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* [PATCH] recordmcount: Correct st_shndx handling
@ 2021-06-08 10:34 Peter Zijlstra
  2021-06-08 10:37 ` Ard Biesheuvel
  0 siblings, 1 reply; 2+ messages in thread
From: Peter Zijlstra @ 2021-06-08 10:34 UTC (permalink / raw)
  To: Steven Rostedt; +Cc: linux-kernel, mark-pk.tsai, ardb


One should only use st_shndx when >SHN_UNDEF and <SHN_LORESERVE. When
SHN_XINDEX, then use .symtab_shndx. Otherwise use 0.

This handles the case: st_shndx >= SHN_LORESERVE && st_shndx != SHN_XINDEX.

Reported-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
---
 scripts/recordmcount.h |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -194,13 +194,18 @@ static unsigned int get_symindex(Elf_Sym
 	unsigned long offset;
 	int index;
 
-	if (sym->st_shndx != SHN_XINDEX)
+	if (sym->st_shndx > SHN_UNDEF &&
+	    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)

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [PATCH] recordmcount: Correct st_shndx handling
  2021-06-08 10:34 [PATCH] recordmcount: Correct st_shndx handling Peter Zijlstra
@ 2021-06-08 10:37 ` Ard Biesheuvel
  0 siblings, 0 replies; 2+ messages in thread
From: Ard Biesheuvel @ 2021-06-08 10:37 UTC (permalink / raw)
  To: Peter Zijlstra; +Cc: Steven Rostedt, Linux Kernel Mailing List, Mark-PK Tsai

On Tue, 8 Jun 2021 at 12:34, Peter Zijlstra <peterz@infradead.org> wrote:
>
>
> One should only use st_shndx when >SHN_UNDEF and <SHN_LORESERVE. When
> SHN_XINDEX, then use .symtab_shndx. Otherwise use 0.
>
> This handles the case: st_shndx >= SHN_LORESERVE && st_shndx != SHN_XINDEX.
>
> Reported-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Tested-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>

Acked-by: Ard Biesheuvel <ardb@kernel.org>

> ---
>  scripts/recordmcount.h |   13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
>
> --- a/scripts/recordmcount.h
> +++ b/scripts/recordmcount.h
> @@ -194,13 +194,18 @@ static unsigned int get_symindex(Elf_Sym
>         unsigned long offset;
>         int index;
>
> -       if (sym->st_shndx != SHN_XINDEX)
> +       if (sym->st_shndx > SHN_UNDEF &&
> +           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)

^ permalink raw reply	[flat|nested] 2+ messages in thread

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