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Date: Mon, 7 Jun 2021 17:40:11 +0200 From: Peter Zijlstra <peterz@...radead.org> To: Ard Biesheuvel <ardb@...nel.org> Cc: Mark-PK Tsai <mark-pk.tsai@...iatek.com>, Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>, linux-toolchains@...r.kernel.org, Linux ARM <linux-arm-kernel@...ts.infradead.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, linux-mediatek@...ts.infradead.org, Matthias Brugger <matthias.bgg@...il.com>, Matt Helsley <mhelsley@...are.com>, "Steven Rostedt (VMware)" <rostedt@...dmis.org>, Sami Tolvanen <samitolvanen@...gle.com>, yj.chiang@...iatek.com Subject: Re: [PATCH] recordmcount: avoid using ABS symbol as reference On Mon, Jun 07, 2021 at 01:44:21PM +0200, Peter Zijlstra wrote: > 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. > Apparently I'm consistently bad at spelling SHM_UNDEF today.. > 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)
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