linux-kernel - Re: [PATCH v2 2/2] scripts/faddr2line: Constrain readelf output to symbols from System.map

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Message-ID: <20230727121851.GA19653@willie-the-truck>
Date:   Thu, 27 Jul 2023 13:18:52 +0100
From:   Will Deacon <will@...nel.org>
To:     Josh Poimboeuf <jpoimboe@...nel.org>
Cc:     linux-kernel@...r.kernel.org, kernel-team@...roid.com,
        Masahiro Yamada <masahiroy@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nicolas Schier <nicolas@...sle.eu>,
        John Stultz <jstultz@...gle.com>, linux-kbuild@...r.kernel.org
Subject: Re: [PATCH v2 2/2] scripts/faddr2line: Constrain readelf output to
 symbols from System.map

On Tue, Jul 25, 2023 at 02:38:05PM -0700, Josh Poimboeuf wrote:
> On Tue, Jul 25, 2023 at 10:11:57PM +0100, Will Deacon wrote:
> > @@ -185,7 +186,7 @@ __faddr2line() {
> >  				found=2
> >  				break
> >  			fi
> > -		done < <(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2)
> > +		done < <(${READELF} --symbols --wide $objfile | sed -f ${IGNORED_SYMS} -e 's/\[.*\]//' | ${AWK} -v sec=$sym_sec '$7 == sec' | sort --key=2)
> >  
> >  		if [[ $found = 0 ]]; then
> >  			warn "can't find symbol: sym_name: $sym_name sym_sec: $sym_sec sym_addr: $sym_addr sym_elf_size: $sym_elf_size"
> 
> Looks good, though the outer loop has another readelf incantation:
> 
> 	done < <(${READELF} --symbols --wide $objfile | sed 's/\[.*\]//' | ${AWK} -v fn=$sym_name '$4 == "FUNC" && $8 == fn')
> 
> It should probably have the same sed options?

Hmm, I don't think it's needed there, is it? The awk expression has a
strict match on $sym_name, which is going to be something extracted from
a kernel log and therefore exists in kallsyms.

> Also it looks like it's wrongly checking for FUNC.

Yes, I agree that should be dropped for the reasons you gave before.

So I can spin a v3, with an extra patch to avoid checking against FUNC.

Will