Re: [PATCH] recordmcount: avoid using ABS symbol as reference

On Mon, Jun 07, 2021 at 01:44:21PM +0200, Peter Zijlstra wrote:

quoted

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..

I test the below patch and it work for me.
I only correct the UNDEF typo without any other modification.

Could I push this patch or you will push it?
I guess I have to add your signed-off-by.

quoted

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)

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel