From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (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 AB8093DFC6B; Fri, 21 Aug 2026 19:53:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.163.156.1 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787342020; cv=none; b=frQudqBGbKip6BN96VSNbeFnj7FRbhPyHS5UdzU5y7vm+rTStqY7qBfSZcWlnu915VSwTbm4zx+QFL75+xSpyD+RVkmEjki/uU1ZsjmiUwy6t7a/lZzO6Fhb4quYTt7FpO5hOou7MZOftbKsptS2KDuHO85eJPKg939iwOgdrI0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787342020; c=relaxed/simple; bh=WMyBpQzaz7z8JbLlLulfrQmBGsKPHDahtYmddyFk8/k=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ihkypqxoHc2md2mEvcfobc8Kg3EYNYRqBq6tZt/QtPeVOZnRDvw525dYPlOqSh33fW761C20yzRIEY2a3rdIfXTggCAdNcQPAcha5GvjOfCR/EblOKk3kBtuE43/XPg8Mc/4jKV0H3PPk8t8yn4AJrAAPemg+AyW88VbFlCkYzA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com; spf=pass smtp.mailfrom=linux.ibm.com; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b=tPG47Xxv; arc=none smtp.client-ip=148.163.156.1 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.ibm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ibm.com header.i=@ibm.com header.b="tPG47Xxv" Received: from pps.filterd (m0356517.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 67LIVVOS2363561; Fri, 21 Aug 2026 19:53:16 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=cc :content-transfer-encoding:date:from:in-reply-to:message-id :mime-version:references:subject:to; s=pp1; bh=dFCr5T9phyYLehboO bVirVwXB3O2bo8jq4xPArTF4sg=; b=tPG47Xxv2G0jIEfBuDf3JDM3KivNVLIBX huX0P2Ix2x0u8rl47N8K4Y2RcpgXBi6KleljqJ4GVz6beEMEoQuxK+7PNR5c5dwt DA5O7Kkirtdix6F66ND8/WuaPZA2xkdIw2VyJXuG6CLEVVrZ8yCaGMLEW6CjOA9U jpomlA/0XQTnVYPDdDabv7FY9i8NDY6CxAjHD1iJQ/B370/jHcQxyyUSa4TWQfQO 31UqHofuAbVARIjJlkxhauq43E9xBkMdM/iSY7ikzi3lCf9OIHFkawuShtimCdES Wt8D0RDOpfEvoqi2fmnWMNoKV3EiAC2mtk/yglSWHuwqnFYYLC4Dw== Received: from ppma22.wdc07v.mail.ibm.com (5c.69.3da9.ip4.static.sl-reverse.com [169.61.105.92]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 4g4yu0uxm9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 21 Aug 2026 19:53:15 +0000 (GMT) Received: from pps.filterd (ppma22.wdc07v.mail.ibm.com [127.0.0.1]) by ppma22.wdc07v.mail.ibm.com (8.18.1.7/8.18.1.7) with ESMTP id 67LJfKY4023504; Fri, 21 Aug 2026 19:53:14 GMT Received: from smtprelay04.fra02v.mail.ibm.com ([9.218.2.228]) by ppma22.wdc07v.mail.ibm.com (PPS) with ESMTPS id 4g32twprb1-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 21 Aug 2026 19:53:13 +0000 (GMT) Received: from smtpav03.fra02v.mail.ibm.com (smtpav03.fra02v.mail.ibm.com [10.20.54.102]) by smtprelay04.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 67LJrAUP10420730 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 21 Aug 2026 19:53:10 GMT Received: from smtpav03.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0125B20040; Fri, 21 Aug 2026 19:53:10 +0000 (GMT) Received: from smtpav03.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AFECB2004B; Fri, 21 Aug 2026 19:53:09 +0000 (GMT) Received: from tuxmaker.boeblingen.de.ibm.com (unknown [9.87.85.9]) by smtpav03.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 21 Aug 2026 19:53:09 +0000 (GMT) From: Jens Remus To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-s390@vger.kernel.org, x86@kernel.org, Steven Rostedt , Josh Poimboeuf , Peter Zijlstra , Mathieu Desnoyers Cc: Jens Remus , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Ilya Leoshkevich , Indu Bhagat , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Namhyung Kim , Andrii Nakryiko , Kees Cook , Sam James , Fangrui Song Subject: [RFC PATCH v2 17/24] unwind_user/eh_frame: Add support for DWARF expressions Date: Fri, 21 Aug 2026 21:52:52 +0200 Message-ID: <20260821195259.2688377-18-jremus@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260821195259.2688377-1-jremus@linux.ibm.com> References: <20260821195259.2688377-1-jremus@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Authority-Analysis: v=2.4 cv=MthiLWae c=1 sm=1 tr=0 ts=6a88acab cx=c_pps a=5BHTudwdYE3Te8bg5FgnPg==:117 a=5BHTudwdYE3Te8bg5FgnPg==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=U7nrCbtTmkRpXpFmAIza:22 a=VnNF1IyMAAAA:8 a=KkslVM8iKOnbzSZrsQ8A:9 X-Proofpoint-ORIG-GUID: F2cjGmsoF7SvFBo8kVlmsC1HIOVJwAev X-Proofpoint-GUID: fAPKUeWmHTvd3YCRHPSSzwsgZPa1dlqI X-Proofpoint-Spam-Info: AW1haW4tMjYwODIxMDE1NSBTYWx0ZWRfXx3eKJIgdtg9W nwtLi0HNVNV33Tn1knPX1VtuU8kCNbfy6fZZs8XqoxWShIbRQAmCDBE96CT3A04OS11l9iYA7Py cyVFdTDshHFZrkiRq7Wg6wfwrHf0ujI= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODIxMDE1NSBTYWx0ZWRfX9EAjLZQE0Ac+ 84OyBff4e8QawnTvJghqcf5h2DcsxunjbiY/iZAjGNOGpSgRNDj81IjxKDf8z05Ksj0gx/Mfqfl oOFf23+XhTo9ZHQ0ueJXArT4I1DID0bRWT7Ih6NyJoD5AdwF9z4rCoR1IOmsg14+y7TKd03dMfj iRlGgORsaJZNDgf/WhG6hVoKky9O204MaVyxku+XLtA7V4Mo0el54FMZ+AsB/4w8Wol3NYbeF// KP7IYPpb64uuMj0MOsYFVQoJsZa8dQnqyQ+omsNPv2K7Q4U96cvUkbwRWrUmG1BXaBSXech7Rb6 rMpm4VGTFojHH8t6lZcsTGmzfMxogYI0D9WMLGQib3r2dFaoRXBLNU0TcsoKGDNBKNlOQMTU6ho W5bLvh1DZaPV4WKic3v0KRF8pQOcDoRWF/Bc9LGWs7qNzicOqVCYpP2sZhbJgfX3Er1SW0L7lNX EHaFFC27KaQP/8eckHg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-21_06,2026-08-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 impostorscore=0 bulkscore=0 phishscore=0 clxscore=1015 spamscore=0 adultscore=0 lowpriorityscore=0 priorityscore=1501 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608210155 Enable architectures to handle DWARF expressions in DWARF CFI instructions DW_CFA_def_cfa_expression, DW_CFA_expression, and DW_CFA_val_expression. Limit the maximum expression length to a reasonable size, while enabling architectures to override the limit. Architectures are supposed to only handle specific known expressions or expression patterns, not to implement a stack-based expression evaluation machinery. Signed-off-by: Jens Remus --- Notes (jremus): Changes in RFC v2: - Fix expression length overflow checks. (Sashiko AI) include/asm-generic/unwind_user_eh_frame.h | 41 ++++++++++++ include/linux/unwind_user_eh_frame_types.h | 37 +++++++++++ kernel/unwind/eh_frame.c | 72 +++++++++++----------- 3 files changed, 114 insertions(+), 36 deletions(-) create mode 100644 include/linux/unwind_user_eh_frame_types.h diff --git a/include/asm-generic/unwind_user_eh_frame.h b/include/asm-generic/unwind_user_eh_frame.h index da238557605b..a3cd3b3b55c7 100644 --- a/include/asm-generic/unwind_user_eh_frame.h +++ b/include/asm-generic/unwind_user_eh_frame.h @@ -2,6 +2,8 @@ #ifndef _ASM_GENERIC_UNWIND_USER_EH_FRAME_H #define _ASM_GENERIC_UNWIND_USER_EH_FRAME_H +#include + #ifndef EH_FRAME_MAX_CIE_LENGTH #define EH_FRAME_MAX_CIE_LENGTH 128 #endif @@ -14,6 +16,10 @@ #define EH_FRAME_MAX_AUGSTR_LENGTH 16 #endif +#ifndef EH_FRAME_MAX_EXPRESSION_LENGTH +#define EH_FRAME_MAX_EXPRESSION_LENGTH 32 +#endif + #ifndef EH_FRAME_MAX_STATE_STACK #define EH_FRAME_MAX_STATE_STACK 1 #endif @@ -47,5 +53,40 @@ static inline bool eh_frame_reject_sp_rule(void) #define eh_frame_reject_sp_rule eh_frame_reject_sp_rule #endif +#ifndef eh_frame_do_def_cfa_expression +static inline int eh_frame_do_def_cfa_expression(const char *expr, + int size, + unsigned long ip, + struct eh_frame_reg_state *reg_state) +{ + return -EOPNOTSUPP; +} +#define eh_frame_do_def_cfa_expression eh_frame_do_def_cfa_expression +#endif + +#ifndef eh_frame_do_expression +static inline int eh_frame_do_expression(unsigned int reg, + const char *expr, + int size, + unsigned long ip, + struct eh_frame_reg_state *reg_state) +{ + return -EOPNOTSUPP; +} +#define eh_frame_do_expression eh_frame_do_expression +#endif + +#ifndef eh_frame_do_val_expression +static inline int eh_frame_do_val_expression(unsigned int reg, + const char *expr, + int size, + unsigned long ip, + struct eh_frame_reg_state *reg_state) +{ + return -EOPNOTSUPP; +} +#define eh_frame_do_val_expression eh_frame_do_val_expression +#endif + #endif /* _ASM_GENERIC_UNWIND_USER_EH_FRAME_H */ diff --git a/include/linux/unwind_user_eh_frame_types.h b/include/linux/unwind_user_eh_frame_types.h new file mode 100644 index 000000000000..e9f9d1abb76f --- /dev/null +++ b/include/linux/unwind_user_eh_frame_types.h @@ -0,0 +1,37 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_UNWIND_USER_EH_FRAME_TYPES_H +#define _LINUX_UNWIND_USER_EH_FRAME_TYPES_H + +enum eh_frame_cfa_rule { + CFA_UNDEFINED, /* unrecoverable */ + CFA_REG_OFFSET, /* CFA = reg + offset */ +}; + +enum eh_frame_reg_rule { + REG_UNDEFINED_IMPLICIT, /* reg = reg */ + REG_UNDEFINED_EXPLICIT, /* unrecoverable; RA: outermost frame */ + REG_SAME_VALUE, /* reg = reg; TODO: reset to CIE initial CFI */ + REG_OFFSET, /* reg = *(CFA + offset) */ + REG_VAL_OFFSET, /* reg = CFA + offset */ + REG_REGISTER, /* reg = other_reg */ +}; + +enum eh_frame_reg_index { + FP_IDX, /* frame pointer (FP) */ + RA_IDX, /* return address (RA) */ + NR_REGS +}; + +struct eh_frame_reg_state { + /* CFA recovery rule */ + enum eh_frame_cfa_rule cfa_rule; + unsigned long cfa_regnum; + long cfa_offset; + + /* FP and RA recovery rules (SP uses implicit recovery) */ + enum eh_frame_reg_rule reg_rule[NR_REGS]; + unsigned long reg_regnum[NR_REGS]; + long reg_offset[NR_REGS]; +}; + +#endif /* _LINUX_UNWIND_USER_EH_FRAME_TYPES_H */ diff --git a/kernel/unwind/eh_frame.c b/kernel/unwind/eh_frame.c index d185187b0c34..a98804dbe588 100644 --- a/kernel/unwind/eh_frame.c +++ b/kernel/unwind/eh_frame.c @@ -12,45 +12,14 @@ #include #include #include +#include #include +#include #include #include "eh_frame.h" #include "eh_frame_debug.h" -/* Register state for CFI interpreter */ -enum eh_frame_cfa_rule { - CFA_UNDEFINED, /* unrecoverable */ - CFA_REG_OFFSET, /* CFA = reg + offset */ -}; - -enum eh_frame_reg_rule { - REG_UNDEFINED_IMPLICIT, /* reg = reg */ - REG_UNDEFINED_EXPLICIT, /* unrecoverable; RA: outermost frame */ - REG_SAME_VALUE, /* reg = reg; TODO: reset to CIE initial CFI */ - REG_OFFSET, /* reg = *(CFA + offset) */ - REG_VAL_OFFSET, /* reg = CFA + offset */ - REG_REGISTER, /* reg = other_reg */ -}; - -enum eh_frame_reg_index { - FP_IDX, /* frame pointer (FP) */ - RA_IDX, /* return address (RA) */ - NR_REGS -}; - -struct eh_frame_reg_state { - /* CFA recovery rule */ - enum eh_frame_cfa_rule cfa_rule; - unsigned long cfa_regnum; - long cfa_offset; - - /* FP and RA recovery rules (SP uses implicit recovery) */ - enum eh_frame_reg_rule reg_rule[NR_REGS]; - unsigned long reg_regnum[NR_REGS]; - long reg_offset[NR_REGS]; -}; - struct eh_frame_cfi_context { struct eh_frame_reg_state state; struct eh_frame_reg_state stack[EH_FRAME_MAX_STATE_STACK]; @@ -803,6 +772,27 @@ static __always_inline int __do_cfi_insn(struct eh_frame_section *sec, break; } + case DW_CFA_def_cfa_expression: { + unsigned long expr_len; + char expr[EH_FRAME_MAX_EXPRESSION_LENGTH]; + + ret = read_uleb128(&cur, end, &expr_len); + if (ret) + return ret; + + if (cur + expr_len < cur || cur + expr_len > end) + return -EINVAL; + + if (expr_len > sizeof(expr)) + return -EOPNOTSUPP; + unsafe_copy_from_user(&expr, (void __user *)cur, expr_len, Efault); + ret = eh_frame_do_def_cfa_expression(expr, expr_len, target_ip, &ctx->state); + if (ret) + return ret; + cur += expr_len; + break; + } + case DW_CFA_undefined: { unsigned long reg; int idx; @@ -970,12 +960,22 @@ static __always_inline int __do_cfi_insn(struct eh_frame_section *sec, if (ret) return ret; - if (cur + expr_len > end) + if (cur + expr_len < cur || cur + expr_len > end) return -EINVAL; - if (reg == EH_FRAME_REG_SP || reg == EH_FRAME_REG_FP || reg == EH_FRAME_REG_RA) - return -EOPNOTSUPP; + if (reg == EH_FRAME_REG_SP || reg == EH_FRAME_REG_FP || reg == EH_FRAME_REG_RA) { + char expr[EH_FRAME_MAX_EXPRESSION_LENGTH]; + if (expr_len > sizeof(expr)) + return -EOPNOTSUPP; + unsafe_copy_from_user(&expr, (void __user *)cur, expr_len, Efault); + if (opcode == DW_CFA_expression) + ret = eh_frame_do_expression(reg, expr, expr_len, target_ip, &ctx->state); + else + ret = eh_frame_do_val_expression(reg, expr, expr_len, target_ip, &ctx->state); + if (ret) + return ret; + } cur += expr_len; break; } -- 2.53.0