linux-kernel - [PATCH 3.16 49/83] ptrace,x86: Make user_64bit

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Message-ID: <lsq.1574264230.800450209@decadent.org.uk>
Date:   Wed, 20 Nov 2019 15:37:59 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Thomas Garnier" <thgarnie@...gle.com>,
        "Dmitry Vyukov" <dvyukov@...gle.com>,
        "Paul Gortmaker" <paul.gortmaker@...driver.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        "Chen Yucong" <slaoub@...il.com>,
        "Masami Hiramatsu" <mhiramat@...nel.org>,
        "Jonathan Corbet" <corbet@....net>,
        "Shuah Khan" <shuah@...nel.org>,
        "Chris Metcalf" <cmetcalf@...lanox.com>,
        "Ricardo Neri" <ricardo.neri-calderon@...ux.intel.com>,
        "Arnaldo Carvalho de Melo" <acme@...hat.com>,
        ricardo.neri@...el.com, "Kees Cook" <keescook@...omium.org>,
        "Adam Buchbinder" <adam.buchbinder@...il.com>,
        "Colin Ian King" <colin.king@...onical.com>,
        "Vlastimil Babka" <vbabka@...e.cz>,
        "Dave Hansen" <dave.hansen@...ux.intel.com>,
        "Paolo Bonzini" <pbonzini@...hat.com>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "Qiaowei Ren" <qiaowei.ren@...el.com>,
        "Brian Gerst" <brgerst@...il.com>,
        "Andy Lutomirski" <luto@...nel.org>,
        "Huang Rui" <ray.huang@....com>,
        "Lorenzo Stoakes" <lstoakes@...il.com>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        "Borislav Petkov" <bp@...e.de>,
        "Adrian Hunter" <adrian.hunter@...el.com>,
        "Jiri Slaby" <jslaby@...e.cz>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>
Subject: [PATCH 3.16 49/83] ptrace,x86: Make user_64bit_mode() available
 to 32-bit builds

3.16.78-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>

commit e27c310af5c05cf876d9cad006928076c27f54d4 upstream.

In its current form, user_64bit_mode() can only be used when CONFIG_X86_64
is selected. This implies that code built with CONFIG_X86_64=n cannot use
it. If a piece of code needs to be built for both CONFIG_X86_64=y and
CONFIG_X86_64=n and wants to use this function, it needs to wrap it in
an #ifdef/#endif; potentially, in multiple places.

This can be easily avoided with a single #ifdef/#endif pair within
user_64bit_mode() itself.

Suggested-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Borislav Petkov <bp@...e.de>
Cc: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: ricardo.neri@...el.com
Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Paul Gortmaker <paul.gortmaker@...driver.com>
Cc: Huang Rui <ray.huang@....com>
Cc: Qiaowei Ren <qiaowei.ren@...el.com>
Cc: Shuah Khan <shuah@...nel.org>
Cc: Kees Cook <keescook@...omium.org>
Cc: Jonathan Corbet <corbet@....net>
Cc: Jiri Slaby <jslaby@...e.cz>
Cc: Dmitry Vyukov <dvyukov@...gle.com>
Cc: "Ravi V. Shankar" <ravi.v.shankar@...el.com>
Cc: Chris Metcalf <cmetcalf@...lanox.com>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Colin Ian King <colin.king@...onical.com>
Cc: Chen Yucong <slaoub@...il.com>
Cc: Adam Buchbinder <adam.buchbinder@...il.com>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: Lorenzo Stoakes <lstoakes@...il.com>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Thomas Garnier <thgarnie@...gle.com>
Link: https://lkml.kernel.org/r/1509135945-13762-4-git-send-email-ricardo.neri-calderon@linux.intel.com
[bwh: Backported to 3.16 as dependency of "uprobes/x86: Fix detection of
 32-bit user mode":
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/x86/include/asm/ptrace.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/arch/x86/include/asm/ptrace.h
+++ b/arch/x86/include/asm/ptrace.h
@@ -118,9 +118,9 @@ static inline int v8086_mode(struct pt_r
 #endif
 }
 
-#ifdef CONFIG_X86_64
 static inline bool user_64bit_mode(struct pt_regs *regs)
 {
+#ifdef CONFIG_X86_64
 #ifndef CONFIG_PARAVIRT
 	/*
 	 * On non-paravirt systems, this is the only long mode CPL 3
@@ -131,8 +131,12 @@ static inline bool user_64bit_mode(struc
 	/* Headers are too twisted for this to go in paravirt.h. */
 	return regs->cs == __USER_CS || regs->cs == pv_info.extra_user_64bit_cs;
 #endif
+#else /* !CONFIG_X86_64 */
+	return false;
+#endif
 }
 
+#ifdef CONFIG_X86_64
 #define current_user_stack_pointer()	this_cpu_read(old_rsp)
 /* ia32 vs. x32 difference */
 #define compat_user_stack_pointer()	\