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From: Jakub Jelinek <jakub@redhat.com>
To: Maxim Ostapenko <m.ostapenko@samsung.com>
Cc: GCC Patches <gcc-patches@gcc.gnu.org>,
	       Ramana Radhakrishnan <ramana.radhakrishnan@foss.arm.com>
Subject: Re: [Ping][PATCH v3] Fix Incorrect ASan global variables alignment on arm (PR sanitizer/81697)
Date: Thu, 30 Nov 2017 11:55:00 -0000	[thread overview]
Message-ID: <20171130115452.GF2353@tucnak> (raw)
In-Reply-To: <5A1FEDB1.9040408@samsung.com>

On Thu, Nov 30, 2017 at 02:38:25PM +0300, Maxim Ostapenko wrote:
> Hi Jakub, thanks for review.
> 
> I've fixed the issues you've pointed in review.
> Regarding a testcase -- I've cooked a runtime test, but it shows FP on
> unpatched GCC version only when linking with Gold (because it strips
> redzones more aggressively).

I think we can live with that.

> --- a/gcc/varasm.c
> +++ b/gcc/varasm.c
> @@ -6550,7 +6550,19 @@ categorize_decl_for_section (const_tree decl, int reloc)
>  	ret = reloc == 1 ? SECCAT_DATA_REL_RO_LOCAL : SECCAT_DATA_REL_RO;
>        else if (reloc || flag_merge_constants < 2
>  	       || ((flag_sanitize & SANITIZE_ADDRESS)
> -		   && asan_protect_global (CONST_CAST_TREE (decl))))
> +		   /* PR 81697: for architectures that use section anchors we
> +		      need to ignore DECL_RTL_SET_P (decl) for string constants
> +		      inside this asan_protect_global call because otherwise
> +		      we'll wrongly put them into SECCAT_RODATA_MERGE_CONST
> +		      section, set DECL_RTL (decl) later on and add DECL to
> +		      protected globals via successive asan_protect_global
> +		      calls.  In this scenario we'll end up with wrong
> +		      alignment of these strings at runtime and possible ASan
> +		      false positives.  */
> +		   && asan_protect_global (CONST_CAST_TREE (decl),
> +					   use_object_blocks_p ()
> +					     && use_blocks_for_decl_p (
> +						  CONST_CAST_TREE (decl)))))

Formatting is too bad here.  && should go below use_object_block_p..
The opening ( should either go on the next line, like:
					   use_object_blocks_p ()
					   && use_blocks_for_decl_p
						(CONST_CAST_TREE (decl)))))
or perhaps better just introduce a temporary somewhere:
   else if (VAR_P (decl))
     {
+      tree d = CONST_CAST_TREE (decl);
       if (bss_initializer_p (decl))
         ret = SECCAT_BSS;
and use d instead of CONST_CAST_TREE (decl) later?

Ok with those changes.

	Jakub

  reply	other threads:[~2017-11-30 11:55 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20171121084326eucas1p1b6791865d9d8c4d2b17939650b66da45@eucas1p1.samsung.com>
2017-11-21  8:57 ` Maxim Ostapenko
     [not found]   ` <CGME20171128070454eucas1p2ecf098de3fc9ced1e4e283b5e24f4c6f@eucas1p2.samsung.com>
2017-11-28  7:42     ` Maxim Ostapenko
2017-11-29 11:05       ` Jakub Jelinek
2017-11-30 11:55         ` Maxim Ostapenko
2017-11-30 11:55           ` Jakub Jelinek [this message]
2017-11-30 12:47             ` Maxim Ostapenko

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