From mboxrd@z Thu Jan 1 00:00:00 1970 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 50BE3522F; Thu, 5 Sep 2024 17:16:28 +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=1725556588; cv=none; b=O530iULN5Mmd2dTv3J16ORNW/o6H251zA6i0twfTe/x5aOesZByWHikZqSdqbwbJWFbB848w4m/zV+Vx3ff6kOtVS9BnmEDvI9EySEAcIvTYpkDCsLD+3TKkk3/nENu8CZIAChOOD6CtlL7VUf5QdgT2sB3XVlQZOlhIljazxT8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725556588; c=relaxed/simple; bh=H2OP04J4RUYnSKeA1cXeJ7eXawYISo2nhtstKNwQ4Bg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nk2ozxC/4u/plKm6aHnx4CfQXJWHvtqIzNt24YmOGw+prxxA094O3sH+vteV54C6BQXAnp/6ZNKajQ6r/qqA7FLp0kBvXPCCMMWDFtjbCwybqWf6eJvloYJ5AkfJhWW2uj0EtZ08RF9MJjLqvJeQvYthIc/ETZ//pFPJF1/8G+M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b=hCjAgG29; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="hCjAgG29" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0216CC4CEC3; Thu, 5 Sep 2024 17:16:25 +0000 (UTC) Authentication-Results: smtp.kernel.org; dkim=pass (1024-bit key) header.d=zx2c4.com header.i=@zx2c4.com header.b="hCjAgG29" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zx2c4.com; s=20210105; t=1725556584; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=U/i7kxMFedYKvorYnbQF73cn+5NdhIM30ISsp20UbHg=; b=hCjAgG292GvjSYLd7cIJbV9+sE37uAJnudlmH79DWrvxKhI1aT+MkTsEmZIqTXhYJC3AjG GKu0T3GOiKFo6Gd/ZQwz0mjJ7G8jNN7vZoXVVqlMX+NTR4p/v66KLBzSg7LZ0ZRymTcpi5 z8NptxebJrjClHLK2svu5ZYfVCDOfJ0= Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id c27291d3 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO); Thu, 5 Sep 2024 17:16:24 +0000 (UTC) Date: Thu, 5 Sep 2024 19:16:20 +0200 From: "Jason A. Donenfeld" To: Christophe Leroy Cc: Andrew Morton , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Michael Ellerman , Nicholas Piggin , Naveen N Rao , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , Shuah Khan , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-kselftest@vger.kernel.org, llvm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, Adhemerval Zanella , Xi Ruoyao Subject: Re: [PATCH v5 4/5] powerpc/vdso: Wire up getrandom() vDSO implementation on VDSO32 Message-ID: References: <1f49c2ce009f8b007ab0676fb41187b2d54f28b2.1725304404.git.christophe.leroy@csgroup.eu> <85c02620-e8b2-4c97-9905-685a9a4e556d@csgroup.eu> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Thu, Sep 05, 2024 at 07:03:34PM +0200, Jason A. Donenfeld wrote: > On Thu, Sep 05, 2024 at 06:55:27PM +0200, Christophe Leroy wrote: > > > > > > Le 05/09/2024 à 18:13, Jason A. Donenfeld a écrit : > > >> +/* > > >> + * The macro sets two stack frames, one for the caller and one for the callee > > >> + * because there are no requirement for the caller to set a stack frame when > > >> + * calling VDSO so it may have omitted to set one, especially on PPC64 > > >> + */ > > >> + > > >> +.macro cvdso_call funct > > >> + .cfi_startproc > > >> + PPC_STLU r1, -PPC_MIN_STKFRM(r1) > > >> + .cfi_adjust_cfa_offset PPC_MIN_STKFRM > > >> + mflr r0 > > >> + PPC_STLU r1, -PPC_MIN_STKFRM(r1) > > >> + .cfi_adjust_cfa_offset PPC_MIN_STKFRM > > >> + PPC_STL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1) > > >> + .cfi_rel_offset lr, PPC_MIN_STKFRM + PPC_LR_STKOFF > > >> + get_datapage r8 > > >> + addi r8, r8, VDSO_RNG_DATA_OFFSET > > >> + bl CFUNC(DOTSYM(\funct)) > > >> + PPC_LL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1) > > >> + cmpwi r3, 0 > > >> + mtlr r0 > > >> + addi r1, r1, 2 * PPC_MIN_STKFRM > > >> + .cfi_restore lr > > >> + .cfi_def_cfa_offset 0 > > >> + crclr so > > >> + bgelr+ > > >> + crset so > > >> + neg r3, r3 > > >> + blr > > >> + .cfi_endproc > > >> +.endm > > > > > > You wrote in an earlier email that this worked with time namespaces, but > > > in my testing that doesn't seem to be the case. > > > > Did I write that ? I can't remember and neither can I remember testing > > it with time namespaces. > > It's possible I confused you with someone else? Hum. Anyway... > > > > From my test harness [1]: > > > > > > Normal single thread > > > vdso: 25000000 times in 12.494133131 seconds > > > libc: 25000000 times in 69.594625188 seconds > > > syscall: 25000000 times in 67.349243972 seconds > > > Time namespace single thread > > > vdso: 25000000 times in 71.673057436 seconds > > > libc: 25000000 times in 71.712774121 seconds > > > syscall: 25000000 times in 66.902318080 seconds > > > > > > I'm seeing this on ppc, ppc64, and ppc64le. > > > > What is the command to use to test with time namespace ? > > Look at the C in the commit I linked. The below also seems to work well for testing on x86. I'll clean that up and send a patch to the list. diff --git a/tools/testing/selftests/vDSO/vdso_test_getrandom.c b/tools/testing/selftests/vDSO/vdso_test_getrandom.c index 8866b65a4605..4df80f769aa7 100644 --- a/tools/testing/selftests/vDSO/vdso_test_getrandom.c +++ b/tools/testing/selftests/vDSO/vdso_test_getrandom.c @@ -16,8 +16,11 @@ #include #include #include +#include +#include #include #include +#include #include "../kselftest.h" #include "parse_vdso.h" @@ -239,9 +242,10 @@ static void fill(void) static void kselftest(void) { uint8_t weird_size[1263]; + pid_t child; ksft_print_header(); - ksft_set_plan(1); + ksft_set_plan(2); for (size_t i = 0; i < 1000; ++i) { ssize_t ret = vgetrandom(weird_size, sizeof(weird_size), 0); @@ -250,6 +254,39 @@ static void kselftest(void) } ksft_test_result_pass("getrandom: PASS\n"); + + assert(unshare(CLONE_NEWTIME) == 0); + child = fork(); + assert(child >= 0); + + if (!child) { + vgetrandom_init(); + child = getpid(); + assert(ptrace(PTRACE_TRACEME, 0, NULL, NULL) == 0); + assert(kill(child, SIGSTOP) == 0); + assert(vgetrandom(weird_size, sizeof(weird_size), 0) == sizeof(weird_size)); + _exit(0); + } + for (;;) { + struct ptrace_syscall_info info = { 0 }; + int status, ret; + assert(waitpid(child, &status, 0) >= 0); + if (WIFEXITED(status)) + break; + assert(WIFSTOPPED(status)); + if (WSTOPSIG(status) == SIGSTOP) + assert(ptrace(PTRACE_SETOPTIONS, child, 0, PTRACE_O_TRACESYSGOOD) == 0); + else if (WSTOPSIG(status) == SIGTRAP | 0x80) { + assert(ptrace(PTRACE_GET_SYSCALL_INFO, child, sizeof(info), &info) > 0); + if (info.entry.nr == __NR_getrandom && + ((void *)info.entry.args[0] == &weird_size && info.entry.args[1] == sizeof(weird_size))) + exit(KSFT_FAIL); + } + assert(ptrace(PTRACE_SYSCALL, child, 0, 0) == 0); + } + + ksft_test_result_pass("getrandom timens: PASS\n"); + exit(KSFT_PASS); }