Date: Sat, 18 Aug 2018 10:23:27 +0200 From: Dimitry Andric <dim@FreeBSD.org> To: sgk@troutmask.apl.washington.edu Cc: Ed Maste <emaste@freebsd.org>, Warner Losh <imp@bsdimp.com>, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: kldref: unhandled relocation type 2 Message-ID: <C2E89211-755A-4358-B8F4-9E31106D754E@FreeBSD.org> In-Reply-To: <20180817225012.GA92976@troutmask.apl.washington.edu> References: <20180808165819.GA87623@troutmask.apl.washington.edu> <CANCZdfp7pcpNjsmdGDYUaxm6j6tkr9Y5JWqq7VAQ7jBezh8cCw@mail.gmail.com> <20180808171936.GA87930@troutmask.apl.washington.edu> <CANCZdfq=ToZ6oS=dsZ_8n5R5JNLpejpv%2Bb8=GyoytY5g_8YDkw@mail.gmail.com> <CAPyFy2C46ianx_V36gPR9fM=9-GzbrbFnaeiBrzDn9Q3nVy70Q@mail.gmail.com> <20180817225012.GA92976@troutmask.apl.washington.edu>
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On 18 Aug 2018, at 00:50, Steve Kargl <sgk@troutmask.apl.washington.edu> wrote:
>
> On Fri, Aug 17, 2018 at 05:50:06PM -0400, Ed Maste wrote:
>> On 8 August 2018 at 13:27, Warner Losh <imp@bsdimp.com> wrote:
>>>
>>>> % /usr/obj/usr/src/i386.i386/usr.sbin/kldxref/kldxref /boot/kernel
>>>> kldxref: unhandled relocation type 2
>>>> (40+ messages...)
>>>
>>>
>>> Oh, wait: relocation type, not module info.... That's not me, that's ed and
>>> the new linker I think, or Dimitry and the new clang...
>>
>> 2 is R_386_PC32. It looks like the kernel's relocation code handles
>> this, but not kldxref. I hope to be able to look at it soon.
>
> Thanks, Ed. If you need any other information, just ask.
This rabbit hole is a bit deeper though. Almost all .ko files in
/boot/kernel contain R_386_PC32 relocations:
$ for i in /boot/kernel/*.ko; do readelf -r $i | grep -q R_386_PC32 && echo $i; done | wc -l
861
But kldxref *only* complains specifically about if_bge.ko, and it is not
clear to me why.
Maybe the R_386_PC32 relocations are first preprocessed away, somehow,
before they end up in kldxref's ef_reloc(), where the "unhandled
relocation type" warning is produced?
In any case, I tried the following patch, which at least makes the
warning go away, but might not be the right solution:
Index: usr.sbin/kldxref/ef_i386.c
===================================================================
--- usr.sbin/kldxref/ef_i386.c (revision 337959)
+++ usr.sbin/kldxref/ef_i386.c (working copy)
@@ -82,11 +82,17 @@ ef_reloc(struct elf_file *ef, const void *reldata,
addr = (Elf_Addr)addend + relbase;
*where = addr;
break;
- case R_386_32: /* S + A - P */
+ case R_386_32: /* S + A */
addr = EF_SYMADDR(ef, symidx);
addr += addend;
*where = addr;
break;
+ case R_386_PC32: /* S + A - P */
+ addr = EF_SYMADDR(ef, symidx);
+ addr += addend;
+ addr -= (Elf_Addr)where;
+ *where = addr;
+ break;
case R_386_GLOB_DAT: /* S */
addr = EF_SYMADDR(ef, symidx);
*where = addr;
===================================================================
While here, I corrected the comment for R_386_32 relocations. At least,
all the documentation I could find states that such relocations only add
the addend to the symbol, and the actual code also does that.
-Dimitry
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