diff options
Diffstat (limited to 'arch/riscv/include/asm')
| -rw-r--r-- | arch/riscv/include/asm/csr.h | 37 | ||||
| -rw-r--r-- | arch/riscv/include/asm/page.h | 62 | ||||
| -rw-r--r-- | arch/riscv/include/asm/pgtable.h | 55 | ||||
| -rw-r--r-- | arch/riscv/include/asm/sections.h | 50 |
4 files changed, 204 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h new file mode 100644 index 0000000..42f1eb4 --- /dev/null +++ b/arch/riscv/include/asm/csr.h @@ -0,0 +1,37 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* Copyright (C) 2026 Richard Qin */ + +#ifndef _ASM_RISCV_CSR_H +#define _ASM_RISCV_CSR_H + +/* + * RISC-V CSR (Control & Status Register) definitions used by the early + * boot / MMU-switch path. + * + * LumeOS-native subset of Linux arch/riscv/include/asm/csr.h. Only the + * symbols head.S and mm/init.cc actually reference are defined — adding + * the rest is straightforward when new code needs them, and skipping the + * Linux ALTERNATIVE / vendor-extension machinery keeps the cascade flat. + */ + +/* SATP (Supervisor Address Translation and Protection) layout — RV64 */ +#define SATP_PPN_MASK 0x00000FFFFFFFFFFFUL /* bits [43:0] = root PPN */ +#define SATP_ASID_SHIFT 44 +#define SATP_MODE_SHIFT 60 + +/* SATP MODE encodings (RV64) */ +#define SATP_MODE_BARE (0UL << SATP_MODE_SHIFT) +#define SATP_MODE_SV39 (8UL << SATP_MODE_SHIFT) +#define SATP_MODE_SV48 (9UL << SATP_MODE_SHIFT) + +/* Compose a SATP value from a page-table physical address. + * Result: MODE | (root_ppn) where root_ppn = pgd_pa >> PAGE_SHIFT. */ +#define MAKE_SATP(mode, pgd_pa) ((mode) | (((pgd_pa) >> 12) & SATP_PPN_MASK)) + +/* SSTATUS bits we touch at boot — disable FP / vector at entry so that an + * accidental FP / V instruction in early code traps cleanly rather than + * silently using dirty state from before reset. */ +#define SR_FS_OFF (0UL << 13) +#define SR_VS_OFF (0UL << 9) + +#endif /* _ASM_RISCV_CSR_H */ diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h new file mode 100644 index 0000000..7b9f155 --- /dev/null +++ b/arch/riscv/include/asm/page.h @@ -0,0 +1,62 @@ +/* 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 */ diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h new file mode 100644 index 0000000..28fc4c5 --- /dev/null +++ b/arch/riscv/include/asm/pgtable.h @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* Copyright (C) 2026 Richard Qin */ + +#ifndef _ASM_RISCV_PGTABLE_H +#define _ASM_RISCV_PGTABLE_H + +/* + * Early page-table construction API used by arch/riscv/mm/init.cc::setup_vm. + * + * Mirrors the create_pgd_mapping interface from Linux's + * arch/riscv/mm/init.c — same name, same semantics: + * + * create_pgd_mapping(pgdir, va, pa, sz, prot) + * + * pgdir : root of the page table to populate + * va : virtual address to map + * pa : physical address to map to + * sz : mapping size — must be a supported leaf size (PAGE_SIZE, + * 2 MiB megapage, or 1 GiB gigapage) + * prot : PTE flag bits (PAGE_KERNEL_EXEC etc., from <asm/page.h>) + * + * The boot-time variant in this file only supports gigapage (1 GiB) + * mappings — that is all setup_vm needs for the early_pg_dir / trampoline_pg_dir + * built before the slab allocator exists. Finer-grained mappings come + * later via vmm_init(). + */ + +#include <lume/types.h> +#include <asm/page.h> + +#ifdef __cplusplus +extern "C" { +#endif + +typedef struct { unsigned long pgd; } pgd_t; + +/* Linker-provided early page-table storage (defined in lumeos.lds.S + * ARCH_BSS_EXTRA, lives in .bss so it's zero-initialized). Allocating + * them in the linker script — not in C — mirrors Linux and keeps the + * symbols visible from head.S without a forward C decl mismatch. */ +extern pgd_t early_pg_dir[PTRS_PER_PGD]; +extern pgd_t trampoline_pg_dir[PTRS_PER_PGD]; +extern pgd_t fixmap_pg_dir[PTRS_PER_PGD]; + +/* Install a single PGD entry mapping `va` → `pa` with size `sz` and PTE + * flags `prot`. Only sz == PGDIR_SIZE (1 GiB) is supported in this early + * variant — vmm_init() takes over with create_pgd_mapping_pmd later. */ +void create_pgd_mapping(pgd_t *pgdir, unsigned long va, unsigned long pa, + unsigned long sz, unsigned long prot); + +#ifdef __cplusplus +} +#endif + +#endif /* _ASM_RISCV_PGTABLE_H */ diff --git a/arch/riscv/include/asm/sections.h b/arch/riscv/include/asm/sections.h new file mode 100644 index 0000000..454d9de --- /dev/null +++ b/arch/riscv/include/asm/sections.h @@ -0,0 +1,50 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* Copyright (C) 2026 Richard Qin */ + +#ifndef _ASM_RISCV_SECTIONS_H +#define _ASM_RISCV_SECTIONS_H + +/* + * Linker-emitted symbols that bracket each section of the kernel image. + * + * The lumeos.lds.S linker script defines these as the start / end + * addresses of contiguous regions. Code that walks a section + * (relocate_kernel walks .rela.dyn, the C++ ctor loop walks + * .init_array, the VMM mapping code walks .text vs .rodata, ...) + * imports the pair via this header. + * + * Mirrors Linux arch/riscv/include/asm/sections.h / asm-generic/sections.h. + * Each name and pair is identical to Linux so that direct ports of mm/init.c + * relocate_kernel logic compile unchanged against LumeOS. + */ + +#ifdef __cplusplus +extern "C" { +#endif + +extern char _start[]; +extern char _end[]; + +extern char _stext[]; +extern char _etext[]; +extern char _srodata[]; +extern char _erodata[]; +extern char _sdata[]; +extern char _edata[]; +extern char _sbss[]; +extern char _ebss[]; + +extern char __init_array_start[]; +extern char __init_array_end[]; + +/* .rela.dyn — array of Elf64_Rela entries emitted by the linker under + * `-shared -Bsymbolic`. relocate_kernel walks this range and patches + * each R_RISCV_RELATIVE slot. */ +extern char __rela_dyn_start[]; +extern char __rela_dyn_end[]; + +#ifdef __cplusplus +} +#endif + +#endif /* _ASM_RISCV_SECTIONS_H */ |