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Revision 3af57f78c38131b7a66e2b01e06fdacae01992a3 authored by Heiko Carstens on 17 January 2014, 08:37:15 UTC, committed by David S. Miller on 18 January 2014, 02:54:49 UTC 
s390/bpf,jit: fix 32 bit divisions, use unsigned divide instructions
 
The s390 bpf jit compiler emits the signed divide instructions "dr" and "d"
for unsigned divisions.
This can cause problems: the dividend will be zero extended to a 64 bit value
and the divisor is the 32 bit signed value as specified A or X accumulator,
even though A and X are supposed to be treated as unsigned values.

The divide instrunctions will generate an exception if the result cannot be
expressed with a 32 bit signed value.
This is the case if e.g. the dividend is 0xffffffff and the divisor either 1
or also 0xffffffff (signed: -1).

To avoid all these issues simply use unsigned divide instructions.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent 75b99db
Raw File
Kconfig 
menuconfig SAMPLES
	bool "Sample kernel code"
	help
	  You can build and test sample kernel code here.

if SAMPLES

config SAMPLE_TRACE_EVENTS
	tristate "Build trace_events examples -- loadable modules only"
	depends on EVENT_TRACING && m
	help
	  This build trace event example modules.

config SAMPLE_KOBJECT
	tristate "Build kobject examples -- loadable modules only"
	depends on m
	help
	  This config option will allow you to build a number of
	  different kobject sample modules showing how to use kobjects,
	  ksets, and ktypes properly.

	  If in doubt, say "N" here.

config SAMPLE_KPROBES
	tristate "Build kprobes examples -- loadable modules only"
	depends on KPROBES && m
	help
	  This build several kprobes example modules.

config SAMPLE_KRETPROBES
	tristate "Build kretprobes example -- loadable modules only"
	default m
	depends on SAMPLE_KPROBES && KRETPROBES

config SAMPLE_HW_BREAKPOINT
	tristate "Build kernel hardware breakpoint examples -- loadable module only"
	depends on HAVE_HW_BREAKPOINT && m
	help
	  This builds kernel hardware breakpoint example modules.

config SAMPLE_KFIFO
	tristate "Build kfifo examples -- loadable modules only"
	depends on m
	help
	  This config option will allow you to build a number of
	  different kfifo sample modules showing how to use the
	  generic kfifo API.

	  If in doubt, say "N" here.

config SAMPLE_KDB
	tristate "Build kdb command example -- loadable modules only"
	depends on KGDB_KDB && m
	help
	  Build an example of how to dynamically add the hello
	  command to the kdb shell.

config SAMPLE_RPMSG_CLIENT
	tristate "Build rpmsg client sample -- loadable modules only"
	depends on RPMSG && m
	help
	  Build an rpmsg client sample driver, which demonstrates how
	  to communicate with an AMP-configured remote processor over
	  the rpmsg bus.

endif # SAMPLES
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