On Mon, Dec 9, 2013 at 8:57 PM, H. Peter Anvin <h...@zytor.com> wrote: > Where do the _32 and _32S relocations come from? Are we mixing multiple > things inside -pie?
They come from crt1.o and crtbegin.o. -pie uses Scrt1.o and crtbeginS.o. > "H.J. Lu" <hjl.to...@gmail.com> wrote: >>On Mon, Dec 9, 2013 at 7:23 PM, H. Peter Anvin <h...@zytor.com> wrote: >>> On 12/09/2013 07:05 PM, H.J. Lu wrote: >>>>> >>>>> I see. Maybe linker can set ET_EXEC if vaddr is non-zero. >>>>> >>>> >>>> Linker sets e_type in ELF header to ET_DYN for -pie >>-Ttext-segment=0xXXX. >>>> When I added -Ttext-segment=0xXXX, one goal was to load >>>> small model executable above 4GB on Linux/x86-64, which >>>> was done with -pie -Ttext-segment=0xXXX. But -pie sets >>>> e_type in ELF header to ET_DYN and kernel may ignore >>>> p_vaddr in ELF header to load ET_DYN binary at a random >>>> address. This patch changes ld to set e_type in ELF header >>>> to ET_EXEC if the first PT_LOAD segment has non-zero >>>> p_vaddr. If this is unacceptable as generic ELF change, >>>> I can make it specific to x86. >>>> >>> >>> Why not just drop the -pie from the command line? I would expect >>-pie >>> to set ET_DYN, but if you want to load at a specific address one >>would >>> expect to use -Ttext-segment=... and *not* -pie. >>> >> >>No. We must keep -pie. Without -pie, we can't set -Ttext-segment= >>to above 4GB: >> >>[hjl@gnu-6 tmp]$ gcc a.c -Wl,-Ttext-segment=0x7ff000000 >>/usr/lib/gcc/x86_64-redhat-linux/4.8.2/../../../../lib64/crt1.o: In >>function `_start': >>(.text+0x12): relocation truncated to fit: R_X86_64_32S against symbol >>`__libc_csu_fini' defined in .text section in >>/usr/lib64/libc_nonshared.a(elf-init.oS) >>/usr/lib/gcc/x86_64-redhat-linux/4.8.2/../../../../lib64/crt1.o: In >>function `_start': >>(.text+0x19): relocation truncated to fit: R_X86_64_32S against symbol >>`__libc_csu_init' defined in .text section in >>/usr/lib64/libc_nonshared.a(elf-init.oS) >>/usr/lib/gcc/x86_64-redhat-linux/4.8.2/../../../../lib64/crt1.o: In >>function `_start': >>(.text+0x20): relocation truncated to fit: R_X86_64_32S against symbol >>`main' defined in .text section in /tmp/ccV9AIMR.o >>/usr/lib/gcc/x86_64-redhat-linux/4.8.2/crtbegin.o: In function >>`deregister_tm_clones': >>crtstuff.c:(.text+0x1): relocation truncated to fit: R_X86_64_32 >>against symbol `__TMC_END__' defined in .data section in a.out >>crtstuff.c:(.text+0x8): relocation truncated to fit: R_X86_64_32S >>against `.tm_clone_table' >>crtstuff.c:(.text+0x23): relocation truncated to fit: R_X86_64_32 >>against `.tm_clone_table' >>/usr/lib/gcc/x86_64-redhat-linux/4.8.2/crtbegin.o: In function >>`register_tm_clones': >>crtstuff.c:(.text+0x31): relocation truncated to fit: R_X86_64_32 >>against symbol `__TMC_END__' defined in .data section in a.out >>crtstuff.c:(.text+0x38): relocation truncated to fit: R_X86_64_32S >>against `.tm_clone_table' >>crtstuff.c:(.text+0x63): relocation truncated to fit: R_X86_64_32 >>against `.tm_clone_table' >>/usr/lib/gcc/x86_64-redhat-linux/4.8.2/crtbegin.o: In function >>`frame_dummy': >>crtstuff.c:(.text+0xa6): relocation truncated to fit: R_X86_64_32 >>against `.jcr' >>/tmp/ccV9AIMR.o: In function `main': >>a.c:(.text+0x5): additional relocation overflows omitted from the >>output >>collect2: error: ld returned 1 exit status >>[hjl@gnu-6 tmp]$ gcc -fpie -pie a.c -Wl,-Ttext-segment=0x7ff000000 >>[hjl@gnu-6 tmp]$ >> > -- H.J. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
