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/* SPDX-License-Identifier: GPL-2.0-or-later */
/* Copyright (C) 2026 Richard Qin */
#ifndef _ASM_RISCV_PAGE_H
#define _ASM_RISCV_PAGE_H
/*
* RISC-V page / virtual-memory layout constants.
*
* Mirrors the subset of Linux arch/riscv/include/asm/page.h that LumeOS's
* early boot path needs:
* - PAGE_SIZE / PAGE_SHIFT / PAGE_MASK
* - PAGE_OFFSET (start of the higher-half direct map)
* - KERNEL_LINK_ADDR (link-time VA of _start)
* - SV39 PTE flag bits
* - PTRS_PER_PGD (512 for SV39)
*
* Values match Linux RISC-V SV39 defaults so that struct kernel_mapping
* (filled by setup_vm in arch/riscv/mm/init.cc) carries the same numeric
* relations Linux's mm/init.c maintains.
*/
#define PAGE_SHIFT 12
#define PAGE_SIZE (1UL << PAGE_SHIFT)
#define PAGE_MASK (~(PAGE_SIZE - 1))
/* Higher-half base of the kernel direct map. Bottom of the SV39 supervisor
* address space minus the unmapped guard region. Identical to Linux's
* CONFIG_PAGE_OFFSET default on RV64. */
#define PAGE_OFFSET 0xFFFFFFC000000000UL
/* Where _start was linked. OpenSBI hands control to PHYS_BASE; the kernel
* runs at KERNEL_LINK_ADDR after relocate_enable_mmu jumps to higher-half. */
#define PHYS_BASE 0x80200000UL
#define KERNEL_LINK_ADDR 0xFFFFFFC080200000UL
/* SATP mode field — SV39 = 8, shifted to bits [63:60]. */
#define SATP_MODE_SV39 (8UL << 60)
#define PTRS_PER_PGD 512
/* 1 GB superpage size — entry.S used to build the early page table with
* these; setup_vm in arch/riscv/mm/init.cc now does the same. */
#define PGDIR_SHIFT 30
#define PGDIR_SIZE (1UL << PGDIR_SHIFT)
#define PGDIR_MASK (~(PGDIR_SIZE - 1))
/* SV39 PTE flag bits (one byte). */
#define _PAGE_PRESENT (1UL << 0) /* aka VALID — historic Linux name */
#define _PAGE_READ (1UL << 1)
#define _PAGE_WRITE (1UL << 2)
#define _PAGE_EXEC (1UL << 3)
#define _PAGE_USER (1UL << 4)
#define _PAGE_GLOBAL (1UL << 5)
#define _PAGE_ACCESSED (1UL << 6)
#define _PAGE_DIRTY (1UL << 7)
#define PAGE_KERNEL_EXEC \
(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | _PAGE_EXEC | \
_PAGE_ACCESSED | _PAGE_DIRTY)
#endif /* _ASM_RISCV_PAGE_H */
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