From patchwork Tue Apr 1 11:32:45 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Newton X-Patchwork-Id: 368 Return-Path: X-Original-To: siddhesh@wilcox.dreamhost.com Delivered-To: siddhesh@wilcox.dreamhost.com Received: from homiemail-mx20.g.dreamhost.com (mx2.sub5.homie.mail.dreamhost.com [208.113.200.128]) by wilcox.dreamhost.com (Postfix) with ESMTP id E66E73600D9 for ; Tue, 1 Apr 2014 04:33:01 -0700 (PDT) Received: by homiemail-mx20.g.dreamhost.com (Postfix, from userid 14307373) id 866D040C56641; Tue, 1 Apr 2014 04:33:01 -0700 (PDT) X-Original-To: glibc@patchwork.siddhesh.in Delivered-To: x14307373@homiemail-mx20.g.dreamhost.com Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by homiemail-mx20.g.dreamhost.com (Postfix) with ESMTPS id 6704040C56626 for ; Tue, 1 Apr 2014 04:33:01 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:subject:date:message-id; q=dns; s= default; b=avWqIryoHy/pgmLDz5iSAImwwC6OPTu5xPgEiYtgEa5hgKa+tihpS 2i3NBGpD8txckqKhi8WtwcoRfwzfea6nYq+AJ4QcdNllRTm0CLpROyA8irFWjENT J9IWxIRq6/nz3YcE06xlW6Xu+hw6UIYxjA/IbCb/emboMDZcZgW0Ag= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=sourceware.org; h=list-id :list-unsubscribe:list-subscribe:list-archive:list-post :list-help:sender:from:to:subject:date:message-id; s=default; bh=i9tUNUp5I8Va34tL+W77qLFcydM=; b=qsPdogUdykHSHLY5G++R5fea7OWL F/5gvO9H8rJ8ccsQ8LoFAJKMYR56szYWx2J3AFl0LjZsJ4G0Vh9xfAfzLWFY9KI3 oOqVjzQv1y3ByZDNYHsi5un//yyLVvLKT5rmI+h2va4tR6ApRwMZc59CQoC3GT6S 17nwTRoYdIt5D2E= Received: (qmail 4865 invoked by alias); 1 Apr 2014 11:32:58 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 4852 invoked by uid 89); 1 Apr 2014 11:32:57 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=0.2 required=5.0 tests=AWL, BAYES_50, KAM_STOCKGEN, RCVD_IN_DNSWL_LOW, SPF_PASS autolearn=no version=3.3.2 X-HELO: mail-wg0-f52.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:subject:date:message-id; bh=KSGVkQTZi01cszf1+DPZSlsLrCwxA/fp/fd2fsxhgXo=; b=Qa5XpvQNPDJDRIfoD3le/1lKulNsC3axY0FE1BrdRETrHVuSXD77huWqwOb+3O+jt7 0YaVLMkuZaRQw5nDgFCb86NClENipb86fNt1xLZ45a0ZKBPML09ueVKDV2VJinzArN1m whq6K05TYDyET8tPGMVxgEbAdJ/QI87b1PjUSwDjDcs8YzQXGhMyQoPqzG/Z33CUJO+V qp//oC/IGa1PsHwTy3NevnYPBVLyZ/tpxtIYzb0zu14pJ+3v7VIaXjNazaZbaqdomYk2 HGlAtsYEMyqew1aqI/PRN2akBqb6Zye7h45VTMCuXT7ktmw1B88AFVNAK2W1QGJiTnK1 wu7A== X-Gm-Message-State: ALoCoQmNR7352XgXNue1xlo2Y8RxZe2qr167N8fFlfMjWfA7lRDiJFD4+gvbp8h3ShUzKTJXhb1x X-Received: by 10.194.2.145 with SMTP id 17mr13290361wju.60.1396351972555; Tue, 01 Apr 2014 04:32:52 -0700 (PDT) From: Will Newton To: libc-alpha@sourceware.org Subject: [PATCH v2 1/3] aarch64: Re-implement setcontext without rt_sigreturn syscall Date: Tue, 1 Apr 2014 12:32:45 +0100 Message-Id: <1396351967-1952-1-git-send-email-will.newton@linaro.org> X-DH-Original-To: glibc@patchwork.siddhesh.in The current implementation of setcontext uses rt_sigreturn to restore the contents of registers. This contrasts with the way most other architectures implement setcontext: powerpc64, mips, tile: Call rt_sigreturn if context was created by a call to a signal handler, otherwise restore in user code. powerpc32: Call swapcontext system call and don't call sigreturn or rt_sigreturn. x86_64, sparc, hppa, sh, ia64, m68k, s390, arm: Only support restoring "synchronous" contexts, that is contexts created by getcontext, and restoring in user code and don't call sigreturn or rt_sigreturn. alpha: Call sigreturn (but not rt_sigreturn) in all cases to do the restore. The text of the setcontext manpage suggests that the requirement to be able to restore a signal handler created context has been dropped from SUSv2: If the context was obtained by a call to a signal handler, then old standard text says that "program execution continues with the program instruction following the instruction interrupted by the signal". However, this sentence was removed in SUSv2, and the present verdict is "the result is unspecified". Implementing setcontext by calling rt_sigreturn unconditionally causes problems when used with sigaltstack as in BZ #16629. On this basis it seems that aarch64 is broken and that new ports should only support restoring contexts created with getcontext and do not need to call rt_sigreturn at all. This patch re-implements the aarch64 setcontext function to restore the context in user code in a similar manner to x86_64 and other ports. ChangeLog: 2014-04-01 Will Newton [BZ #16629] * sysdeps/unix/sysv/linux/aarch64/setcontext.S (__setcontext): Re-implement to restore registers in user code and avoid rt_sigreturn system call. --- NEWS | 6 +- sysdeps/unix/sysv/linux/aarch64/setcontext.S | 147 +++++++++++++++++---------- 2 files changed, 95 insertions(+), 58 deletions(-) Changes in v2: - Added NEWS entry - Fixed bug in handling sigmask value - Improved commit message diff --git a/NEWS b/NEWS index 1574ab4..219198d 100644 --- a/NEWS +++ b/NEWS @@ -11,9 +11,9 @@ Version 2.20 6804, 15347, 15804, 15894, 16002, 16198, 16284, 16348, 16349, 16357, 16362, 16447, 16532, 16545, 16574, 16599, 16600, 16609, 16610, 16611, - 16613, 16623, 16632, 16634, 16639, 16642, 16648, 16649, 16670, 16674, - 16677, 16680, 16683, 16689, 16695, 16701, 16706, 16707, 16712, 16713, - 16714, 16731, 16743, 16758, 16759, 16760, 16770. + 16613, 16623, 16629, 16632, 16634, 16639, 16642, 16648, 16649, 16670, + 16674, 16677, 16680, 16683, 16689, 16695, 16701, 16706, 16707, 16712, + 16713, 16714, 16731, 16743, 16758, 16759, 16760, 16770. * Running the testsuite no longer terminates as soon as a test fails. Instead, a file tests.sum (xtests.sum from "make xcheck") is generated, diff --git a/sysdeps/unix/sysv/linux/aarch64/setcontext.S b/sysdeps/unix/sysv/linux/aarch64/setcontext.S index d220c41..aef5149 100644 --- a/sysdeps/unix/sysv/linux/aarch64/setcontext.S +++ b/sysdeps/unix/sysv/linux/aarch64/setcontext.S @@ -22,68 +22,105 @@ #include "ucontext_i.h" #include "ucontext-internal.h" -/* int setcontext (const ucontext_t *ucp) */ +/* int __setcontext (const ucontext_t *ucp) - .text - -ENTRY(__setcontext) - - /* Create a signal frame on the stack: - - fp - lr - ... - sp-> rt_sigframe - */ - - stp x29, x30, [sp, -16]! - cfi_adjust_cfa_offset (16) - cfi_rel_offset (x29, 0) - cfi_rel_offset (x30, 8) - - mov x29, sp - cfi_def_cfa_register (x29) - - /* Allocate space for the sigcontext. */ - mov w3, #((RT_SIGFRAME_SIZE + SP_ALIGN_SIZE) & SP_ALIGN_MASK) - sub sp, sp, x3 + Restores the machine context in UCP and thereby resumes execution + in that context. - /* Compute the base address of the ucontext structure. */ - add x1, sp, #RT_SIGFRAME_UCONTEXT + This implementation is intended to be used for *synchronous* context + switches only. Therefore, it does not have to restore anything + other than the PRESERVED state. */ - /* Only ucontext is required in the frame, *copy* it in. */ - -#if UCONTEXT_SIZE % 16 -#error The implementation of setcontext.S assumes sizeof(ucontext_t) % 16 == 0 -#endif - - mov x2, #UCONTEXT_SIZE / 16 -0: - ldp x3, x4, [x0], #16 - stp x3, x4, [x1], #16 - sub x2, x2, 1 - cbnz x2, 0b + .text - /* rt_sigreturn () -- no arguments, sp points to struct rt_sigframe. */ - mov x8, SYS_ify (rt_sigreturn) +ENTRY (__setcontext) + /* Save a copy of UCP. */ + mov x9, x0 + + /* Set the signal mask with + rt_sigprocmask (SIG_SETMASK, mask, NULL, _NSIG/8). */ + mov x0, #SIG_SETMASK + add x1, x9, #UCONTEXT_SIGMASK + mov x2, #0 + mov x3, #_NSIG8 + mov x8, SYS_ify (rt_sigprocmask) svc 0 - - /* Ooops we failed. Recover the stack */ - - mov sp, x29 - cfi_def_cfa_register (sp) - - ldp x29, x30, [sp], 16 - cfi_adjust_cfa_offset (16) - cfi_restore (x29) - cfi_restore (x30) - b C_SYMBOL_NAME(__syscall_error) - + cbz x0, 1f + b C_SYMBOL_NAME (__syscall_error) +1: + /* Restore the general purpose registers. */ + mov x0, x9 + cfi_def_cfa (x0, 0) + cfi_offset (x18, oX0 + 18 * SZREG) + cfi_offset (x19, oX0 + 19 * SZREG) + cfi_offset (x20, oX0 + 20 * SZREG) + cfi_offset (x21, oX0 + 21 * SZREG) + cfi_offset (x22, oX0 + 22 * SZREG) + cfi_offset (x23, oX0 + 23 * SZREG) + cfi_offset (x24, oX0 + 24 * SZREG) + cfi_offset (x25, oX0 + 25 * SZREG) + cfi_offset (x26, oX0 + 26 * SZREG) + cfi_offset (x27, oX0 + 27 * SZREG) + cfi_offset (x28, oX0 + 28 * SZREG) + cfi_offset (x29, oX0 + 29 * SZREG) + cfi_offset (x30, oX0 + 30 * SZREG) + + cfi_offset ( d8, oV0 + 8 * SZVREG) + cfi_offset ( d9, oV0 + 9 * SZVREG) + cfi_offset (d10, oV0 + 10 * SZVREG) + cfi_offset (d11, oV0 + 11 * SZVREG) + cfi_offset (d12, oV0 + 12 * SZVREG) + cfi_offset (d13, oV0 + 13 * SZVREG) + cfi_offset (d14, oV0 + 14 * SZVREG) + cfi_offset (d15, oV0 + 15 * SZVREG) + ldp x18, x19, [x0, oX0 + 18 * SZREG] + ldp x20, x21, [x0, oX0 + 20 * SZREG] + ldp x22, x23, [x0, oX0 + 22 * SZREG] + ldp x24, x25, [x0, oX0 + 24 * SZREG] + ldp x26, x27, [x0, oX0 + 26 * SZREG] + ldp x28, x29, [x0, oX0 + 28 * SZREG] + ldr x30, [x0, oX0 + 30 * SZREG] + ldr x2, [x0, oSP] + mov sp, x2 + + /* Check for FP SIMD context. */ + add x2, x0, #oEXTENSION + + mov w3, #(FPSIMD_MAGIC & 0xffff) + movk w3, #(FPSIMD_MAGIC >> 16), lsl #16 + ldr w1, [x2, #oHEAD + oMAGIC] + cmp w1, w3 + b.ne 2f + + /* Restore the FP SIMD context. */ + add x3, x2, #oV0 + 8 * SZVREG + ldp d8, d9, [x3], #2 * SZVREG + ldp d10, d11, [x3], #2 * SZVREG + ldp d12, d13, [x3], #2 * SZVREG + ldp d14, d15, [x3], #2 * SZVREG + + add x3, x2, oFPSR + + ldr w4, [x3] + msr fpsr, x4 + + ldr w4, [x3, oFPCR - oFPSR] + msr fpcr, x4 + +2: + ldr x16, [x0, oPC] + /* Restore arg registers. */ + ldp x2, x3, [x0, oX0 + 2 * SZREG] + ldp x4, x5, [x0, oX0 + 4 * SZREG] + ldp x6, x7, [x0, oX0 + 6 * SZREG] + ldp x0, x1, [x0, oX0 + 0 * SZREG] + /* Jump to the new pc value. */ + br x16 PSEUDO_END (__setcontext) weak_alias (__setcontext, setcontext) -ENTRY(__startcontext) +ENTRY (__startcontext) mov x0, x19 cbnz x0, __setcontext -1: b HIDDEN_JUMPTARGET(_exit) -END(__startcontext) +1: b HIDDEN_JUMPTARGET (_exit) +END (__startcontext)