[4.14,22/24] ARM: use __inttype() in get_user()

Message ID	1539617538-22328-23-git-send-email-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State	Superseded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 4.14 22/24] ARM: use __inttype() in get_user() Date: Mon, 15 Oct 2018 11:32:16 -0400 Message-Id: <1539617538-22328-23-git-send-email-dave.long@linaro.org> In-Reply-To: <1539617538-22328-1-git-send-email-dave.long@linaro.org> References: <1539617538-22328-1-git-send-email-dave.long@linaro.org>
Series	V4.14 backport of 32-bit arm spectre patches \| expand [4.14,00/24] V4.14 backport of 32-bit arm spectre patches [4.14,01/24] ARM: add more CPU part numbers for Cortex and Brahma B15 CPUs [4.14,02/24] ARM: bugs: prepare processor bug infrastructure [4.14,03/24] ARM: bugs: hook processor bug checking into SMP and suspend paths [4.14,04/24] ARM: bugs: add support for per-processor bug checking [4.14,05/24] ARM: spectre: add Kconfig symbol for CPUs vulnerable to Spectre [4.14,06/24] ARM: spectre-v2: harden branch predictor on context switches [4.14,07/24] ARM: spectre-v2: add Cortex A8 and A15 validation of the IBE bit [4.14,08/24] ARM: spectre-v2: harden user aborts in kernel space [4.14,09/24] ARM: spectre-v2: add firmware based hardening [4.14,10/24] ARM: spectre-v2: warn about incorrect context switching functions [4.14,11/24] ARM: KVM: invalidate BTB on guest exit for Cortex-A12/A17 [4.14,12/24] ARM: KVM: invalidate icache on guest exit for Cortex-A15 [4.14,13/24] ARM: spectre-v2: KVM: invalidate icache on guest exit for Brahma B15 [4.14,14/24] ARM: KVM: Add SMCCC_ARCH_WORKAROUND_1 fast handling [4.14,15/24] ARM: KVM: report support for SMCCC_ARCH_WORKAROUND_1 [4.14,16/24] ARM: spectre-v1: add speculation barrier (csdb) macros [4.14,17/24] ARM: spectre-v1: add array_index_mask_nospec() implementation [4.14,18/24] ARM: spectre-v1: fix syscall entry [4.14,19/24] ARM: signal: copy registers using __copy_from_user() [4.14,20/24] ARM: vfp: use __copy_from_user() when restoring VFP state [4.14,21/24] ARM: oabi-compat: copy semops using __copy_from_user() [4.14,22/24] ARM: use __inttype() in get_user() [4.14,23/24] ARM: spectre-v1: use get_user() for __get_user() [4.14,24/24] ARM: spectre-v1: mitigate user accesses

Message ID

1539617538-22328-23-git-send-email-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 4.14 22/24] ARM: use __inttype() in get_user()
Date: Mon, 15 Oct 2018 11:32:16 -0400
Message-Id: <1539617538-22328-23-git-send-email-dave.long@linaro.org>
In-Reply-To: <1539617538-22328-1-git-send-email-dave.long@linaro.org>
References: <1539617538-22328-1-git-send-email-dave.long@linaro.org>

Series

V4.14 backport of 32-bit arm spectre patches | expand

Commit Message

David Long Oct. 15, 2018, 3:32 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(-)

-- 
2.5.0

diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h
index 0bf2347..29fa6f3 100644
--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -85,6 +85,13 @@  static inline void set_fs(mm_segment_t fs)
 	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
  * which read from user space (*get_*) need to take care not to leak
@@ -153,7 +160,7 @@  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();	\

[4.14,22/24] ARM: use __inttype() in get_user()

Commit Message

Patch