From patchwork Thu Apr 11 01:25:51 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 13625297 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 B532769314; Thu, 11 Apr 2024 01:26:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712798787; cv=none; b=Mo2oEqnXZ8tukVHUHf8jf/T8SdNg5cHikzLtlnBkXb54Uo0rLEWzdmJJCFpxIW89N2dHM9JiayxLFMtgdUJgP6rIkXpREPTXcZfuAzQUFiUWzGG0smMxXX44AkYvz9TpECj+/NFgCFvfYLMcu2MbzX8vEdDMNodBdE+qlF6QqpA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712798787; c=relaxed/simple; bh=Ertzit/1teBML8ZsgAn3OsCPk/nGsMK+MB0FCFsLJMA=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=IT1x/wX1tdwtMlG7VD7J7ABXmvfcsUSI/9fEvr+cCefJ3hiLIgpUqyPp4c44nMKFZpJgpRf2hJWyttkvWbpBpr2YgduErXj87YM/yUNR2wL6fzrE8DznDFVa9pRvBS30Iyj57mEgkkX/smP4VpXGW5PCYdoGDNwVP5WG0S6ModI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 67857C4163B; Thu, 11 Apr 2024 01:26:27 +0000 (UTC) Received: from rostedt by gandalf with local (Exim 4.97) (envelope-from ) id 1rujFR-00000000nYu-3O3p; Wed, 10 Apr 2024 21:29:05 -0400 Message-ID: <20240411012905.668885748@goodmis.org> User-Agent: quilt/0.67 Date: Wed, 10 Apr 2024 21:25:51 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Vincent Donnefort , Joel Fernandes , Daniel Bristot de Oliveira , Ingo Molnar , Peter Zijlstra , suleiman@google.com, Thomas Gleixner , Vineeth Pillai , Youssef Esmat , Beau Belgrave , Alexander Graf , Baoquan He , Borislav Petkov , "Paul E. McKenney" , David Howells Subject: [PATCH v2 10/11] tracing: Handle old buffer mappings for event strings and functions References: <20240411012541.285904543@goodmis.org> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: "Steven Rostedt (Google)" Use the saved text_delta and data_delta of a persistent memory mapped ring buffer that was saved from a previous boot, and use the delta in the trace event print output so that strings and functions show up normally. That is, for an event like trace_kmalloc() that prints the callsite via "%pS", if it used the address saved in the ring buffer it will not match the function that was saved in the previous boot if the kernel remaps itself between boots. For RCU events that point to saved static strings where only the address of the string is saved in the ring buffer, it too will be adjusted to point to where the string is on the current boot. Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace.c | 42 +++++++++++++++++++++++++++++++++++++++--- 1 file changed, 39 insertions(+), 3 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 33ef5311fa39..bac5db67cf15 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3671,8 +3671,11 @@ static void test_can_verify(void) void trace_check_vprintf(struct trace_iterator *iter, const char *fmt, va_list ap) { + long text_delta = iter->tr->text_delta; + long data_delta = iter->tr->data_delta; const char *p = fmt; const char *str; + bool good; int i, j; if (WARN_ON_ONCE(!fmt)) @@ -3691,7 +3694,10 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt, j = 0; - /* We only care about %s and variants */ + /* + * We only care about %s and variants + * as well as %p[sS] if delta is non-zero + */ for (i = 0; p[i]; i++) { if (i + 1 >= iter->fmt_size) { /* @@ -3720,6 +3726,11 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt, } if (p[i+j] == 's') break; + + if (text_delta && p[i+1] == 'p' && + ((p[i+2] == 's' || p[i+2] == 'S'))) + break; + star = false; } j = 0; @@ -3733,6 +3744,24 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt, iter->fmt[i] = '\0'; trace_seq_vprintf(&iter->seq, iter->fmt, ap); + /* Add delta to %pS pointers */ + if (p[i+1] == 'p') { + unsigned long addr; + char fmt[4]; + + fmt[0] = '%'; + fmt[1] = 'p'; + fmt[2] = p[i+2]; /* Either %ps or %pS */ + fmt[3] = '\0'; + + addr = va_arg(ap, unsigned long); + addr += text_delta; + trace_seq_printf(&iter->seq, fmt, (void *)addr); + + p += i + 3; + continue; + } + /* * If iter->seq is full, the above call no longer guarantees * that ap is in sync with fmt processing, and further calls @@ -3751,6 +3780,14 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt, /* The ap now points to the string data of the %s */ str = va_arg(ap, const char *); + good = trace_safe_str(iter, str, star, len); + + /* Could be from the last boot */ + if (data_delta && !good) { + str += data_delta; + good = trace_safe_str(iter, str, star, len); + } + /* * If you hit this warning, it is likely that the * trace event in question used %s on a string that @@ -3760,8 +3797,7 @@ void trace_check_vprintf(struct trace_iterator *iter, const char *fmt, * instead. See samples/trace_events/trace-events-sample.h * for reference. */ - if (WARN_ONCE(!trace_safe_str(iter, str, star, len), - "fmt: '%s' current_buffer: '%s'", + if (WARN_ONCE(!good, "fmt: '%s' current_buffer: '%s'", fmt, seq_buf_str(&iter->seq.seq))) { int ret;