linux-kernel - [RFC UKL 05/10] x86/uaccess: Make access

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Message-Id: <20221003222133.20948-6-aliraza@bu.edu>
Date:   Mon,  3 Oct 2022 18:21:28 -0400
From:   Ali Raza <aliraza@...edu>
To:     linux-kernel@...r.kernel.org
Cc:     corbet@....net, masahiroy@...nel.org, michal.lkml@...kovi.net,
        ndesaulniers@...gle.com, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, hpa@...or.com,
        luto@...nel.org, ebiederm@...ssion.com, keescook@...omium.org,
        peterz@...radead.org, viro@...iv.linux.org.uk, arnd@...db.de,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, bristot@...hat.com, vschneid@...hat.com,
        pbonzini@...hat.com, jpoimboe@...nel.org,
        linux-doc@...r.kernel.org, linux-kbuild@...r.kernel.org,
        linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
        linux-arch@...r.kernel.org, x86@...nel.org, rjones@...hat.com,
        munsoner@...edu, tommyu@...edu, drepper@...hat.com,
        lwoodman@...hat.com, mboydmcse@...il.com, okrieg@...edu,
        rmancuso@...edu, Ali Raza <aliraza@...edu>
Subject: [RFC UKL 05/10] x86/uaccess: Make access_ok UKL aware

When configured for UKL, access_ok needs to account for the unified address
space that is used by the kernel and the process being run. To do this,
they need to check the task struct field added earlier to determine where
the execution that is making the check is running. For a zero value, the
normal boundary definitions apply, but non-zero value indicates a UKL
thread and a shared address space should be assumed.

Cc: Jonathan Corbet <corbet@....net>
Cc: Masahiro Yamada <masahiroy@...nel.org>
Cc: Michal Marek <michal.lkml@...kovi.net>
Cc: Nick Desaulniers <ndesaulniers@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Eric Biederman <ebiederm@...ssion.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Alexander Viro <viro@...iv.linux.org.uk>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Vincent Guittot <vincent.guittot@...aro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@....com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Ben Segall <bsegall@...gle.com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Daniel Bristot de Oliveira <bristot@...hat.com>
Cc: Valentin Schneider <vschneid@...hat.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Josh Poimboeuf <jpoimboe@...nel.org>

Signed-off-by: Ali Raza <aliraza@...edu>
---
 arch/x86/include/asm/uaccess.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 913e593a3b45..adef521b2e59 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -37,11 +37,19 @@ static inline bool pagefault_disabled(void);
  * Return: true (nonzero) if the memory block may be valid, false (zero)
  * if it is definitely invalid.
  */
+#ifdef CONFIG_UNIKERNEL_LINUX
+#define access_ok(addr, size)					\
+({									\
+	WARN_ON_IN_IRQ();						\
+	(is_ukl_thread() ? 1 : likely(__access_ok(addr, size)));	\
+})
+#else
 #define access_ok(addr, size)					\
 ({									\
 	WARN_ON_IN_IRQ();						\
 	likely(__access_ok(addr, size));				\
 })
+#endif

 #include <asm-generic/access_ok.h>

-- 
2.21.3