From patchwork Tue Oct 20 18:19:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "H.J. Lu" X-Patchwork-Id: 40783 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id F2AE4394D826; Tue, 20 Oct 2020 18:20:06 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org F2AE4394D826 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1603218007; bh=bNb9IWzyXxkOYJujjeHls8FsMUu9qDVC4a06ZSlhmRs=; h=References:In-Reply-To:Date:Subject:To:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=gM6jGCY5r6XLfDyBpFa4cM+9ZAvzSjfNXlLC3yrP39P4f0uujy45dSGMnIp/mYtJ6 tqpErfeLzIknCCCOe26FoHnIvPpaJP740NYZ7x4u31D1v6bBekBqCb6OeZmrqD30TF 7iJF52fU/g3jeaBdYrn28u5+/3zJit70qAYGC4Ns= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from mail-ot1-x344.google.com (mail-ot1-x344.google.com [IPv6:2607:f8b0:4864:20::344]) by sourceware.org (Postfix) with ESMTPS id 44A84394743D for ; Tue, 20 Oct 2020 18:20:02 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 44A84394743D Received: by mail-ot1-x344.google.com with SMTP id m11so2532653otk.13 for ; Tue, 20 Oct 2020 11:20:02 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=bNb9IWzyXxkOYJujjeHls8FsMUu9qDVC4a06ZSlhmRs=; b=aj1G0MVAdR4LesIAxVl0P60siYTgwaxaUl/eGcpBeKHtlH+xV6Og0Fdq/vuSUyygji yytJz31QR4rQC3CjR7Dm0986U9NieVTnWigPRY7oNu0bVWgVIz8kSKxyzQm2VcQ+JJVR tT29kG6auroTlC57c3/wt4FF4LKx1jtoreHQvH7p/HSrjNX5K1++fZEEo4oHbPUySS0j IyXqzSl2QBQFpDGqlYGus4MZgAHFpDmmuzn3z2zqMYlA0TC2e7WNms4fiqjztAy9PIj3 IH4Np/JOsh1+JgNi32lbV8AcXmvBDP5VaeTol5ZwNdKq3SSdrrr8n8o1CvU822cr8MkC 4uNQ== X-Gm-Message-State: AOAM533NH0tys1ArDWLcMJ35igERsOdcZKRPyvQoGY30PK0P3pNaXXZM 6zbxncTm5ARkGkqj2DjshrsauPM/7ApP12liL8Q= X-Google-Smtp-Source: ABdhPJwW/3S9ESsUsTDKoBHY8+qG2Qm4z+r6jK41J30rwsCL76KJhdLb/2VQiSW3A8rirntuKQZUy+SI+PZbGfGkz/g= X-Received: by 2002:a05:6830:4028:: with SMTP id i8mr2463845ots.90.1603218001616; Tue, 20 Oct 2020 11:20:01 -0700 (PDT) MIME-Version: 1.0 References: <20201010121935.3263605-1-hjl.tools@gmail.com> <20201014174659.GL32292@arm.com> <20201015115728.GA64160@gmail.com> <20201019150846.GP32292@arm.com> <20201020091912.GS32292@arm.com> In-Reply-To: Date: Tue, 20 Oct 2020 11:19:25 -0700 Message-ID: Subject: V7 [PATCH] sysconf: Add _SC_MINSIGSTKSZ/_SC_SIGSTKSZ [BZ #20305] To: Dave Martin X-Spam-Status: No, score=-3035.9 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, KAM_ASCII_DIVIDERS, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: "H.J. Lu via Libc-alpha" From: "H.J. Lu" Reply-To: "H.J. Lu" Cc: GNU C Library , Joseph Myers Errors-To: libc-alpha-bounces@sourceware.org Sender: "Libc-alpha" On Tue, Oct 20, 2020 at 7:59 AM H.J. Lu wrote: > > On Tue, Oct 20, 2020 at 2:19 AM Dave Martin wrote: > > > > On Mon, Oct 19, 2020 at 02:32:35PM -0700, H.J. Lu via Libc-alpha wrote: > > > On Mon, Oct 19, 2020 at 8:08 AM Dave Martin wrote: > > > > > > > > On Thu, Oct 15, 2020 at 04:57:28AM -0700, H.J. Lu via Libc-alpha wrote: > > > > [...] > > > > > > > > > diff --git a/sysdeps/unix/sysv/linux/x86/dl-minsigstacksize.h b/sysdeps/unix/sysv/linux/x86/dl-minsigstacksize.h > > > > [...] > > > > > > > > > +/* Emulate AT_MINSIGSTKSZ with XSAVE. */ > > > > > > > + > > > > > > > +static inline void > > > > > > > +dl_check_minsigstacksize (void) > > > > > > > +{ > > > > > > > + /* NB: Default to a constant MINSIGSTKSZ. */ > > > > > > > + _Static_assert (__builtin_constant_p (MINSIGSTKSZ), > > > > > > > + "MINSIGSTKSZ is constant"); > > > > > > > + /* Return if AT_MINSIGSTKSZ is provide by kernel. */ > > > > > > > + if (GLRO(dl_minsigstacksize) != MINSIGSTKSZ) > > > > > > > + return; > > > > > > > > > > > > Couldn't the kernel actually yield MINSIGSTKSZ or a smaller value, say, > > > > > > if running on hardware that doesn't have AVX-512? > > > > > > > > > > > It is OK for MINSIGSTKSZ > AT_MINSIGSTKSZ. For _SC_SIGSTKSZ_SOURCE, > > > > > dynamic MINSIGSTKSZ is defined as sysconf (_SC_SIGSTKSZ) which is > > > > > > > > > > MAX (SIGSTKSZ, MAX (MINSIGSTKSZ, sysconf (_SC_MINSIGSTKSZ)) * 4) > > > > > > > > > > and dynamic MINSIGSTKSZ is always > MINSIGSTKSZ. > > > > > > > > > > > We might want a separate flag to indicate whether we obtained a value > > > > > > from the auxv, rather relying on MINSIGSTKSZ having this magic meaning. > > > > > > > > > > AT_MINSIGSTKSZ is the only way for GLRO(dl_minsigstacksize) != MINSIGSTKSZ. > > > > > > > > Yes, but reading AT_MINSIGSTKSZ doesn't guarantee that > > > > GLRO(dl_minsigstkszsize) != MINSIGSTKSZ, no? > > > > > > > > What if the value reported for AT_MINSIGSTKSZ is actually the same as > > > > MINSIGSTKSZ? This could be the case on some arches in future even if > > > > it's never true today. But the code here assumes that AT_MINSIGSTKSZ > > > > wasn't available in this case, and reverts to a fallback guess. > > > > > > Since the fallback tracks what the kernel does, if AT_MINSIGSTKSZ > > > is 2KB, the fallback will be 2KB or slightly larger. > > > > Well, I guess that should be safe. It still feels a bit like it works > > by accident, but I may be being too paranoid. > > Let me work on that. > Here is the updated patch to initialize GLRO(dl_minsigstacksize) to 0 on x86. From 38eb69fdc50cc9b44259f549f4ea023f61ed843f Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Fri, 25 Sep 2020 13:10:08 -0700 Subject: [PATCH] sysconf: Add _SC_MINSIGSTKSZ/_SC_SIGSTKSZ [BZ #20305] Add _SC_MINSIGSTKSZ for the minimum signal stack size derived from AT_MINSIGSTKSZ, which is the minimum number of bytes of free stack space required in order to gurantee successful, non-nested handling of a single signal whose handler is an empty function, and _SC_SIGSTKSZ which is the suggested minimum number of bytes of stack space required for a signal stack. If AT_MINSIGSTKSZ isn't available, sysconf (_SC_MINSIGSTKSZ) returns MINSIGSTKSZ. On Linux/x86 with XSAVE, the signal frame used by kernel is composed of the following areas and laid out as: ------------------------------ | alignment padding | ------------------------------ | xsave buffer | ------------------------------ | fsave header (32-bit only) | ------------------------------ | siginfo + ucontext | ------------------------------ Compute AT_MINSIGSTKSZ value as size of xsave buffer + size of fsave header (32-bit only) + size of siginfo and ucontext + alignment padding. If _SC_SIGSTKSZ_SOURCE is defined, MINSIGSTKSZ and SIGSTKSZ are redefined as /* Default stack size for a signal handler: sysconf (SC_SIGSTKSZ). */ # undef SIGSTKSZ # define SIGSTKSZ sysconf (_SC_SIGSTKSZ) /* Minimum stack size for a signal handler: SIGSTKSZ. */ # undef MINSIGSTKSZ # define MINSIGSTKSZ SIGSTKSZ Compilation will fail if the source assumes constant MINSIGSTKSZ or SIGSTKSZ. The reason for not simply increasing the kernel's MINSIGSTKSZ #define (apart from the fact that it is rarely used, due to glibc's shadowing definitions) was that userspace binaries will have baked in the old value of the constant and may be making assumptions about it. For example, the type (char [MINSIGSTKSZ]) changes if this #define changes. This could be a problem if an newly built library tries to memcpy() or dump such an object defined by and old binary. Bounds-checking and the stack sizes passed to things like sigaltstack() and makecontext() could similarly go wrong. --- NEWS | 5 ++ bits/confname.h | 8 +- bits/sigstksz.h | 21 +++++ elf/dl-support.c | 5 ++ elf/dl-sysdep.c | 9 ++ include/bits/sigstack.h | 5 ++ include/features.h | 12 +++ manual/conf.texi | 21 +++++ manual/creature.texi | 6 ++ posix/sysconf.c | 3 + signal/Makefile | 5 +- signal/signal.h | 1 + signal/tst-minsigstksz-5.c | 84 +++++++++++++++++++ sysdeps/generic/ldsodefs.h | 3 + sysdeps/unix/sysv/linux/Makefile | 8 ++ sysdeps/unix/sysv/linux/bits/sigstksz.h | 33 ++++++++ .../unix/sysv/linux/ia64/sysconf-sigstksz.h | 27 ++++++ sysdeps/unix/sysv/linux/sysconf-sigstksz.h | 38 +++++++++ sysdeps/unix/sysv/linux/sysconf.c | 9 ++ .../unix/sysv/linux/x86/dl-minsigstacksize.h | 83 ++++++++++++++++++ .../sysv/linux/x86/include/bits/sigstack.h | 5 ++ sysdeps/x86/cpu-features.c | 3 + sysdeps/x86/dl-minsigstacksize.h | 27 ++++++ 23 files changed, 418 insertions(+), 3 deletions(-) create mode 100644 bits/sigstksz.h create mode 100644 include/bits/sigstack.h create mode 100644 signal/tst-minsigstksz-5.c create mode 100644 sysdeps/unix/sysv/linux/bits/sigstksz.h create mode 100644 sysdeps/unix/sysv/linux/ia64/sysconf-sigstksz.h create mode 100644 sysdeps/unix/sysv/linux/sysconf-sigstksz.h create mode 100644 sysdeps/unix/sysv/linux/x86/dl-minsigstacksize.h create mode 100644 sysdeps/unix/sysv/linux/x86/include/bits/sigstack.h create mode 100644 sysdeps/x86/dl-minsigstacksize.h diff --git a/NEWS b/NEWS index 3c1e509744..0fc57afc3f 100644 --- a/NEWS +++ b/NEWS @@ -9,6 +9,11 @@ Version 2.33 Major new features: +* Add _SC_MINSIGSTKSZ and _SC_SIGSTKSZ. When _SC_SIGSTKSZ_SOURCE is + defined, MINSIGSTKSZ and SIGSTKSZ are no longer constant on Linux. + MINSIGSTKSZ is redefined to sysconf(_SC_MINSIGSTKSZ) and SIGSTKSZ + is redefined to sysconf (_SC_SIGSTKSZ). + * The dynamic linker accepts the --argv0 argument and provides opportunity to change argv[0] string. diff --git a/bits/confname.h b/bits/confname.h index 5dc8215093..451d3eb636 100644 --- a/bits/confname.h +++ b/bits/confname.h @@ -525,8 +525,14 @@ enum _SC_THREAD_ROBUST_PRIO_INHERIT, #define _SC_THREAD_ROBUST_PRIO_INHERIT _SC_THREAD_ROBUST_PRIO_INHERIT - _SC_THREAD_ROBUST_PRIO_PROTECT + _SC_THREAD_ROBUST_PRIO_PROTECT, #define _SC_THREAD_ROBUST_PRIO_PROTECT _SC_THREAD_ROBUST_PRIO_PROTECT + + _SC_MINSIGSTKSZ, +#define _SC_MINSIGSTKSZ _SC_MINSIGSTKSZ + + _SC_SIGSTKSZ +#define _SC_SIGSTKSZ _SC_SIGSTKSZ }; /* Values for the NAME argument to `confstr'. */ diff --git a/bits/sigstksz.h b/bits/sigstksz.h new file mode 100644 index 0000000000..5535d873b5 --- /dev/null +++ b/bits/sigstksz.h @@ -0,0 +1,21 @@ +/* Definition of MINSIGSTKSZ. Generic version. + Copyright (C) 2020 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C 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; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C 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 the GNU C Library; if not, see + . */ + +#ifndef _SIGNAL_H +# error "Never include directly; use instead." +#endif diff --git a/elf/dl-support.c b/elf/dl-support.c index afbc94df54..1bbce03f9f 100644 --- a/elf/dl-support.c +++ b/elf/dl-support.c @@ -136,6 +136,8 @@ void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls; size_t _dl_pagesize = EXEC_PAGESIZE; +size_t _dl_minsigstacksize = CONSTANT_MINSIGSTKSZ; + int _dl_inhibit_cache; unsigned int _dl_osversion; @@ -294,6 +296,9 @@ _dl_aux_init (ElfW(auxv_t) *av) case AT_RANDOM: _dl_random = (void *) av->a_un.a_val; break; + case AT_MINSIGSTKSZ: + _dl_minsigstacksize = av->a_un.a_val; + break; DL_PLATFORM_AUXV } if (seen == 0xf) diff --git a/elf/dl-sysdep.c b/elf/dl-sysdep.c index 854570821c..47400f2937 100644 --- a/elf/dl-sysdep.c +++ b/elf/dl-sysdep.c @@ -117,6 +117,11 @@ _dl_sysdep_start (void **start_argptr, user_entry = (ElfW(Addr)) ENTRY_POINT; GLRO(dl_platform) = NULL; /* Default to nothing known about the platform. */ + /* NB: Default to a constant CONSTANT_MINSIGSTKSZ. */ + _Static_assert (__builtin_constant_p (CONSTANT_MINSIGSTKSZ), + "CONSTANT_MINSIGSTKSZ is constant"); + GLRO(dl_minsigstacksize) = CONSTANT_MINSIGSTKSZ; + for (av = GLRO(dl_auxv); av->a_type != AT_NULL; set_seen (av++)) switch (av->a_type) { @@ -181,6 +186,9 @@ _dl_sysdep_start (void **start_argptr, case AT_RANDOM: _dl_random = (void *) av->a_un.a_val; break; + case AT_MINSIGSTKSZ: + GLRO(dl_minsigstacksize) = av->a_un.a_val; + break; DL_PLATFORM_AUXV } @@ -308,6 +316,7 @@ _dl_show_auxv (void) [AT_SYSINFO_EHDR - 2] = { "SYSINFO_EHDR: 0x", hex }, [AT_RANDOM - 2] = { "RANDOM: 0x", hex }, [AT_HWCAP2 - 2] = { "HWCAP2: 0x", hex }, + [AT_MINSIGSTKSZ - 2] = { "MINSIGSTKSZ ", dec }, [AT_L1I_CACHESIZE - 2] = { "L1I_CACHESIZE: ", dec }, [AT_L1I_CACHEGEOMETRY - 2] = { "L1I_CACHEGEOMETRY: 0x", hex }, [AT_L1D_CACHESIZE - 2] = { "L1D_CACHESIZE: ", dec }, diff --git a/include/bits/sigstack.h b/include/bits/sigstack.h new file mode 100644 index 0000000000..eea939f59d --- /dev/null +++ b/include/bits/sigstack.h @@ -0,0 +1,5 @@ +#include_next + +#if !defined _ISOMAC && !defined CONSTANT_MINSIGSTKSZ +# define CONSTANT_MINSIGSTKSZ MINSIGSTKSZ +#endif diff --git a/include/features.h b/include/features.h index f3e62d3362..b202301ad8 100644 --- a/include/features.h +++ b/include/features.h @@ -55,6 +55,9 @@ _FORTIFY_SOURCE Add security hardening to many library functions. Set to 1 or 2; 2 performs stricter checks than 1. + _SC_SIGSTKSZ_SOURCE Select correct (but non compile-time constant) + MINSIGSTKSZ and SIGSTKSZ. + _REENTRANT, _THREAD_SAFE Obsolete; equivalent to _POSIX_C_SOURCE=199506L. @@ -96,6 +99,8 @@ __USE_ATFILE Define *at interfaces and AT_* constants for them. __USE_GNU Define GNU extensions. __USE_FORTIFY_LEVEL Additional security measures used, according to level. + __USE_SC_SIGSTKSZ Define correct (but non compile-time constant) + MINSIGSTKSZ and SIGSTKSZ. The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are defined by this file unconditionally. `__GNU_LIBRARY__' is provided @@ -139,6 +144,7 @@ #undef __USE_ATFILE #undef __USE_GNU #undef __USE_FORTIFY_LEVEL +#undef __USE_SC_SIGSTKSZ #undef __KERNEL_STRICT_NAMES #undef __GLIBC_USE_ISOC2X #undef __GLIBC_USE_DEPRECATED_GETS @@ -407,6 +413,12 @@ # define __USE_FORTIFY_LEVEL 0 #endif +#ifdef _SC_SIGSTKSZ_SOURCE +# define __USE_SC_SIGSTKSZ 1 +#else +# define __USE_SC_SIGSTKSZ 0 +#endif + /* The function 'gets' existed in C89, but is impossible to use safely. It has been removed from ISO C11 and ISO C++14. Note: for compatibility with various implementations of , this test diff --git a/manual/conf.texi b/manual/conf.texi index f959b00bb6..ba9847aaa4 100644 --- a/manual/conf.texi +++ b/manual/conf.texi @@ -913,6 +913,27 @@ Inquire about the parameter corresponding to @code{NL_SETMAX}. @item _SC_NL_TEXTMAX @standards{X/Open, unistd.h} Inquire about the parameter corresponding to @code{NL_TEXTMAX}. + +@item _SC_MINSIGSTKSZ +@standards{GNU, unistd.h} +Inquire about the minimum number of bytes of free stack space required +in order to guarantee successful, non-nested handling of a single signal +whose handler is an empty function. + +@item _SC_SIGSTKSZ +@standards{GNU, unistd.h} +Inquire about the suggested minimum number of bytes of stack space +required for a signal stack. + +This is not guaranteed to be enough for any specific purpose other than +the invocation of a single, non-nested, empty handler, but nonetheless +should be enough for basic scenarios involving simple signal handlers +and very low levels of signal nesting (say, 2 or 3 levels at the very +most). + +This value is provided for developer convenience and to ease migration +from the legacy @code{SIGSTKSZ} constant. Programs requiring stronger +guarantees should avoid using it if at all possible. @end vtable @node Examples of Sysconf diff --git a/manual/creature.texi b/manual/creature.texi index be5050468b..8fef4150fa 100644 --- a/manual/creature.texi +++ b/manual/creature.texi @@ -257,6 +257,12 @@ various library functions. If defined to @math{2}, even stricter checks are applied. @end defvr +@defvr Macro _SC_SIGSTKSZ_SOURCE +@standards{GNU, (none)} +If this macro is defined, correct (but non compile-time constant) +MINSIGSTKSZ and SIGSTKSZ are defined. +@end defvr + @defvr Macro _REENTRANT @defvrx Macro _THREAD_SAFE @standards{Obsolete, (none)} diff --git a/posix/sysconf.c b/posix/sysconf.c index ba303384c1..ca7833e6c4 100644 --- a/posix/sysconf.c +++ b/posix/sysconf.c @@ -266,6 +266,9 @@ __sysconf (int name) case _SC_XOPEN_REALTIME: case _SC_XOPEN_REALTIME_THREADS: + case _SC_MINSIGSTKSZ: + case _SC_SIGSTKSZ: + break; } diff --git a/signal/Makefile b/signal/Makefile index 2ec3ddd74f..641d30582d 100644 --- a/signal/Makefile +++ b/signal/Makefile @@ -31,7 +31,8 @@ headers := signal.h sys/signal.h \ bits/types/sigevent_t.h bits/types/siginfo_t.h \ bits/types/sigset_t.h bits/types/sigval_t.h \ bits/types/stack_t.h bits/types/struct_sigstack.h \ - bits/types/__sigval_t.h bits/signal_ext.h + bits/types/__sigval_t.h bits/signal_ext.h \ + bits/sigstksz.h routines := signal raise killpg \ sigaction sigprocmask kill \ @@ -48,7 +49,7 @@ routines := signal raise killpg \ tests := tst-signal tst-sigset tst-sigsimple tst-raise tst-sigset2 \ tst-sigwait-eintr tst-sigaction \ tst-minsigstksz-1 tst-minsigstksz-2 tst-minsigstksz-3 \ - tst-minsigstksz-3a tst-minsigstksz-4 \ + tst-minsigstksz-3a tst-minsigstksz-4 tst-minsigstksz-5 \ tst-sigisemptyset include ../Rules diff --git a/signal/signal.h b/signal/signal.h index effe3d698f..0311eb2a66 100644 --- a/signal/signal.h +++ b/signal/signal.h @@ -312,6 +312,7 @@ extern int siginterrupt (int __sig, int __interrupt) __THROW __attribute_deprecated_msg__ ("Use sigaction with SA_RESTART instead"); # include +# include # include /* Alternate signal handler stack interface. diff --git a/signal/tst-minsigstksz-5.c b/signal/tst-minsigstksz-5.c new file mode 100644 index 0000000000..d657d2f4e6 --- /dev/null +++ b/signal/tst-minsigstksz-5.c @@ -0,0 +1,84 @@ +/* Test of signal delivery on an alternate stack with MINSIGSTKSZ size. + Copyright (C) 2020 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C 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; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C 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 the GNU C Library; if not, see + . */ + +#include +#include +#include +#include +#include +#include + +static volatile sig_atomic_t handler_run; + +static void +handler (int signo) +{ + /* Clear a bit of on-stack memory. */ + volatile char buffer[256]; + for (size_t i = 0; i < sizeof (buffer); ++i) + buffer[i] = 0; + handler_run = 1; +} + +int +do_test (void) +{ + size_t stack_buffer_size = 64 * 1024 * 1024; + void *stack_buffer = xmalloc (stack_buffer_size); + void *stack_end = stack_buffer + stack_buffer_size; + memset (stack_buffer, 0xCC, stack_buffer_size); + + void *stack_bottom = stack_buffer + (stack_buffer_size + MINSIGSTKSZ) / 2; + void *stack_top = stack_bottom + MINSIGSTKSZ; + stack_t stack = + { + .ss_sp = stack_bottom, + .ss_size = MINSIGSTKSZ, + }; + if (sigaltstack (&stack, NULL) < 0) + FAIL_RET ("sigaltstack: %m\n"); + + struct sigaction act = + { + .sa_handler = handler, + .sa_flags = SA_ONSTACK, + }; + if (sigaction (SIGUSR1, &act, NULL) < 0) + FAIL_RET ("sigaction: %m\n"); + + if (kill (getpid (), SIGUSR1) < 0) + FAIL_RET ("kill: %m\n"); + + if (handler_run != 1) + FAIL_RET ("handler did not run\n"); + + for (void *p = stack_buffer; p < stack_bottom; ++p) + if (*(unsigned char *) p != 0xCC) + FAIL_RET ("changed byte %ld bytes below configured stack\n", + (long) (stack_bottom - p)); + for (void *p = stack_top; p < stack_end; ++p) + if (*(unsigned char *) p != 0xCC) + FAIL_RET ("changed byte %ld bytes above configured stack\n", + (long) (p - stack_top)); + + free (stack_buffer); + + return 0; +} + +#include diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index 382eeb9be0..5ce847aeac 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -528,6 +528,9 @@ struct rtld_global_ro /* Cached value of `getpagesize ()'. */ EXTERN size_t _dl_pagesize; + /* Cached value of `sysconf (_SC_MINSIGSTKSZ)'. */ + EXTERN size_t _dl_minsigstacksize; + /* Do we read from ld.so.cache? */ EXTERN int _dl_inhibit_cache; diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile index 09604e128b..b51a02a6e6 100644 --- a/sysdeps/unix/sysv/linux/Makefile +++ b/sysdeps/unix/sysv/linux/Makefile @@ -190,6 +190,9 @@ sysdep_routines += ntp_gettime ntp_gettimex endif ifeq ($(subdir),signal) +# Compile tst-minsigstksz-5.c with _SC_SIGSTKSZ_SOURCE. +CFLAGS-tst-minsigstksz-5.c += -D_SC_SIGSTKSZ_SOURCE + tests-special += $(objpfx)tst-signal-numbers.out # Depending on signal.o* is a hack. What we actually want is a dependency # on signal.h and everything it includes. That's impractical to write @@ -228,6 +231,11 @@ ifeq ($(subdir),sunrpc) sysdep_headers += nfs/nfs.h endif +ifeq ($(subdir),support) +# Compile xsigstack.c with _SC_SIGSTKSZ_SOURCE. +CFLAGS-xsigstack.c += -D_SC_SIGSTKSZ_SOURCE +endif + ifeq ($(subdir),termios) sysdep_headers += termio.h endif diff --git a/sysdeps/unix/sysv/linux/bits/sigstksz.h b/sysdeps/unix/sysv/linux/bits/sigstksz.h new file mode 100644 index 0000000000..cd5b3cc895 --- /dev/null +++ b/sysdeps/unix/sysv/linux/bits/sigstksz.h @@ -0,0 +1,33 @@ +/* Definition of MINSIGSTKSZ and SIGSTKSZ. Linux version. + Copyright (C) 2020 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C 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; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C 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 the GNU C Library; if not, see + . */ + +#ifndef _SIGNAL_H +# error "Never include directly; use instead." +#endif + +#if __USE_SC_SIGSTKSZ +# include + +/* Default stack size for a signal handler: sysconf (SC_SIGSTKSZ). */ +# undef SIGSTKSZ +# define SIGSTKSZ sysconf (_SC_SIGSTKSZ) + +/* Minimum stack size for a signal handler: SIGSTKSZ. */ +# undef MINSIGSTKSZ +# define MINSIGSTKSZ SIGSTKSZ +#endif diff --git a/sysdeps/unix/sysv/linux/ia64/sysconf-sigstksz.h b/sysdeps/unix/sysv/linux/ia64/sysconf-sigstksz.h new file mode 100644 index 0000000000..7e5ceba151 --- /dev/null +++ b/sysdeps/unix/sysv/linux/ia64/sysconf-sigstksz.h @@ -0,0 +1,27 @@ +/* sysconf_sigstksz (). Linux/ia64 version. + Copyright (C) 2020 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C 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; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C 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 the GNU C Library; if not, see + . */ + +/* Return sysconf (_SC_SIGSTKSZ). */ + +static long int +sysconf_sigstksz (void) +{ + _Static_assert (__builtin_constant_p (SIGSTKSZ), + "SIGSTKSZ is constant"); + return SIGSTKSZ; +} diff --git a/sysdeps/unix/sysv/linux/sysconf-sigstksz.h b/sysdeps/unix/sysv/linux/sysconf-sigstksz.h new file mode 100644 index 0000000000..64d450b22c --- /dev/null +++ b/sysdeps/unix/sysv/linux/sysconf-sigstksz.h @@ -0,0 +1,38 @@ +/* sysconf_sigstksz (). Linux version. + Copyright (C) 2020 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C 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; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C 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 the GNU C Library; if not, see + . */ + +/* Return sysconf (_SC_SIGSTKSZ). */ + +static long int +sysconf_sigstksz (void) +{ + long int minsigstacksize = GLRO(dl_minsigstacksize); + assert (minsigstacksize != 0); + _Static_assert (__builtin_constant_p (MINSIGSTKSZ), + "MINSIGSTKSZ is constant"); + if (minsigstacksize < MINSIGSTKSZ) + minsigstacksize = MINSIGSTKSZ; + /* MAX (MINSIGSTKSZ, sysconf (_SC_MINSIGSTKSZ)) * 4. */ + long int sigstacksize = minsigstacksize * 4; + /* Return MAX (SIGSTKSZ, sigstacksize). */ + _Static_assert (__builtin_constant_p (SIGSTKSZ), + "SIGSTKSZ is constant"); + if (sigstacksize < SIGSTKSZ) + sigstacksize = SIGSTKSZ; + return sigstacksize; +} diff --git a/sysdeps/unix/sysv/linux/sysconf.c b/sysdeps/unix/sysv/linux/sysconf.c index 7958a74164..d1d86df3fb 100644 --- a/sysdeps/unix/sysv/linux/sysconf.c +++ b/sysdeps/unix/sysv/linux/sysconf.c @@ -16,6 +16,7 @@ License along with the GNU C Library; if not, see . */ +#include #include #include #include @@ -26,6 +27,7 @@ #include #include #include +#include /* Legacy value of ARG_MAX. The macro is now not defined since the actual value varies based on the stack size. */ @@ -75,6 +77,13 @@ __sysconf (int name) } break; + case _SC_MINSIGSTKSZ: + assert (GLRO(dl_minsigstacksize) != 0); + return GLRO(dl_minsigstacksize); + + case _SC_SIGSTKSZ: + return sysconf_sigstksz (); + default: break; } diff --git a/sysdeps/unix/sysv/linux/x86/dl-minsigstacksize.h b/sysdeps/unix/sysv/linux/x86/dl-minsigstacksize.h new file mode 100644 index 0000000000..6088bbc99e --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86/dl-minsigstacksize.h @@ -0,0 +1,83 @@ +/* Emulate AT_MINSIGSTKSZ. Linux/x86 version. + Copyright (C) 2020 Free Software Foundation, Inc. + + The GNU C 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; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C 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 the GNU C Library; if not, see + . */ + +/* Emulate AT_MINSIGSTKSZ with XSAVE. */ + +static inline void +dl_check_minsigstacksize (const struct cpu_features *cpu_features) +{ + /* Return if AT_MINSIGSTKSZ is provide by kernel. */ + if (GLRO(dl_minsigstacksize) != 0) + return; + + if (cpu_features->basic.max_cpuid >= 0xd + && CPU_FEATURES_CPU_P (cpu_features, OSXSAVE)) + { + /* Emulate AT_MINSIGSTKSZ. In Linux kernel, the signal frame data + with XSAVE is composed of the following areas and laid out as: + ------------------------------ + | alignment padding | + ------------------------------ + | xsave buffer | + ------------------------------ + | fsave header (32-bit only) | + ------------------------------ + | siginfo + ucontext | + ------------------------------ + */ + + unsigned int sigframe_size; + +#ifdef __x86_64__ + /* NB: sizeof(struct rt_sigframe) + 8-byte return address in Linux + kernel. */ + sigframe_size = 440 + 8; +#else + /* NB: sizeof(struct sigframe_ia32) + sizeof(struct fregs_state)) + + 4-byte return address + 3 * 4-byte arguments in Linux kernel. */ + sigframe_size = 736 + 112 + 4 + 3 * 4; +#endif + + /* Add 15 bytes to align the stack to 16 bytes. */ + sigframe_size += 15; + + /* Make the space before xsave buffer multiple of 16 bytes. */ + sigframe_size = ALIGN_UP (sigframe_size, 16); + + /* Add (64 - 16)-byte padding to align xsave buffer at 64 bytes. */ + sigframe_size += 64 - 16; + + unsigned int eax, ebx, ecx, edx; + __cpuid_count (0xd, 0, eax, ebx, ecx, edx); + + /* Add the size of xsave buffer. */ + sigframe_size += ebx; + + /* Add the size of FP_XSTATE_MAGIC2. */ +#define FP_XSTATE_MAGIC2 0x46505845U + sigframe_size += sizeof (FP_XSTATE_MAGIC2); + + GLRO(dl_minsigstacksize) = sigframe_size; + } + else + { + /* NB: Default to a constant MINSIGSTKSZ. */ + _Static_assert (__builtin_constant_p (MINSIGSTKSZ), + "MINSIGSTKSZ is constant"); + GLRO(dl_minsigstacksize) = MINSIGSTKSZ; + } +} diff --git a/sysdeps/unix/sysv/linux/x86/include/bits/sigstack.h b/sysdeps/unix/sysv/linux/x86/include/bits/sigstack.h new file mode 100644 index 0000000000..208754c497 --- /dev/null +++ b/sysdeps/unix/sysv/linux/x86/include/bits/sigstack.h @@ -0,0 +1,5 @@ +#include_next + +#ifndef _ISOMAC +# define CONSTANT_MINSIGSTKSZ 0 +#endif diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c index f26deba38d..bef6084f5e 100644 --- a/sysdeps/x86/cpu-features.c +++ b/sysdeps/x86/cpu-features.c @@ -19,6 +19,7 @@ #include #include #include +#include #if IS_IN (libc) && !defined SHARED # include # include @@ -367,6 +368,8 @@ get_common_indices (struct cpu_features *cpu_features, cpu_features->features[COMMON_CPUID_INDEX_19].cpuid.ebx, cpu_features->features[COMMON_CPUID_INDEX_19].cpuid.ecx, cpu_features->features[COMMON_CPUID_INDEX_19].cpuid.edx); + + dl_check_minsigstacksize (cpu_features); } _Static_assert (((index_arch_Fast_Unaligned_Load diff --git a/sysdeps/x86/dl-minsigstacksize.h b/sysdeps/x86/dl-minsigstacksize.h new file mode 100644 index 0000000000..959871c970 --- /dev/null +++ b/sysdeps/x86/dl-minsigstacksize.h @@ -0,0 +1,27 @@ +/* Emulate AT_MINSIGSTKSZ. Generic x86 version. + Copyright (C) 2020 Free Software Foundation, Inc. + + The GNU C 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; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C 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 the GNU C Library; if not, see + . */ + +/* Emulate AT_MINSIGSTKSZ with XSAVE. */ + +static inline void +dl_check_minsigstacksize (const struct cpu_features *cpu_features) +{ + /* NB: Default to a constant MINSIGSTKSZ. */ + _Static_assert (__builtin_constant_p (MINSIGSTKSZ), + "MINSIGSTKSZ is constant"); + GLRO(dl_minsigstacksize) = MINSIGSTKSZ; +} -- 2.26.2