linux-kernel - [PATCH 13/13] ARM: avoid 'Q' asm constraint for gcc-4.1 and earlier

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 16 Dec 2016 11:56:34 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     linux-arch@...r.kernel.org
Cc:     linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...r.kernel.org,
        Russell King <rmk+kernel@...linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        kernel-build-reports@...ts.linaro.org,
        kvmarm@...ts.cs.columbia.edu, Arnd Bergmann <arnd@...db.de>
Subject: [PATCH 13/13] ARM: avoid 'Q' asm constraint for gcc-4.1 and earlier

Building with ancient gcc versions results in a stream of build errors
like:

arch/arm/include/asm/io.h:100: error: impossible constraint in 'asm'
arch/arm/include/asm/io.h:118: error: impossible constraint in 'asm'

This reverts to an older version of __raw_readl, __raw_writel
and __my_cpu_offset, which seem to be the only functions affected
by this.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 arch/arm/include/asm/io.h     | 8 ++++++++
 arch/arm/include/asm/percpu.h | 5 ++++-
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
index 6f89a4d9fc85..d0f89c4cb8e2 100644
--- a/arch/arm/include/asm/io.h
+++ b/arch/arm/include/asm/io.h
@@ -97,8 +97,12 @@ static inline void __raw_writeb(u8 val, volatile void __iomem *addr)
 #define __raw_writel __raw_writel
 static inline void __raw_writel(u32 val, volatile void __iomem *addr)
 {
+#if GCC_VERSION < 40200
+	*(volatile u32 __force *)addr = val;
+#else
 	asm volatile("str %1, %0"
 		     : : "Qo" (*(volatile u32 __force *)addr), "r" (val));
+#endif
 }
 
 #define __raw_readb __raw_readb
@@ -115,9 +119,13 @@ static inline u8 __raw_readb(const volatile void __iomem *addr)
 static inline u32 __raw_readl(const volatile void __iomem *addr)
 {
 	u32 val;
+#if GCC_VERSION < 40200
+	val = *(volatile u32 __force *)addr;
+#else
 	asm volatile("ldr %0, %1"
 		     : "=r" (val)
 		     : "Qo" (*(volatile u32 __force *)addr));
+#endif
 	return val;
 }
 
diff --git a/arch/arm/include/asm/percpu.h b/arch/arm/include/asm/percpu.h
index a89b4076cde4..dee4c89b4458 100644
--- a/arch/arm/include/asm/percpu.h
+++ b/arch/arm/include/asm/percpu.h
@@ -36,9 +36,12 @@ static inline unsigned long __my_cpu_offset(void)
 	 * We want to allow caching the value, so avoid using volatile and
 	 * instead use a fake stack read to hazard against barrier().
 	 */
+#if GCC_VERSION < 40200
+	asm("mrc p15, 0, %0, c13, c0, 4" : "=r" (off) : : "memory");
+#else
 	asm("mrc p15, 0, %0, c13, c0, 4" : "=r" (off)
 		: "Q" (*(const unsigned long *)current_stack_pointer));
-
+#endif
 	return off;
 }
 #define __my_cpu_offset __my_cpu_offset()
-- 
2.9.0