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>
diff --git a/arch/arm/include/asm/tls.h b/arch/arm/include/asm/tls.h
new file mode 100644
index 0000000..e71d6ff
--- /dev/null
+++ b/arch/arm/include/asm/tls.h
@@ -0,0 +1,46 @@
+#ifndef __ASMARM_TLS_H
+#define __ASMARM_TLS_H
+
+#ifdef __ASSEMBLY__
+ .macro set_tls_none, tp, tmp1, tmp2
+ .endm
+
+ .macro set_tls_v6k, tp, tmp1, tmp2
+ mcr p15, 0, \tp, c13, c0, 3 @ set TLS register
+ .endm
+
+ .macro set_tls_v6, tp, tmp1, tmp2
+ ldr \tmp1, =elf_hwcap
+ ldr \tmp1, [\tmp1, #0]
+ mov \tmp2, #0xffff0fff
+ tst \tmp1, #HWCAP_TLS @ hardware TLS available?
+ mcrne p15, 0, \tp, c13, c0, 3 @ yes, set TLS register
+ streq \tp, [\tmp2, #-15] @ set TLS value at 0xffff0ff0
+ .endm
+
+ .macro set_tls_software, tp, tmp1, tmp2
+ mov \tmp1, #0xffff0fff
+ str \tp, [\tmp1, #-15] @ set TLS value at 0xffff0ff0
+ .endm
+#endif
+
+#ifdef CONFIG_TLS_REG_EMUL
+#define tls_emu 1
+#define has_tls_reg 1
+#define set_tls set_tls_none
+#elif __LINUX_ARM_ARCH__ >= 7 || \
+ (__LINUX_ARM_ARCH__ == 6 && defined(CONFIG_CPU_32v6K))
+#define tls_emu 0
+#define has_tls_reg 1
+#define set_tls set_tls_v6k
+#elif __LINUX_ARM_ARCH__ == 6
+#define tls_emu 0
+#define has_tls_reg (elf_hwcap & HWCAP_TLS)
+#define set_tls set_tls_v6
+#else
+#define tls_emu 0
+#define has_tls_reg 0
+#define set_tls set_tls_software
+#endif
+
+#endif /* __ASMARM_TLS_H */