From a280455fa87053eed59de8464200d03ae4caa8c3 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 27 Nov 2014 14:48:42 -0500 Subject: [PATCH] iov_iter.c: handle ITER_KVEC directly ... without bothering with copy_..._user() Signed-off-by: Al Viro --- include/linux/uio.h | 1 + mm/iov_iter.c | 82 ++++++++++++++++++++++++++++++++++++++------- 2 files changed, 70 insertions(+), 13 deletions(-) diff --git a/include/linux/uio.h b/include/linux/uio.h index 9b1581414cd4..6e16945ec832 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -31,6 +31,7 @@ struct iov_iter { size_t count; union { const struct iovec *iov; + const struct kvec *kvec; const struct bio_vec *bvec; }; unsigned long nr_segs; diff --git a/mm/iov_iter.c b/mm/iov_iter.c index 666654498ccf..1618e378277e 100644 --- a/mm/iov_iter.c +++ b/mm/iov_iter.c @@ -32,6 +32,29 @@ n = wanted - n; \ } +#define iterate_kvec(i, n, __v, __p, skip, STEP) { \ + size_t wanted = n; \ + __p = i->kvec; \ + __v.iov_len = min(n, __p->iov_len - skip); \ + if (likely(__v.iov_len)) { \ + __v.iov_base = __p->iov_base + skip; \ + (void)(STEP); \ + skip += __v.iov_len; \ + n -= __v.iov_len; \ + } \ + while (unlikely(n)) { \ + __p++; \ + __v.iov_len = min(n, __p->iov_len); \ + if (unlikely(!__v.iov_len)) \ + continue; \ + __v.iov_base = __p->iov_base; \ + (void)(STEP); \ + skip = __v.iov_len; \ + n -= __v.iov_len; \ + } \ + n = wanted; \ +} + #define iterate_bvec(i, n, __v, __p, skip, STEP) { \ size_t wanted = n; \ __p = i->bvec; \ @@ -57,12 +80,16 @@ n = wanted; \ } -#define iterate_all_kinds(i, n, v, I, B) { \ +#define iterate_all_kinds(i, n, v, I, B, K) { \ size_t skip = i->iov_offset; \ if (unlikely(i->type & ITER_BVEC)) { \ const struct bio_vec *bvec; \ struct bio_vec v; \ iterate_bvec(i, n, v, bvec, skip, (B)) \ + } else if (unlikely(i->type & ITER_KVEC)) { \ + const struct kvec *kvec; \ + struct kvec v; \ + iterate_kvec(i, n, v, kvec, skip, (K)) \ } else { \ const struct iovec *iov; \ struct iovec v; \ @@ -70,7 +97,7 @@ } \ } -#define iterate_and_advance(i, n, v, I, B) { \ +#define iterate_and_advance(i, n, v, I, B, K) { \ size_t skip = i->iov_offset; \ if (unlikely(i->type & ITER_BVEC)) { \ const struct bio_vec *bvec; \ @@ -82,6 +109,16 @@ } \ i->nr_segs -= bvec - i->bvec; \ i->bvec = bvec; \ + } else if (unlikely(i->type & ITER_KVEC)) { \ + const struct kvec *kvec; \ + struct kvec v; \ + iterate_kvec(i, n, v, kvec, skip, (K)) \ + if (skip == kvec->iov_len) { \ + kvec++; \ + skip = 0; \ + } \ + i->nr_segs -= kvec - i->kvec; \ + i->kvec = kvec; \ } else { \ const struct iovec *iov; \ struct iovec v; \ @@ -270,7 +307,7 @@ done: */ int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes) { - if (!(i->type & ITER_BVEC)) { + if (!(i->type & (ITER_BVEC|ITER_KVEC))) { char __user *buf = i->iov->iov_base + i->iov_offset; bytes = min(bytes, i->iov->iov_len - i->iov_offset); return fault_in_pages_readable(buf, bytes); @@ -284,10 +321,14 @@ void iov_iter_init(struct iov_iter *i, int direction, size_t count) { /* It will get better. Eventually... */ - if (segment_eq(get_fs(), KERNEL_DS)) + if (segment_eq(get_fs(), KERNEL_DS)) { direction |= ITER_KVEC; - i->type = direction; - i->iov = iov; + i->type = direction; + i->kvec = (struct kvec *)iov; + } else { + i->type = direction; + i->iov = iov; + } i->nr_segs = nr_segs; i->iov_offset = 0; i->count = count; @@ -328,7 +369,8 @@ size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i) __copy_to_user(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len), memcpy_to_page(v.bv_page, v.bv_offset, - (from += v.bv_len) - v.bv_len, v.bv_len) + (from += v.bv_len) - v.bv_len, v.bv_len), + memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len) ) return bytes; @@ -348,7 +390,8 @@ size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i) __copy_from_user((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), memcpy_from_page((to += v.bv_len) - v.bv_len, v.bv_page, - v.bv_offset, v.bv_len) + v.bv_offset, v.bv_len), + memcpy((to += v.iov_len) - v.iov_len, v.iov_base, v.iov_len) ) return bytes; @@ -371,7 +414,7 @@ EXPORT_SYMBOL(copy_page_to_iter); size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes, struct iov_iter *i) { - if (i->type & ITER_BVEC) { + if (i->type & (ITER_BVEC|ITER_KVEC)) { void *kaddr = kmap_atomic(page); size_t wanted = copy_from_iter(kaddr + offset, bytes, i); kunmap_atomic(kaddr); @@ -391,7 +434,8 @@ size_t iov_iter_zero(size_t bytes, struct iov_iter *i) iterate_and_advance(i, bytes, v, __clear_user(v.iov_base, v.iov_len), - memzero_page(v.bv_page, v.bv_offset, v.bv_len) + memzero_page(v.bv_page, v.bv_offset, v.bv_len), + memset(v.iov_base, 0, v.iov_len) ) return bytes; @@ -406,7 +450,8 @@ size_t iov_iter_copy_from_user_atomic(struct page *page, __copy_from_user_inatomic((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len), memcpy_from_page((p += v.bv_len) - v.bv_len, v.bv_page, - v.bv_offset, v.bv_len) + v.bv_offset, v.bv_len), + memcpy((p += v.iov_len) - v.iov_len, v.iov_base, v.iov_len) ) kunmap_atomic(kaddr); return bytes; @@ -415,7 +460,7 @@ EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); void iov_iter_advance(struct iov_iter *i, size_t size) { - iterate_and_advance(i, size, v, 0, 0) + iterate_and_advance(i, size, v, 0, 0, 0) } EXPORT_SYMBOL(iov_iter_advance); @@ -443,7 +488,8 @@ unsigned long iov_iter_alignment(const struct iov_iter *i) iterate_all_kinds(i, size, v, (res |= (unsigned long)v.iov_base | v.iov_len, 0), - res |= v.bv_offset | v.bv_len + res |= v.bv_offset | v.bv_len, + res |= (unsigned long)v.iov_base | v.iov_len ) return res; } @@ -478,6 +524,8 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, *start = v.bv_offset; get_page(*pages = v.bv_page); return v.bv_len; + }),({ + return -EFAULT; }) ) return 0; @@ -530,6 +578,8 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, return -ENOMEM; get_page(*p = v.bv_page); return v.bv_len; + }),({ + return -EFAULT; }) ) return 0; @@ -554,6 +604,12 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages) npages++; if (npages >= maxpages) return maxpages; + }),({ + unsigned long p = (unsigned long)v.iov_base; + npages += DIV_ROUND_UP(p + v.iov_len, PAGE_SIZE) + - p / PAGE_SIZE; + if (npages >= maxpages) + return maxpages; }) ) return npages;