From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f49.google.com (mail-wr1-f49.google.com [209.85.221.49]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 774363C061E for ; Wed, 27 May 2026 09:58:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.49 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779875904; cv=none; b=TkTB7mBeLJ4J7/zWGIAjEw1bjjiIGgOwvuWRNyzwfTyErrmbAi+HhcuVVona2Y+idtSB057zlhVc/+BwbLDrMsLIwOQO1GT3jmy78mKAzQdqsGl+VDy7e9Frua8k1HraHJ3YFg8FnlGNSS96EXvD0bQO53gXYbpNn23vTRSx1uE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779875904; c=relaxed/simple; bh=RZBmb/HkDW7Oy/X6gZO+I2XelRRa/7kXnKWxiTpxHv8=; h=From:Date:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Jti4i4KPkrZ6S5UhESqKV+QVxTSPUeq9gyC+Mxe7YuFLDe85VXXxAHbln7uV1xBY6E+RPbGmXEdDkEg/mqfq3bMgVnFFouOsu4Mj8VROZ7bTq7X+6+3R0cRmjlTQ3vWM3SUWhcwzRkgUSTbfDJkknmzlBlOQgKh98Affmt7j+LI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=IVzl9FrU; arc=none smtp.client-ip=209.85.221.49 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="IVzl9FrU" Received: by mail-wr1-f49.google.com with SMTP id ffacd0b85a97d-4526a8170ceso5905202f8f.2 for ; Wed, 27 May 2026 02:58:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779875902; x=1780480702; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:from:to:cc:subject:date:message-id:reply-to; bh=B1tyU2uydFHOb+Dk+vd6ZsdbLeHHkFq8Fgb/EaBviEA=; b=IVzl9FrUFZZK58/iCMmyKTQjjVgaDprUsZ9lqqDTQbY68mgON1PcAgbUR6/D1UtQtc 13pqkWT4zTIC7lwTT0QHol5T3+EE2fEjuCZlj/OK+94RsK3AQaX0RCH0chGZWDbXOGRb sju+ztpkhxKBqaP8eOug9k943UIF/9AAu6VZnKHVufJiuOjLsyvYTGZl3ILvuFBTXlrI /xOt1pef0ThMi0RW4qtFOSgIIrJtCfbTfjRzp+cuFZeCuEpeZYpUiNAvtkSE8eZHFo/X xgpSgdHdd61LzfKwXzPoErdUjugzYNqD6dcTSqwq45mF+SWGUGSUFpZCtl+L7qjep88k eQzw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779875902; x=1780480702; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:date:from:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=B1tyU2uydFHOb+Dk+vd6ZsdbLeHHkFq8Fgb/EaBviEA=; b=O7gF+NucBt3azA8dIVFIc5HZgceuNxtydO7OidMAn/NajLgRvFMya5hCtQoE1yEfA0 vaU6fxqF7oVLYGQAgyV0Gce7aUHvisKd4sWE5THh6GPU8DIwRs2vLARhvJFtPMXnaAsB T+p6Ypna90CEe8APRCqjvX9H7Krd6j76nPONS/B2LAYXoKYned+FbwxRVG9ZLHydk24O pGJYZvqfio5fcXj0vpXGBJ/G2dDzwICEryS6rV8N0QePOtR7eRQn6aupDgW+BA2Oi24Z Alfzi32wbh3NSS/jI6Daquq3TV0nn4wn7IoQWTH9rIbFThEap6oY1eVnHTF8ZfgnOhPg VmUA== X-Forwarded-Encrypted: i=1; AFNElJ+TfvtXyY7hJeuJDuTzIWug7JlcetVFljxIYX7xFZWAoAhyTK+YxSMQlSRDuwNiPQIqu2/uDzhVoCaJ7UUFjFj7yus=@vger.kernel.org X-Gm-Message-State: AOJu0YySehXZlcY83JzfefQisJM59FnFv0bNfUmxHPYJodJm6A8szNq1 D8oy3ia1GXlDsPtd+SgO5LBOx30pc33Lk/UwK0GM0XEfXZ2g1evm75vx X-Gm-Gg: Acq92OGduN5fKsaqNpx3Jqm75Sc4hW39U7tZkioLwSV8HNIkb/9gUHYHE8iRcRKb3kO aL9rJAKZzlv/VFnUtRUh7dXnKDsSqnTfSjrbctd4mADb285mh/C38BWhFKCwMHFM3HhLcopXXz6 qltmk4qVc3b9TZFqmz/u7JQgwAq0F/5WEHHf5DEKjKz3x0c+YpD3+A9X7XNwEdToFxwMSFYHLDT U8bAIZWE18HSaUoz0cDOh6Roz2V6OrS5KGoxwLOd+O+czc5nF3xCWryMQeg9ABrqacfGUJgDHAx v3PS30Ex2A8B0Ys2c+umT50l44YG7HMto5JEiSjquP6qtQQbs5Byykw9pWX9E7CGFka5oXASshZ 1dGf0h8joz+nQRcZoDORJIuTfaZnbaujbKhL2+QfA7bHabZf7T5CfEVFexOf7QY7dWVHFvU1H8t gDqcO4YBjOmQVU3I8= X-Received: by 2002:a05:6000:2408:b0:45e:941e:77b3 with SMTP id ffacd0b85a97d-45eb38c9299mr39465897f8f.41.1779875901635; Wed, 27 May 2026 02:58:21 -0700 (PDT) Received: from krava ([2a02:8308:a00c:e200:b655:ff13:e355:16a3]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-45edb5b28absm4908881f8f.27.2026.05.27.02.58.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 May 2026 02:58:21 -0700 (PDT) From: Jiri Olsa X-Google-Original-From: Jiri Olsa Date: Wed, 27 May 2026 11:58:19 +0200 To: bot+bpf-ci@kernel.org Cc: oleg@redhat.com, peterz@infradead.org, mingo@kernel.org, mhiramat@kernel.org, andrii@kernel.org, bpf@vger.kernel.org, linux-trace-kernel@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, martin.lau@kernel.org, eddyz87@gmail.com, yonghong.song@linux.dev, clm@meta.com, ihor.solodrai@linux.dev Subject: Re: [PATCHv4 09/13] selftests/bpf: Change uprobe syscall tests to use nop10 Message-ID: References: <20260526205840.173790-10-jolsa@kernel.org> <3bec8cfe67b2e52b7316d77f6907373a99ee0443a27c15ad26b90d6c5539ecdf@mail.kernel.org> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3bec8cfe67b2e52b7316d77f6907373a99ee0443a27c15ad26b90d6c5539ecdf@mail.kernel.org> On Tue, May 26, 2026 at 09:46:38PM +0000, bot+bpf-ci@kernel.org wrote: SNIP > > diff --git a/tools/testing/selftests/bpf/prog_tests/usdt.c b/tools/testing/selftests/bpf/prog_tests/usdt.c > > index 69759b27794d..fda3a298ccfc 100644 > > --- a/tools/testing/selftests/bpf/prog_tests/usdt.c > > +++ b/tools/testing/selftests/bpf/prog_tests/usdt.c > > @@ -252,7 +252,7 @@ extern void usdt_1(void); > > extern void usdt_2(void); > > > > static unsigned char nop1[1] = { 0x90 }; > > -static unsigned char nop1_nop5_combo[6] = { 0x90, 0x0f, 0x1f, 0x44, 0x00, 0x00 }; > > +static unsigned char nop1_nop10_combo[11] = { 0x90, 0x66, 0x2e, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00 }; > > > > static void *find_instr(void *fn, unsigned char *instr, size_t cnt) > > { > > Is the loop in find_instr() adequate to find the updated instruction > sequence? In uprobe_syscall.c, find_nop10() was updated to search up > to 128 bytes to account for compiler-generated prologues: > > tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c:find_nop10() { > for (i = 0; i < 128; i++) { > if (!memcmp(nop10, fn + i, 10)) > return fn + i; > } > } > > But find_instr() in usdt.c only searches the first 10 bytes: > > tools/testing/selftests/bpf/prog_tests/usdt.c:find_instr() { > for (i = 0; i < 10; i++) { > if (!memcmp(instr, fn + i, cnt)) > return fn + i; > } > } > > If a modern compiler generates a prologue longer than 9 bytes for > usdt_2(), find_instr() will prematurely terminate and cause > subtest_optimized_attach() to fail. This concern was raised by > reviewers in v2 and v3 of the patch series: find_instr is ok for its usage in subtest_optimized_attach, we first use it to verify the combo was not generated in usdt_1, and having 128 bytes search we'd find combo from usdt_2 function modern compilers seems to be smart emough not to generate long prologue for usdt_2 function jirka