (formerly libgcc). Now, add an ability > to rebuild libcompiler_rt source files in the rtld-elf environment. We > don't yet have a need for an object file extraction mechanism. > > libcompiler_rt could also supply udivdi3 and umoddi3, but leave them > alone for now. > > Reviewed by:arichardson, kib > Sponsored by: Dell EMC Isilon > Differential Revision: https://reviews.freebsd.org/D27665 Hmm, I had just linked against libcompiler_rt directly as we do on arm: https://reviews.freebsd.org/D26199 It was stuck waiting for review feedback. Given libcompiler_rt is a static archive, we could probably safely link against it directly unlike libc where we have to pick specific object files. -- John Baldwin ___ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
svn commit: r368789 - head/libexec/rtld-elf/rtld-libc
Author: rlibby
Date: Sat Dec 19 08:38:31 2020
New Revision: 368789
URL: https://svnweb.freebsd.org/changeset/base/368789
Log:
rtld-elf: link udivmoddi4 from compiler_rt
This fixes the gcc9 build of rtld-elf32 on amd64, which needed an
implementation of udivmoddi4.
rtld-elf uses certain functions normally found in libc, and so it
includes certain files from libc in its own build. It has two
mechanisms to include files from libc: one that rebuilds source files in
the rtld-elf environment, and one that extracts object files from a
purpose-built no-SSP PIC archive.
In addition to libc functions, rtld-elf may need to link functions
normally found in libcompiler_rt (formerly libgcc). Now, add an ability
to rebuild libcompiler_rt source files in the rtld-elf environment. We
don't yet have a need for an object file extraction mechanism.
libcompiler_rt could also supply udivdi3 and umoddi3, but leave them
alone for now.
Reviewed by: arichardson, kib
Sponsored by: Dell EMC Isilon
Differential Revision:https://reviews.freebsd.org/D27665
Modified:
head/libexec/rtld-elf/rtld-libc/Makefile.inc
Modified: head/libexec/rtld-elf/rtld-libc/Makefile.inc
==
--- head/libexec/rtld-elf/rtld-libc/Makefile.incSat Dec 19 08:38:27
2020(r368788)
+++ head/libexec/rtld-elf/rtld-libc/Makefile.incSat Dec 19 08:38:31
2020(r368789)
@@ -51,8 +51,12 @@ _libc_other_objects= sigsetjmp lstat stat fstat fstata
getdirentries _getdirentries _close _fcntl _open _openat _read \
_sigprocmask _write readlink __realpathat _setjmp setjmp setjmperr
+# Allow building files from libcompiler_rt. Beware, there are some name
+# collisions between libcompiler_rt files and libc files.
+CRTSRC=${SRCTOP}/contrib/llvm-project/compiler-rt/lib/builtins
+.PATH: ${CRTSRC}
-# Finally add additional architecture-dependent libc dependencies
+# Finally add additional architecture-dependent dependencies
.if ${LIBC_ARCH} == "arm"
# ARM needs aeabi_unwind_cpp for _setjmp
_libc_other_objects+=aeabi_unwind_cpp
@@ -60,6 +64,7 @@ _libc_other_objects+=aeabi_unwind_cpp
# __udivdi3 is needed by kvprintf() in rtld_printf.c
# i386 also needs i386_set_gsbase for allocate_initial_tls()
_libc_other_objects+=umoddi3 udivdi3 qdivrem i386_set_gsbase
+SRCS+= udivmoddi4.c
.elif ${LIBC_ARCH} == "powerpc" || ${LIBC_ARCH} == "powerpcspe"
# ppc needs __syncicache for reloc.c and __umoddi3+__udivdi3 for rtld_printf.c
_libc_other_objects+=syncicache umoddi3 udivdi3 qdivrem
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