[PATCH] ARM: 2663/1: straightify TLS register emulation a bit more
Patch from Nicolas Pitre
This better express things, and should cover RMK's weird SMP toys.
Signed-off-by: Nicolas Pitre
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 27892e3..c4fc6be 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -410,17 +410,23 @@
help
Say Y here to disable branch prediction. If unsure, say N.
+config TLS_REG_EMUL
+ bool
+ default y if (SMP || CPU_32v6) && (CPU_32v5 || CPU_32v4 || CPU_32v3)
+ help
+ We might be running on an ARMv6+ processor which should have the TLS
+ register but for some reason we can't use it, or maybe an SMP system
+ using a pre-ARMv6 processor (there are apparently a few prototypes
+ like that in existence) and therefore access to that register must
+ be emulated.
+
config HAS_TLS_REG
bool
- depends on CPU_32v6 && !CPU_32v5 && !CPU_32v4 && !CPU_32v3
- default y
+ depends on CPU_32v6
+ default y if !TLS_REG_EMUL
help
This selects support for the CP15 thread register.
- It is defined to be available on ARMv6 or later. However
- if the kernel is configured to support multiple CPUs including
- a pre-ARMv6 processors, or if a given ARMv6 processor doesn't
- implement the thread register for some reason, then access to
- this register from user space must be trapped and emulated.
- If user space is relying on the __kuser_get_tls code then
- there should not be any impact.
+ It is defined to be available on ARMv6 or later. If a particular
+ ARMv6 or later CPU doesn't support it then it must omc;ide "select
+ TLS_REG_EMUL" along with its other caracteristics.