MIPS64: Support of at least 48 bits of SEGBITS
SEGBITS is 40 bits or more, depending on CPU type. Introduces optional
support for 48 bits of application virtual address space. Only 16K and
64K pages are supported.
Enabling will result in a memory overhead of a small number of pages for
small applications. For 64K pages a 3rd level of page tables is required
which has some impact during software TLB refill.
[ralf@linux-mips.org: Fixed things raised in the review of the version
posted and changed kconfig to be a bit more userfriendly.]
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: aleksey.makarov@auriga.com
Cc: james.hogan@imgtec.com
Cc: paul.burton@imgtec.com
Cc: david.daney@cavium.com
Cc: peterz@infradead.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: davidlohr@hp.com
Cc: kirill@shutemov.name
Cc: akpm@linux-foundation.org
Cc: mingo@kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/10051/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h
index cfa15ba..7e78b62 100644
--- a/arch/mips/include/asm/processor.h
+++ b/arch/mips/include/asm/processor.h
@@ -63,7 +63,11 @@
* 8192EB ...
*/
#define TASK_SIZE32 0x7fff8000UL
-#define TASK_SIZE64 0x10000000000UL
+#ifdef CONFIG_MIPS_VA_BITS_48
+#define TASK_SIZE64 (0x1UL << ((cpu_data[0].vmbits>48)?48:cpu_data[0].vmbits))
+#else
+#define TASK_SIZE64 0x10000000000UL
+#endif
#define TASK_SIZE (test_thread_flag(TIF_32BIT_ADDR) ? TASK_SIZE32 : TASK_SIZE64)
#define STACK_TOP_MAX TASK_SIZE64