X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=lib%2Fringbuffer%2Fbackend.h;h=b362a04a436bfe64c640f694968032fb7de5aa32;hb=d723e9056812fdee222f1156f45f7a43393c5863;hp=541dc531ca76765e990635edc1c2a526e2ccdddb;hpb=4ea00e4f764eb18686121161a98e4ef442fed2c0;p=lttng-modules.git diff --git a/lib/ringbuffer/backend.h b/lib/ringbuffer/backend.h index 541dc531..b362a04a 100644 --- a/lib/ringbuffer/backend.h +++ b/lib/ringbuffer/backend.h @@ -1,14 +1,26 @@ -#ifndef _LINUX_RING_BUFFER_BACKEND_H -#define _LINUX_RING_BUFFER_BACKEND_H +#ifndef _LIB_RING_BUFFER_BACKEND_H +#define _LIB_RING_BUFFER_BACKEND_H /* - * linux/ringbuffer/backend.h - * - * Copyright (C) 2008-2010 - Mathieu Desnoyers + * lib/ringbuffer/backend.h * * Ring buffer backend (API). * - * Dual LGPL v2.1/GPL v2 license. + * Copyright (C) 2010-2012 Mathieu Desnoyers + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; only + * version 2.1 of the License. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA * * Credits to Steven Rostedt for proposing to use an extra-subbuffer owned by * the reader in flight recorder mode. @@ -22,10 +34,11 @@ #include #include #include +#include /* Internal helpers */ -#include "../../wrapper/ringbuffer/backend_internal.h" -#include "../../wrapper/ringbuffer/frontend_internal.h" +#include +#include /* Ring buffer backend API */ @@ -41,8 +54,8 @@ extern int __lib_ring_buffer_copy_to_user(struct lib_ring_buffer_backend *bufb, extern int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb, size_t offset, void *dest, size_t len); -extern struct page ** -lib_ring_buffer_read_get_page(struct lib_ring_buffer_backend *bufb, size_t offset, +extern unsigned long * +lib_ring_buffer_read_get_pfn(struct lib_ring_buffer_backend *bufb, size_t offset, void ***virt); /* @@ -70,19 +83,20 @@ lib_ring_buffer_read_offset_address(struct lib_ring_buffer_backend *bufb, * backend-specific memcpy() operation. Calls the slow path (_ring_buffer_write) * if copy is crossing a page boundary. */ -static inline +static inline __attribute__((always_inline)) void lib_ring_buffer_write(const struct lib_ring_buffer_config *config, struct lib_ring_buffer_ctx *ctx, const void *src, size_t len) { struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; struct channel_backend *chanb = &ctx->chan->backend; - size_t sbidx, index; + size_t sbidx, index, pagecpy; size_t offset = ctx->buf_offset; - ssize_t pagecpy; struct lib_ring_buffer_backend_pages *rpages; unsigned long sb_bindex, id; + if (unlikely(!len)) + return; offset &= chanb->buf_size - 1; sbidx = offset >> chanb->subbuf_size_order; index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; @@ -123,12 +137,13 @@ void lib_ring_buffer_memset(const struct lib_ring_buffer_config *config, struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; struct channel_backend *chanb = &ctx->chan->backend; - size_t sbidx, index; + size_t sbidx, index, pagecpy; size_t offset = ctx->buf_offset; - ssize_t pagecpy; struct lib_ring_buffer_backend_pages *rpages; unsigned long sb_bindex, id; + if (unlikely(!len)) + return; offset &= chanb->buf_size - 1; sbidx = offset >> chanb->subbuf_size_order; index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; @@ -148,8 +163,129 @@ void lib_ring_buffer_memset(const struct lib_ring_buffer_config *config, ctx->buf_offset += len; } +/* + * Copy up to @len string bytes from @src to @dest. Stop whenever a NULL + * terminating character is found in @src. Returns the number of bytes + * copied. Does *not* terminate @dest with NULL terminating character. + */ +static inline __attribute__((always_inline)) +size_t lib_ring_buffer_do_strcpy(const struct lib_ring_buffer_config *config, + char *dest, const char *src, size_t len) +{ + size_t count; + + for (count = 0; count < len; count++) { + char c; + + /* + * Only read source character once, in case it is + * modified concurrently. + */ + c = ACCESS_ONCE(src[count]); + if (!c) + break; + lib_ring_buffer_do_copy(config, &dest[count], &c, 1); + } + return count; +} + +/* + * Copy up to @len string bytes from @src to @dest. Stop whenever a NULL + * terminating character is found in @src, or when a fault occurs. + * Returns the number of bytes copied. Does *not* terminate @dest with + * NULL terminating character. + * + * This function deals with userspace pointers, it should never be called + * directly without having the src pointer checked with access_ok() + * previously. + */ +static inline __attribute__((always_inline)) +size_t lib_ring_buffer_do_strcpy_from_user_inatomic(const struct lib_ring_buffer_config *config, + char *dest, const char __user *src, size_t len) +{ + size_t count; + + for (count = 0; count < len; count++) { + int ret; + char c; + + ret = __copy_from_user_inatomic(&c, src + count, 1); + if (ret || !c) + break; + lib_ring_buffer_do_copy(config, &dest[count], &c, 1); + } + return count; +} + /** - * lib_ring_buffer_copy_from_user - write userspace data to a buffer backend + * lib_ring_buffer_strcpy - write string data to a buffer backend + * @config : ring buffer instance configuration + * @ctx: ring buffer context. (input arguments only) + * @src : source pointer to copy from + * @len : length of data to copy + * @pad : character to use for padding + * + * This function copies @len - 1 bytes of string data from a source + * pointer to a buffer backend, followed by a terminating '\0' + * character, at the current context offset. This is more or less a + * buffer backend-specific strncpy() operation. If a terminating '\0' + * character is found in @src before @len - 1 characters are copied, pad + * the buffer with @pad characters (e.g. '#'). Calls the slow path + * (_ring_buffer_strcpy) if copy is crossing a page boundary. + */ +static inline +void lib_ring_buffer_strcpy(const struct lib_ring_buffer_config *config, + struct lib_ring_buffer_ctx *ctx, + const char *src, size_t len, int pad) +{ + struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; + struct channel_backend *chanb = &ctx->chan->backend; + size_t sbidx, index, pagecpy; + size_t offset = ctx->buf_offset; + struct lib_ring_buffer_backend_pages *rpages; + unsigned long sb_bindex, id; + + if (unlikely(!len)) + return; + offset &= chanb->buf_size - 1; + sbidx = offset >> chanb->subbuf_size_order; + index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; + pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); + id = bufb->buf_wsb[sbidx].id; + sb_bindex = subbuffer_id_get_index(config, id); + rpages = bufb->array[sb_bindex]; + CHAN_WARN_ON(ctx->chan, + config->mode == RING_BUFFER_OVERWRITE + && subbuffer_id_is_noref(config, id)); + if (likely(pagecpy == len)) { + size_t count; + + count = lib_ring_buffer_do_strcpy(config, + rpages->p[index].virt + + (offset & ~PAGE_MASK), + src, len - 1); + offset += count; + /* Padding */ + if (unlikely(count < len - 1)) { + size_t pad_len = len - 1 - count; + + lib_ring_buffer_do_memset(rpages->p[index].virt + + (offset & ~PAGE_MASK), + pad, pad_len); + offset += pad_len; + } + /* Ending '\0' */ + lib_ring_buffer_do_memset(rpages->p[index].virt + + (offset & ~PAGE_MASK), + '\0', 1); + } else { + _lib_ring_buffer_strcpy(bufb, offset, src, len, 0, pad); + } + ctx->buf_offset += len; +} + +/** + * lib_ring_buffer_copy_from_user_inatomic - write userspace data to a buffer backend * @config : ring buffer instance configuration * @ctx: ring buffer context. (input arguments only) * @src : userspace source pointer to copy from @@ -158,22 +294,25 @@ void lib_ring_buffer_memset(const struct lib_ring_buffer_config *config, * This function copies "len" bytes of data from a userspace pointer to a * buffer backend, at the current context offset. This is more or less a buffer * backend-specific memcpy() operation. Calls the slow path - * (_ring_buffer_write_from_user) if copy is crossing a page boundary. + * (_ring_buffer_write_from_user_inatomic) if copy is crossing a page boundary. + * Disable the page fault handler to ensure we never try to take the mmap_sem. */ -static inline -void lib_ring_buffer_copy_from_user(const struct lib_ring_buffer_config *config, +static inline __attribute__((always_inline)) +void lib_ring_buffer_copy_from_user_inatomic(const struct lib_ring_buffer_config *config, struct lib_ring_buffer_ctx *ctx, const void __user *src, size_t len) { struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; struct channel_backend *chanb = &ctx->chan->backend; - size_t sbidx, index; + size_t sbidx, index, pagecpy; size_t offset = ctx->buf_offset; - ssize_t pagecpy; struct lib_ring_buffer_backend_pages *rpages; unsigned long sb_bindex, id; unsigned long ret; + mm_segment_t old_fs = get_fs(); + if (unlikely(!len)) + return; offset &= chanb->buf_size - 1; sbidx = offset >> chanb->subbuf_size_order; index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; @@ -185,26 +324,31 @@ void lib_ring_buffer_copy_from_user(const struct lib_ring_buffer_config *config, config->mode == RING_BUFFER_OVERWRITE && subbuffer_id_is_noref(config, id)); + set_fs(KERNEL_DS); + pagefault_disable(); if (unlikely(!access_ok(VERIFY_READ, src, len))) goto fill_buffer; if (likely(pagecpy == len)) { - ret = lib_ring_buffer_do_copy_from_user( + ret = lib_ring_buffer_do_copy_from_user_inatomic( rpages->p[index].virt + (offset & ~PAGE_MASK), src, len); if (unlikely(ret > 0)) { - len -= (pagecpy - ret); - offset += (pagecpy - ret); + /* Copy failed. */ goto fill_buffer; } } else { - _lib_ring_buffer_copy_from_user(bufb, offset, src, len, 0); + _lib_ring_buffer_copy_from_user_inatomic(bufb, offset, src, len, 0); } + pagefault_enable(); + set_fs(old_fs); ctx->buf_offset += len; return; fill_buffer: + pagefault_enable(); + set_fs(old_fs); /* * In the error path we call the slow path version to avoid * the pollution of static inline code. @@ -212,6 +356,98 @@ fill_buffer: _lib_ring_buffer_memset(bufb, offset, 0, len, 0); } +/** + * lib_ring_buffer_strcpy_from_user_inatomic - write userspace string data to a buffer backend + * @config : ring buffer instance configuration + * @ctx: ring buffer context (input arguments only) + * @src : userspace source pointer to copy from + * @len : length of data to copy + * @pad : character to use for padding + * + * This function copies @len - 1 bytes of string data from a userspace + * source pointer to a buffer backend, followed by a terminating '\0' + * character, at the current context offset. This is more or less a + * buffer backend-specific strncpy() operation. If a terminating '\0' + * character is found in @src before @len - 1 characters are copied, pad + * the buffer with @pad characters (e.g. '#'). Calls the slow path + * (_ring_buffer_strcpy_from_user_inatomic) if copy is crossing a page + * boundary. Disable the page fault handler to ensure we never try to + * take the mmap_sem. + */ +static inline +void lib_ring_buffer_strcpy_from_user_inatomic(const struct lib_ring_buffer_config *config, + struct lib_ring_buffer_ctx *ctx, + const void __user *src, size_t len, int pad) +{ + struct lib_ring_buffer_backend *bufb = &ctx->buf->backend; + struct channel_backend *chanb = &ctx->chan->backend; + size_t sbidx, index, pagecpy; + size_t offset = ctx->buf_offset; + struct lib_ring_buffer_backend_pages *rpages; + unsigned long sb_bindex, id; + mm_segment_t old_fs = get_fs(); + + if (unlikely(!len)) + return; + offset &= chanb->buf_size - 1; + sbidx = offset >> chanb->subbuf_size_order; + index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT; + pagecpy = min_t(size_t, len, (-offset) & ~PAGE_MASK); + id = bufb->buf_wsb[sbidx].id; + sb_bindex = subbuffer_id_get_index(config, id); + rpages = bufb->array[sb_bindex]; + CHAN_WARN_ON(ctx->chan, + config->mode == RING_BUFFER_OVERWRITE + && subbuffer_id_is_noref(config, id)); + + set_fs(KERNEL_DS); + pagefault_disable(); + if (unlikely(!access_ok(VERIFY_READ, src, len))) + goto fill_buffer; + + if (likely(pagecpy == len)) { + size_t count; + + count = lib_ring_buffer_do_strcpy_from_user_inatomic(config, + rpages->p[index].virt + + (offset & ~PAGE_MASK), + src, len - 1); + offset += count; + /* Padding */ + if (unlikely(count < len - 1)) { + size_t pad_len = len - 1 - count; + + lib_ring_buffer_do_memset(rpages->p[index].virt + + (offset & ~PAGE_MASK), + pad, pad_len); + offset += pad_len; + } + /* Ending '\0' */ + lib_ring_buffer_do_memset(rpages->p[index].virt + + (offset & ~PAGE_MASK), + '\0', 1); + } else { + _lib_ring_buffer_strcpy_from_user_inatomic(bufb, offset, src, + len, 0, pad); + } + pagefault_enable(); + set_fs(old_fs); + ctx->buf_offset += len; + + return; + +fill_buffer: + pagefault_enable(); + set_fs(old_fs); + /* + * In the error path we call the slow path version to avoid + * the pollution of static inline code. + */ + _lib_ring_buffer_memset(bufb, offset, pad, len - 1, 0); + offset += len - 1; + _lib_ring_buffer_memset(bufb, offset, '\0', 1, 0); +} + /* * This accessor counts the number of unread records in a buffer. * It only provides a consistent value if no reads not writes are performed @@ -242,9 +478,29 @@ unsigned long lib_ring_buffer_get_records_unread( return records_unread; } -ssize_t lib_ring_buffer_file_splice_read(struct file *in, loff_t *ppos, - struct pipe_inode_info *pipe, - size_t len, unsigned int flags); -loff_t lib_ring_buffer_no_llseek(struct file *file, loff_t offset, int origin); +/* + * We use __copy_from_user_inatomic to copy userspace data after + * checking with access_ok() and disabling page faults. + * + * Return 0 if OK, nonzero on error. + */ +static inline +unsigned long lib_ring_buffer_copy_from_user_check_nofault(void *dest, + const void __user *src, + unsigned long len) +{ + unsigned long ret; + mm_segment_t old_fs; + + if (!access_ok(VERIFY_READ, src, len)) + return 1; + old_fs = get_fs(); + set_fs(KERNEL_DS); + pagefault_disable(); + ret = __copy_from_user_inatomic(dest, src, len); + pagefault_enable(); + set_fs(old_fs); + return ret; +} -#endif /* _LINUX_RING_BUFFER_BACKEND_H */ +#endif /* _LIB_RING_BUFFER_BACKEND_H */