ARM: 6207/1: Replace CONFIG_HAS_TLS_REG with HWCAP_TLS and check for it on V6

The TLS register is only available on ARM1136 r1p0 and later.
Set HWCAP_TLS flags if hardware TLS is available and test for
it if CONFIG_CPU_32v6K is not set for V6.

Note that we set the TLS instruction in __kuser_get_tls
dynamically as suggested by Jamie Lokier <jamie@shareable.org>.

Also the __switch_to code is optimized out in most cases as
suggested by Nicolas Pitre <nico@fluxnic.net>.

Reviewed-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 4 insertions, 14 deletions

diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index 346ae14824a5..71d5d5efceef 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -717,17 +717,6 @@ config TLS_REG_EMUL
           a few prototypes like that in existence) and therefore access to
           that required register must be emulated.
 
-config HAS_TLS_REG
-        bool
-        depends on !TLS_REG_EMUL
-        default y if SMP || CPU_32v7
-        help
-          This selects support for the CP15 thread register.
-          It is defined to be available on some ARMv6 processors (including
-          all SMP capable ARMv6's) or later processors.  User space may
-          assume directly accessing that register and always obtain the
-          expected value only on ARMv7 and above.
-
 config NEEDS_SYSCALL_FOR_CMPXCHG
         bool
         help
diff --git a/arch/arm/mm/proc-v6.S b/arch/arm/mm/proc-v6.S
index 7a5337ed7d68..2f5a3c23a0fe 100644
--- a/arch/arm/mm/proc-v6.S
+++ b/arch/arm/mm/proc-v6.S
@@ -239,7 +239,8 @@ __v6_proc_info:
         b       __v6_setup
         .long   cpu_arch_name
         .long   cpu_elf_name
-        .long   HWCAP_SWP|HWCAP_HALF|HWCAP_THUMB|HWCAP_FAST_MULT|HWCAP_EDSP|HWCAP_JAVA
+        /* See also feat_v6_fixup() for HWCAP_TLS */
+        .long   HWCAP_SWP|HWCAP_HALF|HWCAP_THUMB|HWCAP_FAST_MULT|HWCAP_EDSP|HWCAP_JAVA|HWCAP_TLS
         .long   cpu_v6_name
         .long   v6_processor_functions
         .long   v6wbi_tlb_fns
@@ -262,7 +263,7 @@ __pj4_v6_proc_info:
         b       __v6_setup
         .long   cpu_arch_name
         .long   cpu_elf_name
-        .long   HWCAP_SWP|HWCAP_HALF|HWCAP_THUMB|HWCAP_FAST_MULT|HWCAP_EDSP
+        .long   HWCAP_SWP|HWCAP_HALF|HWCAP_THUMB|HWCAP_FAST_MULT|HWCAP_EDSP|HWCAP_TLS
         .long   cpu_pj4_name
         .long   v6_processor_functions
         .long   v6wbi_tlb_fns
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 7aaf88a3b7aa..8071bcd4c995 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -344,7 +344,7 @@ __v7_proc_info:
         b       __v7_setup
         .long   cpu_arch_name
         .long   cpu_elf_name
-        .long   HWCAP_SWP|HWCAP_HALF|HWCAP_THUMB|HWCAP_FAST_MULT|HWCAP_EDSP
+        .long   HWCAP_SWP|HWCAP_HALF|HWCAP_THUMB|HWCAP_FAST_MULT|HWCAP_EDSP|HWCAP_TLS
         .long   cpu_v7_name
         .long   v7_processor_functions
         .long   v7wbi_tlb_fns