MIPS: 64-bit: Detect virtual memory size

Linux kernel 2.6.32 and later allocate address space from the top of the
kernel virtual memory address space.

This patch implements virtual memory size detection for 64 bit MIPS CPUs
to avoid resulting crashes.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/935/
Reviewed-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h
index 1f4df647c384..272c5ef35bbb 100644
--- a/arch/mips/include/asm/cpu-features.h
+++ b/arch/mips/include/asm/cpu-features.h
@@ -191,6 +191,9 @@
 # ifndef cpu_has_64bit_addresses
 # define cpu_has_64bit_addresses        0
 # endif
+# ifndef cpu_vmbits
+# define cpu_vmbits 31
+# endif
 #endif
 
 #ifdef CONFIG_64BIT
@@ -209,6 +212,10 @@
 # ifndef cpu_has_64bit_addresses
 # define cpu_has_64bit_addresses        1
 # endif
+# ifndef cpu_vmbits
+# define cpu_vmbits cpu_data[0].vmbits
+# define __NEED_VMBITS_PROBE
+# endif
 #endif
 
 #if defined(CONFIG_CPU_MIPSR2_IRQ_VI) && !defined(cpu_has_vint)