linux-kernel - Re: [PATCH 4/5] x86: entry_64.S: always allocate complete "struct pt

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <53E8C476.8000800@redhat.com>
Date:	Mon, 11 Aug 2014 15:26:14 +0200
From:	Denys Vlasenko <dvlasenk@...hat.com>
To:	Jan Beulich <JBeulich@...e.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Denys Vlasenko <vda.linux@...glemail.com>
CC:	Andy Lutomirski <luto@...capital.net>,
	Kees Cook <keescook@...omium.org>,
	Will Drewry <wad@...omium.org>, X86 ML <x86@...nel.org>,
	Alexei Starovoitov <ast@...mgrid.com>,
	Oleg Nesterov <oleg@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH 4/5] x86: entry_64.S: always allocate complete "struct
 pt_regs"

On 08/11/2014 10:40 AM, Jan Beulich wrote:
>>>>>       CFI_ESCAPE      0x0f /* DW_CFA_def_cfa_expression */, 6, \
>>>>>                       0x77 /* DW_OP_breg7 */, 0, \
>>>>>                       0x06 /* DW_OP_deref */, \
>>>>> -                     0x08 /* DW_OP_const1u */, SS+8-RBP, \
>>>>> +                     0x08 /* DW_OP_const1u */, SS+8, \
>>>>>                       0x22 /* DW_OP_plus */
>>>>>       /* We entered an interrupt context - irqs are off: */
>>>>>       TRACE_IRQS_OFF
...
...
>>> While we are at it, what this  CFI_ESCAPE thing does here?
>>> As usual, it has no comment :/
> 
> Each of its lines has a comment; with other CFI annotations not
> each having comments, I don't see what else is needed here.

The existing comments explain what every byte means.
They are useful if CFI-literate reader wants to check correctness
of the encoding of this annotation.

There is no overall comment what this CFI annotation
*achieves*. In human language, what do we say
to DWARF decoder here?

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/