MIPS: Put PGD in C0_CONTEXT for 64-bit R2 processors.

Processors that support the mips64r2 ISA can in four instructions
convert a shifted PGD pointer stored in the upper bits of c0_context
into a usable pointer.  By doing this we save a memory load and
associated potential cache miss in the TLB exception handlers.

Since the upper bits of c0_context were holding the CPU number, we
move this to the upper bits of c0_xcontext which doesn't have enough
bits to hold the PGD pointer, but has plenty for the CPU number.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 10 insertions, 10 deletions

diff --git a/arch/mips/include/asm/stackframe.h b/arch/mips/include/asm/stackframe.h
index dd7e220e087..3b6da3330e3 100644
--- a/arch/mips/include/asm/stackframe.h
+++ b/arch/mips/include/asm/stackframe.h
@@ -87,15 +87,19 @@
 #ifdef CONFIG_SMP
 #ifdef CONFIG_MIPS_MT_SMTC
 #define PTEBASE_SHIFT   19      /* TCBIND */
+#define CPU_ID_REG CP0_TCBIND
+#define CPU_ID_MFC0 mfc0
+#elif defined(CONFIG_MIPS_PGD_C0_CONTEXT)
+#define PTEBASE_SHIFT   48      /* XCONTEXT */
+#define CPU_ID_REG CP0_XCONTEXT
+#define CPU_ID_MFC0 MFC0
 #else
 #define PTEBASE_SHIFT   23      /* CONTEXT */
+#define CPU_ID_REG CP0_CONTEXT
+#define CPU_ID_MFC0 MFC0
 #endif
                 .macro  get_saved_sp    /* SMP variation */
-#ifdef CONFIG_MIPS_MT_SMTC
-                mfc0    k0, CP0_TCBIND
-#else
-                MFC0    k0, CP0_CONTEXT
-#endif
+                CPU_ID_MFC0     k0, CPU_ID_REG
 #if defined(CONFIG_32BIT) || defined(KBUILD_64BIT_SYM32)
                 lui     k1, %hi(kernelsp)
 #else
@@ -111,11 +115,7 @@
                 .endm
 
                 .macro  set_saved_sp stackp temp temp2
-#ifdef CONFIG_MIPS_MT_SMTC
-                mfc0    \temp, CP0_TCBIND
-#else
-                MFC0    \temp, CP0_CONTEXT
-#endif
+                CPU_ID_MFC0     \temp, CPU_ID_REG
                 LONG_SRL        \temp, PTEBASE_SHIFT
                 LONG_S  \stackp, kernelsp(\temp)
                 .endm