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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)

  reply	other threads:[~2021-06-07 17:31 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-07  2:38 [PATCH] recordmcount: avoid using ABS symbol as reference Mark-PK Tsai
2021-06-07  6:37 ` Ard Biesheuvel
2021-06-07  6:59   ` Mark-PK Tsai
2021-06-07  7:07     ` Ard Biesheuvel
2021-06-07  7:42       ` Mark-PK Tsai
2021-06-07  8:06         ` Mark-PK Tsai
2021-06-07  9:50           ` 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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