ARM: mm: Recreate kernel mappings in early_paging_init()

This patch adds a step in the init sequence, in order to recreate
the kernel code/data page table mappings prior to full paging
initialization.  This is necessary on LPAE systems that run out of
a physical address space outside the 4G limit.  On these systems,
this implementation provides a machine descriptor hook that allows
the PHYS_OFFSET to be overridden in a machine specific fashion.

Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: R Sricharan <r.sricharan@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

diff --git a/arch/arm/include/asm/mach/arch.h b/arch/arm/include/asm/mach/arch.h
index 402a2bc..17a3fa2 100644 (file)
--- a/arch/arm/include/asm/mach/arch.h
+++ b/arch/arm/include/asm/mach/arch.h
@@ -49,6 +49,7 @@ struct machine_desc {
        bool                    (*smp_init)(void);
        void                    (*fixup)(struct tag *, char **,
                                         struct meminfo *);
+       void                    (*init_meminfo)(void);
        void                    (*reserve)(void);/* reserve mem blocks  */
        void                    (*map_io)(void);/* IO mapping function  */
        void                    (*init_early)(void);

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 0e1e2b3..af7b7db 100644 (file)
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -73,6 +73,8 @@ __setup("fpe=", fpe_setup);
 #endif
 
 extern void paging_init(const struct machine_desc *desc);
+extern void early_paging_init(const struct machine_desc *,
+                             struct proc_info_list *);
 extern void sanity_check_meminfo(void);
 extern enum reboot_mode reboot_mode;
 extern void setup_dma_zone(const struct machine_desc *desc);
@@ -878,6 +880,8 @@ void __init setup_arch(char **cmdline_p)
        parse_early_param();
 
        sort(&meminfo.bank, meminfo.nr_banks, sizeof(meminfo.bank[0]), meminfo_cmp, NULL);
+
+       early_paging_init(mdesc, lookup_processor_type(read_cpuid_id()));
        sanity_check_meminfo();
        arm_memblock_init(&meminfo, mdesc);
 

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index b1d17ee..78eeeca 100644 (file)
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -28,6 +28,8 @@
 #include <asm/highmem.h>
 #include <asm/system_info.h>
 #include <asm/traps.h>
+#include <asm/procinfo.h>
+#include <asm/memory.h>
 
 #include <asm/mach/arch.h>
 #include <asm/mach/map.h>
@@ -1315,6 +1317,86 @@ static void __init map_lowmem(void)
        }
 }
 
+#ifdef CONFIG_ARM_LPAE
+/*
+ * early_paging_init() recreates boot time page table setup, allowing machines
+ * to switch over to a high (>4G) address space on LPAE systems
+ */
+void __init early_paging_init(const struct machine_desc *mdesc,
+                             struct proc_info_list *procinfo)
+{
+       pmdval_t pmdprot = procinfo->__cpu_mm_mmu_flags;
+       unsigned long map_start, map_end;
+       pgd_t *pgd0, *pgdk;
+       pud_t *pud0, *pudk, *pud_start;
+       pmd_t *pmd0, *pmdk;
+       phys_addr_t phys;
+       int i;
+
+       if (!(mdesc->init_meminfo))
+               return;
+
+       /* remap kernel code and data */
+       map_start = init_mm.start_code;
+       map_end   = init_mm.brk;
+
+       /* get a handle on things... */
+       pgd0 = pgd_offset_k(0);
+       pud_start = pud0 = pud_offset(pgd0, 0);
+       pmd0 = pmd_offset(pud0, 0);
+
+       pgdk = pgd_offset_k(map_start);
+       pudk = pud_offset(pgdk, map_start);
+       pmdk = pmd_offset(pudk, map_start);
+
+       mdesc->init_meminfo();
+
+       /* Run the patch stub to update the constants */
+       fixup_pv_table(&__pv_table_begin,
+               (&__pv_table_end - &__pv_table_begin) << 2);
+
+       /*
+        * Cache cleaning operations for self-modifying code
+        * We should clean the entries by MVA but running a
+        * for loop over every pv_table entry pointer would
+        * just complicate the code.
+        */
+       flush_cache_louis();
+       dsb();
+       isb();
+
+       /* remap level 1 table */
+       for (i = 0; i < PTRS_PER_PGD; pud0++, i++) {
+               set_pud(pud0,
+                       __pud(__pa(pmd0) | PMD_TYPE_TABLE | L_PGD_SWAPPER));
+               pmd0 += PTRS_PER_PMD;
+       }
+
+       /* remap pmds for kernel mapping */
+       phys = __pa(map_start) & PMD_MASK;
+       do {
+               *pmdk++ = __pmd(phys | pmdprot);
+               phys += PMD_SIZE;
+       } while (phys < map_end);
+
+       flush_cache_all();
+       cpu_switch_mm(pgd0, &init_mm);
+       cpu_set_ttbr(1, __pa(pgd0) + TTBR1_OFFSET);
+       local_flush_bp_all();
+       local_flush_tlb_all();
+}
+
+#else
+
+void __init early_paging_init(const struct machine_desc *mdesc,
+                             struct proc_info_list *procinfo)
+{
+       if (mdesc->init_meminfo)
+               mdesc->init_meminfo();
+}
+
+#endif
+
 /*
  * paging_init() sets up the page tables, initialises the zone memory
  * maps, and sets up the zero page, bad page and bad page tables.