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https://github.com/Mathewnd/Astral.git
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Matheus
107 lines
2.6 KiB
C
107 lines
2.6 KiB
C
#include <kernel/syscalls.h>
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#include <kernel/abi.h>
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#include <errno.h>
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#include <kernel/vmm.h>
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#include <logging.h>
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#define PROT_READ 0x01
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#define PROT_WRITE 0x02
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#define PROT_EXEC 0x04
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#define MAP_SHARED 0x01
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#define MAP_PRIVATE 0x02
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#define MAP_FIXED 0x10
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#define MAP_ANON 0x20
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#define MAP_ANONYMOUS MAP_ANON
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#define KNOWN_PROT (PROT_READ | PROT_WRITE | PROT_EXEC)
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#define KNOWN_FLAGS (MAP_SHARED | MAP_PRIVATE | MAP_FIXED | MAP_ANONYMOUS)
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syscallret_t syscall_mmap(context_t *context, void *hint, size_t len, int prot, int flags, int fd, off_t offset) {
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syscallret_t ret = {
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.errno = 0,
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.ret = -1
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};
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__assert((~KNOWN_FLAGS & flags) == 0);
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__assert((~KNOWN_PROT & prot) == 0);
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__assert(!((flags & MAP_PRIVATE) && (flags & MAP_SHARED)));
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// check alignment
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if (len == 0 || (uintptr_t)hint % PAGE_SIZE) {
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ret.errno = EINVAL;
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return ret;
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}
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mmuflags_t mmuflags = ARCH_MMU_FLAGS_USER;
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if (prot & PROT_READ)
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mmuflags |= ARCH_MMU_FLAGS_READ;
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if (prot & PROT_WRITE)
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mmuflags |= ARCH_MMU_FLAGS_WRITE;
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if ((prot & PROT_EXEC) == 0)
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mmuflags |= ARCH_MMU_FLAGS_NOEXEC;
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bool isfile = (flags & MAP_ANONYMOUS) == 0;
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int vmmflags = 0;
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if (flags & MAP_FIXED)
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vmmflags |= VMM_FLAGS_REPLACE;
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if ((flags & MAP_ANONYMOUS) == 0)
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vmmflags |= VMM_FLAGS_FILE;
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if (flags & MAP_SHARED)
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vmmflags |= VMM_FLAGS_SHARED;
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vmmfiledesc_t vfd;
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file_t *file = NULL;
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if (isfile) {
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// make sure offset is page aligned
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if (offset % PAGE_SIZE) {
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ret.errno = EINVAL;
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return ret;
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}
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file = fd_get(fd);
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if (file == NULL) {
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ret.errno = EBADF;
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return ret;
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}
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// check if the file is of a type that can be mapped
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// and if the fd was opened with the required permissions
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int type = file->vnode->type;
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if ((type != V_TYPE_REGULAR && type != V_TYPE_BLKDEV && type != V_TYPE_CHDEV)
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|| ((prot & PROT_READ) && (file->flags & FILE_READ) == 0)
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|| ((flags & MAP_SHARED) && (prot & PROT_WRITE) && (file->flags & FILE_WRITE) == 0)) {
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ret.errno = EACCES;
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goto cleanup;
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}
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// not all charcter devices support mapping, so check if its supported
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// (regular files and block devices go through the page cache)
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// TODO move this check to vmm_map once the return value of mmap is fixed to return an errno
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if (type == V_TYPE_CHDEV) {
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ret.errno = VOP_MMAP(file->vnode, VOP_MMAP_ADDRESS_MMAP_SUPPORTED, 0, 0, NULL);
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if (ret.errno)
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goto cleanup;
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}
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vfd.node = file->vnode;
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vfd.offset = offset;
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}
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if (hint < USERSPACE_START)
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hint = USERSPACE_START;
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ret.ret = (uint64_t)vmm_map(hint, len, vmmflags, mmuflags, &vfd);
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if (ret.ret == 0)
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ret.errno = ENOMEM;
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cleanup:
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if (isfile)
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fd_release(file);
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return ret;
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}
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