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/kernel/traps.c b/arch/arm/kernel/traps.c
index 1621e53..cda78d5 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -30,6 +30,7 @@
#include <asm/unistd.h>
#include <asm/traps.h>
#include <asm/unwind.h>
+#include <asm/tls.h>
#include "ptrace.h"
#include "signal.h"
@@ -518,17 +519,20 @@
case NR(set_tls):
thread->tp_value = regs->ARM_r0;
-#if defined(CONFIG_HAS_TLS_REG)
- asm ("mcr p15, 0, %0, c13, c0, 3" : : "r" (regs->ARM_r0) );
-#elif !defined(CONFIG_TLS_REG_EMUL)
- /*
- * User space must never try to access this directly.
- * Expect your app to break eventually if you do so.
- * The user helper at 0xffff0fe0 must be used instead.
- * (see entry-armv.S for details)
- */
- *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
-#endif
+ if (tls_emu)
+ return 0;
+ if (has_tls_reg) {
+ asm ("mcr p15, 0, %0, c13, c0, 3"
+ : : "r" (regs->ARM_r0));
+ } else {
+ /*
+ * User space must never try to access this directly.
+ * Expect your app to break eventually if you do so.
+ * The user helper at 0xffff0fe0 must be used instead.
+ * (see entry-armv.S for details)
+ */
+ *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
+ }
return 0;
#ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
@@ -743,6 +747,16 @@
return;
}
+static void __init kuser_get_tls_init(unsigned long vectors)
+{
+ /*
+ * vectors + 0xfe0 = __kuser_get_tls
+ * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
+ */
+ if (tls_emu || has_tls_reg)
+ memcpy((void *)vectors + 0xfe0, (void *)vectors + 0xfe8, 4);
+}
+
void __init early_trap_init(void)
{
unsigned long vectors = CONFIG_VECTORS_BASE;
@@ -761,6 +775,11 @@
memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
/*
+ * Do processor specific fixups for the kuser helpers
+ */
+ kuser_get_tls_init(vectors);
+
+ /*
* Copy signal return handlers into the vector page, and
* set sigreturn to be a pointer to these.
*/