* [PATCH] Clean up dangling pointers in cgraph_edge (PR ipa/89330).
@ 2019-07-30 7:28 Martin Liška
2019-07-30 8:41 ` Richard Biener
0 siblings, 1 reply; 8+ messages in thread
From: Martin Liška @ 2019-07-30 7:28 UTC (permalink / raw)
To: gcc-patches; +Cc: Andreas Schwab
[-- Attachment #1: Type: text/plain, Size: 494 bytes --]
Hi.
We have to clean up dangling pointers before we call ggc_free for a cgraph_edge.
Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
And it survives --enable-checking=release bootstrap on x86_64-linux-gnu.
Ready to be installed?
Thanks,
Martin
gcc/ChangeLog:
2019-07-30 Martin Liska <mliska@suse.cz>
PR ipa/89330
* cgraph.c (symbol_table::free_edge): Memset 0 to cgraph_edge
before we call ggc_free.
---
gcc/cgraph.c | 2 ++
1 file changed, 2 insertions(+)
[-- Attachment #2: 0001-Clean-up-dangling-pointers-in-cgraph_edge-PR-ipa-893.patch --]
[-- Type: text/x-patch, Size: 439 bytes --]
diff --git a/gcc/cgraph.c b/gcc/cgraph.c
index 81250acb70c..372974f12df 100644
--- a/gcc/cgraph.c
+++ b/gcc/cgraph.c
@@ -1008,6 +1008,8 @@ symbol_table::free_edge (cgraph_edge *e)
if (e->m_summary_id != -1)
edge_released_summary_ids.safe_push (e->m_summary_id);
+ /* Clear out the edge so we do not dangle pointers. */
+ memset (e, 0, sizeof (*e));
if (e->indirect_info)
ggc_free (e->indirect_info);
ggc_free (e);
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] Clean up dangling pointers in cgraph_edge (PR ipa/89330).
2019-07-30 7:28 [PATCH] Clean up dangling pointers in cgraph_edge (PR ipa/89330) Martin Liška
@ 2019-07-30 8:41 ` Richard Biener
2019-07-30 8:49 ` Martin Liška
0 siblings, 1 reply; 8+ messages in thread
From: Richard Biener @ 2019-07-30 8:41 UTC (permalink / raw)
To: Martin Liška; +Cc: GCC Patches, Andreas Schwab
On Tue, Jul 30, 2019 at 9:27 AM Martin Liška <mliska@suse.cz> wrote:
>
> Hi.
>
> We have to clean up dangling pointers before we call ggc_free for a cgraph_edge.
>
> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
> And it survives --enable-checking=release bootstrap on x86_64-linux-gnu.
>
> Ready to be installed?
Eh? The only "real" effect I see is that e->indirect_info test is now
never true.
I think it rather means the edge we ggc_free is still referenced to
from somewhere
and _that_ needs to be fixed or we ggc_free the edge wrongly.
Richard.
> Thanks,
> Martin
>
> gcc/ChangeLog:
>
> 2019-07-30 Martin Liska <mliska@suse.cz>
>
> PR ipa/89330
> * cgraph.c (symbol_table::free_edge): Memset 0 to cgraph_edge
> before we call ggc_free.
> ---
> gcc/cgraph.c | 2 ++
> 1 file changed, 2 insertions(+)
>
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] Clean up dangling pointers in cgraph_edge (PR ipa/89330).
2019-07-30 8:41 ` Richard Biener
@ 2019-07-30 8:49 ` Martin Liška
2019-07-30 13:39 ` [PATCH v2] Use edge->indirect_unknown_callee in cgraph_edge::make_direct " Martin Liška
0 siblings, 1 reply; 8+ messages in thread
From: Martin Liška @ 2019-07-30 8:49 UTC (permalink / raw)
To: Richard Biener; +Cc: GCC Patches, Andreas Schwab
On 7/30/19 10:36 AM, Richard Biener wrote:
> On Tue, Jul 30, 2019 at 9:27 AM Martin Liška <mliska@suse.cz> wrote:
>>
>> Hi.
>>
>> We have to clean up dangling pointers before we call ggc_free for a cgraph_edge.
>>
>> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>> And it survives --enable-checking=release bootstrap on x86_64-linux-gnu.
>>
>> Ready to be installed?
>
> Eh? The only "real" effect I see is that e->indirect_info test is now
> never true.
Yep, you are right.
>
> I think it rather means the edge we ggc_free is still referenced to
> from somewhere
> and _that_ needs to be fixed or we ggc_free the edge wrongly.
Yes, that's one another situation IPA CP is touching a dead cgraph_edge.
Martin will help me latter.
I'm reducing a test-case now..
Martin
>
> Richard.
>
>> Thanks,
>> Martin
>>
>> gcc/ChangeLog:
>>
>> 2019-07-30 Martin Liska <mliska@suse.cz>
>>
>> PR ipa/89330
>> * cgraph.c (symbol_table::free_edge): Memset 0 to cgraph_edge
>> before we call ggc_free.
>> ---
>> gcc/cgraph.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>>
^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH v2] Use edge->indirect_unknown_callee in cgraph_edge::make_direct (PR ipa/89330).
2019-07-30 8:49 ` Martin Liška
@ 2019-07-30 13:39 ` Martin Liška
2019-07-30 14:54 ` Martin Liška
2019-08-07 22:21 ` Jeff Law
0 siblings, 2 replies; 8+ messages in thread
From: Martin Liška @ 2019-07-30 13:39 UTC (permalink / raw)
To: Richard Biener; +Cc: GCC Patches, Andreas Schwab, Martin Jambor
[-- Attachment #1: Type: text/plain, Size: 437 bytes --]
Hi.
Thanks to Martin I was able to prepare a proper fix. The issue is that
cgraph_edge::resolve_speculation can delete this pointer (yes, it's
super nasty) and so that the caller can't use this->something
right after the function returns.
For the long term, I'll rework the ::resolve_speculation function.
The patch survives --enable-checking bootstrap on x86_64-linux-gnu.
Ready to be installed after proper testing?
Thanks,
Martin
[-- Attachment #2: 0001-Use-edge-indirect_unknown_callee-in-cgraph_edge-make.patch --]
[-- Type: text/x-patch, Size: 986 bytes --]
From 15873b0ebfca4cf4ce06b49f6ebb798a14414eb2 Mon Sep 17 00:00:00 2001
From: Martin Liska <mliska@suse.cz>
Date: Tue, 30 Jul 2019 15:12:52 +0200
Subject: [PATCH] Use edge->indirect_unknown_callee in cgraph_edge::make_direct
(PR ipa/89330).
gcc/ChangeLog:
2019-07-30 Martin Liska <mliska@suse.cz>
PR ipa/89330
* cgraph.c (cgraph_edge::make_direct): Use
edge->indirect_unknown_callee as edge->resolve_speculation can
deallocate edge which is this pointer.
---
gcc/cgraph.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/gcc/cgraph.c b/gcc/cgraph.c
index 81250acb70c..8dbe705af68 100644
--- a/gcc/cgraph.c
+++ b/gcc/cgraph.c
@@ -1215,7 +1215,7 @@ cgraph_edge::make_direct (cgraph_node *callee)
edge = edge->resolve_speculation (callee->decl);
/* On successful speculation just return the pre existing direct edge. */
- if (!indirect_unknown_callee)
+ if (!edge->indirect_unknown_callee)
return edge;
}
--
2.22.0
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] Use edge->indirect_unknown_callee in cgraph_edge::make_direct (PR ipa/89330).
2019-07-30 13:39 ` [PATCH v2] Use edge->indirect_unknown_callee in cgraph_edge::make_direct " Martin Liška
@ 2019-07-30 14:54 ` Martin Liška
2019-08-07 22:21 ` Jeff Law
1 sibling, 0 replies; 8+ messages in thread
From: Martin Liška @ 2019-07-30 14:54 UTC (permalink / raw)
To: Richard Biener; +Cc: GCC Patches, Andreas Schwab, Martin Jambor
On 7/30/19 3:37 PM, Martin Liška wrote:
> Hi.
>
> Thanks to Martin I was able to prepare a proper fix. The issue is that
> cgraph_edge::resolve_speculation can delete this pointer (yes, it's
> super nasty) and so that the caller can't use this->something
> right after the function returns.
>
> For the long term, I'll rework the ::resolve_speculation function.
>
> The patch survives --enable-checking bootstrap on x86_64-linux-gnu.
>
> Ready to be installed after proper testing?
> Thanks,
> Martin
>
Honza approved me the patch offline.
Martin
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] Use edge->indirect_unknown_callee in cgraph_edge::make_direct (PR ipa/89330).
2019-07-30 13:39 ` [PATCH v2] Use edge->indirect_unknown_callee in cgraph_edge::make_direct " Martin Liška
2019-07-30 14:54 ` Martin Liška
@ 2019-08-07 22:21 ` Jeff Law
2019-08-08 8:14 ` Martin Liška
1 sibling, 1 reply; 8+ messages in thread
From: Jeff Law @ 2019-08-07 22:21 UTC (permalink / raw)
To: Martin Liška, Richard Biener
Cc: GCC Patches, Andreas Schwab, Martin Jambor
On 7/30/19 7:37 AM, Martin Liška wrote:
> Hi.
>
> Thanks to Martin I was able to prepare a proper fix. The issue is that
> cgraph_edge::resolve_speculation can delete this pointer (yes, it's
> super nasty) and so that the caller can't use this->something
> right after the function returns.
>
> For the long term, I'll rework the ::resolve_speculation function.
>
> The patch survives --enable-checking bootstrap on x86_64-linux-gnu.
>
> Ready to be installed after proper testing?
> Thanks,
> Martin
>
Would this possibly be the cause of this error building the kernel:
> /opt/notnfs/law/jenkins/workspace/x86_64-linux-gnu/linux/lib/iov_iter.c: In function 'memcpy_to_page':
> /opt/notnfs/law/jenkins/workspace/x86_64-linux-gnu/linux/lib/iov_iter.c:1718:1: internal compiler error: in gt_ggc_mx_symtab_node, at gtype-desc.c:1382
> 1718 | EXPORT_SYMBOL(iov_iter_for_each_range);
> | ^~~~~~~~~~~~~
> 0x66537c gt_ggc_mx_symtab_node(void*)
> /opt/notnfs/law/jenkins/workspace/x86_64-linux-gnu/obj/gcc/gcc/gtype-desc.c:1382
> CC fs/super.o
> 0xcafbcd gt_ggc_ma_order
> ./gt-passes.h:31
> 0xcafbcd gt_ggc_ma_order
> ./gt-passes.h:26
> 0xac0555 ggc_mark_root_tab
> ../../../gcc/gcc/ggc-common.c:77
> 0xac075c ggc_mark_roots()
> ../../../gcc/gcc/ggc-common.c:94
> 0x8ee485 ggc_collect()
> ../../../gcc/gcc/ggc-page.c:2201
> Please submit a full bug report,
Jeff
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] Use edge->indirect_unknown_callee in cgraph_edge::make_direct (PR ipa/89330).
2019-08-07 22:21 ` Jeff Law
@ 2019-08-08 8:14 ` Martin Liška
2019-08-08 22:06 ` Jeff Law
0 siblings, 1 reply; 8+ messages in thread
From: Martin Liška @ 2019-08-08 8:14 UTC (permalink / raw)
To: Jeff Law, Richard Biener; +Cc: GCC Patches, Andreas Schwab, Martin Jambor
On 8/8/19 12:08 AM, Jeff Law wrote:
> Would this possibly be the cause of this error building the kernel:
Probably yes. You see the same as H.J.:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91334
Can you please create a pre-processed source with and command line options?
And please tell me how you configure your compiler?
Thanks,
Martin
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] Use edge->indirect_unknown_callee in cgraph_edge::make_direct (PR ipa/89330).
2019-08-08 8:14 ` Martin Liška
@ 2019-08-08 22:06 ` Jeff Law
0 siblings, 0 replies; 8+ messages in thread
From: Jeff Law @ 2019-08-08 22:06 UTC (permalink / raw)
To: Martin Liška, Richard Biener
Cc: GCC Patches, Andreas Schwab, Martin Jambor
On 8/8/19 1:41 AM, Martin Liška wrote:
> On 8/8/19 12:08 AM, Jeff Law wrote:
>> Would this possibly be the cause of this error building the kernel:
>
> Probably yes. You see the same as H.J.:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91334
>
> Can you please create a pre-processed source with and command line options?
> And please tell me how you configure your compiler?
Ugh. I was going to do a litle bisection and investigation and, of
course, it's not triggering. I'm moving a bit between multiple tasks
as a dig out from vacation, but will try to get you something useful as
soon as I can.
jeff
^ permalink raw reply [flat|nested] 8+ messages in thread
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2019-07-30 7:28 [PATCH] Clean up dangling pointers in cgraph_edge (PR ipa/89330) Martin Liška
2019-07-30 8:41 ` Richard Biener
2019-07-30 8:49 ` Martin Liška
2019-07-30 13:39 ` [PATCH v2] Use edge->indirect_unknown_callee in cgraph_edge::make_direct " Martin Liška
2019-07-30 14:54 ` Martin Liška
2019-08-07 22:21 ` Jeff Law
2019-08-08 8:14 ` Martin Liška
2019-08-08 22:06 ` Jeff Law
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