From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:39471 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754620AbbHFJNS (ORCPT ); Thu, 6 Aug 2015 05:13:18 -0400 Subject: Re: [Patch V2] x86/ldt: correct fpu emulation access to ldt To: billm@melbpc.org.au, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, linux-kernel@vger.kernel.org, luto@amacapital.net References: <1438852060-22725-1-git-send-email-jgross@suse.com> Cc: stable@vger.kernel.org From: Juergen Gross Message-ID: <55C3252C.2090606@suse.com> Date: Thu, 6 Aug 2015 11:13:16 +0200 MIME-Version: 1.0 In-Reply-To: <1438852060-22725-1-git-send-email-jgross@suse.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: stable-owner@vger.kernel.org List-ID: Please ignore, V3 coming soon. Juergen On 08/06/2015 11:07 AM, Juergen Gross wrote: > Commit 37868fe113ff ("x86/ldt: Make modify_ldt synchronous") introduced > a new struct ldt_struct anchored at mm->context.ldt. > > Adapt the x86 fpu emulation to use that new structure. > > Cc: # 37868fe113ff: x86/ldt: Make modify_ldt synchronous > Cc: # a5b9e5a2f14f: x86/ldt: Make modify_ldt optional > Signed-off-by: Juergen Gross > --- > arch/x86/math-emu/fpu_entry.c | 3 +-- > arch/x86/math-emu/fpu_system.h | 18 +++++++++++++++--- > arch/x86/math-emu/get_address.c | 3 +-- > 3 files changed, 17 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/math-emu/fpu_entry.c b/arch/x86/math-emu/fpu_entry.c > index f37e84a..203318a 100644 > --- a/arch/x86/math-emu/fpu_entry.c > +++ b/arch/x86/math-emu/fpu_entry.c > @@ -29,7 +29,6 @@ > > #include > #include > -#include > #include > #include > > @@ -181,7 +180,7 @@ void math_emulate(struct math_emu_info *info) > math_abort(FPU_info, SIGILL); > } > > - code_descriptor = LDT_DESCRIPTOR(FPU_CS); > + code_descriptor = *FPU_get_ldt_descriptor(FPU_CS); > if (SEG_D_SIZE(code_descriptor)) { > /* The above test may be wrong, the book is not clear */ > /* Segmented 32 bit protected mode */ > diff --git a/arch/x86/math-emu/fpu_system.h b/arch/x86/math-emu/fpu_system.h > index 9ccecb6..9330583 100644 > --- a/arch/x86/math-emu/fpu_system.h > +++ b/arch/x86/math-emu/fpu_system.h > @@ -16,9 +16,21 @@ > #include > #include > > -/* s is always from a cpu register, and the cpu does bounds checking > - * during register load --> no further bounds checks needed */ > -#define LDT_DESCRIPTOR(s) (((struct desc_struct *)current->mm->context.ldt)[(s) >> 3]) > +#include > +#include > + > +static inline struct desc_struct *FPU_get_ldt_descriptor(unsigned seg) > +{ > + static struct desc_struct zero_desc; > + > +#ifdef CONFIG_MODIFY_LDT_SYSCALL > + seg >>= 3; > + if (seg < current->mm->context.ldt->size) > + return current->mm->context.ldt->entries + seg; > +#endif > + return &zero_desc; > +} > + > #define SEG_D_SIZE(x) ((x).b & (3 << 21)) > #define SEG_G_BIT(x) ((x).b & (1 << 23)) > #define SEG_GRANULARITY(x) (((x).b & (1 << 23)) ? 4096 : 1) > diff --git a/arch/x86/math-emu/get_address.c b/arch/x86/math-emu/get_address.c > index 6ef5e99..f912edd 100644 > --- a/arch/x86/math-emu/get_address.c > +++ b/arch/x86/math-emu/get_address.c > @@ -20,7 +20,6 @@ > #include > > #include > -#include > > #include "fpu_system.h" > #include "exception.h" > @@ -158,7 +157,7 @@ static long pm_address(u_char FPU_modrm, u_char segment, > addr->selector = PM_REG_(segment); > } > > - descriptor = LDT_DESCRIPTOR(PM_REG_(segment)); > + descriptor = *FPU_get_ldt_descriptor(segment); > base_address = SEG_BASE_ADDR(descriptor); > address = base_address + offset; > limit = base_address >