help! why a 'so' can't load its dependent 'so' to the pre-defined address

[Xing-Hao Chen]

Dear GCC experts

Please forgive me if it¡¯s bothering you.

I have a question about LD and dynamic library, which I have been struggling with for a while
it will be great if you can help me out,

in my program, two "so" - libcpss.so and libhelper.so have to be loaded into a fixed virtual address, it¡¯s done by the ld script,

SECTIONS
{
/* Code section, access rights RX */
. = 0x14600000;
¡­
}

readelf -l libhelper.so | less

Elf file type is DYN (Shared object file) Entry point 0x14607ad8 There are 8 program headers, starting at offset 64

Program Headers:
  Type           Offset             VirtAddr           PhysAddr
                 FileSiz            MemSiz              Flags  Align
  LOAD           0x0000000000010000 0x0000000014600000 0x0000000014600000
                 0x000000000001aaec 0x000000000001aaec  R E    0x10000

an elf program(appDemo) linked with these two ".so", we can see the two so indeed were loaded into the expected fixed address,

ldd ./appDemo

linux-vdso.so.1 => (0x0000ffff917ec000)
libcpss.so => ./libcpss.so (0x0000000010000000)
libhelper.so => ./libhelper.so (0x0000000014600000)
libpthread.so.0 => /lib/aarch64-linux-gnu/libpthread.so.0 (0x0000ffff917b5000)
librt.so.1 => /lib/aarch64-linux-gnu/librt.so.1 (0x0000ffff9179d000)
libdl.so.2 => /lib/aarch64-linux-gnu/libdl.so.2 (0x0000ffff91789000)
libm.so.6 => /lib/aarch64-linux-gnu/libm.so.6 (0x0000ffff916d7000)
libc.so.6 => /lib/aarch64-linux-gnu/libc.so.6 (0x0000ffff91583000)
/lib/ld-linux-aarch64.so.1 (0x0000aaaadd94f000)

however, i built another "so" ¨C libtestScript.so that linking(depending on) these two so, seems not able to load these two so into proper fixed address, see below -

ldd ./libtestScript.so

linux-vdso.so.1 => (0x0000ffff8d87c000)
libcpss.so => ./libcpss.so (0x0000ffff89d50000)
libhelper.so => ./libhelper.so (0x0000ffff5e350000)
libpthread.so.0 => /lib/aarch64-linux-gnu/libpthread.so.0 (0x0000ffff5e31c000)
librt.so.1 => /lib/aarch64-linux-gnu/librt.so.1 (0x0000ffff5e304000)
libdl.so.2 => /lib/aarch64-linux-gnu/libdl.so.2 (0x0000ffff5e2f0000)
libm.so.6 => /lib/aarch64-linux-gnu/libm.so.6 (0x0000ffff5e23e000)
libc.so.6 => /lib/aarch64-linux-gnu/libc.so.6 (0x0000ffff5e0ea000)
/lib/ld-linux-aarch64.so.1 (0x0000aaaae0958000)

do i missed any LD flags during building of the ¡°joint .so" ? i saw the only difference between elf main program and ¡°joint¡± so is the flag of ¡°-shared¡±, so why ¡°joint .so" missed the info of the two dependent so¡¯s loading address? seems when the ld.so load "joint .so" and try to resolve and load the dependency two ".so", but it doesn't load them into the fixed address(0x10000000 / 0x14600000)

NOK: LD_DEBUG=all ldd ./libtestScript.so

  2349:     file=libhelper.so [0];  generating link map
  2349:       dynamic: 0x0000ffff5d581ba0  base: 0x0000ffff48f57000   size: 0x000000002b9ff004
  2349:         entry: 0x0000ffff5d55ead8  phdr: 0x0000ffff8ca6fcc0  phnum:                  8

OK: LD_DEBUG=all ldd ./appDemo

  2289:       trying file=./libhelper.so
  2289:
  2289:     file=libhelper.so [0];  generating link map
  2289:       dynamic: 0x000000001462aba0  base: 0x0000000000000000   size: 0x000000002b9ff004
  2289:         entry: 0x0000000014607ad8  phdr: 0x0000ffffb2e24cc0  phnum:                  8

readelf -h ./libhelper.so

ELF Header:
  Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
  Class:                             ELF64
  Data:                              2's complement, little endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              DYN (Shared object file)
  Machine:                           AArch64
  Version:                           0x1
  Entry point address:               0x14607ad8
  Start of program headers:          64 (bytes into file)
  Start of section headers:          228680 (bytes into file)
  Flags:                             0x0
  Size of this header:               64 (bytes)
  Size of program headers:           56 (bytes)
  Number of program headers:         8
  Size of section headers:           64 (bytes)
  Number of section headers:         34
  Section header string table index: 31

i appreciate if you can help me out.

For your reference on how I built the elf executable program and shared lib.
/home/ericxh/work/toolchain/marvell-gcc-5.2.1-16.02.0-armv8/armv8/le/aarch64v8-
marvell-linux-gnu-5.2.1_i686_20151110/bin/aarch64-marvell-linux-gnu-gcc  -shared
-Xlinker                                                         --whole-archive
compilation_root/cpss_4.2/armv8_DX_SHARED/cpssEnabler/libs/TESTSCRIPT.a -Xlinker
--no-whole-archive    \     compilation_root/cpss_4.2/armv8_DX_SHARED/libcpss.so
compilation_root/cpss_4.2/armv8_DX_SHARED/libhelper.so   -Xlinker   -z  -Xlinker
nocopyreloc  -rdynamic   -lpthread  -lrt   -ldl  -lm    -Xlinker  -Map  -Xlinker
compilation_root/cpss_4.2/armv8_DX_SHARED/libtestScript.map \ -Xlinker -soname -
Xlinker                           libtestScript.so                            -o
compilation_root/cpss_4.2/armv8_DX_SHARED/libtestScript.so


/home/ericxh/work/toolchain/marvell-gcc-5.2.1-16.02.0-armv8/armv8/le/aarch64v8-
marvell-linux-gnu-5.2.1_i686_20151110/bin/aarch64-marvell-linux-gnu-gcc -Xlinker
--whole-archive
compilation_root/cpss_4.2/armv8_DX_SHARED/referenceCode/libs/REFERENCECODE.a
¡­
¡­
compilation_root/cpss_4.2/armv8_DX_SHARED/cpssEnabler/libs/CPSSAPPREF.a
compilation_root/cpss_4.2/armv8_DX_SHARED/version_info.o  -Xlinker   --no-whole-
archive          \          compilation_root/cpss_4.2/armv8_DX_SHARED/libcpss.so
compilation_root/cpss_4.2/armv8_DX_SHARED/libhelper.so   -Xlinker   -z  -Xlinker
nocopyreloc  -rdynamic   -lpthread  -lrt   -ldl  -lm    -Xlinker  -Map  -Xlinker
compilation_root/cpss_4.2/armv8_DX_SHARED/appDemo.map                         -o
compilation_root/cpss_4.2/armv8_DX_SHARED/appDemo





Best regards

Xinghao Chen £¨³ÂÐкƣ©