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From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
	"Wei Liu" <wl@xen.org>, "Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [PATCH 11/16] x86/spec-ctrl: Adjust DO_OVERWRITE_RSB to be shadow stack compatible
Date: Thu, 7 May 2020 14:25:31 +0100	[thread overview]
Message-ID: <bdf2d248-aabb-8913-1d79-355623b47dfb@citrix.com> (raw)
In-Reply-To: <3c01d6c3-5a61-018b-13df-6e75256f6d6c@suse.com>

On 07/05/2020 14:22, Jan Beulich wrote:
> On 02.05.2020 00:58, Andrew Cooper wrote:
>> @@ -114,6 +114,16 @@
>>      sub $1, %ecx
>>      jnz .L\@_fill_rsb_loop
>>      mov %\tmp, %rsp                 /* Restore old %rsp */
>> +
>> +#ifdef CONFIG_XEN_SHSTK
>> +    mov $1, %ecx
>> +    rdsspd %ecx
>> +    cmp $1, %ecx
>> +    je .L\@_shstk_done
>> +    mov $64, %ecx                   /* 64 * 4 bytes, given incsspd */
>> +    incsspd %ecx                    /* Restore old SSP */
>> +.L\@_shstk_done:
>> +#endif
> The latest here I wonder why you don't use alternatives patching.
> I thought that's what you've introduced the synthetic feature
> flag for.

We're already in the middle of an alternative and they don't nest.  More
importantly, this path gets used on the BSP, after patching and before
CET gets enabled.

~Andrew


  reply	other threads:[~2020-05-07 13:26 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-01 22:58 [PATCH 00/16] x86: Support for CET Supervisor Shadow Stacks Andrew Cooper
2020-05-01 22:58 ` [PATCH 01/16] x86/traps: Drop last_extable_addr Andrew Cooper
2020-05-04 12:44   ` Jan Beulich
2020-05-11 14:53     ` Andrew Cooper
2020-05-11 15:00       ` Jan Beulich
2020-05-01 22:58 ` [PATCH 02/16] x86/traps: Clean up printing in do_reserved_trap()/fatal_trap() Andrew Cooper
2020-05-04 13:08   ` Jan Beulich
2020-05-11 15:01     ` Andrew Cooper
2020-05-11 15:09       ` Jan Beulich
2020-05-18 16:54         ` Andrew Cooper
2020-05-19  8:50           ` Jan Beulich
2020-05-26 15:38             ` Andrew Cooper
2020-05-27  6:54               ` Jan Beulich
2020-05-01 22:58 ` [PATCH 03/16] x86/traps: Factor out exception_fixup() and make printing consistent Andrew Cooper
2020-05-04 13:20   ` Jan Beulich
2020-05-11 15:14     ` Andrew Cooper
2020-05-12 13:05       ` Jan Beulich
2020-05-26 18:06         ` Andrew Cooper
2020-05-27  7:01           ` Jan Beulich
2020-05-01 22:58 ` [PATCH 04/16] x86/smpboot: Write the top-of-stack block in cpu_smpboot_alloc() Andrew Cooper
2020-05-04 13:22   ` Jan Beulich
2020-05-01 22:58 ` [PATCH 05/16] x86/shstk: Introduce Supervisor Shadow Stack support Andrew Cooper
2020-05-04 13:52   ` Jan Beulich
2020-05-11 15:46     ` Andrew Cooper
2020-05-12 13:54       ` Jan Beulich
2020-05-15 16:21     ` Anthony PERARD
2020-05-01 22:58 ` [PATCH 06/16] x86/traps: Implement #CP handler and extend #PF for shadow stacks Andrew Cooper
2020-05-04 14:10   ` Jan Beulich
2020-05-11 17:20     ` Andrew Cooper
2020-05-12 13:58       ` Jan Beulich
2020-05-01 22:58 ` [PATCH 07/16] x86/shstk: Re-layout the stack block " Andrew Cooper
2020-05-04 14:24   ` Jan Beulich
2020-05-11 17:48     ` Andrew Cooper
2020-05-12 14:07       ` Jan Beulich
2020-05-01 22:58 ` [PATCH 08/16] x86/shstk: Create " Andrew Cooper
2020-05-04 14:55   ` Jan Beulich
2020-05-04 15:08     ` Andrew Cooper
2020-05-01 22:58 ` [PATCH 09/16] x86/cpu: Adjust enable_nmis() to be shadow stack compatible Andrew Cooper
2020-05-05 14:48   ` Jan Beulich
2020-05-11 18:48     ` Andrew Cooper
2020-05-01 22:58 ` [PATCH 10/16] x86/cpu: Adjust reset_stack_and_jump() " Andrew Cooper
2020-05-07 13:17   ` Jan Beulich
2020-05-11 20:07     ` Andrew Cooper
2020-05-01 22:58 ` [PATCH 11/16] x86/spec-ctrl: Adjust DO_OVERWRITE_RSB " Andrew Cooper
2020-05-07 13:22   ` Jan Beulich
2020-05-07 13:25     ` Andrew Cooper [this message]
2020-05-07 13:38       ` Jan Beulich
2020-05-01 22:58 ` [PATCH 12/16] x86/extable: Adjust extable handling " Andrew Cooper
2020-05-07 13:35   ` Jan Beulich
2020-05-11 21:09     ` Andrew Cooper
2020-05-12 14:31       ` Jan Beulich
2020-05-12 16:14         ` Andrew Cooper
2020-05-13  9:22           ` Jan Beulich
2020-05-01 22:58 ` [PATCH 13/16] x86/ioemul: Rewrite stub generation " Andrew Cooper
2020-05-07 13:46   ` Jan Beulich
2020-05-01 22:58 ` [PATCH 14/16] x86/alt: Adjust _alternative_instructions() to not create shadow stacks Andrew Cooper
2020-05-07 13:49   ` Jan Beulich
2020-05-01 22:58 ` [PATCH 15/16] x86/entry: Adjust guest paths to be shadow stack compatible Andrew Cooper
2020-05-07 14:12   ` Jan Beulich
2020-05-07 15:50     ` Andrew Cooper
2020-05-07 16:15       ` Jan Beulich
2020-05-11 21:45         ` Andrew Cooper
2020-05-12 14:56           ` Jan Beulich
2020-05-01 22:58 ` [PATCH 16/16] x86/shstk: Activate Supervisor Shadow Stacks Andrew Cooper
2020-05-07 14:54   ` Jan Beulich
2020-05-11 23:46     ` Andrew Cooper

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