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>

1 files changed, 7 insertions, 16 deletions

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 7ee48e7f8f31..a6cfb1791af3 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -22,6 +22,7 @@
 #include <asm/thread_notify.h>
 #include <asm/unwind.h>
 #include <asm/unistd.h>
+#include <asm/tls.h>
 
 #include "entry-header.S"
 
@@ -739,12 +740,7 @@ ENTRY(__switch_to)
 #ifdef CONFIG_MMU
         ldr     r6, [r2, #TI_CPU_DOMAIN]
 #endif
-#if defined(CONFIG_HAS_TLS_REG)
-        mcr     p15, 0, r3, c13, c0, 3          @ set TLS register
-#elif !defined(CONFIG_TLS_REG_EMUL)
-        mov     r4, #0xffff0fff
-        str     r3, [r4, #-15]                  @ TLS val at 0xffff0ff0
-#endif
+        set_tls r3, r4, r5
 #ifdef CONFIG_MMU
         mcr     p15, 0, r6, c3, c0, 0           @ Set domain register
 #endif
@@ -1009,17 +1005,12 @@ kuser_cmpxchg_fixup:
  */
 
 __kuser_get_tls:                                @ 0xffff0fe0
-
-#if !defined(CONFIG_HAS_TLS_REG) && !defined(CONFIG_TLS_REG_EMUL)
-        ldr     r0, [pc, #(16 - 8)]             @ TLS stored at 0xffff0ff0
-#else
-        mrc     p15, 0, r0, c13, c0, 3          @ read TLS register
-#endif
+        ldr     r0, [pc, #(16 - 8)]     @ read TLS, set in kuser_get_tls_init
         usr_ret lr
-
-        .rep    5
-        .word   0                       @ pad up to __kuser_helper_version
-        .endr
+        mrc     p15, 0, r0, c13, c0, 3  @ 0xffff0fe8 hardware TLS code
+        .rep    4
+        .word   0                       @ 0xffff0ff0 software TLS value, then
+        .endr                           @ pad up to __kuser_helper_version
 
 /*
  * Reference declaration: