From patchwork Fri Oct 20 03:35:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 13430008 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C304A15BD; Fri, 20 Oct 2023 03:36:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="PZ4qps3I" Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EAC99D65; Thu, 19 Oct 2023 20:35:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=Fel4JalyKRIhjPBnV4WS6ZXnJeqWrW5INpDaPeCTsGw=; b=PZ4qps3IUQwoqN5NvZkPfD0fMS x2+krMi8qxaLxlxFcjgV6dUg6us6tXPT4HZaCy5BFtJApPNIltdXVeoEurkPQSbqhw12G9lgq6Z37 yNt212+yq6XHGUHoUnr+8Xxfhuzve5cmTooQqP9798utwTqzeKWUZ1JaUQjVsxq3OiH+9NsU/1MLr Mqt0ffg3J4m8QfC/kdHjlijrr0WXMvEg2DkI4IDBo7zo2qp5ukGyPralU1kiWcU9SzzaK+DkN+/RL aTjMGITJaeL9nnSXB1Opvan4A90XMFPxeYKr6TbnaQjzRrQYp+XGI+y5lvTNoDpyZNEymMxPno2NQ c09GcE3Q==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qtgIe-00Ar92-O5; Fri, 20 Oct 2023 03:35:48 +0000 From: "Matthew Wilcox (Oracle)" To: Steven Rostedt Cc: "Matthew Wilcox (Oracle)" , Kees Cook , Christoph Hellwig , Justin Stitt , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, Kent Overstreet , Petr Mladek , Andy Shevchenko , Rasmus Villemoes , Sergey Senozhatsky , linux-trace-kernel@vger.kernel.org Subject: [PATCH v2 1/1] trace: Move readpos from seq_buf to trace_seq Date: Fri, 20 Oct 2023 04:35:45 +0100 Message-Id: <20231020033545.2587554-2-willy@infradead.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20231020033545.2587554-1-willy@infradead.org> References: <20231020033545.2587554-1-willy@infradead.org> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 To make seq_buf more lightweight as a string buf, move the readpos member from seq_buf to its container, trace_seq. That puts the responsibility of maintaining the readpos entirely in the tracing code. If some future users want to package up the readpos with a seq_buf, we can define a new struct then. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig Acked-by: Greg Kroah-Hartman --- include/linux/seq_buf.h | 5 +---- include/linux/trace_seq.h | 2 ++ kernel/trace/trace.c | 10 +++++----- kernel/trace/trace_seq.c | 6 +++++- lib/seq_buf.c | 22 ++++++++++------------ 5 files changed, 23 insertions(+), 22 deletions(-) diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h index 515d7fcb9634..a0fb013cebdf 100644 --- a/include/linux/seq_buf.h +++ b/include/linux/seq_buf.h @@ -14,19 +14,16 @@ * @buffer: pointer to the buffer * @size: size of the buffer * @len: the amount of data inside the buffer - * @readpos: The next position to read in the buffer. */ struct seq_buf { char *buffer; size_t size; size_t len; - loff_t readpos; }; static inline void seq_buf_clear(struct seq_buf *s) { s->len = 0; - s->readpos = 0; } static inline void @@ -143,7 +140,7 @@ extern __printf(2, 0) int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args); extern int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s); extern int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, - int cnt); + size_t start, int cnt); extern int seq_buf_puts(struct seq_buf *s, const char *str); extern int seq_buf_putc(struct seq_buf *s, unsigned char c); extern int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len); diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h index 6be92bf559fe..3691e0e76a1a 100644 --- a/include/linux/trace_seq.h +++ b/include/linux/trace_seq.h @@ -14,6 +14,7 @@ struct trace_seq { char buffer[PAGE_SIZE]; struct seq_buf seq; + size_t readpos; int full; }; @@ -22,6 +23,7 @@ trace_seq_init(struct trace_seq *s) { seq_buf_init(&s->seq, s->buffer, PAGE_SIZE); s->full = 0; + s->readpos = 0; } /** diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index abaaf516fcae..217cabd09c3e 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -1730,15 +1730,15 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt) { int len; - if (trace_seq_used(s) <= s->seq.readpos) + if (trace_seq_used(s) <= s->readpos) return -EBUSY; - len = trace_seq_used(s) - s->seq.readpos; + len = trace_seq_used(s) - s->readpos; if (cnt > len) cnt = len; - memcpy(buf, s->buffer + s->seq.readpos, cnt); + memcpy(buf, s->buffer + s->readpos, cnt); - s->seq.readpos += cnt; + s->readpos += cnt; return cnt; } @@ -7006,7 +7006,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, /* Now copy what we have to the user */ sret = trace_seq_to_user(&iter->seq, ubuf, cnt); - if (iter->seq.seq.readpos >= trace_seq_used(&iter->seq)) + if (iter->seq.readpos >= trace_seq_used(&iter->seq)) trace_seq_init(&iter->seq); /* diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c index bac06ee3b98b..7be97229ddf8 100644 --- a/kernel/trace/trace_seq.c +++ b/kernel/trace/trace_seq.c @@ -370,8 +370,12 @@ EXPORT_SYMBOL_GPL(trace_seq_path); */ int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt) { + int ret; __trace_seq_init(s); - return seq_buf_to_user(&s->seq, ubuf, cnt); + ret = seq_buf_to_user(&s->seq, ubuf, s->readpos, cnt); + if (ret > 0) + s->readpos += ret; + return ret; } EXPORT_SYMBOL_GPL(trace_seq_to_user); diff --git a/lib/seq_buf.c b/lib/seq_buf.c index 45c450f423fa..b7477aefff53 100644 --- a/lib/seq_buf.c +++ b/lib/seq_buf.c @@ -324,23 +324,24 @@ int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc) * seq_buf_to_user - copy the sequence buffer to user space * @s: seq_buf descriptor * @ubuf: The userspace memory location to copy to + * @start: The first byte in the buffer to copy * @cnt: The amount to copy * * Copies the sequence buffer into the userspace memory pointed to - * by @ubuf. It starts from the last read position (@s->readpos) - * and writes up to @cnt characters or till it reaches the end of - * the content in the buffer (@s->len), which ever comes first. + * by @ubuf. It starts from @start and writes up to @cnt characters + * or until it reaches the end of the content in the buffer (@s->len), + * whichever comes first. * * On success, it returns a positive number of the number of bytes * it copied. * * On failure it returns -EBUSY if all of the content in the * sequence has been already read, which includes nothing in the - * sequence (@s->len == @s->readpos). + * sequence (@s->len == @start). * * Returns -EFAULT if the copy to userspace fails. */ -int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt) +int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, size_t start, int cnt) { int len; int ret; @@ -350,20 +351,17 @@ int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt) len = seq_buf_used(s); - if (len <= s->readpos) + if (len <= start) return -EBUSY; - len -= s->readpos; + len -= start; if (cnt > len) cnt = len; - ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt); + ret = copy_to_user(ubuf, s->buffer + start, cnt); if (ret == cnt) return -EFAULT; - cnt -= ret; - - s->readpos += cnt; - return cnt; + return cnt - ret; } /**