[4.4,16/18] ARM: use __inttype() in get_user()

Message ID	20181031140436.2964-17-dave.long@linaro.org
State	Superseded
Headers	show Delivered-To: patches@linaro.org Received-SPF: pass (google.com: domain of dave.long@linaro.org designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; From: David Long <dave.long@linaro.org> To: stable@vger.kernel.org, Russell King - ARM Linux <linux@armlinux.org.uk>, Florian Fainelli <f.fainelli@gmail.com>, Tony Lindgren <tony@atomide.com>, Marc Zyngier <marc.zyngier@arm.com>, Mark Rutland <mark.rutland@arm.com> Cc: Greg KH <gregkh@linuxfoundation.org>, Mark Brown <broonie@kernel.org> Subject: [PATCH 4.4 16/18] ARM: use __inttype() in get_user() Date: Wed, 31 Oct 2018 10:04:34 -0400 Message-Id: <20181031140436.2964-17-dave.long@linaro.org> In-Reply-To: <20181031140436.2964-1-dave.long@linaro.org> References: <20181031140436.2964-1-dave.long@linaro.org>
Series	V4.4 backport of 32-bit arm spectre patches \| expand [4.4,00/18] V4.4 backport of 32-bit arm spectre patches [4.4,01/18] ARM: add more CPU part numbers for Cortex and Brahma B15 CPUs [4.4,02/18] ARM: bugs: prepare processor bug infrastructure [4.4,03/18] ARM: bugs: hook processor bug checking into SMP and suspend paths [4.4,04/18] ARM: bugs: add support for per-processor bug checking [4.4,05/18] ARM: spectre: add Kconfig symbol for CPUs vulnerable to Spectre [4.4,06/18] ARM: spectre-v2: harden branch predictor on context switches [4.4,07/18] ARM: spectre-v2: add Cortex A8 and A15 validation of the IBE bit [4.4,08/18] ARM: spectre-v2: harden user aborts in kernel space [4.4,09/18] ARM: spectre-v2: warn about incorrect context switching functions [4.4,10/18] ARM: spectre-v1: add speculation barrier (csdb) macros [4.4,11/18] ARM: spectre-v1: add array_index_mask_nospec() implementation [4.4,12/18] ARM: spectre-v1: fix syscall entry [4.4,13/18] ARM: signal: copy registers using __copy_from_user() [4.4,14/18] ARM: vfp: use __copy_from_user() when restoring VFP state [4.4,15/18] ARM: oabi-compat: copy semops using __copy_from_user() [4.4,16/18] ARM: use __inttype() in get_user() [4.4,17/18] ARM: spectre-v1: use get_user() for __get_user() [4.4,18/18] ARM: spectre-v1: mitigate user accesses

Message ID

20181031140436.2964-17-dave.long@linaro.org

State

Superseded

Headers

Received-SPF: pass (google.com: domain of dave.long@linaro.org designates
	209.85.220.65 as permitted sender) client-ip=209.85.220.65; 
From: David Long <dave.long@linaro.org>
To: stable@vger.kernel.org, Russell King - ARM Linux <linux@armlinux.org.uk>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Tony Lindgren <tony@atomide.com>, Marc Zyngier <marc.zyngier@arm.com>,
	Mark Rutland <mark.rutland@arm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>,
	Mark Brown <broonie@kernel.org>
Subject: [PATCH 4.4 16/18] ARM: use __inttype() in get_user()
Date: Wed, 31 Oct 2018 10:04:34 -0400
Message-Id: <20181031140436.2964-17-dave.long@linaro.org>
In-Reply-To: <20181031140436.2964-1-dave.long@linaro.org>
References: <20181031140436.2964-1-dave.long@linaro.org>

Series

V4.4 backport of 32-bit arm spectre patches | expand

Commit Message

David Long Oct. 31, 2018, 2:04 p.m. UTC

From: Russell King <rmk+kernel@armlinux.org.uk>


Commit d09fbb327d670737ab40fd8bbb0765ae06b8b739 upstream.

Borrow the x86 implementation of __inttype() to use in get_user() to
select an integer type suitable to temporarily hold the result value.
This is necessary to avoid propagating the volatile nature of the
result argument, which can cause the following warning:

lib/iov_iter.c:413:5: warning: optimization may eliminate reads and/or writes to register variables [-Wvolatile-register-var]

Acked-by: Mark Rutland <mark.rutland@arm.com>

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

Signed-off-by: David A. Long <dave.long@linaro.org>

---
 arch/arm/include/asm/uaccess.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

-- 
2.17.1

diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index cd8b589111ba..968b50063431 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -122,6 +122,13 @@  static inline void set_fs(mm_segment_t fs)
 		: "cc"); \
 	flag; })
 
+/*
+ * This is a type: either unsigned long, if the argument fits into
+ * that type, or otherwise unsigned long long.
+ */
+#define __inttype(x) \
+	__typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
+
 /*
  * Single-value transfer routines.  They automatically use the right
  * size if we just have the right pointer type.  Note that the functions
@@ -191,7 +198,7 @@  extern int __get_user_64t_4(void *);
 	({								\
 		unsigned long __limit = current_thread_info()->addr_limit - 1; \
 		register const typeof(*(p)) __user *__p asm("r0") = (p);\
-		register typeof(x) __r2 asm("r2");			\
+		register __inttype(x) __r2 asm("r2");			\
 		register unsigned long __l asm("r1") = __limit;		\
 		register int __e asm("r0");				\
 		unsigned int __ua_flags = uaccess_save_and_enable();	\

[4.4,16/18] ARM: use __inttype() in get_user()

Commit Message

Patch