Messages in this thread | | | Date | Wed, 19 Jan 2022 13:21:26 -0800 | From | Josh Poimboeuf <> | Subject | Re: Issue using faddr2line on kernel modules |
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On Wed, Jan 19, 2022 at 09:27:18AM +0530, Kaiwan N Billimoria wrote: > On Tue, Jan 18, 2022 at 11:22 PM Josh Poimboeuf <jpoimboe@redhat.com> wrote: > > > > On Tue, Jan 18, 2022 at 08:10:28AM +0530, Kaiwan N Billimoria wrote: > > > Hi Josh, > > > > > > Actually your first patch - the one you mentioned had other issues - > > > worked perfectly when applied: > > > > > > scripts/faddr2line ./oops_tryv2.ko do_the_work+0x16f/0x194 > > > do_the_work+0x16f/0x0000000000000194: > > > do_the_work at <...>/oops_tryv2/oops_tryv2.c:62 > > > > > > The second one still failed in the same manner: > > > > > > scripts/faddr2line ./oops_tryv2.ko do_the_work+0x16f/0x194 > > > bad symbol size: base: 0x0000000000000000 end: 0x0000000000000000 > > > > > > So, is it possible to fixup issues with the first version? > > > What are these issues? > > > > The first patch basically reverts the fix in commit efdb4167e676 > > ("scripts/faddr2line: Fix "size mismatch" error"). That would be nice > > as it's simpler and more robust, but unfortunately it would cause a lot > > of "size mismatch" errors with vmlinux symbols. > > I see... if it comes to it, could there be a workaround where the > script detects a vmlinux image and works in a given manner, > else in this manner for other images - in effect, for modules?
I think I misspoke about the vmlinux behavior being different, so I don't think that would work.
> > Can you give the output of 'nm -n ./oops_tryv2.ko'? There must be some > > text symbol immediately after the do_the_work() symbol which is either > > out of order, or part of another section. > > > > Is do_the_work() in the .text section? > Yes... > Here's the output I get: > > $ nm -n ./oops_tryv2.ko |grep -C5 do_the_work > 0000000000000000 r __func__.24215 > 0000000000000000 r __param_bug_in_workq > 0000000000000000 D __this_module > 0000000000000000 r _note_7 > 0000000000000000 T cleanup_module > 0000000000000000 t do_the_work > 0000000000000000 t do_the_work.cold > 0000000000000000 b gctx > 0000000000000000 T init_module > 0000000000000000 t try_oops_exit > 0000000000000000 t try_oops_init > 0000000000000008 b t1 > $ > > BTW, here's the code: > https://github.com/PacktPublishing/Linux-Kernel-Debugging/tree/main/ch7/oops_tryv2
Ok, it looks like the symbols aren't sorted like the code expects. I need to do a more robust fix.
-- Josh
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