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Commit a77e0c7b authored by Santosh Shilimkar's avatar Santosh Shilimkar
Browse files

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: default avatarNicolas Pitre <nico@linaro.org>
Signed-off-by: default avatarR Sricharan <r.sricharan@ti.com>
Signed-off-by: default avatarSantosh Shilimkar <santosh.shilimkar@ti.com>
parent f52bb722

arch/arm/include/asm/mach/arch.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

arch/arm/kernel/setup.c

+4 −0
Original line number Diff line number Diff line
@@ -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);

arch/arm/mm/mmu.c

+82 −0
Original line number Diff line number Diff line
@@ -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.