linux.git/arch/arm/include/asm/div64.h, branch v4.3 Linux kernel source tree ARM: 8027/1: fix do_div() bug in big-endian systems 2014-04-22T21:23:57+00:00 Xiangyu Lu luxiangyu@huawei.com 2014-04-15T08:38:17+00:00 80bb3ef109ff40a7593d9481c17de9bbc4d7c0e2 In big-endian systems, "%1" get the most significant part of the value, cause the instruction to get the wrong result. When viewing ftrace record in big-endian ARM systems, we found that the timestamp errors: swapper-0 [001] 1325.970000: 0:120:R ==> [001] 16:120:R events/1 events/1-16 [001] 1325.970000: 16:120:S ==> [001] 0:120:R swapper swapper-0 [000] 1325.1000000: 0:120:R + [000] 15:120:R events/0 swapper-0 [000] 1325.1000000: 0:120:R ==> [000] 15:120:R events/0 swapper-0 [000] 1326.030000: 0:120:R + [000] 1150:120:R sshd swapper-0 [000] 1326.030000: 0:120:R ==> [000] 1150:120:R sshd When viewed ftrace records, it will call the do_div(n, base) function, which achieved arch/arm/include/asm/div64.h in. When n = 10000000, base = 1000000, in do_div(n, base) will execute "umull %Q0, %R0, %1, %Q2". Reviewed-by: Dave Martin <Dave.Martin@arm.com> Reviewed-by: Nicolas Pitre <nico@linaro.org> Cc: <stable@vger.kernel.org> # 2.6.20+ Signed-off-by: Alex Wu <wuquanming@huawei.com> Signed-off-by: Xiangyu Lu <luxiangyu@huawei.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
In big-endian systems, "%1" get the most significant part of the value, cause the instruction to get the wrong result.

When viewing ftrace record in big-endian ARM systems, we found that
the timestamp errors:

swapper-0   [001] 1325.970000:   0:120:R ==> [001]    16:120:R events/1
events/1-16 [001] 1325.970000:   16:120:S ==> [001]    0:120:R swapper
swapper-0   [000] 1325.1000000:  0:120:R   + [000]    15:120:R events/0
swapper-0   [000] 1325.1000000:  0:120:R ==> [000]    15:120:R events/0
swapper-0   [000] 1326.030000:   0:120:R   + [000]  1150:120:R sshd
swapper-0   [000] 1326.030000:   0:120:R ==> [000]  1150:120:R sshd

When viewed ftrace records, it will call the do_div(n, base) function, which achieved arch/arm/include/asm/div64.h in. When n = 10000000, base = 1000000, in do_div(n, base) will execute "umull %Q0, %R0, %1, %Q2".

Reviewed-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Cc: <stable@vger.kernel.org> # 2.6.20+
Signed-off-by: Alex Wu <wuquanming@huawei.com>
Signed-off-by: Xiangyu Lu <luxiangyu@huawei.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARM: 7705/1: use optimized do_div only for EABI 2013-05-15T18:35:53+00:00 Arnd Bergmann arnd@arndb.de 2013-04-29T15:06:10+00:00 049f3e84d34bfc37f25c91715f2e24a90fb8665e In OABI configurations, some uses of the do_div function cause gcc to run out of registers. To work around that, we can force the use of the out-of-line version for configurations that build a OABI kernel. Without this patch, building netx_defconfig results in: net/core/pktgen.c: In function 'pktgen_if_show': net/core/pktgen.c:682:2775: error: can't find a register in class 'GENERAL_REGS' while reloading 'asm' net/core/pktgen.c:682:3153: error: can't find a register in class 'GENERAL_REGS' while reloading 'asm' net/core/pktgen.c:682:2775: error: 'asm' operand has impossible constraints net/core/pktgen.c:682:3153: error: 'asm' operand has impossible constraints Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
In OABI configurations, some uses of the do_div function
cause gcc to run out of registers. To work around that,
we can force the use of the out-of-line version for
configurations that build a OABI kernel.

Without this patch, building netx_defconfig results in:

net/core/pktgen.c: In function 'pktgen_if_show':
net/core/pktgen.c:682:2775: error: can't find a register in class 'GENERAL_REGS' while reloading 'asm'
net/core/pktgen.c:682:3153: error: can't find a register in class 'GENERAL_REGS' while reloading 'asm'
net/core/pktgen.c:682:2775: error: 'asm' operand has impossible constraints
net/core/pktgen.c:682:3153: error: 'asm' operand has impossible constraints

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Disintegrate asm/system.h for ARM 2012-03-28T17:30:01+00:00 David Howells dhowells@redhat.com 2012-03-28T17:30:01+00:00 9f97da78bf018206fb623cd351d454af2f105fe0 Disintegrate asm/system.h for ARM. Signed-off-by: David Howells <dhowells@redhat.com> cc: Russell King <linux@arm.linux.org.uk> cc: linux-arm-kernel@lists.infradead.org 
Disintegrate asm/system.h for ARM.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Russell King <linux@arm.linux.org.uk>
cc: linux-arm-kernel@lists.infradead.org
[ARM] 5320/1: fix assembly constraints in implementation of do_div() 2008-10-23T11:53:32+00:00 Nicolas Pitre nico@cam.org 2008-10-23T03:34:08+00:00 884afaab44c9f92eb618ce53b3d2b5316f174a39 Those inline assembly segments using the umlal instruction must have the & modifier so to be sure that a purely input register won't alias one of the registers used as input+output. In most cases, the inputs are still used after the outputs are touched, and most binutil versions insist on "rdhi, rdlo and rm must all be different" even for ARMv6+. Signed-off-by: Nicolas Pitre <nico@marvell.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
Those inline assembly segments using the umlal instruction must have
the & modifier so to be sure that a purely input register won't alias
one of the registers used as input+output.  In most cases, the inputs
are still used after the outputs are touched, and most binutil versions
insist on "rdhi, rdlo and rm must all be different" even for ARMv6+.

Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
[ARM] move include/asm-arm to arch/arm/include/asm 2008-08-02T20:32:35+00:00 Russell King rmk@dyn-67.arm.linux.org.uk 2008-08-02T09:55:55+00:00 4baa9922430662431231ac637adedddbb0cfb2d7 Move platform independent header files to arch/arm/include/asm, leaving those in asm/arch* and asm/plat* alone. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> 
Move platform independent header files to arch/arm/include/asm, leaving
those in asm/arch* and asm/plat* alone.

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