similar to: Proposal: arbitrary relocations in constant global initializers

Hi, I’d like to make this proposal for extending the Constant hierarchy with a mechanism for introducing custom relocations in global initializers. This could also be seen as a first step towards adding a “bag-of-bytes with relocations” representation for global initializers. Problem In order to implement control flow integrity for indirect function calls, we would like to add a set of

On Wed, Aug 26, 2015 at 03:53:33PM -0400, Rafael Espíndola wrote: > > I'm not sure if this would be sufficient. The R_ARM_JUMP24 relocation > > on ARM has specific semantics to implement ARM/Thumb interworking; see > > http://infocenter.arm.com/help/topic/com.arm.doc.ihi0044e/IHI0044E_aaelf.pdf > > Note that R_ARM_CALL has the same operation but different semantics.

On Fri, Oct 7, 2016 at 12:20 PM, Evgenii Stepanov <eugeni.stepanov at gmail.com > wrote: > I've tried implementing some of the alternatives mentioned in this > thread, and so far I like this syntax the most: > > i32 reloc (29, void ()* @f, 3925868544) > ; 29 = 0x1d = R_ARM_JUMP24 > ; 3925868544 = 0xea000000 > > Note the zeroes in the relocated data instead of

On Fri, Oct 7, 2016 at 1:55 PM, Evgenii Stepanov <eugeni.stepanov at gmail.com> wrote: > On Fri, Oct 7, 2016 at 1:22 PM, Peter Collingbourne <peter at pcc.me.uk> > wrote: > > On Fri, Oct 7, 2016 at 12:20 PM, Evgenii Stepanov > > <eugeni.stepanov at gmail.com> wrote: > >> > >> I've tried implementing some of the alternatives mentioned in

On Fri, Oct 7, 2016 at 2:48 PM, Evgenii Stepanov <eugeni.stepanov at gmail.com> wrote: > On Fri, Oct 7, 2016 at 2:28 PM, Peter Collingbourne <peter at pcc.me.uk> > wrote: > > On Fri, Oct 7, 2016 at 1:55 PM, Evgenii Stepanov < > eugeni.stepanov at gmail.com> > > wrote: > >> > >> On Fri, Oct 7, 2016 at 1:22 PM, Peter Collingbourne <peter

On Wed, Aug 26, 2015 at 11:49:46AM -0400, Rafael Espíndola wrote: > This is pr10368. > > Do we really need to support hard coded relocation numbers? Looks like > the examples above have a representation as constant expressions: > > (sub (add (ptrtoint @foo) 0xeafffffe) cur_pos) > > no? I'm not sure if this would be sufficient. The R_ARM_JUMP24 relocation on ARM

Hi Lang, Yeah, I remember this case. Basically what’s happening is that there are relocations for ELF on x86 that use a value that is present in the object image as part of the calculation for the final value that goes in the same location. If you ever find yourself applying relocations for a second time (for instance, because the loaded object location is remapped for out-of-proc execution)

Currently llvm-dwarfdump isn't very useful on ELF .o files because it doesn't apply relocations. nlewycky at ducttape:~$ llvm-dwarfdump helloworld.o | grep debug_str\\[ 0x0000000c: DW_AT_producer [DW_FORM_strp] ( .debug_str[0x00000000] = "clang version 3.2 (trunk 163034)") 0x00000012: DW_AT_name [DW_FORM_strp] ( .debug_str[0x00000000] = "clang version 3.2 (trunk

A bit off topic: ARM Group relocations define a logical set of consequent instructions to be relocated to form one single address. For such relocations a 1 to 1 relation is also met, so no need of special processing in applyRelocation. Concerning native format: it also introduced unneeded code complexity to me when I wanted to set calculated relocation addend back into the Reference object in the

Hi Akira, This is looking good. Some specific comments on the details below. Thanks! Jim > diff --git a/include/llvm/MC/MCELFObjectWriter.h b/include/llvm/MC/MCELFObjectWriter.h > index 6e9f5d8..220ecd0 100644 > --- a/include/llvm/MC/MCELFObjectWriter.h > +++ b/include/llvm/MC/MCELFObjectWriter.h > @@ -13,6 +13,7 @@ > #include "llvm/MC/MCObjectWriter.h" >

Here is the patch. On Thu, Mar 22, 2012 at 11:11 AM, Akira Hatanaka <ahatanak at gmail.com> wrote: > Hi Jim, > > Yes, the relocation entries have to be reordered so that the > got16/lo16 or hi16/lo16 pairs appear consecutively in the relocation > table. As a result, relocations can appear in a different order than > the instructions that they're for. > > For

Bringing the discussion to llvmdev. For the purposed of this discussion, object files can be thought as having just a few thing we care about: data, labels and relocations. Data is what at llvm ir would be just the contents of variables or functions. Relocations are utilities to compute the data at link time when it is not possible to do so earlier. For example, to compute a pcrel relocation we

Hi Jim, Thanks for reviewing the patch. I couldn't get rid of STLExtras.h, but other than that, I followed all the suggestions in your email. Please let me know if you notice anything else that needs fixing. On Thu, Mar 22, 2012 at 4:42 PM, Jim Grosbach <grosbach at apple.com> wrote: > Hi Akira, > > This is looking good. Some specific comments on the details below. > >

Hi Akira, Just two very minor things that I missed the first time around. 1. The 'fixup" member of ELFRelocation entry should be "Fixup" instead. 2. Since we're always passing in a non-NULL fixup, that should probably be a reference, not a pointer. Good for commit with those tweaks. Thanks! -Jim On Mar 23, 2012, at 1:07 PM, Akira Hatanaka wrote: > Hi Jim, >

Hi, Alexei On 2015/7/30 1:13, Alexei Starovoitov wrote: > On 7/29/15 2:38 AM, He Kuang wrote: >> Hi, Alexei >> >> On 2015/7/28 10:18, Alexei Starovoitov wrote: >>> On 7/25/15 3:04 AM, He Kuang wrote: >>>> I noticed that for 64-bit elf format, the reloc sections have >>>> 'Addend' in the entry, but there's no 'Addend' info

Hi, The round trip passes just tries to load a *complete* object file in YAML/Native format back. The internal state should be the complete object file in native/yaml format. If some state is not recorded and that is really needed in the writer, we should add that to the Atom model. Shankar Easwaran On 2/9/2015 1:29 PM, Rui Ueyama wrote: > I want to bring this again because I think

Hi Jim, Yes, the relocation entries have to be reordered so that the got16/lo16 or hi16/lo16 pairs appear consecutively in the relocation table. As a result, relocations can appear in a different order than the instructions that they're for. For example, in this code, the post-RA scheduler inserts an instruction with relocation %got(body_ok) between %got(scope_top) and %lo(scope_top). $ cat

On 2020-07-29, Eric Christopher wrote: >I think the arguments are largely compatibility for software that's already >deployed and can't easily upgrade, and wanting to ensure a larger time >frame for migration with a fallback if things go wrong. A bridge basically >from what we had to where we'd like to be. > >I think we also need to make the change in mainline lld as

On Mon, Nov 5, 2012 at 5:17 PM, Eric Christopher <echristo at gmail.com> wrote: > For llvm-dwarfdump we need to handle relocations inside the debug info > sections in order to successfully dump the dwarf info including strings. > Nick sent out a partial patch that did this not too long ago and I've taken > it and gone in a bit of a different direction, but kept the same basic

FWIW, I think it's probably best to at least initially frame the discussion around non-configurable value for the sake of reducing the scope/possible surface area of the feature/users/etc. I'd probably only encourage adding the user-configurable flag if/when someone has a use case for it. On Thu, Jun 4, 2020 at 2:31 PM Fangrui Song <maskray at google.com> wrote: > > > On