linux-kernel - [RFC PATCH v3 0/2] selftests/x86: sysret

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Message-Id: <20230124100926.637335-1-ammarfaizi2@gnuweeb.org>
Date:   Tue, 24 Jan 2023 17:09:23 +0700
From:   Ammar Faizi <ammarfaizi2@...weeb.org>
To:     "H. Peter Anvin" <hpa@...or.com>, x86 Mailing List <x86@...nel.org>
Cc:     Ammar Faizi <ammarfaizi2@...weeb.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Xin Li <xin3.li@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andrew Cooper <Andrew.Cooper3@...rix.com>,
        Brian Gerst <brgerst@...il.com>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Shuah Khan <shuah@...nel.org>, Ingo Molnar <mingo@...nel.org>,
        Andy Lutomirski <luto@...nel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Linux Kselftest Mailing List 
        <linux-kselftest@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [RFC PATCH v3 0/2] selftests/x86: sysret_rip update for FRED system

From: Ammar Faizi <ammarfaizi2@...weeb.org>

This is an RFC patchset v3:
sysret_rip test update for Intel FRED architecture. 

Xin Li reported sysret_rip test fails at:

        assert(ctx->uc_mcontext.gregs[REG_EFL] ==
               ctx->uc_mcontext.gregs[REG_R11]);

in a FRED system. Let's handle the FRED system scenario too. The
'syscall' instruction in a FRED system doesn't set %r11=%rflags.

There are two patches in this series.

How to test this:

  $ make -C tools/testing/selftests/x86
  $ tools/testing/selftests/x86/sysret_rip_64

Link: https://lore.kernel.org/lkml/5d4ad3e3-034f-c7da-d141-9c001c2343af@intel.com
Fixes: 660602140103 ("selftests/x86: Add a selftest for SYSRET to noncanonical addresses")
Link: https://lore.kernel.org/lkml/25b96960-a07e-a952-5c23-786b55054126@zytor.com
Reported-by: Xin Li <xin3.li@...el.com>
Co-developed-by: H. Peter Anvin (Intel) <hpa@...or.com>
Signed-off-by: H. Peter Anvin (Intel) <hpa@...or.com>
Acked-by: H. Peter Anvin (Intel) <hpa@...or.com>
Signed-off-by: Ammar Faizi <ammarfaizi2@...weeb.org>
---

## Changelog v3:

   - Test that we don't get a mix of REGS_SAVED and REGS_SYSRET,
     which is a major part of the point (hpa).

## Changelog v2:

   - Use "+r"(rsp) as the right way to avoid redzone problems
     per Andrew's comment (hpa).
     (Ref: https://lore.kernel.org/lkml/8f5c24df-514d-5d89-f58f-ec8c3eb1e049@zytor.com )

---

Ammar Faizi (2):
  selftests/x86: sysret_rip: Handle syscall in a FRED system
  selftests/x86: sysret_rip: Add more syscall tests with respect to `%rcx` and `%r11`

 tools/testing/selftests/x86/sysret_rip.c | 120 ++++++++++++++++++++++-
 1 file changed, 119 insertions(+), 1 deletion(-)


base-commit: e12ad468c22065a2826b2fc4c11d2113a7975301
-- 
Ammar Faizi