From mboxrd@z Thu Jan 1 00:00:00 1970 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 35E4B201266; Thu, 17 Jul 2025 01:29:17 +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=1752715757; cv=none; b=TRqCGIrDXJsJNqfZTFfhwBIxn3+nnCMKWrMdlpOB+7G7H8gpUX3UiOCWwzWAJPTZ9qsg5dViOpjUwAkLtHUUdLVP0xaWtb02qfQagFzmwkn7Q1WlVQlchOypeZF5FpD5U/9hctG5fBOVLs30UX0vuDw/rwxhpDb+1B7nsEwzMUE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752715757; c=relaxed/simple; bh=4F5bhtu+AeVLBh1l+vr+oVd4e2NJyQ/WurK8gegYfEo=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=p0ZwptH8UAQ7AuqXnDNjHjV5bfkCc9HCxSDTDQXLt/53ONq0p5qCtTre/+m9pX8Qz+jvPen2IZ52OxjJiPQfdloiA2vD6xle/suz9TldMotELDc/nheE2xeSGXeQnV/OJ9ub1+HDZ+FAuayHvyDCJM+bxMTEe3D36LYUWEpsyr0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=diznEM3B; 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="diznEM3B" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 15973C4CEF5; Thu, 17 Jul 2025 01:29:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752715757; bh=4F5bhtu+AeVLBh1l+vr+oVd4e2NJyQ/WurK8gegYfEo=; h=Date:From:To:Cc:Subject:References:From; b=diznEM3BkP5TBu0y2w1JUY6DwUwLHJP4KCdQw0stMNXyRX/WYE+a7/ysCAnp29Ew0 yGM7hpd7GqEMlHTgBw/0ikpEt1yg/JDS8Qsknnvo2+zIsh+jzJgsSOTH5/uOyR0bdT cXvGNA8Iwqcm4kdrz/oWcx663NRyVnFtYf5HZGFlCXn73YvJZ5TFe4vUohm7L2a2B9 /haqMuDLQeP8kLsE45h7KwaDtISbiJuDio2sqpHccsJM1JByjy79a0TB7iefInwSXd 3H8TS04js8u0Uq3fpI8WTzneyirPKOcWTLB6fb5aONsZf/YUcRgXHI8zALNSrsLafy GlTNZHsbuDKSg== Received: from rostedt by gandalf with local (Exim 4.98.2) (envelope-from ) id 1ucDRJ-000000068zD-1ss1; Wed, 16 Jul 2025 21:29:37 -0400 Message-ID: <20250717012937.297411041@kernel.org> User-Agent: quilt/0.68 Date: Wed, 16 Jul 2025 21:28:58 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, x86@kernel.org Cc: Masami Hiramatsu , Mathieu Desnoyers , Josh Poimboeuf , Peter Zijlstra , Ingo Molnar , Jiri Olsa , Namhyung Kim , Thomas Gleixner , Andrii Nakryiko , Indu Bhagat , "Jose E. Marchesi" , Beau Belgrave , Jens Remus , Linus Torvalds , Andrew Morton , Jens Axboe , Florian Weimer , Sam James Subject: [PATCH v9 10/11] unwind_user/sframe: Add .sframe validation option References: <20250717012848.927473176@kernel.org> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 From: Josh Poimboeuf Add a debug feature to validate all .sframe sections when first loading the file rather than on demand. Signed-off-by: Josh Poimboeuf Signed-off-by: Steven Rostedt (Google) --- Changes since v8: https://lore.kernel.org/20250708021200.223446028@kernel.org - Add "safe_read_fre()" and "safe_read_fde()" to call their respective functions with a user_read_access_begin() wrapper around them so that the validator can simply use dbg_sec() directly instead of a _uaccess() hacked version. arch/Kconfig | 19 +++++++++ kernel/unwind/sframe.c | 96 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 115 insertions(+) diff --git a/arch/Kconfig b/arch/Kconfig index f3b3e5a91f6d..c2f12135db92 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -446,6 +446,25 @@ config HAVE_UNWIND_USER_SFRAME bool select UNWIND_USER +config SFRAME_VALIDATION + bool "Enable .sframe section debugging" + depends on HAVE_UNWIND_USER_SFRAME + depends on DYNAMIC_DEBUG + help + When adding an .sframe section for a task, validate the entire + section immediately rather than on demand. + + This is a debug feature which is helpful for rooting out .sframe + section issues. If the .sframe section is corrupt, it will fail to + load immediately, with more information provided in dynamic printks. + + This has a significant page cache footprint due to its reading of the + entire .sframe section for every loaded executable and shared + library. Also, it's done for all processes, even those which don't + get stack traced by the kernel. Not recommended for general use. + + If unsure, say N. + config HAVE_PERF_REGS bool help diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index 66d3ba3c8389..79ff3c0fc11f 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -319,6 +319,98 @@ int sframe_find(unsigned long ip, struct unwind_user_frame *frame) return ret; } +#ifdef CONFIG_SFRAME_VALIDATION + +static int safe_read_fde(struct sframe_section *sec, + unsigned int fde_num, struct sframe_fde *fde) +{ + int ret; + + if (!user_read_access_begin((void __user *)sec->sframe_start, + sec->sframe_end - sec->sframe_start)) + return -EFAULT; + ret = __read_fde(sec, fde_num, fde); + user_read_access_end(); + return ret; +} + +static int safe_read_fre(struct sframe_section *sec, + struct sframe_fde *fde, unsigned long fre_addr, + struct sframe_fre *fre) +{ + int ret; + + if (!user_read_access_begin((void __user *)sec->sframe_start, + sec->sframe_end - sec->sframe_start)) + return -EFAULT; + ret = __read_fre(sec, fde, fre_addr, fre); + user_read_access_end(); + return ret; +} + +static int sframe_validate_section(struct sframe_section *sec) +{ + unsigned long prev_ip = 0; + unsigned int i; + + for (i = 0; i < sec->num_fdes; i++) { + struct sframe_fre *fre, *prev_fre = NULL; + unsigned long ip, fre_addr; + struct sframe_fde fde; + struct sframe_fre fres[2]; + bool which = false; + unsigned int j; + int ret; + + ret = safe_read_fde(sec, i, &fde); + if (ret) + return ret; + + ip = sec->sframe_start + fde.start_addr; + if (ip <= prev_ip) { + dbg_sec("fde %u not sorted\n", i); + return -EFAULT; + } + prev_ip = ip; + + fre_addr = sec->fres_start + fde.fres_off; + for (j = 0; j < fde.fres_num; j++) { + int ret; + + fre = which ? fres : fres + 1; + which = !which; + + ret = safe_read_fre(sec, &fde, fre_addr, fre); + if (ret) { + dbg_sec("fde %u: __read_fre(%u) failed\n", i, j); + dbg_sec("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); + return ret; + } + + fre_addr += fre->size; + + if (prev_fre && fre->ip_off <= prev_fre->ip_off) { + dbg_sec("fde %u: fre %u not sorted\n", i, j); + return -EFAULT; + } + + prev_fre = fre; + } + } + + return 0; +} + +#else /* !CONFIG_SFRAME_VALIDATION */ + +static int sframe_validate_section(struct sframe_section *sec) { return 0; } + +#endif /* !CONFIG_SFRAME_VALIDATION */ + + static void free_section(struct sframe_section *sec) { dbg_free(sec); @@ -427,6 +519,10 @@ int sframe_add_section(unsigned long sframe_start, unsigned long sframe_end, goto err_free; } + ret = sframe_validate_section(sec); + if (ret) + goto err_free; + ret = mtree_insert_range(sframe_mt, sec->text_start, sec->text_end, sec, GFP_KERNEL); if (ret) { dbg_sec("mtree_insert_range failed: text=%lx-%lx\n", -- 2.47.2