From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>,
Sean Christopherson <seanjc@google.com>,
kernel test robot <oliver.sang@intel.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, lkp@lists.01.org, lkp@intel.com
Subject: Re: [PATCH] x86/entry_32: Fix segment exceptions
Date: Thu, 13 Jan 2022 20:55:37 +0100 [thread overview]
Message-ID: <YeCDudla868Ipf++@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <73020277-d49f-7aae-22db-945e040a31a2@kernel.org>
On Thu, Jan 13, 2022 at 10:54:39AM -0800, Andy Lutomirski wrote:
> On 1/12/22 07:42, Borislav Petkov wrote:
> > On Wed, Jan 12, 2022 at 11:55:41AM +0100, Peter Zijlstra wrote:
> > > Full and proper patch below. Boris, if you could merge in x86/core that
> > > branch should then be ready for a pull req.
> >
> > I've got this as the final version. Scream if something's wrong.
>
> AAAAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHH!!!!!!!!!!!
:-)
> > + /*
> > + * There is no _ASM_EXTABLE_TYPE_REG() for ASM, however since this is
> > + * ASM the registers are known and we can trivially hard-code them.
> > + */
> > + _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_POP_ZERO|EX_REG_DS)
> > + _ASM_EXTABLE_TYPE(2b, 3b, EX_TYPE_POP_ZERO|EX_REG_ES)
> > + _ASM_EXTABLE_TYPE(3b, 4b, EX_TYPE_POP_ZERO|EX_REG_FS)
>
> Aside from POP_ZERO being a bit mystifying to a naive reader...
>
> > .endm
> > .macro RESTORE_ALL_NMI cr3_reg:req pop=0
> > diff --git a/arch/x86/include/asm/extable_fixup_types.h b/arch/x86/include/asm/extable_fixup_types.h
> > index b5ab333e064a..503622627400 100644
> > --- a/arch/x86/include/asm/extable_fixup_types.h
> > +++ b/arch/x86/include/asm/extable_fixup_types.h
> > @@ -16,9 +16,16 @@
> > #define EX_DATA_FLAG_SHIFT 12
> > #define EX_DATA_IMM_SHIFT 16
> > +#define EX_DATA_REG(reg) ((reg) << EX_DATA_REG_SHIFT)
> > #define EX_DATA_FLAG(flag) ((flag) << EX_DATA_FLAG_SHIFT)
> > #define EX_DATA_IMM(imm) ((imm) << EX_DATA_IMM_SHIFT)
> > +/* segment regs */
> > +#define EX_REG_DS EX_DATA_REG(8)
> > +#define EX_REG_ES EX_DATA_REG(9)
> > +#define EX_REG_FS EX_DATA_REG(10)
>
> These three seem likely to work
On IRC Andrew also noted that these EX_REG_* things should be __i386__
only. Previosly when they lived as open-coded EX_DATA_REG() usage in
entry_32.S that was implied, but now ...
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: lkp@lists.01.org
Subject: Re: [PATCH] x86/entry_32: Fix segment exceptions
Date: Thu, 13 Jan 2022 20:55:37 +0100 [thread overview]
Message-ID: <YeCDudla868Ipf++@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <73020277-d49f-7aae-22db-945e040a31a2@kernel.org>
[-- Attachment #1: Type: text/plain, Size: 1867 bytes --]
On Thu, Jan 13, 2022 at 10:54:39AM -0800, Andy Lutomirski wrote:
> On 1/12/22 07:42, Borislav Petkov wrote:
> > On Wed, Jan 12, 2022 at 11:55:41AM +0100, Peter Zijlstra wrote:
> > > Full and proper patch below. Boris, if you could merge in x86/core that
> > > branch should then be ready for a pull req.
> >
> > I've got this as the final version. Scream if something's wrong.
>
> AAAAAAAAAAAAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHH!!!!!!!!!!!
:-)
> > + /*
> > + * There is no _ASM_EXTABLE_TYPE_REG() for ASM, however since this is
> > + * ASM the registers are known and we can trivially hard-code them.
> > + */
> > + _ASM_EXTABLE_TYPE(1b, 2b, EX_TYPE_POP_ZERO|EX_REG_DS)
> > + _ASM_EXTABLE_TYPE(2b, 3b, EX_TYPE_POP_ZERO|EX_REG_ES)
> > + _ASM_EXTABLE_TYPE(3b, 4b, EX_TYPE_POP_ZERO|EX_REG_FS)
>
> Aside from POP_ZERO being a bit mystifying to a naive reader...
>
> > .endm
> > .macro RESTORE_ALL_NMI cr3_reg:req pop=0
> > diff --git a/arch/x86/include/asm/extable_fixup_types.h b/arch/x86/include/asm/extable_fixup_types.h
> > index b5ab333e064a..503622627400 100644
> > --- a/arch/x86/include/asm/extable_fixup_types.h
> > +++ b/arch/x86/include/asm/extable_fixup_types.h
> > @@ -16,9 +16,16 @@
> > #define EX_DATA_FLAG_SHIFT 12
> > #define EX_DATA_IMM_SHIFT 16
> > +#define EX_DATA_REG(reg) ((reg) << EX_DATA_REG_SHIFT)
> > #define EX_DATA_FLAG(flag) ((flag) << EX_DATA_FLAG_SHIFT)
> > #define EX_DATA_IMM(imm) ((imm) << EX_DATA_IMM_SHIFT)
> > +/* segment regs */
> > +#define EX_REG_DS EX_DATA_REG(8)
> > +#define EX_REG_ES EX_DATA_REG(9)
> > +#define EX_REG_FS EX_DATA_REG(10)
>
> These three seem likely to work
On IRC Andrew also noted that these EX_REG_* things should be __i386__
only. Previosly when they lived as open-coded EX_DATA_REG() usage in
entry_32.S that was implied, but now ...
next prev parent reply other threads:[~2022-01-13 19:56 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-06 8:35 [x86/entry_32] aa93e2ad74: BUG:soft_lockup-CPU##stuck_for#s![systemd-logind:#] kernel test robot
2022-01-06 8:35 ` kernel test robot
2022-01-11 11:11 ` Peter Zijlstra
2022-01-11 11:11 ` Peter Zijlstra
2022-01-12 1:28 ` Sean Christopherson
2022-01-12 1:28 ` Sean Christopherson
2022-01-12 10:25 ` Peter Zijlstra
2022-01-12 10:25 ` Peter Zijlstra
2022-01-12 16:14 ` Sean Christopherson
2022-01-12 16:14 ` Sean Christopherson
2022-01-12 10:55 ` [PATCH] x86/entry_32: Fix segment exceptions Peter Zijlstra
2022-01-12 10:55 ` Peter Zijlstra
2022-01-12 15:42 ` Borislav Petkov
2022-01-12 15:42 ` Borislav Petkov
2022-01-13 18:54 ` Andy Lutomirski
2022-01-13 18:54 ` Andy Lutomirski
2022-01-13 19:55 ` Peter Zijlstra [this message]
2022-01-13 19:55 ` Peter Zijlstra
2022-01-14 11:24 ` Borislav Petkov
2022-01-14 11:24 ` Borislav Petkov
2022-01-14 23:48 ` Andy Lutomirski
2022-01-14 23:48 ` Andy Lutomirski
2022-01-15 8:13 ` Borislav Petkov
2022-01-15 8:13 ` Borislav Petkov
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