From patchwork Wed Jan 22 02:31:18 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Josh Poimboeuf X-Patchwork-Id: 13946786 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 A293A1D47AE; Wed, 22 Jan 2025 02:32:19 +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=1737513139; cv=none; b=Q6jlOZSi7/GZC3ntlk1EHv1jC5WvwYXfZ7IzcXFWaKJzqcG6gbo/iDZcifbbeyd2tcb5MGI/Z1B0V4SwWnv2hSNT4YqgSzVUH+sQHRbk5y4Bi0TsY/FNflPP7v1YJMf4uo2oj++MlB+MZROozw6flRRtuaTb5EpxaNjdwF4pOQQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737513139; c=relaxed/simple; bh=B3rzqWK+3dbuAMW6Yd/wHbo0urS3X1S4CoqxAu7Q/kk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iU/Hjkzhqkxy3Rg3isCtRc2X6jsX9j9CgjvMkUwE4pqPYzcHLoj/1unhF2tuG0B17+ze+PLL1OsThSnqlWJRiY2Rln1YNfbr9i8RGNwh9Q4cp1S84sQIMpeRr6G5e7Z29p9CXD7Yh1QW4YmvFQgeghiGCoXRUr+T5/rnnsfYFzI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jOs7iLC+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="jOs7iLC+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 482D1C4CEE2; Wed, 22 Jan 2025 02:32:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737513139; bh=B3rzqWK+3dbuAMW6Yd/wHbo0urS3X1S4CoqxAu7Q/kk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jOs7iLC+5Y5SrGTs+eo1KrPvKXGsuXcr6f96sJ+5cNCVKFqeCSgWZOfXyOSj+RxxN GVMtk7EWG6cvLgFcM5uDToqIKjSMYcN2WGCMOTlx/8smeoo0SFRVHCeaEIBd6KD2bB 3bS5cpt4MN8xVWDNzlc2VldfshL979OlZH2Tr655aqQ35ZTE1YQe71gzifVOUFvl5V Wzr6ve+JcAEpG6dQftuBERuN1RsPlGb/bODQsLn1kSkfTKGR1sX82b4rEMAzWJ8DyA MWnbv/FjR8YnvXWGc0T6y5lyU3QlJD4p6Cn0jElKRpb8Uyy1mf3YnK1q3J4+d21lM+ nI+R1/HzDkmhQ== From: Josh Poimboeuf To: x86@kernel.org Cc: Peter Zijlstra , Steven Rostedt , Ingo Molnar , Arnaldo Carvalho de Melo , linux-kernel@vger.kernel.org, Indu Bhagat , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Ian Rogers , Adrian Hunter , linux-perf-users@vger.kernel.org, Mark Brown , linux-toolchains@vger.kernel.org, Jordan Rome , Sam James , linux-trace-kernel@vger.kernel.org, Andrii Nakryiko , Jens Remus , Mathieu Desnoyers , Florian Weimer , Andy Lutomirski , Masami Hiramatsu , Weinan Liu Subject: [PATCH v4 26/39] unwind_user/sframe: Enable debugging in uaccess regions Date: Tue, 21 Jan 2025 18:31:18 -0800 Message-ID: <990b28ae7855b67c5e6d6385b9de78ffa336dd73.1737511963.git.jpoimboe@kernel.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Objtool warns about calling pr_debug() from uaccess-enabled regions, and rightfully so. Add a dbg_sec_uaccess() macro which temporarily disables uaccess before doing the dynamic printk, and use that to add debug messages throughout the uaccess-enabled regions. Signed-off-by: Josh Poimboeuf --- kernel/unwind/sframe.c | 59 ++++++++++++++++++++++++++++-------- kernel/unwind/sframe_debug.h | 31 +++++++++++++++++++ 2 files changed, 77 insertions(+), 13 deletions(-) diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index f463123f9afe..a2ca26b952d3 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -53,12 +53,15 @@ static __always_inline int __read_fde(struct sframe_section *sec, sizeof(struct sframe_fde), Efault); ip = sec->sframe_start + fde->start_addr; - if (ip < sec->text_start || ip > sec->text_end) + if (ip < sec->text_start || ip > sec->text_end) { + dbg_sec_uaccess("bad fde num %d\n", fde_num); return -EINVAL; + } return 0; Efault: + dbg_sec_uaccess("fde %d usercopy failed\n", fde_num); return -EFAULT; } @@ -85,16 +88,22 @@ static __always_inline int __find_fde(struct sframe_section *sec, unsafe_get_user(func_off, (s32 __user *)mid, Efault); if (ip_off >= func_off) { - if (func_off < func_off_low) + if (func_off < func_off_low) { + dbg_sec_uaccess("fde %u not sorted\n", + (unsigned int)(mid - first)); return -EFAULT; + } func_off_low = func_off; found = mid; low = mid + 1; } else { - if (func_off > func_off_high) + if (func_off > func_off_high) { + dbg_sec_uaccess("fde %u not sorted\n", + (unsigned int)(mid - first)); return -EFAULT; + } func_off_high = func_off; @@ -140,6 +149,8 @@ static __always_inline int __find_fde(struct sframe_section *sec, __UNSAFE_GET_USER_INC(to, from, u32, label); \ break; \ default: \ + dbg_sec_uaccess("%d: bad UNSAFE_GET_USER_INC size %u\n",\ + __LINE__, size); \ return -EFAULT; \ } \ }) @@ -158,24 +169,34 @@ static __always_inline int __read_fre(struct sframe_section *sec, u8 info; addr_size = fre_type_to_size(fre_type); - if (!addr_size) + if (!addr_size) { + dbg_sec_uaccess("bad addr_size in fde info %u\n", fde->info); return -EFAULT; + } - if (fre_addr + addr_size + 1 > sec->fres_end) + if (fre_addr + addr_size + 1 > sec->fres_end) { + dbg_sec_uaccess("fre addr+info goes past end of subsection\n"); return -EFAULT; + } UNSAFE_GET_USER_INC(ip_off, cur, addr_size, Efault); - if (fde_type == SFRAME_FDE_TYPE_PCINC && ip_off > fde->func_size) + if (fde_type == SFRAME_FDE_TYPE_PCINC && ip_off > fde->func_size) { + dbg_sec_uaccess("fre starts past end of function: ip_off=0x%x, func_size=0x%x\n", + ip_off, fde->func_size); return -EFAULT; + } UNSAFE_GET_USER_INC(info, cur, 1, Efault); offset_count = SFRAME_FRE_OFFSET_COUNT(info); offset_size = offset_size_enum_to_size(SFRAME_FRE_OFFSET_SIZE(info)); - if (!offset_count || !offset_size) + if (!offset_count || !offset_size) { + dbg_sec_uaccess("zero offset_count or size in fre info %u\n",info); return -EFAULT; - - if (cur + (offset_count * offset_size) > sec->fres_end) + } + if (cur + (offset_count * offset_size) > sec->fres_end) { + dbg_sec_uaccess("fre goes past end of subsection\n"); return -EFAULT; + } fre->size = addr_size + 1 + (offset_count * offset_size); @@ -184,8 +205,10 @@ static __always_inline int __read_fre(struct sframe_section *sec, ra_off = sec->ra_off; if (!ra_off) { - if (!offset_count--) + if (!offset_count--) { + dbg_sec_uaccess("zero offset_count, can't find ra_off\n"); return -EFAULT; + } UNSAFE_GET_USER_INC(ra_off, cur, offset_size, Efault); } @@ -196,8 +219,10 @@ static __always_inline int __read_fre(struct sframe_section *sec, UNSAFE_GET_USER_INC(fp_off, cur, offset_size, Efault); } - if (offset_count) + if (offset_count) { + dbg_sec_uaccess("non-zero offset_count after reading fre\n"); return -EFAULT; + } fre->ip_off = ip_off; fre->cfa_off = cfa_off; @@ -208,6 +233,7 @@ static __always_inline int __read_fre(struct sframe_section *sec, return 0; Efault: + dbg_sec_uaccess("fre usercopy failed\n"); return -EFAULT; } @@ -241,13 +267,20 @@ static __always_inline int __find_fre(struct sframe_section *sec, which = !which; ret = __read_fre(sec, fde, fre_addr, fre); - if (ret) + if (ret) { + dbg_sec_uaccess("fde addr 0x%x: __read_fre(%u) failed\n", + fde->start_addr, i); + dbg_print_fde_uaccess(sec, fde); return ret; + } fre_addr += fre->size; - if (prev_fre && fre->ip_off <= prev_fre->ip_off) + if (prev_fre && fre->ip_off <= prev_fre->ip_off) { + dbg_sec_uaccess("fde addr 0x%x: fre %u not sorted\n", + fde->start_addr, i); return -EFAULT; + } if (fre->ip_off > ip_off) break; diff --git a/kernel/unwind/sframe_debug.h b/kernel/unwind/sframe_debug.h index 4d121cdbb760..3bb3c5574aee 100644 --- a/kernel/unwind/sframe_debug.h +++ b/kernel/unwind/sframe_debug.h @@ -13,6 +13,26 @@ #define dbg_sec(fmt, ...) \ dbg("%s: " fmt, sec->filename, ##__VA_ARGS__) +#define __dbg_sec_descriptor(fmt, ...) \ + __dynamic_pr_debug(&descriptor, "sframe: %s: " fmt, \ + sec->filename, ##__VA_ARGS__) + +/* + * To avoid breaking uaccess rules, temporarily disable uaccess + * before calling printk. + */ +#define dbg_sec_uaccess(fmt, ...) \ +({ \ + DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, fmt); \ + if (DYNAMIC_DEBUG_BRANCH(descriptor)) { \ + user_read_access_end(); \ + __dbg_sec_descriptor(fmt, ##__VA_ARGS__); \ + BUG_ON(!user_read_access_begin( \ + (void __user *)sec->sframe_start, \ + sec->sframe_end - sec->sframe_start)); \ + } \ +}) + static __always_inline void dbg_print_header(struct sframe_section *sec) { unsigned long fdes_end; @@ -27,6 +47,15 @@ static __always_inline void dbg_print_header(struct sframe_section *sec) sec->ra_off, sec->fp_off); } +static __always_inline void dbg_print_fde_uaccess(struct sframe_section *sec, + struct sframe_fde *fde) +{ + dbg_sec_uaccess("FDE: start_addr:0x%x func_size:0x%x " + "fres_off:0x%x fres_num:%d info:%u rep_size:%u\n", + fde->start_addr, fde->func_size, + fde->fres_off, fde->fres_num, fde->info, fde->rep_size); +} + static inline void dbg_init(struct sframe_section *sec) { struct mm_struct *mm = current->mm; @@ -53,8 +82,10 @@ static inline void dbg_free(struct sframe_section *sec) #define dbg(args...) no_printk(args) #define dbg_sec(args... ) no_printk(args) +#define dbg_sec_uaccess(args...) no_printk(args) static inline void dbg_print_header(struct sframe_section *sec) {} +static inline void dbg_print_fde_uaccess(struct sframe_section *sec, struct sframe_fde *fde) {} static inline void dbg_init(struct sframe_section *sec) {} static inline void dbg_free(struct sframe_section *sec) {}