Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1594509
| From | Josh Poimboeuf <jpoimboe@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: v4.10: kernel stack frame pointer .. has bad value (null) |
| Date | 2017-03-07 19:40 +0100 |
| Message-ID | <tisbD-31Z-11@gated-at.bofh.it> (permalink) |
| References | (5 earlier) <tdOmt-HE-9@gated-at.bofh.it> <te81P-6eq-11@gated-at.bofh.it> <teD5D-33n-3@gated-at.bofh.it> <tgJ6V-1tU-13@gated-at.bofh.it> <ti3ZD-2qv-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Mon, Mar 06, 2017 at 05:38:07PM +0100, Pavel Machek wrote:
> Sorry for the delay. This is on v4.11-rc1, but that should be similar.
>
> pavel@duo:~$ gcc --version
> gcc (Debian 4.9.2-10) 4.9.2
>
> And here's the disassemble:
>
> c402d200 <start_secondary>:
> c402d200: 57 push %edi
> c402d201: 8d 7c 24 08 lea 0x8(%esp),%edi
> c402d205: 83 e4 f8 and $0xfffffff8,%esp
> c402d208: ff 77 fc pushl -0x4(%edi)
> c402d20b: 55 push %ebp
> c402d20c: 89 e5 mov %esp,%ebp
> c402d20e: 57 push %edi
> c402d20f: 56 push %esi
> c402d210: 83 ec 10 sub $0x10,%esp
Thanks. This confirms what I was thinking, the function prologue is
wack. It's realigning the stack, but it's not the "normal" realign
pattern. Instead it makes a fake frame header, which saves a duplicate
copy of the return address ("pushl -0x4(%edi)") in a place the unwinder
wasn't expecting.
I did some digging in gcc to figure out why this can happen. gcc uses
something called a Dynamic Realign Argument Pointer (DRAP), which, when
enabled, makes a prologue like the above. It's almost always enabled
for aligned stacks when -maccumulate-outgoing-args isn't set.
So I'm thinking we should have -maccumulate-outgoing-args always enabled
on x86_32 just like we already do on x86_64.
Can you verify the warning is fixed with the following patch?
-----
diff --git a/arch/x86/Makefile_32.cpu b/arch/x86/Makefile_32.cpu
index 6647ed4..53ec1e4 100644
--- a/arch/x86/Makefile_32.cpu
+++ b/arch/x86/Makefile_32.cpu
@@ -61,7 +61,7 @@ ifeq ($(CONFIG_JUMP_LABEL), y)
ADD_ACCUMULATE_OUTGOING_ARGS := y
endif
-cflags-$(ADD_ACCUMULATE_OUTGOING_ARGS) += $(call cc-option,-maccumulate-outgoing-args)
+cflags-y += $(call cc-option,-maccumulate-outgoing-args)
# Bug fix for binutils: this option is required in order to keep
# binutils from generating NOPL instructions against our will.
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Re: v4.10: kernel stack frame pointer .. has bad value (null) Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-03 01:20 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Pavel Machek <pavel@ucw.cz> - 2017-03-06 17:50 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-07 19:40 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-07 19:40 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-07 19:50 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-08 18:50 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-08 20:00 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Andy Lutomirski <luto@amacapital.net> - 2017-03-08 20:10 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-08 22:40 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Steven Rostedt <rostedt@goodmis.org> - 2017-03-09 15:20 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-09 19:40 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Pavel Machek <pavel@ucw.cz> - 2017-03-09 00:20 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Geert Uytterhoeven <geert@linux-m68k.org> - 2017-03-09 10:40 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Pavel Machek <pavel@ucw.cz> - 2017-03-09 12:00 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Geert Uytterhoeven <geert@linux-m68k.org> - 2017-03-09 13:20 +0100
Compiling kernels faster (was Re: v4.10: kernel stack frame pointer .. has bad value (null)) Pavel Machek <pavel@ucw.cz> - 2017-03-10 14:20 +0100
Re: Compiling kernels faster (was Re: v4.10: kernel stack frame pointer .. has bad value (null)) Geert Uytterhoeven <geert@linux-m68k.org> - 2017-03-10 14:30 +0100
Re: Compiling kernels faster (was Re: v4.10: kernel stack frame pointer .. has bad value (null)) Willy Tarreau <w@1wt.eu> - 2017-03-10 15:20 +0100
Old compiler versions (was Re: v4.10: kernel stack frame pointer .. has bad value (null)) Pavel Machek <pavel@ucw.cz> - 2017-03-09 12:00 +0100
Re: Old compiler versions (was Re: v4.10: kernel stack frame pointer .. has bad value (null)) Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-09 19:10 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Peter Zijlstra <peterz@infradead.org> - 2017-03-09 16:40 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Pavel Machek <pavel@ucw.cz> - 2017-03-09 22:20 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Josh Poimboeuf <jpoimboe@redhat.com> - 2017-03-07 19:40 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Andy Lutomirski <luto@amacapital.net> - 2017-03-07 20:00 +0100
Re: v4.10: kernel stack frame pointer .. has bad value (null) Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-07 20:50 +0100
csiph-web