Hi, I was looking at the ARM ABI docs(http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044e/IHI0044E_aaelf.pdf) and they mention. "A binary file may use REL or RELA relocations or a mixture of the two (but multiple relocations for the same address must use only one type)." Does LLVM emit rel/rela relocations with ARM ? Any tests ? Thanks Shankar Easwaran -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation
On Mon, Nov 4, 2013 at 11:05 AM, Shankar Easwaran <shankare at codeaurora.org>wrote:> Hi, > > I was looking at the ARM ABI docs(http://infocenter.arm. > com/help/topic/com.arm.doc.ihi0044e/IHI0044E_aaelf.pdf) and they mention. > > "A binary file may use REL or RELA relocations or a mixture of the two > (but multiple relocations for the same > address must use only one type)." > > Does LLVM emit rel/rela relocations with ARM ? > >I hope not. Ew. -eric> Any tests ? > > Thanks > > Shankar Easwaran > > -- > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted > by the Linux Foundation > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20131104/fd814646/attachment.html>
Hi Shankar,> Does LLVM emit rel/rela relocations with ARM ?I believe we emit .rel for (32-bit) ARM. Hard-coded in ARMELFObjectWriter.cpp (“HasRelocationAddend”). It seems to be what most toolchains have settled on. AArch64 is .rela always in LLVM, in case it matters.> Any tests ?Well there are tests of what we do, but obviously not of the full scope of functionality permitted by the ABI. Cheers. Tim. -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 841 bytes Desc: Message signed with OpenPGP using GPGMail URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20131104/b3123ae9/attachment.sig>
Thanks a lot for the answers. Mixing rela/rel will make it hard for the linker to handle(especially the lot of configurations in which the linker works - shared libraries/partial linking/dynamic linking etc ). Thanks Shankar Easwaran On 11/4/2013 1:20 PM, Tim Northover wrote:> Hi Shankar, > >> Does LLVM emit rel/rela relocations with ARM ? > I believe we emit .rel for (32-bit) ARM. Hard-coded in ARMELFObjectWriter.cpp (“HasRelocationAddend”). It seems to be what most toolchains have settled on. AArch64 is .rela always in LLVM, in case it matters. > >> Any tests ? > Well there are tests of what we do, but obviously not of the full scope of functionality permitted by the ABI. > > Cheers. > > Tim.-- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation
On 11/04/2013 11:15 AM, Eric Christopher wrote:> > > > On Mon, Nov 4, 2013 at 11:05 AM, Shankar Easwaran > <shankare at codeaurora.org <mailto:shankare at codeaurora.org>> wrote: > > Hi, > > I was looking at the ARM ABI > docs(http://infocenter.arm.__com/help/topic/com.arm.doc.__ihi0044e/IHI0044E_aaelf.pdf > <http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044e/IHI0044E_aaelf.pdf>) > and they mention. > > "A binary file may use REL or RELA relocations or a mixture of the > two (but multiple relocations for the same > address must use only one type)." > > Does LLVM emit rel/rela relocations with ARM ? > > > I hope not. Ew.The only reason this is Ew is that llvm has decided not to prepare for it. There shouldn't be a single rel/rela type for a given output. The one that works for the given situation for the given section should be used. The mechanism for handling both should not be complicated. There are rules about relocation order and multiple relocations can operate on a single point in the binary. There is no reason a section of .rel relocations cannot operate alongside a section of .rela relocations. Unfortunately I believe the single rel/rela type is part and parcel to gnu as well and I have resigned myself to going with the flow for now. Jack> > -eric > > Any tests ? > > Thanks > > Shankar Easwaran > > -- > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, > hosted by the Linux Foundation > > _________________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu <mailto:LLVMdev at cs.uiuc.edu> http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/__mailman/listinfo/llvmdev > <http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev> > > > > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >