Re: [PATCH] recordmcount: avoid using ABS symbol as reference
From: Peter Zijlstra <peterz@infradead.org>
Date: 2021-06-07 15:41:32
Also in:
linux-arm-kernel, linux-kbuild, linux-toolchains, lkml
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..
quoted hunk ↗ jump to hunk
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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