[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>

1 files changed, 7 insertions, 4 deletions

diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 8988c02119fd..14df16b983f4 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -451,9 +451,9 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs)
 
         case NR(set_tls):
                 thread->tp_value = regs->ARM_r0;
-#ifdef CONFIG_HAS_TLS_REG
+#if defined(CONFIG_HAS_TLS_REG)
                 asm ("mcr p15, 0, %0, c13, c0, 3" : : "r" (regs->ARM_r0) );
-#else
+#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.
@@ -498,11 +498,14 @@ asmlinkage int arm_syscall(int no, struct pt_regs *regs)
         return 0;
 }
 
-#if defined(CONFIG_CPU_32v6) && !defined(CONFIG_HAS_TLS_REG)
+#ifdef CONFIG_TLS_REG_EMUL
 
 /*
  * We might be running on an ARMv6+ processor which should have the TLS
- * register, but for some reason we can't use it and have to emulate it.
+ * 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.
  */
 
 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)