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From: "luofengwc at qq dot com" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug libc/31302] New: glibc issue about reloc-type R_X86_64_TPOFF64
 when llvm build golang project with cgo,
Date: Sun, 28 Jan 2024 00:45:35 +0000
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X-Bugzilla-Product: glibc
X-Bugzilla-Component: libc
X-Bugzilla-Version: 2.38
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X-Bugzilla-Severity: normal
X-Bugzilla-Who: luofengwc at qq dot com
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X-Bugzilla-Priority: P2
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D31302

            Bug ID: 31302
           Summary: glibc issue about reloc-type R_X86_64_TPOFF64 when
                    llvm build golang project with cgo,
           Product: glibc
           Version: 2.38
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: luofengwc at qq dot com
                CC: drepper.fsp at gmail dot com
  Target Milestone: ---

hi i want to report glibc issue when i use llvm=EF=BC=8C the following is d=
etail:

when clang build golang on x86 arch, and use cgo function, build to static
linked exec, exec will segment fault.=20

this is demo.go:

package main
// #cgo LDFLAGS: -ldl
// #include <stdlib.h>
// #include <dlfcn.h>
import "C"
import (
 "fmt"
)
func main() {
 fmt.Printf("This is go demo\n")
 C.CString("libsystemd-login.so.0")
 return
}

build static exec command :
export CC=3Dclang
CGO_ENABLED=3D1 CGO_CFLAGS=3D"-fstack-protector-strong -fPIE"
CGO_CPPFLAGS=3D"-fstack-protector-strong -fPIE"
CGO_LDFLAGS_ALLOW=3D'-Wl,-z,relro,-z,now' CGO_LDFLAGS=3D"-Wl,-z,relro,-z,now
-Wl,-z,noexecstack" go build -buildmode=3Dpie -o demo -ldflags '-buildid=3D=
none
-tmpdir=3D. -extldflags=3D-ftrapv -extldflags=3D-Wl,-z,relro,-z,now
-linkmode=3Dexternal -extldflags=3D-static-pie' demo.go

and gdb segment fault stack, indicate crash in glibc

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7e835dc in _dl_signal_error ()
(gdb) bt
#0 0x00007ffff7e835dc in _dl_signal_error ()
#1 0x00007ffff7ebf6f3 in _dl_allocate_static_tls ()
#2 0x00007ffff7e843d0 in _dl_relocate_static_pie ()
#3 0x00007ffff7e46b59 in __libc_start_main_impl ()
#4 0x00007ffff7dc4665 in _start ()
when debug, i found clang change the sym relocate type from R_X86_64_GOTTPO=
FF
to R_X86_64_TPOFF64

readelf -a glibc/dl-error.o | grep R_X86_64_GOTTPOFF
readelf -a demo | grep R_X86_64_TPOFF64
i want to know why glibc does not match this relocation type.

thank you

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