From patchwork Tue Oct 5 18:32:52 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Raphael M Zinsly X-Patchwork-Id: 1536875 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=gcc.gnu.org header.i=@gcc.gnu.org header.a=rsa-sha256 header.s=default header.b=XYk5j29x; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org (client-ip=2620:52:3:1:0:246e:9693:128c; helo=sourceware.org; envelope-from=gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org; receiver=) Received: from sourceware.org (server2.sourceware.org [IPv6:2620:52:3:1:0:246e:9693:128c]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by bilbo.ozlabs.org (Postfix) with ESMTPS id 4HP5nc48Txz9s82 for ; Wed, 6 Oct 2021 05:33:40 +1100 (AEDT) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id B5E7B385C019 for ; Tue, 5 Oct 2021 18:33:37 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B5E7B385C019 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1633458817; bh=YUviohPzxXqQV7VezjkCW+YpRv7y9RK5ZZcV19zaVwg=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:Cc:From; b=XYk5j29xPsRkIbGzkIpUYumzpJjqqQ4Yv0oQVG/lqx5yc/vLlY67FPhhcGWvupPpb s6wEvVVLOkzW7AcqX4mit+39f38CAQm8pXtnXcttQ/L1cT4LvhHhZDYBYyjVqNPw/m 1FytqO7KbOrYOuG1YvS8md24uF4r3v62ZsnDktH0= X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by sourceware.org (Postfix) with ESMTPS id 5DD95385BF93 for ; Tue, 5 Oct 2021 18:33:06 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 5DD95385BF93 Received: from pps.filterd (m0187473.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 195IQNBP031474; Tue, 5 Oct 2021 14:33:04 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3bgus10cws-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 05 Oct 2021 14:33:04 -0400 Received: from m0187473.ppops.net (m0187473.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 195IRg61038510; Tue, 5 Oct 2021 14:33:03 -0400 Received: from ppma04dal.us.ibm.com (7a.29.35a9.ip4.static.sl-reverse.com [169.53.41.122]) by mx0a-001b2d01.pphosted.com with ESMTP id 3bgus10cw3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 05 Oct 2021 14:33:03 -0400 Received: from pps.filterd (ppma04dal.us.ibm.com [127.0.0.1]) by ppma04dal.us.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 195IS2ho029424; Tue, 5 Oct 2021 18:33:02 GMT Received: from b03cxnp08027.gho.boulder.ibm.com (b03cxnp08027.gho.boulder.ibm.com [9.17.130.19]) by ppma04dal.us.ibm.com with ESMTP id 3bef2brd3v-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 05 Oct 2021 18:33:02 +0000 Received: from b03ledav004.gho.boulder.ibm.com (b03ledav004.gho.boulder.ibm.com [9.17.130.235]) by b03cxnp08027.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 195IX12h17957316 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 5 Oct 2021 18:33:01 GMT Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2400678063; Tue, 5 Oct 2021 18:33:01 +0000 (GMT) Received: from b03ledav004.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 9B0B87805E; Tue, 5 Oct 2021 18:33:00 +0000 (GMT) Received: from localhost (unknown [9.160.173.44]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTP; Tue, 5 Oct 2021 18:33:00 +0000 (GMT) To: gcc-patches@gcc.gnu.org Subject: [PATCH v3] libgcc: Add a backchain fallback to _Unwind_Backtrace() on PowerPC Date: Tue, 5 Oct 2021 15:32:52 -0300 Message-Id: <20211005183252.24906-1-rzinsly@linux.ibm.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: M-7LFTqKoT63Gq6ma22vaRnu6qZ7-PNo X-Proofpoint-ORIG-GUID: kuczwIxS23-v60f_F6IpA__eBuJrj1ai X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.182.1,Aquarius:18.0.790,Hydra:6.0.391,FMLib:17.0.607.475 definitions=2021-10-05_03,2021-10-04_01,2020-04-07_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 mlxscore=0 clxscore=1015 spamscore=0 suspectscore=0 bulkscore=0 mlxlogscore=891 priorityscore=1501 adultscore=0 malwarescore=0 phishscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2109230001 definitions=main-2110050111 X-Spam-Status: No, score=-12.2 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Raphael Moreira Zinsly via Gcc-patches From: Raphael M Zinsly Reply-To: Raphael Moreira Zinsly Cc: segher@kernel.crashing.org, amodra@gmail.com, tuliom@linux.ibm.com, wschmidt@linux.ibm.com, dje.gcc@gmail.com, Raphael Moreira Zinsly Errors-To: gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org Sender: "Gcc-patches" Without dwarf2 unwind tables available _Unwind_Backtrace() is not able to return the full backtrace. This patch adds a fallback function on powerpc to get the backtrace by doing a backchain, this code was originally at glibc. libgcc/ChangeLog: * config/rs6000/linux-unwind.h (struct rt_sigframe): Move it to outside of get_regs() in order to use it in another function, this is done twice: for __powerpc64__ and for !__powerpc64__. (struct trace_arg): New struct. (struct layout): New struct. (ppc_backchain_fallback): New function. * unwind.inc (_Unwind_Backtrace): Look for _URC_NORMAL_STOP code state and call MD_BACKCHAIN_FALLBACK. gcc/testsuite/ChangeLog: * gcc.target/powerpc/unwind-backchain.c: New test. --- .../gcc.target/powerpc/unwind-backchain.c | 24 +++++ libgcc/config/rs6000/linux-unwind.h | 102 +++++++++++++++--- libgcc/unwind.inc | 14 ++- 3 files changed, 124 insertions(+), 16 deletions(-) create mode 100644 gcc/testsuite/gcc.target/powerpc/unwind-backchain.c diff --git a/gcc/testsuite/gcc.target/powerpc/unwind-backchain.c b/gcc/testsuite/gcc.target/powerpc/unwind-backchain.c new file mode 100644 index 00000000000..affa9b2efec --- /dev/null +++ b/gcc/testsuite/gcc.target/powerpc/unwind-backchain.c @@ -0,0 +1,24 @@ +/* -linux* targets have a fallback for the absence of unwind tables, thus are + the only ones we can guarantee backtrace returns all addresses. */ +/* { dg-do run { target { *-*-linux* } } } */ +/* { dg-options "-fno-asynchronous-unwind-tables" } */ + +#include + +void +test_backtrace() +{ + int addresses; + void *buffer[10]; + + addresses = backtrace(buffer, 10); + if(addresses != 4) + __builtin_abort(); +} + +int +main() +{ + test_backtrace(); + return 0; +} diff --git a/libgcc/config/rs6000/linux-unwind.h b/libgcc/config/rs6000/linux-unwind.h index acdc948f85d..8deccc1d650 100644 --- a/libgcc/config/rs6000/linux-unwind.h +++ b/libgcc/config/rs6000/linux-unwind.h @@ -94,6 +94,15 @@ struct gcc_ucontext enum { SIGNAL_FRAMESIZE = 128 }; +struct rt_sigframe { + char gap[SIGNAL_FRAMESIZE]; + struct gcc_ucontext uc; + unsigned long pad[2]; + int tramp[6]; + void *pinfo; + struct gcc_ucontext *puc; +}; + /* If PC is at a sigreturn trampoline, return a pointer to the regs. Otherwise return NULL. */ @@ -136,14 +145,7 @@ get_regs (struct _Unwind_Context *context) #endif { /* This works for 2.4.21 and later kernels. */ - struct rt_sigframe { - char gap[SIGNAL_FRAMESIZE]; - struct gcc_ucontext uc; - unsigned long pad[2]; - int tramp[6]; - void *pinfo; - struct gcc_ucontext *puc; - } *frame = (struct rt_sigframe *) context->cfa; + struct rt_sigframe *frame = (struct rt_sigframe *) context->cfa; return frame->uc.regs; } } @@ -154,6 +156,12 @@ get_regs (struct _Unwind_Context *context) enum { SIGNAL_FRAMESIZE = 64 }; +struct rt_sigframe { + char gap[SIGNAL_FRAMESIZE + 16]; + char siginfo[128]; + struct gcc_ucontext uc; +}; + static struct gcc_regs * get_regs (struct _Unwind_Context *context) { @@ -176,11 +184,7 @@ get_regs (struct _Unwind_Context *context) } else if (pc[0] == 0x38006666 || pc[0] == 0x380000AC) { - struct rt_sigframe { - char gap[SIGNAL_FRAMESIZE + 16]; - char siginfo[128]; - struct gcc_ucontext uc; - } *frame = (struct rt_sigframe *) context->cfa; + struct rt_sigframe *frame = (struct rt_sigframe *) context->cfa; return frame->uc.regs; } return NULL; @@ -203,7 +207,7 @@ ppc_fallback_frame_state (struct _Unwind_Context *context, int i; if (regs == NULL) - return _URC_END_OF_STACK; + return _URC_NORMAL_STOP; new_cfa = regs->gpr[__LIBGCC_STACK_POINTER_REGNUM__]; fs->regs.cfa_how = CFA_REG_OFFSET; @@ -352,3 +356,73 @@ frob_update_context (struct _Unwind_Context *context, _Unwind_FrameState *fs ATT } #endif } + +#define MD_BACKCHAIN_FALLBACK ppc_backchain_fallback + +struct trace_arg +{ + /* Stores the list of addresses. */ + void **array; + struct unwind_link *unwind_link; + _Unwind_Word cfa; + /* Number of addresses currently stored. */ + int count; + /* Maximum number of addresses. */ + int size; +}; + +/* This is the stack layout we see with every stack frame. + Note that every routine is required by the ABI to lay out the stack + like this. + + +----------------+ +-----------------+ + %r1 -> | previous frame--------> | previous frame--->... --> NULL + | | | | + | cr save | | cr save | + | | | | + | (unused) | | lr save | + +----------------+ +-----------------+ + + The CR save is only present on 64-bit ABIs. +*/ +struct frame_layout +{ + struct frame_layout *backchain; +#ifdef __powerpc64__ + long int cr_save; +#endif + void *lr_save; +}; + + +void ppc_backchain_fallback (struct _Unwind_Context *context, void *a) +{ + struct frame_layout *current; + struct trace_arg *arg = a; + int count; + + /* Get the last address computed and start with the next. */ + current = context->cfa; + current = current->backchain; + + for (count = arg->count; current != NULL; current = current->backchain) + { + arg->array[count] = current->lr_save; + + /* Check if the symbol is the signal trampoline and get the interrupted + symbol address from the trampoline saved area. */ + context->ra = current->lr_save; + if (current->lr_save && get_regs (context)) + { + struct rt_sigframe *sigframe = (struct rt_sigframe *) current; + if (count + 1 == arg->size) + break; + arg->array[++count] = (void *) sigframe->uc.rsave.nip; + current = (void *) sigframe->uc.rsave.gpr[1]; + } + if (count++ >= arg->size) + break; + } + + arg->count = count-1; +} diff --git a/libgcc/unwind.inc b/libgcc/unwind.inc index aa48d104fd0..456a5ee682f 100644 --- a/libgcc/unwind.inc +++ b/libgcc/unwind.inc @@ -300,14 +300,24 @@ _Unwind_Backtrace(_Unwind_Trace_Fn trace, void * trace_argument) /* Set up fs to describe the FDE for the caller of context. */ code = uw_frame_state_for (&context, &fs); - if (code != _URC_NO_REASON && code != _URC_END_OF_STACK) + if (code != _URC_NO_REASON && code != _URC_END_OF_STACK + && code != _URC_NORMAL_STOP) return _URC_FATAL_PHASE1_ERROR; /* Call trace function. */ if ((*trace) (&context, trace_argument) != _URC_NO_REASON) return _URC_FATAL_PHASE1_ERROR; - /* We're done at end of stack. */ +#ifdef MD_BACKCHAIN_FALLBACK + /* Do a backchain if there is no DWARF data. */ + if (code == _URC_NORMAL_STOP) + { + MD_BACKCHAIN_FALLBACK(&context, trace_argument); + break; + } +#endif + + /* We're done at end of stack. */ if (code == _URC_END_OF_STACK) break;