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>
diff --git a/arch/mips/include/asm/stackframe.h b/arch/mips/include/asm/stackframe.h
index dd7e220..3b6da33 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