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Subject[PATCH 19/22] ARM: recreate kernel mappings in early_paging_init()
Date
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.

Signed-off-by: Cyril Chemparathy <cyril@ti.com>
Signed-off-by: Vitaly Andrianov <vitalya@ti.com>
---
arch/arm/include/asm/mach/arch.h | 1 +
arch/arm/kernel/setup.c | 3 ++
arch/arm/mm/mmu.c | 57 ++++++++++++++++++++++++++++++++++++++
3 files changed, 61 insertions(+)
diff --git a/arch/arm/include/asm/mach/arch.h b/arch/arm/include/asm/mach/arch.h
index 0b1c94b..2b9ecc5 100644
--- a/arch/arm/include/asm/mach/arch.h
+++ b/arch/arm/include/asm/mach/arch.h
@@ -37,6 +37,7 @@ struct machine_desc {
char restart_mode; /* default restart mode */
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 bba3fdc..ccf052c 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -93,6 +93,7 @@ static int __init fpe_setup(char *line)
__setup("fpe=", fpe_setup);
#endif

+extern void early_paging_init(struct machine_desc *, struct proc_info_list *);
extern void paging_init(struct machine_desc *desc);
extern void sanity_check_meminfo(void);
extern void reboot_setup(char *str);
@@ -1152,6 +1153,8 @@ 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 6b0baf3..21fb171 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -28,6 +28,7 @@
#include <asm/highmem.h>
#include <asm/system_info.h>
#include <asm/traps.h>
+#include <asm/procinfo.h>

#include <asm/mach/arch.h>
#include <asm/mach/map.h>
@@ -1175,6 +1176,62 @@ static void __init map_lowmem(void)
}

/*
+ * 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(struct machine_desc *mdesc,
+ struct proc_info_list *procinfo)
+{
+ bool lpae = IS_ENABLED(CONFIG_ARM_LPAE);
+ pmdval_t pmdprot = procinfo->__cpu_mm_mmu_flags;
+ unsigned long map_start, map_end;
+ pgd_t *pgd0, *pgdk;
+ pud_t *pud0, *pudk;
+ pmd_t *pmd0, *pmdk;
+ phys_addr_t phys;
+ int i;
+
+ if (!lpae)
+ 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);
+ 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);
+
+ phys = PHYS_OFFSET;
+
+ if (mdesc->init_meminfo)
+ mdesc->init_meminfo();
+
+ /* remap level 1 table */
+ for (i = 0; i < PTRS_PER_PGD; i++) {
+ *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_set_ttbr(0, __pa(pgd0));
+ cpu_set_ttbr(1, __pa(pgd0) + TTBR1_OFFSET);
+ local_flush_tlb_all();
+}
+
+/*
* paging_init() sets up the page tables, initialises the zone memory
* maps, and sets up the zero page, bad page and bad page tables.
*/
--
1.7.9.5


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