xtensa: add alternative kernel memory layouts

MMUv3 is able to support low memory bigger than 128MB.
Implement 256MB and 512MB KSEG layouts:

- add Kconfig selector for KSEG layout;
- add KSEG base address, size and alignment definitions to
  arch/xtensa/include/asm/kmem_layout.h;
- use new definitions in TLB initialization;
- add build time memory map consistency checks.

See Documentation/xtensa/mmu.txt for the details of new memory layouts.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

9 files changed, 249 insertions, 10 deletions

diff --git a/Documentation/xtensa/mmu.txt b/Documentation/xtensa/mmu.txt
index 0312fe66475c..867c0f837e28 100644
--- a/Documentation/xtensa/mmu.txt
+++ b/Documentation/xtensa/mmu.txt
@@ -62,3 +62,127 @@ limitations apply:
 
 6. The IO area covers the entire 256MB segment of parent-bus-address; the
    "ranges" triplet length field is ignored
+
+
+MMUv3 address space layouts.
+============================
+
+Default MMUv2-compatible layout.
+
+                      Symbol                   VADDR       Size
++------------------+
+| Userspace        |                           0x00000000  TASK_SIZE
++------------------+                           0x40000000
++------------------+
+| Page table       |                           0x80000000
++------------------+                           0x80400000
++------------------+
+| KMAP area        |  PKMAP_BASE                           PTRS_PER_PTE *
+|                  |                                       DCACHE_N_COLORS *
+|                  |                                       PAGE_SIZE
+|                  |                                       (4MB * DCACHE_N_COLORS)
++------------------+
+| Atomic KMAP area |  FIXADDR_START                        KM_TYPE_NR *
+|                  |                                       NR_CPUS *
+|                  |                                       DCACHE_N_COLORS *
+|                  |                                       PAGE_SIZE
++------------------+  FIXADDR_TOP              0xbffff000
++------------------+
+| VMALLOC area     |  VMALLOC_START            0xc0000000  128MB - 64KB
++------------------+  VMALLOC_END
+| Cache aliasing   |  TLBTEMP_BASE_1           0xc7ff0000  DCACHE_WAY_SIZE
+| remap area 1     |
++------------------+
+| Cache aliasing   |  TLBTEMP_BASE_2                       DCACHE_WAY_SIZE
+| remap area 2     |
++------------------+
++------------------+
+| Cached KSEG      |  XCHAL_KSEG_CACHED_VADDR  0xd0000000  128MB
++------------------+
+| Uncached KSEG    |  XCHAL_KSEG_BYPASS_VADDR  0xd8000000  128MB
++------------------+
+| Cached KIO       |  XCHAL_KIO_CACHED_VADDR   0xe0000000  256MB
++------------------+
+| Uncached KIO     |  XCHAL_KIO_BYPASS_VADDR   0xf0000000  256MB
++------------------+
+
+
+256MB cached + 256MB uncached layout.
+
+                      Symbol                   VADDR       Size
++------------------+
+| Userspace        |                           0x00000000  TASK_SIZE
++------------------+                           0x40000000
++------------------+
+| Page table       |                           0x80000000
++------------------+                           0x80400000
++------------------+
+| KMAP area        |  PKMAP_BASE                           PTRS_PER_PTE *
+|                  |                                       DCACHE_N_COLORS *
+|                  |                                       PAGE_SIZE
+|                  |                                       (4MB * DCACHE_N_COLORS)
++------------------+
+| Atomic KMAP area |  FIXADDR_START                        KM_TYPE_NR *
+|                  |                                       NR_CPUS *
+|                  |                                       DCACHE_N_COLORS *
+|                  |                                       PAGE_SIZE
++------------------+  FIXADDR_TOP              0x9ffff000
++------------------+
+| VMALLOC area     |  VMALLOC_START            0xa0000000  128MB - 64KB
++------------------+  VMALLOC_END
+| Cache aliasing   |  TLBTEMP_BASE_1           0xa7ff0000  DCACHE_WAY_SIZE
+| remap area 1     |
++------------------+
+| Cache aliasing   |  TLBTEMP_BASE_2                       DCACHE_WAY_SIZE
+| remap area 2     |
++------------------+
++------------------+
+| Cached KSEG      |  XCHAL_KSEG_CACHED_VADDR  0xb0000000  256MB
++------------------+
+| Uncached KSEG    |  XCHAL_KSEG_BYPASS_VADDR  0xc0000000  256MB
++------------------+
++------------------+
+| Cached KIO       |  XCHAL_KIO_CACHED_VADDR   0xe0000000  256MB
++------------------+
+| Uncached KIO     |  XCHAL_KIO_BYPASS_VADDR   0xf0000000  256MB
++------------------+
+
+
+512MB cached + 512MB uncached layout.
+
+                      Symbol                   VADDR       Size
++------------------+
+| Userspace        |                           0x00000000  TASK_SIZE
++------------------+                           0x40000000
++------------------+
+| Page table       |                           0x80000000
++------------------+                           0x80400000
++------------------+
+| KMAP area        |  PKMAP_BASE                           PTRS_PER_PTE *
+|                  |                                       DCACHE_N_COLORS *
+|                  |                                       PAGE_SIZE
+|                  |                                       (4MB * DCACHE_N_COLORS)
++------------------+
+| Atomic KMAP area |  FIXADDR_START                        KM_TYPE_NR *
+|                  |                                       NR_CPUS *
+|                  |                                       DCACHE_N_COLORS *
+|                  |                                       PAGE_SIZE
++------------------+  FIXADDR_TOP              0x8ffff000
++------------------+
+| VMALLOC area     |  VMALLOC_START            0x90000000  128MB - 64KB
++------------------+  VMALLOC_END
+| Cache aliasing   |  TLBTEMP_BASE_1           0x97ff0000  DCACHE_WAY_SIZE
+| remap area 1     |
++------------------+
+| Cache aliasing   |  TLBTEMP_BASE_2                       DCACHE_WAY_SIZE
+| remap area 2     |
++------------------+
++------------------+
+| Cached KSEG      |  XCHAL_KSEG_CACHED_VADDR  0xa0000000  512MB
++------------------+
+| Uncached KSEG    |  XCHAL_KSEG_BYPASS_VADDR  0xc0000000  512MB
++------------------+
+| Cached KIO       |  XCHAL_KIO_CACHED_VADDR   0xe0000000  256MB
++------------------+
+| Uncached KIO     |  XCHAL_KIO_BYPASS_VADDR   0xf0000000  256MB
++------------------+
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index 64336f666fb6..c17496bc37f0 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -236,6 +236,50 @@ config INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
 
           If in doubt, say Y.
 
+config KSEG_PADDR
+        hex "Physical address of the KSEG mapping"
+        depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX && MMU
+        default 0x00000000
+        help
+          This is the physical address where KSEG is mapped. Please refer to
+          the chosen KSEG layout help for the required address alignment.
+          Unpacked kernel image (including vectors) must be located completely
+          within KSEG.
+          Physical memory below this address is not available to linux.
+
+          If unsure, leave the default value here.
+
+choice
+        prompt "KSEG layout"
+        depends on MMU
+        default XTENSA_KSEG_MMU_V2
+
+config XTENSA_KSEG_MMU_V2
+        bool "MMUv2: 128MB cached + 128MB uncached"
+        help
+          MMUv2 compatible kernel memory map: TLB way 5 maps 128MB starting
+          at KSEG_PADDR to 0xd0000000 with cache and to 0xd8000000
+          without cache.
+          KSEG_PADDR must be aligned to 128MB.
+
+config XTENSA_KSEG_256M
+        bool "256MB cached + 256MB uncached"
+        depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
+        help
+          TLB way 6 maps 256MB starting at KSEG_PADDR to 0xb0000000
+          with cache and to 0xc0000000 without cache.
+          KSEG_PADDR must be aligned to 256MB.
+
+config XTENSA_KSEG_512M
+        bool "512MB cached + 512MB uncached"
+        depends on INITIALIZE_XTENSA_MMU_INSIDE_VMLINUX
+        help
+          TLB way 6 maps 512MB starting at KSEG_PADDR to 0xa0000000
+          with cache and to 0xc0000000 without cache.
+          KSEG_PADDR must be aligned to 256MB.
+
+endchoice
+
 config HIGHMEM
         bool "High Memory Support"
         depends on MMU
diff --git a/arch/xtensa/include/asm/fixmap.h b/arch/xtensa/include/asm/fixmap.h
index 62b507deea9d..0d30403b6c95 100644
--- a/arch/xtensa/include/asm/fixmap.h
+++ b/arch/xtensa/include/asm/fixmap.h
@@ -59,6 +59,11 @@ enum fixed_addresses {
  */
 static __always_inline unsigned long fix_to_virt(const unsigned int idx)
 {
+        /* Check if this memory layout is broken because fixmap overlaps page
+         * table.
+         */
+        BUILD_BUG_ON(FIXADDR_START <
+                     XCHAL_PAGE_TABLE_VADDR + XCHAL_PAGE_TABLE_SIZE);
         BUILD_BUG_ON(idx >= __end_of_fixed_addresses);
         return __fix_to_virt(idx);
 }
diff --git a/arch/xtensa/include/asm/highmem.h b/arch/xtensa/include/asm/highmem.h
index 01cef6b40829..6e070db1022e 100644
--- a/arch/xtensa/include/asm/highmem.h
+++ b/arch/xtensa/include/asm/highmem.h
@@ -68,6 +68,11 @@ void kunmap_high(struct page *page);
 
 static inline void *kmap(struct page *page)
 {
+        /* Check if this memory layout is broken because PKMAP overlaps
+         * page table.
+         */
+        BUILD_BUG_ON(PKMAP_BASE <
+                     XCHAL_PAGE_TABLE_VADDR + XCHAL_PAGE_TABLE_SIZE);
         BUG_ON(in_interrupt());
         if (!PageHighMem(page))
                 return page_address(page);
diff --git a/arch/xtensa/include/asm/initialize_mmu.h b/arch/xtensa/include/asm/initialize_mmu.h
index 7a1e075969a3..46d4bef61655 100644
--- a/arch/xtensa/include/asm/initialize_mmu.h
+++ b/arch/xtensa/include/asm/initialize_mmu.h
@@ -116,22 +116,35 @@
         add     a5, a5, a4
         bne     a5, a2, 3b
 
-        /* Step 4: Setup MMU with the old V2 mappings. */
+        /* Step 4: Setup MMU with the requested static mappings. */
+
         movi    a6, 0x01000000
         wsr     a6, ITLBCFG
         wsr     a6, DTLBCFG
         isync
 
-        movi    a5, 0xd0000005
-        movi    a4, CA_WRITEBACK
+        movi    a5, XCHAL_KSEG_CACHED_VADDR + XCHAL_KSEG_TLB_WAY
+        movi    a4, XCHAL_KSEG_PADDR + CA_WRITEBACK
+        wdtlb   a4, a5
+        witlb   a4, a5
+
+        movi    a5, XCHAL_KSEG_BYPASS_VADDR + XCHAL_KSEG_TLB_WAY
+        movi    a4, XCHAL_KSEG_PADDR + CA_BYPASS
         wdtlb   a4, a5
         witlb   a4, a5
 
-        movi    a5, 0xd8000005
-        movi    a4, CA_BYPASS
+#ifdef CONFIG_XTENSA_KSEG_512M
+        movi    a5, XCHAL_KSEG_CACHED_VADDR + 0x10000000 + XCHAL_KSEG_TLB_WAY
+        movi    a4, XCHAL_KSEG_PADDR + 0x10000000 + CA_WRITEBACK
         wdtlb   a4, a5
         witlb   a4, a5
 
+        movi    a5, XCHAL_KSEG_BYPASS_VADDR + 0x10000000 + XCHAL_KSEG_TLB_WAY
+        movi    a4, XCHAL_KSEG_PADDR + 0x10000000 + CA_BYPASS
+        wdtlb   a4, a5
+        witlb   a4, a5
+#endif
+
         movi    a5, XCHAL_KIO_CACHED_VADDR + 6
         movi    a4, XCHAL_KIO_DEFAULT_PADDR + CA_WRITEBACK
         wdtlb   a4, a5
diff --git a/arch/xtensa/include/asm/kmem_layout.h b/arch/xtensa/include/asm/kmem_layout.h
index 4eb43b65a34d..bfce7ee8efd8 100644
--- a/arch/xtensa/include/asm/kmem_layout.h
+++ b/arch/xtensa/include/asm/kmem_layout.h
@@ -13,13 +13,59 @@
 
 #include <asm/types.h>
 
+#ifdef CONFIG_MMU
+
 /*
  * Fixed TLB translations in the processor.
  */
 
+#define XCHAL_PAGE_TABLE_VADDR  __XTENSA_UL_CONST(0x80000000)
+#define XCHAL_PAGE_TABLE_SIZE   __XTENSA_UL_CONST(0x00400000)
+
+#if defined(CONFIG_XTENSA_KSEG_MMU_V2)
+
 #define XCHAL_KSEG_CACHED_VADDR __XTENSA_UL_CONST(0xd0000000)
 #define XCHAL_KSEG_BYPASS_VADDR __XTENSA_UL_CONST(0xd8000000)
 #define XCHAL_KSEG_SIZE         __XTENSA_UL_CONST(0x08000000)
+#define XCHAL_KSEG_ALIGNMENT    __XTENSA_UL_CONST(0x08000000)
+#define XCHAL_KSEG_TLB_WAY      5
+
+#elif defined(CONFIG_XTENSA_KSEG_256M)
+
+#define XCHAL_KSEG_CACHED_VADDR __XTENSA_UL_CONST(0xb0000000)
+#define XCHAL_KSEG_BYPASS_VADDR __XTENSA_UL_CONST(0xc0000000)
+#define XCHAL_KSEG_SIZE         __XTENSA_UL_CONST(0x10000000)
+#define XCHAL_KSEG_ALIGNMENT    __XTENSA_UL_CONST(0x10000000)
+#define XCHAL_KSEG_TLB_WAY      6
+
+#elif defined(CONFIG_XTENSA_KSEG_512M)
+
+#define XCHAL_KSEG_CACHED_VADDR __XTENSA_UL_CONST(0xa0000000)
+#define XCHAL_KSEG_BYPASS_VADDR __XTENSA_UL_CONST(0xc0000000)
+#define XCHAL_KSEG_SIZE         __XTENSA_UL_CONST(0x20000000)
+#define XCHAL_KSEG_ALIGNMENT    __XTENSA_UL_CONST(0x10000000)
+#define XCHAL_KSEG_TLB_WAY      6
+
+#else
+#error Unsupported KSEG configuration
+#endif
+
+#ifdef CONFIG_KSEG_PADDR
+#define XCHAL_KSEG_PADDR        __XTENSA_UL_CONST(CONFIG_KSEG_PADDR)
+#else
 #define XCHAL_KSEG_PADDR        __XTENSA_UL_CONST(0x00000000)
+#endif
+
+#if XCHAL_KSEG_PADDR & (XCHAL_KSEG_ALIGNMENT - 1)
+#error XCHAL_KSEG_PADDR is not properly aligned to XCHAL_KSEG_ALIGNMENT
+#endif
+
+#else
+
+#define XCHAL_KSEG_CACHED_VADDR __XTENSA_UL_CONST(0xd0000000)
+#define XCHAL_KSEG_BYPASS_VADDR __XTENSA_UL_CONST(0xd8000000)
+#define XCHAL_KSEG_SIZE         __XTENSA_UL_CONST(0x08000000)
+
+#endif
 
 #endif
diff --git a/arch/xtensa/include/asm/page.h b/arch/xtensa/include/asm/page.h
index fd12a1977ba8..8a02438232c4 100644
--- a/arch/xtensa/include/asm/page.h
+++ b/arch/xtensa/include/asm/page.h
@@ -27,10 +27,12 @@
 
 #ifdef CONFIG_MMU
 #define PAGE_OFFSET     XCHAL_KSEG_CACHED_VADDR
-#define MAX_MEM_PFN     XCHAL_KSEG_SIZE
+#define MAX_LOW_PFN     (PHYS_PFN(XCHAL_KSEG_PADDR) + \
+                         PHYS_PFN(XCHAL_KSEG_SIZE))
 #else
 #define PAGE_OFFSET     __XTENSA_UL_CONST(0)
-#define MAX_MEM_PFN     (PLATFORM_DEFAULT_MEM_START + PLATFORM_DEFAULT_MEM_SIZE)
+#define MAX_LOW_PFN     (PHYS_PFN(PLATFORM_DEFAULT_MEM_START) + \
+                         PHYS_PFN(PLATFORM_DEFAULT_MEM_SIZE))
 #endif
 
 #define PGTABLE_START   0x80000000
diff --git a/arch/xtensa/include/uapi/asm/types.h b/arch/xtensa/include/uapi/asm/types.h
index 87ec7ae73cb1..2efc921506c4 100644
--- a/arch/xtensa/include/uapi/asm/types.h
+++ b/arch/xtensa/include/uapi/asm/types.h
@@ -18,7 +18,8 @@
 # define __XTENSA_UL_CONST(x)   x
 #else
 # define __XTENSA_UL(x)         ((unsigned long)(x))
-# define __XTENSA_UL_CONST(x)   x##UL
+# define ___XTENSA_UL_CONST(x)  x##UL
+# define __XTENSA_UL_CONST(x)   ___XTENSA_UL_CONST(x)
 #endif
 
 #ifndef __ASSEMBLY__
diff --git a/arch/xtensa/mm/init.c b/arch/xtensa/mm/init.c
index 4d7142beac72..302fa72d0d5a 100644
--- a/arch/xtensa/mm/init.c
+++ b/arch/xtensa/mm/init.c
@@ -266,8 +266,7 @@ void __init bootmem_init(void)
         if (min_low_pfn > max_pfn)
                 panic("No memory found!\n");
 
-        max_low_pfn = max_pfn < MAX_MEM_PFN >> PAGE_SHIFT ?
-                max_pfn : MAX_MEM_PFN >> PAGE_SHIFT;
+        max_low_pfn = min(max_pfn, MAX_LOW_PFN);
 
         /* Find an area to use for the bootmem bitmap. */