Bug 249121
| Summary: | program compiled with -pg produces ld-elf abort | ||
|---|---|---|---|
| Product: | Base System | Reporter: | wsh |
| Component: | gnu | Assignee: | Konstantin Belousov <kib> |
| Status: | Closed FIXED | ||
| Severity: | Affects Some People | CC: | dim, emaste, kevinz5000, kib, markj, toolchain, wsh |
| Priority: | --- | Flags: | koobs:
mfc-stable12+
markj: mfc-stable11+ |
| Version: | CURRENT | ||
| Hardware: | amd64 | ||
| OS: | Any | ||
Unfortunately my upload has failed since it is to big. If you would like you may pull the repo and modify CMakeLists.txt to compile with -pg. Requires llvm>=10 and openssl>=1.1 https://github.com/riski-sh/crochet Can you create minimal self contained reproducer consisting of single .c or .c++ file and build script ? A minimal self contained recreation consisted of a main.c with contents
int main(int argc, char **argv) {
return 0;
}
Building with `clang main.c -g -pg` and running a.out produced segfault
Building with `clang main.c` and running a.out returns 0 as normal.
Clang+lld produce very strange binary when all linked libraries are static:
Elf file type is EXEC (Executable file)
Entry point 0x2237a0
There are 11 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flg Align
PHDR 0x0000000000000040 0x0000000000200040 0x0000000000200040
0x0000000000000268 0x0000000000000268 R 0x8
INTERP 0x00000000000002a8 0x00000000002002a8 0x00000000002002a8
0x0000000000000015 0x0000000000000015 R 0x1
[Requesting program interpreter: /libexec/ld-elf.so.1]
LOAD 0x0000000000000000 0x0000000000200000 0x0000000000200000
0x000000000002279c 0x000000000002279c R 0x1000
LOAD 0x00000000000227a0 0x00000000002237a0 0x00000000002237a0
0x0000000000091760 0x0000000000091760 R E 0x1000
LOAD 0x00000000000b3f00 0x00000000002b5f00 0x00000000002b5f00
0x0000000000001898 0x0000000000001898 RW 0x1000
LOAD 0x00000000000b57a0 0x00000000002b87a0 0x00000000002b87a0
0x00000000000037c0 0x00000000002247a9 RW 0x1000
TLS 0x00000000000b3f00 0x00000000002b5f00 0x00000000002b5f00
0x0000000000001850 0x0000000000001870 R 0x10
GNU_RELRO 0x00000000000b3f00 0x00000000002b5f00 0x00000000002b5f00
0x0000000000001898 0x0000000000002100 R 0x1
GNU_EH_FRAME 0x000000000000fc80 0x000000000020fc80 0x000000000020fc80
0x000000000000300c 0x000000000000300c R 0x4
GNU_STACK 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 RW 0
NOTE 0x00000000000002c0 0x00000000002002c0 0x00000000002002c0
0x0000000000000048 0x0000000000000048 R 0x4
...
There is no dynamic section in this file.
Relocation section with addend (.rela.dyn):
r_offset r_info r_type st_value st_name + r_addend
0000002bbf50 000000000025 R_X86_64_IRELATIVE 0000000000000000 + 223dd0
0000002bbf58 000000000025 R_X86_64_IRELATIVE 0000000000000000 + 2a91e0
As you see, it specifies PHDR INTERP, which brings rtld into action.
But there is no dynamic segment, so rtld cannot see any relocs, which results
in the IRELATIVE relocation sites to still point to the resolver functions.
This is arguably a bug in lld.
There are also two bugs in rtld which fixes I will commit shortly. I assumes
dynamic segment is there and dereferences NULL pointer otherwise. Also, it
terminates the image if there is no dynamic symbol table.
A commit references this bug: Author: kib Date: Sat Sep 5 22:41:31 UTC 2020 New revision: 365368 URL: https://svnweb.freebsd.org/changeset/base/365368 Log: rtld: do not process absent dynamic. If object has no dynamic phdr, do not try to dereference NULL. This means that we cannot process any relocation, and that there cannot be symbols defined, but it is up to static linker to produce meaningful objects. PR: 249121 Reported by: wsh@riski.sh Sponsored by: The FreeBSD Foundation MFC after: 1 week Changes: head/libexec/rtld-elf/rtld.c A commit references this bug: Author: kib Date: Sat Sep 5 22:44:38 UTC 2020 New revision: 365369 URL: https://svnweb.freebsd.org/changeset/base/365369 Log: rtld: do not refuse to relocate objects without dynamic symtabs. Such objects can still have valid relocations not requiring symbolic references. PR: 249121 Reported by: wsh@riski.sh Sponsored by: The FreeBSD Foundation MFC after: 1 week Changes: head/libexec/rtld-elf/rtld.c And there seems to be one more bug with lld, besides omitting dynamic. It seems to be really confused about what type of binary (static/dynamic) it produces. Since &_DYNAMIC is NULL, I realized that linker should have filled values for __rela_iplt_start and __rela_iplt_end, which are used by csu to locate irelocs. But apparently linker did not that either. Dimitry, can you fill lld bugs, please ? A commit references this bug: Author: kib Date: Sat Sep 12 09:44:50 UTC 2020 New revision: 365653 URL: https://svnweb.freebsd.org/changeset/base/365653 Log: MFC r365368: rtld: do not process absent dynamic. PR: 249121 Changes: _U stable/12/ stable/12/libexec/rtld-elf/rtld.c A commit references this bug: Author: kib Date: Sat Sep 12 09:46:14 UTC 2020 New revision: 365654 URL: https://svnweb.freebsd.org/changeset/base/365654 Log: MFC r365369: rtld: do not refuse to relocate objects without dynamic symtabs. PR: 249121 Changes: _U stable/12/ stable/12/libexec/rtld-elf/rtld.c A commit references this bug: Author: kib Date: Sat Sep 12 09:47:25 UTC 2020 New revision: 365655 URL: https://svnweb.freebsd.org/changeset/base/365655 Log: MFC r365368: rtld: do not process absent dynamic. PR: 249121 Changes: _U stable/11/ stable/11/libexec/rtld-elf/rtld.c A commit references this bug: Author: kib Date: Sat Sep 12 09:47:58 UTC 2020 New revision: 365656 URL: https://svnweb.freebsd.org/changeset/base/365656 Log: MFC r365369: rtld: do not refuse to relocate objects without dynamic symtabs. PR: 249121 Changes: _U stable/11/ stable/11/libexec/rtld-elf/rtld.c ^Triage: Assign to committer resolving
Is this now resolved (head+stable{11,12) or their more commits or merges to come?
I seem to have come across this issue in 12.2-REELASE. Will this fix be available in a 12.3-REELASE? |
Attempting to profile my code with gprof. Currently compiling with clang with arguments; -Weverything -Werror -Wpedantic -O2 -g -pg Without -pg program runs perfectly fine. With -pg lib-elf haults with message ld-elf.so.1: /lib/libc.so.7: Undefined symbol "__progname". On FreeBSD-12.1-p8 I received a different error of unsupported relocation type 37 in non-plt relocations with the same compile options on the same executable. I have attached the executable compiled with pg and no pg.