From: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
To: <rostedt@goodmis.org>
Cc: <ardb@kernel.org>, <linux-arm-kernel@lists.infradead.org>,
<linux-kbuild@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-mediatek@lists.infradead.org>,
<linux-toolchains@vger.kernel.org>, <mark-pk.tsai@mediatek.com>,
<matthias.bgg@gmail.com>, <mhelsley@vmware.com>,
<peterz@infradead.org>, <samitolvanen@google.com>,
<yj.chiang@mediatek.com>
Subject: Re: [PATCH] recordmcount: avoid using ABS symbol as reference
Date: Tue, 8 Jun 2021 01:31:38 +0800 [thread overview]
Message-ID: <20210607173138.3882-1-mark-pk.tsai@mediatek.com> (raw)
In-Reply-To: <20210607094433.473100d9@oasis.local.home>
> On Mon, 7 Jun 2021 13:44:21 +0200
> Peter Zijlstra <peterz@infradead.org> wrote:
>
> > There's an extended section header index section for just that. And
> > recordmcount actually seems to use that as well.
> >
> > I can't seem to find enough of the thread to figure out what the actual
> > problem is though. The lore archive doesn't have anything prior to this
> > message.
> >
> > One should only use st_shndx when >SHN_UDEF and <SHN_LORESERVE. When
> > SHN_XINDEX, then use .symtab_shndx.
> >
> > Apparently you've found a case where neither is true? In that case
> > objtool seems to use shndx 0. A matching recordmcount patch would be
> > something like this.
Hi Peter,
Should I resend the below patch as v2?
>
> Mark-PK,
>
> Does the below patch fix it for you too (if you backport it to your
> kernel). I much rather have recordmcount match objtool, as one day the
> two will hopefully merge to one executable.
>
> -- Steve
>
Yes, this patch fix it.
>
> >
> >
> > diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
> > index f9b19524da11..d99cc0aed6fe 100644
> > --- a/scripts/recordmcount.h
> > +++ b/scripts/recordmcount.h
> > @@ -194,13 +194,18 @@ static unsigned int get_symindex(Elf_Sym const *sym, Elf32_Word const *symtab,
> > unsigned long offset;
> > int index;
> >
> > - if (sym->st_shndx != SHN_XINDEX)
> > + if (sym->st_shndx > SHN_UDEF &&
> > + sym->st_shndx < SHN_LORESERVE)
> > return w2(sym->st_shndx);
> >
> > - offset = (unsigned long)sym - (unsigned long)symtab;
> > - index = offset / sizeof(*sym);
> > + if (sym->st_shndx == SHN_XINDEX) {
> > + offset = (unsigned long)sym - (unsigned long)symtab;
> > + index = offset / sizeof(*sym);
> >
> > - return w(symtab_shndx[index]);
> > + return w(symtab_shndx[index]);
> > + }
> > +
> > + return 0;
> > }
> >
> > static unsigned int get_shnum(Elf_Ehdr const *ehdr, Elf_Shdr const *shdr0)
next prev parent reply other threads:[~2021-06-07 17:31 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210607074258.32322-1-mark-pk.tsai@mediatek.com>
[not found] ` <20210607080626.32612-1-mark-pk.tsai@mediatek.com>
2021-06-07 9:50 ` [PATCH] recordmcount: avoid using ABS symbol as reference Ard Biesheuvel
2021-06-07 10:32 ` Mark-PK Tsai
2021-06-07 11:44 ` Peter Zijlstra
2021-06-07 13:18 ` Mark-PK Tsai
2021-06-07 13:44 ` Steven Rostedt
2021-06-07 17:31 ` Mark-PK Tsai [this message]
2021-06-07 15:40 ` Peter Zijlstra
2021-06-08 1:15 ` Mark-PK Tsai
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