From d8eaa13f2efc1eeca4e5f230d5a2d535aaf27338 Mon Sep 17 00:00:00 2001 From: Richard Qin Date: Fri, 2 Jan 2026 00:47:16 +0800 Subject: dev(file-system): establish VFS and Read-only FAT32 File System --- src/kernel/bio.cc | 135 +++++++++++++++++++++++++++++++++++++++ src/kernel/cxx.cc | 68 ++++++++++++++++++++ src/kernel/main.cc | 8 +++ src/kernel/mm/vm.cc | 47 ++++++++++++++ src/kernel/proc/proc.cc | 33 ++++++++++ src/kernel/syscall.cc | 165 ++++++++++++++++++++++++++++++++++++++---------- 6 files changed, 423 insertions(+), 33 deletions(-) create mode 100644 src/kernel/bio.cc create mode 100644 src/kernel/cxx.cc (limited to 'src/kernel') diff --git a/src/kernel/bio.cc b/src/kernel/bio.cc new file mode 100644 index 0000000..6e63d60 --- /dev/null +++ b/src/kernel/bio.cc @@ -0,0 +1,135 @@ +#include "kernel/buf.h" +#include "kernel/spinlock.h" +#include "kernel/riscv.h" +#include "drivers/virtio.h" +#include "drivers/uart.h" + +namespace BufferCache +{ + struct + { + Spinlock lock; + struct Buf buf[NBUF]; + struct Buf head; + } bcache; + + void init() + { + bcache.lock.init("bcache"); + // Initialize LRU doubly circular linked list + bcache.head.prev = &bcache.head; + bcache.head.next = &bcache.head; + for (struct Buf *b = bcache.buf; b < bcache.buf + NBUF; ++b) + { + b->lock.init("buffer"); + b->next = bcache.head.next; + b->prev = &bcache.head; + bcache.head.next->prev = b; + bcache.head.next = b; + } + Drivers::uart_puts("[Bio] Buffer cache initialized.\n"); + } + + static struct Buf* bget(uint32 dev, uint32 blockno) + { + struct Buf* b; + bcache.lock.acquire(); + + // Attempt to hit the cache + for (b = bcache.head.next; b != &bcache.head; b = b->next) + { + if (b->dev == dev && b->blockno == blockno) + { + b->refcnt++; + bcache.lock.release(); + b->lock.acquire(); // Acquire Sleep Lock + return b; + } + } + + // Cache miss, evicting LRU + for (b = bcache.head.prev; b != &bcache.head; b = b->prev) + { + if (b->refcnt == 0) + { + b->dev = dev; + b->blockno = blockno; + b->valid = 0; + b->refcnt = 1; + bcache.lock.release(); + b->lock.acquire(); + return b; + } + } + + Drivers::uart_puts("panic: bget: no buffers\n"); + while (1) + ; + } + + struct Buf* bread(uint32 dev, uint32 blockno) + { + struct Buf *b = bget(dev, blockno); + + if (!b->valid) + { + VirtIO::rw(0, b->blockno, (char *)b->data); + b->valid = 1; + } + + return b; + } + + void bwrite(struct Buf *b) + { + if (!b->lock.holding()) + { + Drivers::uart_puts("panic: bwrite\n"); + while (1) + ; + } + VirtIO::rw(1, b->blockno, (char *)b->data); + } + + void brelse(struct Buf *b) + { + if (!b->lock.holding()) + { + Drivers::uart_puts("panic: brelse\n"); + while (1) + ; + } + b->lock.release(); + + bcache.lock.acquire(); + b->refcnt--; + + if (b->refcnt == 0) + { + b->next->prev = b->prev; + b->prev->next = b->next; + + b->next = bcache.head.next; + b->prev = &bcache.head; + bcache.head.next->prev = b; + bcache.head.next = b; + } + + bcache.lock.release(); + } + + void bpin(struct Buf *b) + { + bcache.lock.acquire(); + b->refcnt++; + bcache.lock.release(); + } + + void bunpin(struct Buf* b) + { + bcache.lock.acquire(); + b->refcnt --; + bcache.lock.release(); + } + +} // namespace BufferCache diff --git a/src/kernel/cxx.cc b/src/kernel/cxx.cc new file mode 100644 index 0000000..f9541b5 --- /dev/null +++ b/src/kernel/cxx.cc @@ -0,0 +1,68 @@ +#include "common/types.h" +#include "kernel/pmm.h" +#include "drivers/uart.h" + +/* + * C++ Kernel Runtime Support + * + * * Strategy: Map directly to PMM::alloc_page(). + * Pros: Simple, works immediately for VFS. + * Cons: Allocates 4KB for every object (wasteful for small objects), + * but acceptable for current stage. + */ + +void *operator new(unsigned long size) +{ + // Safety check: PMM allocates 4096 bytes max per call + if (size > 4096) + { + Drivers::uart_puts("panic: new allocation too big (max 4096)\n"); + while (1) + ; + } + + void *p = PMM::alloc_page(); + if (!p) + { + Drivers::uart_puts("panic: new out of memory\n"); + while (1) + ; + } + // PMM::alloc_page returns zeroed memory usually, + // but standard 'new' doesn't guarantee it. + // The constructor will handle initialization. + return p; +} + +void *operator new[](unsigned long size) +{ + return operator new(size); +} + +void operator delete(void *p) +{ + if (p) + PMM::free_page(p); +} + +void operator delete[](void *p) +{ + if (p) + PMM::free_page(p); +} + +// C++14 Sized Deallocation (Required by modern compilers) +// The compiler optimizes 'delete' calls to pass the size of the object +void operator delete(void *p, unsigned long size) +{ + (void)size; // We ignore size because PMM always frees a full page + if (p) + PMM::free_page(p); +} + +void operator delete[](void *p, unsigned long size) +{ + (void)size; + if (p) + PMM::free_page(p); +} \ No newline at end of file diff --git a/src/kernel/main.cc b/src/kernel/main.cc index 6e3bdde..9654c18 100644 --- a/src/kernel/main.cc +++ b/src/kernel/main.cc @@ -9,6 +9,11 @@ #include "kernel/trap.h" #include "kernel/timer.h" #include "kernel/cpu.h" +#include "kernel/buf.h" +#include "fs/fs.h" +#include "fs/file.h" +#include "fs/fat32.h" +#include "lib/string.h" extern void fdt_init(uint64 dtb); extern uint64 g_dtb_addr; @@ -34,6 +39,9 @@ extern "C" void kernel_main(uint64 hartid, uint64 dtb) PLIC::init(); PLIC::inithart(); VirtIO::init(); + BufferCache::init(); + VFS::init(); + FileTable::init(); Timer::init(); ProcManager::init(); // Process Management ProcManager::user_init(); // Initialize first user process diff --git a/src/kernel/mm/vm.cc b/src/kernel/mm/vm.cc index 7057d88..29e9eb7 100644 --- a/src/kernel/mm/vm.cc +++ b/src/kernel/mm/vm.cc @@ -313,6 +313,53 @@ namespace VM return 0; } + int copyinstr(uint64 *pagetable, char *dst, uint64 srcva, uint64 max) + { + uint64 n, va0, pa0; + uint64 *pte; + int got_null = 0; + uint64 len = 0; + + while (len < max) + { + va0 = PGROUNDDOWN(srcva); + pte = walk(pagetable, va0, 0); + + if (pte == nullptr || (*pte & PTE_V) == 0 || (*pte & PTE_U) == 0) + return -1; + + pa0 = PTE2PA(*pte); + + n = PGSIZE - (srcva - va0); + if (n > max - len) + n = max - len; + + char *p = (char *)(pa0 + (srcva - va0)); + while (n > 0) + { + if (*p == '\0') + { + *dst = '\0'; + got_null = 1; + break; + } + *dst = *p; + n--; + srcva++; + dst++; + p++; + len++; + } + if (got_null) + break; + } + + if (got_null) + return 0; + + return -1; + } + int handle_cow_fault(uint64 *pagetable, uint64 va) { if (va >= MAXVA) diff --git a/src/kernel/proc/proc.cc b/src/kernel/proc/proc.cc index c8b6d1d..f1f1c1d 100644 --- a/src/kernel/proc/proc.cc +++ b/src/kernel/proc/proc.cc @@ -8,6 +8,8 @@ #include "kernel/trap.h" #include "kernel/riscv.h" #include "drivers/uart.h" +#include "fs/fs.h" +#include "fs/file.h" #include "lib/string.h" #define NPROC 64 @@ -172,6 +174,9 @@ found: p->pid = nextpid++; p->priority = 0; p->cpu = mycpu(); + p->cwd = nullptr; + for (int i = 0; i < NOFILE; i++) + p->ofile[i] = nullptr; if ((p->tf = (struct Trapframe *)PMM::alloc_page()) == 0) { @@ -206,6 +211,19 @@ static void freeproc(struct Proc *p) p->kstack = 0; if (p->pagetable) VM::uvmfree(p->pagetable, p->sz); + for (int i = 0; i < NOFILE; i++) + { + if (p->ofile[i]) + { + FileTable::close(p->ofile[i]); + p->ofile[i] = nullptr; + } + } + if (p->cwd) + { + VFS::iput(p->cwd); + p->cwd = nullptr; + } p->pagetable = 0; p->sz = 0; p->pid = 0; @@ -245,6 +263,19 @@ int fork() np->parent = p; np->priority = p->priority; + for (int i = 0; i < NOFILE; i++) + { + if (p->ofile[i]) + { + np->ofile[i] = FileTable::dup(p->ofile[i]); + } + } + + if (p->cwd) + { + np->cwd = VFS::idup(p->cwd); + } + proc_mem_lock.release(); struct cpu *c = mycpu(); @@ -394,6 +425,8 @@ namespace ProcManager p->sz = stack_va + PGSIZE; strcpy(p->name, "initcode"); + p->cwd = nullptr; + proc_mem_lock.release(); struct cpu *c = &cpus[0]; diff --git a/src/kernel/syscall.cc b/src/kernel/syscall.cc index 837ac2c..afa20a1 100644 --- a/src/kernel/syscall.cc +++ b/src/kernel/syscall.cc @@ -1,5 +1,6 @@ #include "kernel/syscall.h" #include "common/types.h" +#include "common/fcntl.h" #include "kernel/proc.h" #include "kernel/riscv.h" #include "drivers/uart.h" @@ -7,6 +8,8 @@ #include "kernel/timer.h" #include "kernel/mm.h" #include "kernel/trap.h" +#include "fs/fat32.h" +#include "fs/file.h" extern "C++" int fork(); @@ -45,47 +48,126 @@ static int argint(int n, int *ip) return 0; } +static int argstr(int n, char *buf, int max) +{ + uint64 addr = argraw(n); + return VM::copyinstr(myproc()->pagetable, buf, addr, max); +} + +static int fdalloc(struct file *f) +{ + struct Proc *p = myproc(); + for (int i = 0; i < NOFILE; i++) + { + if (p->ofile[i] == 0) + { + p->ofile[i] = f; + return i; + } + } + return -1; +} + +static uint64 sys_open() +{ + char path[128]; + int omode; + int fd; + struct file *f; + Inode *ip; + + if (argstr(0, path, 128) < 0 || argint(1, &omode) < 0) + return -1; + + ip = VFS::namei(path); + if (ip == nullptr) + { + return -1; + } + + f = FileTable::alloc(); + if (f == nullptr) + { + VFS::iput(ip); + return -1; + } + + fd = fdalloc(f); + if (fd < 0) + { + f->ref = 0; + f->type = FD_NONE; + VFS::iput(ip); + return -1; + } + + f->type = FD_INODE; + f->ip = ip; + f->off = 0; + f->readable = !(omode & O_WRONLY); + f->writable = (omode & O_WRONLY) || (omode & O_RDWR); -static uint64_t sys_exit() + return fd; +} + +static uint64 sys_close() +{ + int fd; + if (argint(0, &fd) < 0) + return -1; + + struct Proc *p = myproc(); + if (fd < 0 || fd >= NOFILE || p->ofile[fd] == 0) + return -1; + + FileTable::close(p->ofile[fd]); + p->ofile[fd] = 0; + return 0; +} + +static uint64 sys_exit() { int n; if (argint(0, &n) < 0) - return static_cast(-1); + return static_cast(-1); ProcManager::exit(n); return 0; } -static uint64_t sys_fork() +static uint64 sys_fork() { - return static_cast(fork()); + return static_cast(fork()); } -static uint64_t sys_wait() +static uint64 sys_wait() { - uint64_t p = argraw(0); - return static_cast(ProcManager::wait(p)); + uint64 p = argraw(0); + return static_cast(ProcManager::wait(p)); } -static uint64_t sys_getpid() +static uint64 sys_getpid() { - return static_cast(myproc()->pid); + return static_cast(myproc()->pid); } -static uint64_t sys_putc() +static uint64 sys_putc() { char c = static_cast(argraw(0)); Drivers::uart_putc(c); return 0; } -static uint64_t sys_write() +static uint64 sys_write() { - int fd; + struct file *f; int n; - uint64_t p; + uint64 p; + int fd; - if (argint(0, &fd) < 0 || argint(2, &n) < 0) - return static_cast(-1); + if (argint(0, &fd) < 0 || argint(2, &n) < 0 || argint(1, (int *)&p) < 0) + return -1; + + struct Proc *proc = myproc(); p = argraw(1); @@ -95,9 +177,8 @@ static uint64_t sys_write() // Drivers::uart_put_int(n); // Drivers::uart_puts("\n"); - if (fd == 1) // stdout + if (fd == 1 && proc->ofile[fd] == nullptr) // stdout { - Proc *proc = myproc(); constexpr int MAX_WRITE_BUF = 128; char buf[MAX_WRITE_BUF]; int i = 0; @@ -108,10 +189,10 @@ static uint64_t sys_write() if (len > MAX_WRITE_BUF) len = MAX_WRITE_BUF; - if (VM::copyin(proc->pagetable, buf, p + i, static_cast(len)) < 0) + if (VM::copyin(proc->pagetable, buf, p + i, static_cast(len)) < 0) { Drivers::uart_puts("sys_write: copyin failed\n"); - return static_cast(-1); + return static_cast(-1); } for (int j = 0; j < len; j++) @@ -120,45 +201,57 @@ static uint64_t sys_write() } i += len; } - return static_cast(n); + return static_cast(n); } - return static_cast(-1); + if (fd < 0 || fd >= NOFILE || (f = proc->ofile[fd]) == 0) + return static_cast(-1); + + return FileTable::write(f, p, n); } static uint64_t sys_read() { - int fd; + struct file *f; int n; - uint64_t p; + uint64 p; + int fd; // get param: fd, buf, len - if (argint(0, &fd) < 0 || argint(2, &n) < 0) + if (argint(0, &fd) < 0 || argint(2, &n) < 0 || argint(1, (int *)&p) < 0) return -1; - p = argraw(1); - - if (fd == 0) // stdin + + struct Proc* proc = myproc(); + if (fd == 0 && proc->ofile[fd] == nullptr) { return Drivers::console_read(p, n); } + + if (fd < 0 || fd >= NOFILE || (f = proc->ofile[fd]) == 0) + return -1; + + return FileTable::read(f, p, n); + return -1; } -static uint64_t sys_sbrk() +static uint64 sys_sbrk() { int n; if (argint(0, &n) < 0) return -1; - uint64_t addr = myproc()->sz; + uint64 addr = myproc()->sz; if (ProcManager::growproc(n) < 0) return -1; return addr; } -static uint64_t sys_disk_test() +static uint64 sys_disk_test() { - VirtIO::test_rw(); + // VirtIO::test_rw(); + // VirtIO::test_bio(); + fat32_test(); return 0; } @@ -166,7 +259,7 @@ void syscall() { Proc *p = myproc(); int num = p->tf->a7; - uint64_t ret = static_cast(-1); + uint64 ret = static_cast(-1); /* Just For Debug */ // Drivers::uart_puts("Syscall: "); @@ -175,6 +268,12 @@ void syscall() switch (num) { + case SYS_open: + ret = sys_open(); + break; + case SYS_close: + ret = sys_close(); + break; case SYS_write: ret = sys_write(); break; @@ -206,7 +305,7 @@ void syscall() Drivers::uart_puts("Unknown Syscall ID: "); Drivers::print_hex(num); Drivers::uart_puts("\n"); - ret = static_cast(-1); + ret = static_cast(-1); break; } -- cgit v1.2.3