digitalmars.D.bugs - [Issue 4583] New: PIC code not working: EBX register set incorrectly
- d-bugmail puremagic.com (63/63) Aug 05 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4583
- d-bugmail puremagic.com (11/11) Aug 05 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4583
- d-bugmail puremagic.com (13/13) Aug 06 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4583
- d-bugmail puremagic.com (10/10) Aug 06 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4583
- d-bugmail puremagic.com (10/10) Sep 20 2010 http://d.puremagic.com/issues/show_bug.cgi?id=4583
- d-bugmail puremagic.com (22/22) Nov 30 2011 http://d.puremagic.com/issues/show_bug.cgi?id=4583
- d-bugmail puremagic.com (7/12) Nov 30 2011 http://d.puremagic.com/issues/show_bug.cgi?id=4583
- d-bugmail puremagic.com (8/8) Dec 01 2011 http://d.puremagic.com/issues/show_bug.cgi?id=4583
- d-bugmail puremagic.com (8/9) Apr 27 2012 http://d.puremagic.com/issues/show_bug.cgi?id=4583
- d-bugmail puremagic.com (8/8) May 04 2012 http://d.puremagic.com/issues/show_bug.cgi?id=4583
- d-bugmail puremagic.com (8/8) May 04 2012 http://d.puremagic.com/issues/show_bug.cgi?id=4583
- d-bugmail puremagic.com (8/8) May 04 2012 http://d.puremagic.com/issues/show_bug.cgi?id=4583
- d-bugmail puremagic.com (8/8) May 04 2012 http://d.puremagic.com/issues/show_bug.cgi?id=4583
- d-bugmail puremagic.com (9/9) May 04 2012 http://d.puremagic.com/issues/show_bug.cgi?id=4583
http://d.puremagic.com/issues/show_bug.cgi?id=4583 Summary: PIC code not working: EBX register set incorrectly Product: D Version: D2 Platform: Other OS/Version: Linux Status: NEW Severity: major Priority: P2 Component: DMD AssignedTo: nobody puremagic.com ReportedBy: johannespfau gmail.com PDT --- Mostly copy and pasting from an old post in the newsgroup. I tried to build druntime as a shared library and encountered this bug. I tried to reduce it to a simpler testcase, but that didn't work. To reproduce: Download the druntime shared library makefile (so.mak) from this site: http://www.curoles.com/j/dso/dso.html (at the bottom of the page) and compile druntime with it. Compile this very simple test program, as described at the top of that page. ---- void main(){ } ---- The problem seems to be in the assembler code generated for main: http://www.dsource.org/projects/druntime/browser/trunk/src/rt/dmain2.d : extern (C) int main(int argc, char **argv) --------------------------------------- (gdb) disassemble 0xb7f9f36c Dump of assembler code for function main: #ebx=0xb7f16ff4 ebp=0xbffff0a8 0xb7f9f338 <+0>: push %ebp 0xb7f9f339 <+1>: mov %esp,%ebp 0xb7f9f33b <+3>: sub $0x3c,%esp 0xb7f9f33e <+6>: push %ebx #ebx=0xb7f16ff4 0xb7f9f33f <+7>: mov 0xc(%ebp),%ebx 0xb7f9f342 <+10>: push %esi #ebx=0xbffff154 0xb7f9f343 <+11>: push %edi 0xb7f9f344 <+12>: call 0xb7f9f349 <main+17> 0xb7f9f349 <+17>: pop %eax 0xb7f9f34a <+18>: add $0x15343,%eax 0xb7f9f34f <+23>: mov %eax,-0x38(%ebp) 0xb7f9f352 <+26>: movl $0x0,-0x34(%ebp) 0xb7f9f359 <+33>: movl $0x0,-0x30(%ebp) 0xb7f9f360 <+40>: movl $0x0,-0x2c(%ebp) 0xb7f9f367 <+47>: call 0xb7f8813c <_STI_monitor_staticctor at plt> --------------------------------------- (gdb) disassemble '_STI_monitor_staticctor at plt' Dump of assembler code for function _STI_monitor_staticctor at plt: 0xb7f8813c <+0>: jmp *0x2b4(%ebx) -->Segfault here 0xb7f88142 <+6>: push $0x550 0xb7f88147 <+11>: jmp 0xb7f8768c -------------------------------------- The problem is the ebx register. If I understood elf files correctly, the ebx register must hold the address of the GOT when calling a PLT entry. I guess when the main function is called by libc, ebx should be set correctly, in this case to 0xb7f16ff4. I also guess the "push %ebx" instruction is meant to save the GOT adress to stack, because ebx is used for other stuff. But the ebx register is not restored to the GOT address before calling <_STI_monitor_staticctor at plt> and therefore "*jmp 0x2b4(%ebx) " crashes. So this seems to be a problem with dmds PIC support / -fPIC switch. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Aug 05 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4583 Walter Bright <bugzilla digitalmars.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bugzilla digitalmars.com 14:20:51 PDT --- I don't think EBX is required to pass between functions. Each function reloads it as necessary. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Aug 05 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4583 PDT --- Yes I know, but the problem occurs even before the called function is executed: The PLT is a table containing executable code. If you do an position independent function call, you call into this PLT code, not directly into your target function. And these PLT instructions require EBX to be set to the GOT address. I strogly recommend reading http://www.skyfree.org/linux/references/ELF_Format.pdf especially the section about PLT, page 48 and page 49, I think the explanation there is very good. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Aug 06 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4583 PDT --- Btw, that's different on x86_64 which uses "Instruction pointer relative data access". http://www.x86-64.org/documentation/abi.pdf (I guess you already know this document, as you're implementing 64 bit support, but just in case...) -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Aug 06 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4583 Don <clugdbug yahoo.com.au> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |wrong-code CC| |clugdbug yahoo.com.au Severity|major |critical -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Sep 20 2010
http://d.puremagic.com/issues/show_bug.cgi?id=4583 Created an attachment (id=1047) my Makefile adjustments I tried it on x64: $ make MODEL=64 -f posix.mak -j2 cc -c -m64 -O -fPIC src/core/stdc/errno.c -oobj/errno_c.o cc -Wa,-noexecstack -c -m64 -O -fPIC src/core/threadasm.S -oobj/threadasm.o cc -c -m64 -O -fPIC src/rt/complex.c -oobj/complex.o ... dmd -c -oflib/ofdrt.o -m64 -O -fPIC -release -inline -nofloat -w -d -Isrc -Iimport src/object_.d [......] gcc -shared -Wl,-export-dynamic,-soname,lib/libdruntime.so.1 -o lib/libdruntime.so.1.0.1 lib/ofdrt.o obj/errno_c.o obj/threadasm.o obj/complex.o /usr/bin/ld: lib/ofdrt.o: relocation R_X86_64_PC32 against symbol `_Dmodule_ref' can not be used when making a shared object; recompile with -fPIC /usr/bin/ld: final link failed: Bad value -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Nov 30 2011
http://d.puremagic.com/issues/show_bug.cgi?id=4583 14:31:30 PST ---Yes I know, but the problem occurs even before the called function is executed: The PLT is a table containing executable code. If you do an position independent function call, you call into this PLT code, not directly into your target function. And these PLT instructions require EBX to be set to the GOT address.You're right. DMD doesn't do this at the moment. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Nov 30 2011
http://d.puremagic.com/issues/show_bug.cgi?id=4583 10:53:36 PST --- https://github.com/D-Programming-Language/dmd/commit/887dda0ba2439ca4dbeec38b0434377ba831cf40 https://github.com/D-Programming-Language/dmd/commit/70904844f652f53d80b3f379060638fe91811721 This addresses setting EBX before the function call, not any other issues. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Dec 01 2011
http://d.puremagic.com/issues/show_bug.cgi?id=4583 23:34:02 PDT ---This addresses setting EBX before the function call, not any other issues.Still, a couple of the runtime compiler helper functions pass arguments in EBX. This still needs fixing. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Apr 27 2012
http://d.puremagic.com/issues/show_bug.cgi?id=4583 Commit pushed to master at https://github.com/D-Programming-Language/druntime https://github.com/D-Programming-Language/druntime/commit/2a5385345c17a65f8280efab1674c23bde3df68e fix Issue 4583 - PIC code not working: EBX register set incorrectly -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
May 04 2012
http://d.puremagic.com/issues/show_bug.cgi?id=4583 Commit pushed to phobos-1.x at https://github.com/D-Programming-Language/phobos https://github.com/D-Programming-Language/phobos/commit/df21e384a4207e6f888b5abed0f7b3298a2d0320 fix Issue 4583 - PIC code not working: EBX register set incorrectly -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
May 04 2012
http://d.puremagic.com/issues/show_bug.cgi?id=4583 Commit pushed to dmd-1.x at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/39c0a6ec5e2d1ae412d5d60834feb8ab610b090e fix Issue 4583 - PIC code not working: EBX register set incorrectly -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
May 04 2012
http://d.puremagic.com/issues/show_bug.cgi?id=4583 Commit pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/ca53f96c09be934c51b2ea1d91c277639181cfec fix Issue 4583 - PIC code not working: EBX register set incorrectly -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
May 04 2012
http://d.puremagic.com/issues/show_bug.cgi?id=4583 Walter Bright <bugzilla digitalmars.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution| |FIXED -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
May 04 2012