From: Dave Hansen <dave.hansen@intel.com>
To: "Li, Xin3" <xin3.li@intel.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>,
"peterz@infradead.org" <peterz@infradead.org>,
"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
"H.Peter Anvin" <hpa@zytor.com>
Cc: "x86@kernel.org" <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: the x86 sysret_rip test fails on the Intel FRED architecture
Date: Fri, 20 Jan 2023 09:45:26 -0800 [thread overview]
Message-ID: <5d4ad3e3-034f-c7da-d141-9c001c2343af@intel.com> (raw)
In-Reply-To: <SA1PR11MB6734FA9139B9C9F6CC2ED123A8C59@SA1PR11MB6734.namprd11.prod.outlook.com>
On 1/19/23 23:49, Li, Xin3 wrote:
> The x86 sysret_rip test has the following assertion:
>
> /* R11 and EFLAGS should already match. */
> assert(ctx->uc_mcontext.gregs[REG_EFL] ==
> ctx->uc_mcontext.gregs[REG_R11]);
>
> This is being tested to avoid kernel state leak due to sysret vs iret,
> but that on FRED r11 is *always* preserved, and the test just fails.
Let's figure out the reason that FRED acts differently, first. Right
now, the SDM says:
SYSCALL also saves RFLAGS into R11
so that behavior of SYSCALL _looks_ architectural to me. Was this
change in SYSCALL behavior with FRED intentional?
If not intentional, it might be something that can still be fixed. If
it is intentional and is going to be with us for a while we have a few
options. If userspace is _really_ depending on this behavior, we could
just clobber r11 ourselves in the FRED entry path. If not, we can
remove the assertion in the selftest.
next parent reply other threads:[~2023-01-20 17:45 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <SA1PR11MB6734FA9139B9C9F6CC2ED123A8C59@SA1PR11MB6734.namprd11.prod.outlook.com>
2023-01-20 17:45 ` Dave Hansen [this message]
[not found] ` <eb81f7f2-d266-d999-b41a-e6eae086e731@citrix.com>
2023-01-20 20:50 ` the x86 sysret_rip test fails on the Intel FRED architecture H. Peter Anvin
2023-01-20 21:10 ` Andrew Cooper
2023-01-20 21:17 ` H. Peter Anvin
2023-01-20 21:29 ` Andrew Cooper
2023-01-21 4:59 ` H. Peter Anvin
2023-01-21 16:46 ` Dave Hansen
2023-01-21 21:47 ` Brian Gerst
2023-01-22 3:01 ` Li, Xin3
2023-01-22 3:28 ` H. Peter Anvin
2023-01-22 3:38 ` Li, Xin3
2023-01-22 4:34 ` Dave Hansen
2023-01-22 4:44 ` H. Peter Anvin
2023-01-22 8:22 ` Li, Xin3
2023-01-22 8:54 ` Ammar Faizi
2023-01-22 9:40 ` H. Peter Anvin
2023-01-22 23:45 ` H. Peter Anvin
2023-01-23 9:02 ` Ammar Faizi
2023-01-23 19:43 ` H. Peter Anvin
2023-01-23 23:43 ` Ammar Faizi
2023-01-23 23:58 ` H. Peter Anvin
2023-01-24 0:26 ` [RFC PATCH v1 0/2] selftests/x86: sysret_rip update for FRED system Ammar Faizi
2023-01-24 0:26 ` [RFC PATCH v1 1/2] selftests/x86: sysret_rip: Handle syscall in a " Ammar Faizi
2023-01-24 1:40 ` H. Peter Anvin
2023-01-24 2:31 ` Ammar Faizi
2023-01-26 20:08 ` Ammar Faizi
2023-02-15 9:17 ` Andrew Cooper
2023-02-15 10:29 ` Andrew Cooper
2023-02-15 10:44 ` Ammar Faizi
2023-02-15 10:42 ` Ammar Faizi
2023-01-26 20:16 ` Ammar Faizi
2023-01-24 0:26 ` [RFC PATCH v1 2/2] selftests/x86: sysret_rip: Add more syscall tests with respect to `%rcx` and `%r11` Ammar Faizi
2023-01-23 23:53 ` the x86 sysret_rip test fails on the Intel FRED architecture Andrew Cooper
2023-01-24 0:01 ` H. Peter Anvin
2023-01-24 2:27 ` [RFC PATCH v2 0/2] selftests/x86: sysret_rip update for FRED system Ammar Faizi
2023-01-24 2:27 ` [RFC PATCH v2 1/2] selftests/x86: sysret_rip: Handle syscall in a " Ammar Faizi
2023-01-24 5:44 ` H. Peter Anvin
2023-01-24 2:27 ` [RFC PATCH v2 2/2] selftests/x86: sysret_rip: Add more syscall tests with respect to `%rcx` and `%r11` Ammar Faizi
2023-01-24 6:16 ` H. Peter Anvin
2023-01-24 6:41 ` Ammar Faizi
2023-01-24 6:47 ` Ammar Faizi
2023-01-24 9:07 ` H. Peter Anvin
2023-01-24 9:12 ` Ammar Faizi
2023-01-24 10:09 ` [RFC PATCH v3 0/2] selftests/x86: sysret_rip update for FRED system Ammar Faizi
2023-01-24 10:09 ` [RFC PATCH v3 1/2] selftests/x86: sysret_rip: Handle syscall in a " Ammar Faizi
2023-01-24 10:09 ` [RFC PATCH v3 2/2] selftests/x86: sysret_rip: Add more syscall tests with respect to `%rcx` and `%r11` Ammar Faizi
2023-01-24 20:59 ` H. Peter Anvin
2023-01-25 3:29 ` Ammar Faizi
2023-01-24 21:32 ` [RFC PATCH v3 0/2] selftests/x86: sysret_rip update for FRED system Li, Xin3
2023-01-24 21:37 ` H. Peter Anvin
2023-01-24 23:20 ` Li, Xin3
2023-01-25 3:27 ` Ammar Faizi
2023-01-24 21:51 ` Andrew Cooper
2023-01-24 23:58 ` Li, Xin3
2023-01-25 3:22 ` [RFC PATCH v4 0/2] sysret_rip update for the Intel FRED architecture Ammar Faizi
2023-01-25 3:22 ` [RFC PATCH v4 1/2] selftests/x86: sysret_rip: Handle syscall in a FRED system Ammar Faizi
2023-01-25 3:37 ` Ammar Faizi
2023-01-25 3:44 ` Ammar Faizi
2023-01-25 3:22 ` [RFC PATCH v4 2/2] selftests/x86: sysret_rip: Add more syscall tests with respect to `%rcx` and `%r11` Ammar Faizi
2023-01-25 3:49 ` [RFC PATCH v5 0/2] sysret_rip update for the Intel FRED architecture Ammar Faizi
2023-01-25 3:49 ` [RFC PATCH v5 1/2] selftests/x86: sysret_rip: Handle syscall in a FRED system Ammar Faizi
2023-01-25 8:39 ` H. Peter Anvin
2023-01-25 8:53 ` Ammar Faizi
2023-01-25 9:57 ` Ammar Faizi
2023-01-25 10:01 ` Ammar Faizi
2023-01-25 10:17 ` H. Peter Anvin
2023-01-25 11:37 ` Ammar Faizi
2023-01-25 17:25 ` H. Peter Anvin
2023-01-25 3:49 ` [RFC PATCH v5 2/2] selftests/x86: sysret_rip: Add more syscall tests with respect to `%rcx` and `%r11` Ammar Faizi
2023-01-25 8:22 ` [RFC PATCH v5 0/2] sysret_rip update for the Intel FRED architecture Li, Xin3
2023-01-25 8:32 ` Ammar Faizi
2023-01-25 17:07 ` Li, Xin3
2023-01-25 17:24 ` H. Peter Anvin
2023-01-25 17:41 ` Ammar Faizi
2023-01-25 17:48 ` Li, Xin3
2023-02-15 7:42 ` Li, Xin3
2023-02-15 7:51 ` Ammar Faizi
2023-02-18 4:27 ` Ammar Faizi
2023-02-18 4:51 ` H. Peter Anvin
2023-01-25 21:17 ` [RFC PATCH v6 0/3] " Ammar Faizi
2023-01-25 21:17 ` [RFC PATCH v6 1/3] selftests/x86: sysret_rip: Handle syscall in a FRED system Ammar Faizi
2023-01-25 23:01 ` Ammar Faizi
2023-01-25 21:17 ` [RFC PATCH v6 2/3] selftests/x86: sysret_rip: Add more syscall tests with respect to `%rcx` and `%r11` Ammar Faizi
2023-01-25 21:17 ` [RFC PATCH v6 3/3] selftests/x86: sysret_rip: Test opportunistic SYSRET Ammar Faizi
2023-01-25 23:24 ` [RFC PATCH v7 0/3] sysret_rip update for the Intel FRED architecture Ammar Faizi
2023-01-25 23:24 ` [RFC PATCH v7 1/3] selftests/x86: sysret_rip: Handle syscall in a FRED system Ammar Faizi
2023-01-25 23:24 ` [RFC PATCH v7 2/3] selftests/x86: sysret_rip: Add more syscall tests with respect to `%rcx` and `%r11` Ammar Faizi
2023-01-25 23:24 ` [RFC PATCH v7 3/3] selftests/x86: sysret_rip: Test SYSRET with a signal handler Ammar Faizi
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