From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: Borislav Petkov <bp@alien8.de>
Cc: Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@suse.de>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Brian Gerst <brgerst@gmail.com>,
Chris Metcalf <cmetcalf@mellanox.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Liang Z Li <liang.z.li@intel.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Huang Rui <ray.huang@amd.com>, Jiri Slaby <jslaby@suse.cz>,
Jonathan Corbet <corbet@lwn.net>,
"Michael S. Tsirkin" <mst@redhat.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Vlastimil Babka <vbabka@suse.cz>, Chen Yucong <slaoub@gmail.com>,
Alexandre Julliard <julliard@winehq.org>,
Stas Sergeev <stsp@list.ru>, Fenghua Yu <fenghua.yu@intel.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Shuah Khan <shuah@kernel.org>,
linux-kernel@vger.kernel.org, x86@kernel.org,
linux-msdos@vger.kernel.org, wine-devel@winehq.org,
Adam Buchbinder <adam.buchbinder@gmail.com>,
Colin Ian King <colin.king@canonical.com>,
Lorenzo Stoakes <lstoakes@gmail.com>,
Qiaowei Ren <qiaowei.ren@intel.com>,
Nathan Howard <liverlint@gmail.com>,
Adan Hawthorn <adanhawthorn@gmail.com>,
Joe Perches <joe@perches.com>
Subject: Re: [PATCH v7 05/26] x86/mpx: Do not use SIB.base if its value is 101b and ModRM.mod = 0
Date: Mon, 05 Jun 2017 23:08:03 -0700 [thread overview]
Message-ID: <1496729283.24288.83.camel@ranerica-desktop> (raw)
In-Reply-To: <20170529130709.7hv6act6lgoaj5po@pd.tnic>
On Mon, 2017-05-29 at 15:07 +0200, Borislav Petkov wrote:
> On Fri, May 05, 2017 at 11:17:03AM -0700, Ricardo Neri wrote:
> > Section 2.2.1.2 of the Intel 64 and IA-32 Architectures Software
> > Developer's Manual volume 2A states that when a SIB byte is used and the
> > base of the SIB byte points is base = 101b and the mod part
> > of the ModRM byte is zero, the base port on the effective address
> > computation is null. In this case, a 32-bit displacement follows the SIB
> > byte. This is obtained when the instruction decoder parses the operands.
> >
> > To signal this scenario, a -EDOM error is returned to indicate callers that
> > they should ignore the base.
> >
> > Cc: Borislav Petkov <bp@suse.de>
> > Cc: Andy Lutomirski <luto@kernel.org>
> > Cc: Dave Hansen <dave.hansen@linux.intel.com>
> > Cc: Adam Buchbinder <adam.buchbinder@gmail.com>
> > Cc: Colin Ian King <colin.king@canonical.com>
> > Cc: Lorenzo Stoakes <lstoakes@gmail.com>
> > Cc: Qiaowei Ren <qiaowei.ren@intel.com>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Cc: Nathan Howard <liverlint@gmail.com>
> > Cc: Adan Hawthorn <adanhawthorn@gmail.com>
> > Cc: Joe Perches <joe@perches.com>
> > Cc: Ravi V. Shankar <ravi.v.shankar@intel.com>
> > Cc: x86@kernel.org
> > Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
> > ---
> > arch/x86/mm/mpx.c | 27 ++++++++++++++++++++-------
> > 1 file changed, 20 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/x86/mm/mpx.c b/arch/x86/mm/mpx.c
> > index 7397b81..30aef92 100644
> > --- a/arch/x86/mm/mpx.c
> > +++ b/arch/x86/mm/mpx.c
> > @@ -122,6 +122,15 @@ static int get_reg_offset(struct insn *insn, struct pt_regs *regs,
> >
> > case REG_TYPE_BASE:
> > regno = X86_SIB_BASE(insn->sib.value);
> > + /*
> > + * If ModRM.mod is 0 and SIB.base == 5, the base of the
> > + * register-indirect addressing is 0. In this case, a
> > + * 32-bit displacement is expected in this case; the
> > + * instruction decoder finds such displacement for us.
>
> That last sentence reads funny. Just say:
>
> "In this case, a 32-bit displacement follows the SIB byte."
Agreed. I will update the comment to make more sense.
Thanks and BR,
Ricardo
next prev parent reply other threads:[~2017-06-06 6:08 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-05 18:16 [PATCH v7 00/26] x86: Enable User-Mode Instruction Prevention Ricardo Neri
2017-05-05 18:16 ` [PATCH v7 01/26] ptrace,x86: Make user_64bit_mode() available to 32-bit builds Ricardo Neri
2017-05-21 14:19 ` Borislav Petkov
2017-05-05 18:17 ` [PATCH v7 02/26] x86/mm: Relocate page fault error codes to traps.h Ricardo Neri
2017-05-21 14:23 ` Borislav Petkov
2017-05-27 3:40 ` Ricardo Neri
2017-05-27 10:13 ` Borislav Petkov
2017-06-01 3:09 ` Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 03/26] x86/mpx: Use signed variables to compute effective addresses Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 04/26] x86/mpx: Do not use SIB.index if its value is 100b and ModRM.mod is not 11b Ricardo Neri
2017-05-24 13:37 ` Borislav Petkov
2017-05-27 3:36 ` Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 05/26] x86/mpx: Do not use SIB.base if its value is 101b and ModRM.mod = 0 Ricardo Neri
2017-05-29 13:07 ` Borislav Petkov
2017-06-06 6:08 ` Ricardo Neri [this message]
2017-05-05 18:17 ` [PATCH v7 06/26] x86/mpx, x86/insn: Relocate insn util functions to a new insn-eval file Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 07/26] x86/insn-eval: Do not BUG on invalid register type Ricardo Neri
2017-05-29 16:37 ` Borislav Petkov
2017-06-06 6:06 ` Ricardo Neri
2017-06-06 11:58 ` Borislav Petkov
2017-06-07 0:28 ` Ricardo Neri
2017-06-07 12:21 ` Borislav Petkov
2017-05-05 18:17 ` [PATCH v7 08/26] x86/insn-eval: Add a utility function to get register offsets Ricardo Neri
2017-05-29 17:16 ` Borislav Petkov
2017-06-06 6:02 ` Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 09/26] x86/insn-eval: Add utility function to identify string instructions Ricardo Neri
2017-05-29 21:48 ` Borislav Petkov
2017-06-06 6:01 ` Ricardo Neri
2017-06-06 12:04 ` Borislav Petkov
2017-05-05 18:17 ` [PATCH v7 10/26] x86/insn-eval: Add utility functions to get segment selector Ricardo Neri
2017-05-30 10:35 ` Borislav Petkov
2017-06-15 18:37 ` Ricardo Neri
2017-06-15 19:04 ` Ricardo Neri
2017-06-19 15:29 ` Borislav Petkov
2017-06-19 15:37 ` Borislav Petkov
2017-05-05 18:17 ` [PATCH v7 11/26] x86/insn-eval: Add utility function to get segment descriptor Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 12/26] x86/insn-eval: Add utility functions to get segment descriptor base address and limit Ricardo Neri
2017-05-31 16:58 ` Borislav Petkov
2017-06-03 17:23 ` Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 13/26] x86/insn-eval: Add function to get default params of code segment Ricardo Neri
2017-06-07 12:59 ` Borislav Petkov
2017-06-15 19:24 ` Ricardo Neri
2017-06-19 17:11 ` Borislav Petkov
2017-05-05 18:17 ` [PATCH v7 14/26] x86/insn-eval: Indicate a 32-bit displacement if ModRM.mod is 0 and ModRM.rm is 5 Ricardo Neri
2017-06-07 13:15 ` Borislav Petkov
2017-06-15 19:36 ` Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 15/26] x86/insn-eval: Incorporate segment base and limit in linear address computation Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 16/26] x86/insn-eval: Support both signed 32-bit and 64-bit effective addresses Ricardo Neri
2017-06-07 15:48 ` Borislav Petkov
2017-07-25 23:48 ` Ricardo Neri
2017-07-27 13:26 ` Borislav Petkov
2017-07-28 2:04 ` Ricardo Neri
2017-07-28 6:50 ` Borislav Petkov
2017-06-07 15:49 ` Borislav Petkov
2017-06-15 19:58 ` Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 17/26] x86/insn-eval: Handle 32-bit address encodings in virtual-8086 mode Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 18/26] x86/insn-eval: Add support to resolve 16-bit addressing encodings Ricardo Neri
2017-06-07 16:28 ` Borislav Petkov
2017-06-15 21:50 ` Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 19/26] x86/insn-eval: Add wrapper function for 16-bit and 32-bit address encodings Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 20/26] x86/cpufeature: Add User-Mode Instruction Prevention definitions Ricardo Neri
2017-05-06 9:04 ` Paolo Bonzini
2017-05-11 3:23 ` Ricardo Neri
2017-06-07 18:24 ` Borislav Petkov
2017-05-05 18:17 ` [PATCH v7 21/26] x86: Add emulation code for UMIP instructions Ricardo Neri
2017-06-08 18:38 ` Borislav Petkov
2017-06-17 1:34 ` Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 22/26] x86/umip: Force a page fault when unable to copy emulated result to user Ricardo Neri
2017-06-09 11:02 ` Borislav Petkov
2017-07-25 23:50 ` Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 23/26] x86/traps: Fixup general protection faults caused by UMIP Ricardo Neri
2017-06-09 13:02 ` Borislav Petkov
2017-07-25 23:51 ` Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 24/26] x86: Enable User-Mode Instruction Prevention Ricardo Neri
2017-06-09 16:10 ` Borislav Petkov
2017-07-26 0:44 ` Ricardo Neri
2017-07-27 13:57 ` Borislav Petkov
2017-05-05 18:17 ` [PATCH v7 25/26] selftests/x86: Add tests for " Ricardo Neri
2017-05-05 18:17 ` [PATCH v7 26/26] selftests/x86: Add tests for instruction str and sldt Ricardo Neri
2017-05-17 18:42 ` [PATCH v7 00/26] x86: Enable User-Mode Instruction Prevention Ricardo Neri
2017-05-27 3:49 ` Neri, Ricardo
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