[4/4] mm: vmalloc: convert vread() to vread_iter()

Message ID	119871ea9507eac7be5d91db38acdb03981e049e.1679183626.git.lstoakes@gmail.com (mailing list archive)
State	New
Headers	show Return-Path: <owner-linux-mm@kvack.org> From: Lorenzo Stoakes <lstoakes@gmail.com> To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org> Cc: Baoquan He <bhe@redhat.com>, Uladzislau Rezki <urezki@gmail.com>, Matthew Wilcox <willy@infradead.org>, David Hildenbrand <david@redhat.com>, Liu Shixin <liushixin2@huawei.com>, Jiri Olsa <jolsa@kernel.org>, Lorenzo Stoakes <lstoakes@gmail.com> Subject: [PATCH 4/4] mm: vmalloc: convert vread() to vread_iter() Date: Sun, 19 Mar 2023 00:20:12 +0000 Message-Id: <119871ea9507eac7be5d91db38acdb03981e049e.1679183626.git.lstoakes@gmail.com> In-Reply-To: <cover.1679183626.git.lstoakes@gmail.com> References: <cover.1679183626.git.lstoakes@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org Precedence: bulk
Series	convert read_kcore(), vread() to use iterators \| expand [0/4] convert read_kcore(), vread() to use iterators [1/4] fs/proc/kcore: Avoid bounce buffer for ktext data [2/4] mm: vmalloc: use rwsem, mutex for vmap_area_lock and vmap_block->lock [3/4] fs/proc/kcore: convert read_kcore() to read_kcore_iter() [4/4] mm: vmalloc: convert vread() to vread_iter()

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index 25e0eeb8d498..8a07f04c9203 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -307,13 +307,9 @@ static void append_kcore_note(char *notes, size_t *i, const char *name, *i = ALIGN(*i + descsz, 4); } -static ssize_t -read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) +static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) { - struct file *file = iocb->ki_filp; - char *buf = file->private_data; loff_t *ppos = &iocb->ki_pos; - size_t phdrs_offset, notes_offset, data_offset; size_t page_offline_frozen = 1; size_t phdrs_len, notes_len; @@ -507,9 +503,7 @@ read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) switch (m->type) { case KCORE_VMALLOC: - vread(buf, (char *)start, tsz); - /* we have to zero-fill user buffer even if no read */ - if (copy_to_iter(buf, tsz, iter) != tsz) { + if (vread_iter((char *)start, tsz, iter) != tsz) { ret = -EFAULT; goto out; } @@ -582,10 +576,6 @@ static int open_kcore(struct inode *inode, struct file *filp) if (ret) return ret; - filp->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL); - if (!filp->private_data) - return -ENOMEM; - if (kcore_need_update) kcore_update_ram(); if (i_size_read(inode) != proc_root_kcore->size) { @@ -596,16 +586,9 @@ static int open_kcore(struct inode *inode, struct file *filp) return 0; } -static int release_kcore(struct inode *inode, struct file *file) -{ - kfree(file->private_data); - return 0; -} - static const struct proc_ops kcore_proc_ops = { .proc_read_iter = read_kcore_iter, .proc_open = open_kcore, - .proc_release = release_kcore, .proc_lseek = default_llseek, }; diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 69250efa03d1..f70ebdf21f22 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -9,6 +9,7 @@ #include <asm/page.h> /* pgprot_t */ #include <linux/rbtree.h> #include <linux/overflow.h> +#include <linux/uio.h> #include <asm/vmalloc.h> @@ -251,7 +252,7 @@ static inline void set_vm_flush_reset_perms(void *addr) #endif /* for /proc/kcore */ -extern long vread(char *buf, char *addr, unsigned long count); +extern long vread_iter(char *addr, size_t count, struct iov_iter *iter); /* * Internals. Don't use.. diff --git a/mm/vmalloc.c b/mm/vmalloc.c index c24b27664a97..3a32754266dc 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -37,7 +37,6 @@ #include <linux/rbtree_augmented.h> #include <linux/overflow.h> #include <linux/pgtable.h> -#include <linux/uaccess.h> #include <linux/hugetlb.h> #include <linux/sched/mm.h> #include <linux/rwsem.h> @@ -3446,20 +3445,20 @@ EXPORT_SYMBOL(vmalloc_32_user); * small helper routine , copy contents to buf from addr. * If the page is not present, fill zero. */ - -static int aligned_vread(char *buf, char *addr, unsigned long count) +static void aligned_vread_iter(char *addr, size_t count, + struct iov_iter *iter) { - struct page *p; - int copied = 0; + struct page *page; - while (count) { + while (count > 0) { unsigned long offset, length; + size_t copied = 0; offset = offset_in_page(addr); length = PAGE_SIZE - offset; if (length > count) length = count; - p = vmalloc_to_page(addr); + page = vmalloc_to_page(addr); /* * To do safe access to this _mapped_ area, we need * lock. But adding lock here means that we need to add @@ -3467,23 +3466,24 @@ static int aligned_vread(char *buf, char *addr, unsigned long count) * interface, rarely used. Instead of that, we'll use * kmap() and get small overhead in this access function. */ - if (p) { + if (page) { /* We can expect USER0 is not used -- see vread() */ - void *map = kmap_atomic(p); - memcpy(buf, map + offset, length); - kunmap_atomic(map); - } else - memset(buf, 0, length); + void *map = kmap_local_page(page); + + copied = copy_to_iter(map + offset, length, iter); + kunmap_local(map); + } + + if (copied < length) + iov_iter_zero(length - copied, iter); addr += length; - buf += length; - copied += length; count -= length; } - return copied; } -static void vmap_ram_vread(char *buf, char *addr, int count, unsigned long flags) +static void vmap_ram_vread_iter(char *addr, int count, unsigned long flags, + struct iov_iter *iter) { char *start; struct vmap_block *vb; @@ -3496,7 +3496,7 @@ static void vmap_ram_vread(char *buf, char *addr, int count, unsigned long flags * handle it here. */ if (!(flags & VMAP_BLOCK)) { - aligned_vread(buf, addr, count); + aligned_vread_iter(addr, count, iter); return; } @@ -3517,22 +3517,24 @@ static void vmap_ram_vread(char *buf, char *addr, int count, unsigned long flags if (!count) break; start = vmap_block_vaddr(vb->va->va_start, rs); - while (addr < start) { + + if (addr < start) { + size_t to_zero = min_t(size_t, start - addr, count); + + iov_iter_zero(to_zero, iter); + addr += to_zero; + count -= (int)to_zero; if (count == 0) goto unlock; - *buf = '\0'; - buf++; - addr++; - count--; } + /*it could start reading from the middle of used region*/ offset = offset_in_page(addr); n = ((re - rs + 1) << PAGE_SHIFT) - offset; if (n > count) n = count; - aligned_vread(buf, start+offset, n); + aligned_vread_iter(start + offset, n, iter); - buf += n; addr += n; count -= n; } @@ -3541,15 +3543,15 @@ static void vmap_ram_vread(char *buf, char *addr, int count, unsigned long flags finished: /* zero-fill the left dirty or free regions */ - if (count) - memset(buf, 0, count); + if (count > 0) + iov_iter_zero(count, iter); } /** - * vread() - read vmalloc area in a safe way. - * @buf: buffer for reading data - * @addr: vm address. - * @count: number of bytes to be read. + * vread_iter() - read vmalloc area in a safe way to an iterator. + * @addr: vm address. + * @count: number of bytes to be read. + * @iter: the iterator to which data should be written. * * This function checks that addr is a valid vmalloc'ed area, and * copy data from that area to a given buffer. If the given memory range @@ -3569,13 +3571,13 @@ static void vmap_ram_vread(char *buf, char *addr, int count, unsigned long flags * (same number as @count) or %0 if [addr...addr+count) doesn't * include any intersection with valid vmalloc area */ -long vread(char *buf, char *addr, unsigned long count) +long vread_iter(char *addr, size_t count, struct iov_iter *iter) { struct vmap_area *va; struct vm_struct *vm; - char *vaddr, *buf_start = buf; - unsigned long buflen = count; - unsigned long n, size, flags; + char *vaddr; + size_t buflen = count; + size_t n, size, flags; might_sleep(); @@ -3595,7 +3597,7 @@ long vread(char *buf, char *addr, unsigned long count) goto finished; list_for_each_entry_from(va, &vmap_area_list, list) { - if (!count) + if (count == 0) break; vm = va->vm; @@ -3619,36 +3621,39 @@ long vread(char *buf, char *addr, unsigned long count) if (addr >= vaddr + size) continue; - while (addr < vaddr) { + + if (addr < vaddr) { + size_t to_zero = min_t(size_t, vaddr - addr, count); + + iov_iter_zero(to_zero, iter); + addr += to_zero; + count -= to_zero; if (count == 0) goto finished; - *buf = '\0'; - buf++; - addr++; - count--; } + n = vaddr + size - addr; if (n > count) n = count; if (flags & VMAP_RAM) - vmap_ram_vread(buf, addr, n, flags); + vmap_ram_vread_iter(addr, n, flags, iter); else if (!(vm->flags & VM_IOREMAP)) - aligned_vread(buf, addr, n); + aligned_vread_iter(addr, n, iter); else /* IOREMAP area is treated as memory hole */ - memset(buf, 0, n); - buf += n; + iov_iter_zero(n, iter); + addr += n; count -= n; } finished: up_read(&vmap_area_lock); - if (buf == buf_start) + if (count == buflen) return 0; /* zero-fill memory holes */ - if (buf != buf_start + buflen) - memset(buf, 0, buflen - (buf - buf_start)); + if (count > 0) + iov_iter_zero(count, iter); return buflen; }

[4/4] mm: vmalloc: convert vread() to vread_iter()

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