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Commit f2c17aab authored by Anup Patel's avatar Anup Patel Committed by Anup Patel
Browse files

RISC-V: Implement compile-time fixed mappings 



This patch implements compile-time virtual to physical mappings. These
compile-time fixed mappings can be used by earlycon, ACPI, and early
ioremap for creating fixed mappings when FIX_EARLYCON_MEM=y.

To start with, we have enabled compile-time fixed mappings for earlycon.

Signed-off-by: default avatarAnup Patel <anup.patel@wdc.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarPalmer Dabbelt <palmer@sifive.com>
parent 6f1e9e94

arch/riscv/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -89,6 +89,9 @@ config GENERIC_CSUM 
config GENERIC_HWEIGHT

	def_bool y



config FIX_EARLYCON_MEM

	def_bool y



config PGTABLE_LEVELS

	int

	default 3 if 64BIT

arch/riscv/include/asm/fixmap.h

0 → 100644
+44 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/*

 * Copyright (C) 2019 Western Digital Corporation or its affiliates.

 */



#ifndef _ASM_RISCV_FIXMAP_H

#define _ASM_RISCV_FIXMAP_H



#include <linux/kernel.h>

#include <linux/sizes.h>

#include <asm/page.h>

#include <asm/pgtable.h>



/*

 * Here we define all the compile-time 'special' virtual addresses.

 * The point is to have a constant address at compile time, but to

 * set the physical address only in the boot process.

 *

 * These 'compile-time allocated' memory buffers are page-sized. Use

 * set_fixmap(idx,phys) to associate physical memory with fixmap indices.

 */

enum fixed_addresses {

	FIX_HOLE,

	FIX_EARLYCON_MEM_BASE,

	__end_of_fixed_addresses

};



#define FIXADDR_SIZE		(__end_of_fixed_addresses * PAGE_SIZE)

#define FIXADDR_TOP		(PAGE_OFFSET)

#define FIXADDR_START		(FIXADDR_TOP - FIXADDR_SIZE)



#define FIXMAP_PAGE_IO		PAGE_KERNEL



#define __early_set_fixmap	__set_fixmap



#define __late_set_fixmap	__set_fixmap

#define __late_clear_fixmap(idx) __set_fixmap((idx), 0, FIXMAP_PAGE_CLEAR)



extern void __set_fixmap(enum fixed_addresses idx,

			 phys_addr_t phys, pgprot_t prot);



#include <asm-generic/fixmap.h>



#endif /* _ASM_RISCV_FIXMAP_H */

arch/riscv/mm/init.c

+34 −0
Original line number Diff line number Diff line
@@ -19,6 +19,7 @@ 
#include <linux/sizes.h>

#include <linux/of_fdt.h>



#include <asm/fixmap.h>

#include <asm/tlbflush.h>

#include <asm/sections.h>

#include <asm/pgtable.h>
@@ -148,8 +149,28 @@ pgd_t trampoline_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE); 
#define NUM_SWAPPER_PMDS ((uintptr_t)-PAGE_OFFSET >> PGDIR_SHIFT)

pmd_t swapper_pmd[PTRS_PER_PMD*((-PAGE_OFFSET)/PGDIR_SIZE)] __page_aligned_bss;

pmd_t trampoline_pmd[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);

pmd_t fixmap_pmd[PTRS_PER_PMD] __page_aligned_bss;

#endif



pte_t fixmap_pte[PTRS_PER_PTE] __page_aligned_bss;



void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot)

{

	unsigned long addr = __fix_to_virt(idx);

	pte_t *ptep;



	BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses);



	ptep = &fixmap_pte[pte_index(addr)];



	if (pgprot_val(prot)) {

		set_pte(ptep, pfn_pte(phys >> PAGE_SHIFT, prot));

	} else {

		pte_clear(&init_mm, addr, ptep);

		local_flush_tlb_page(addr);

	}

}



asmlinkage void __init setup_vm(void)

{

	extern char _start;
@@ -172,20 +193,33 @@ asmlinkage void __init setup_vm(void) 


	for (i = 0; i < (-PAGE_OFFSET)/PGDIR_SIZE; ++i) {

		size_t o = (PAGE_OFFSET >> PGDIR_SHIFT) % PTRS_PER_PGD + i;



		swapper_pg_dir[o] =

			pfn_pgd(PFN_DOWN((uintptr_t)swapper_pmd) + i,

				__pgprot(_PAGE_TABLE));

	}

	for (i = 0; i < ARRAY_SIZE(swapper_pmd); i++)

		swapper_pmd[i] = pfn_pmd(PFN_DOWN(pa + i * PMD_SIZE), prot);



	swapper_pg_dir[(FIXADDR_START >> PGDIR_SHIFT) % PTRS_PER_PGD] =

		pfn_pgd(PFN_DOWN((uintptr_t)fixmap_pmd),

				__pgprot(_PAGE_TABLE));

	fixmap_pmd[(FIXADDR_START >> PMD_SHIFT) % PTRS_PER_PMD] =

		pfn_pmd(PFN_DOWN((uintptr_t)fixmap_pte),

				__pgprot(_PAGE_TABLE));

#else

	trampoline_pg_dir[(PAGE_OFFSET >> PGDIR_SHIFT) % PTRS_PER_PGD] =

		pfn_pgd(PFN_DOWN(pa), prot);



	for (i = 0; i < (-PAGE_OFFSET)/PGDIR_SIZE; ++i) {

		size_t o = (PAGE_OFFSET >> PGDIR_SHIFT) % PTRS_PER_PGD + i;



		swapper_pg_dir[o] =

			pfn_pgd(PFN_DOWN(pa + i * PGDIR_SIZE), prot);

	}



	swapper_pg_dir[(FIXADDR_START >> PGDIR_SHIFT) % PTRS_PER_PGD] =

		pfn_pgd(PFN_DOWN((uintptr_t)fixmap_pte),

				__pgprot(_PAGE_TABLE));

#endif

}