Instead of using sysarch() to store-retrieve the tp, add a magic address,

ARM_TP_ADDRESS, where the tp will be stored. On CPUs that support it, a cache
line will be allocated and locked for this address, so that it will never go
to RAM. On CPUs that does not, a page is allocated for it (it will be a bit
slower, and is wrong for SMP, but should be fine for UP).
The tp is still stored in the mdthread struct, and at each context switch,
ARM_TP_ADDRESS gets updated.

Suggested by:   davidxu

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/arm/include/sysarch.h b/sys/arm/include/sysarch.h
index d0c0c47..4d6234b 100644
--- a/sys/arm/include/sysarch.h
+++ b/sys/arm/include/sysarch.h
@@ -53,6 +53,8 @@
 #define ARM_SET_TP		2
 #define ARM_GET_TP		3
 
+#define ARM_TP_ADDRESS		0xe0000000 /* Magic */
+
 struct arm_sync_icache_args {
 	uintptr_t	addr;		/* Virtual start address */
 	size_t		len;		/* Region size */