Messages in this thread Patch in this message | | | From | Kaiwan N Billimoria <> | Date | Fri, 6 May 2022 11:34:00 +0530 | Subject | Re: [PATCH] scripts/faddr2line: Only use text symbols to calculate function size |
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Hi Josh,
Unfortunately, it didn't work with my test case (as before): $ <...>/linux-5.10.60/scripts/faddr2line ./oops_tryv2.ko do_the_work+0x124 bad symbol size: base: 0x0000000000000000 end: 0x0000000000000000 $
What _did_ work was the earlier (much longer) patch you'd sent (your email dt 20 Jan 2022), Could you pl recheck... (As before, i have the test case module here: https://github.com/PacktPublishing/Linux-Kernel-Debugging/tree/main/ch7/oops_tryv2 )
Regards, Kaiwan.
On Tue, May 3, 2022 at 12:14 AM Josh Poimboeuf <jpoimboe@redhat.com> wrote: > > With the following commit > > efdb4167e676 ("scripts/faddr2line: Fix "size mismatch" error") > > it was discovered that faddr2line can't just read a function's ELF > size, because that wouldn't match the kallsyms function size which is > printed in the stack trace. The kallsyms size includes any padding > after the function, whereas the ELF size does not. > > So faddr2line has to manually calculate the size of a function similar > to how kallsyms does. It does so by starting with a sorted list of > symbols and subtracting the function address from the subsequent > symbol's address. > > That calculation is broken in the case where the function is the last > (or only) symbol in the .text section, which can occur quite commonly in > a kernel module or a .o file. In that case, the next symbol in the > sorted list might actually be a data symbol, which breaks the function > size detection: > > $ scripts/faddr2line sound/soundcore.ko sound_devnode+0x5/0x35 > bad symbol size: base: 0x0000000000000000 end: 0x0000000000000000 > > Fix it by only including text symbols in the symbol list. > > Fixes: efdb4167e676 ("scripts/faddr2line: Fix "size mismatch" error") > Reported-by: Kaiwan N Billimoria <kaiwan.billimoria@gmail.com> > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> > --- > scripts/faddr2line | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/scripts/faddr2line b/scripts/faddr2line > index 6c6439f69a72..2a130134f1e6 100755 > --- a/scripts/faddr2line > +++ b/scripts/faddr2line > @@ -189,7 +189,7 @@ __faddr2line() { > > DONE=1 > > - done < <(${NM} -n $objfile | awk -v fn=$func -v end=$file_end '$3 == fn { found=1; line=$0; start=$1; next } found == 1 { found=0; print line, "0x"$1 } END {if (found == 1) print line, end; }') > + done < <(${NM} -n $objfile | awk -v fn=$func -v end=$file_end '$2 !~ /[Tt]/ {next} $3 == fn { found=1; line=$0; start=$1; next } found == 1 { found=0; print line, "0x"$1 } END {if (found == 1) print line, end; }') > } > > [[ $# -lt 2 ]] && usage > -- > 2.34.1 >
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