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 63BDD22FDE8; Tue, 8 Jul 2025 02:12:00 +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=1751940720; cv=none; b=rxQvz7okaFDQ0mEZrHuoU3GpyQjbHYFUGtaj50XMdBQzGian7POBewt8CBzdLRkhkhWbegIUy2WVA1q0/MjLoUwDGVaiTD41JEo+HK/a0dXaafAGhkPfmebXduIIY4axyQhcuI7SZlPhZldTMOqhlZU7AW8L17v/z2u050laJOc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751940720; c=relaxed/simple; bh=cQU/IOg2dV3IqPOdj6NyIdrtPpR/u8Ehsn+YFDVM0xo=; h=Message-ID:Date:From:To:Cc:Subject:References:MIME-Version: Content-Type; b=fKKxfSrMr4Zc57P7qgbk3MJiWYnLf6pSZ9msYkPNovBnEgOPdryxB/PxpwPaXAjCCCaFhMQJyRL7dARQOWKdf1gdS1eEmZxOBBhkCvmlgqz2pSqGINYV38xCl/88QLddGSnJATaZ5fxbMXVHWzW5p9zXMNKok7gODai5QkXlTZo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fPA1tQIM; 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="fPA1tQIM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD6B2C4CEE3; Tue, 8 Jul 2025 02:11:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751940720; bh=cQU/IOg2dV3IqPOdj6NyIdrtPpR/u8Ehsn+YFDVM0xo=; h=Date:From:To:Cc:Subject:References:From; b=fPA1tQIMqWWWMvKLXkD89IR5zIbHTYWDwq4rE/Utz13qlxjhuZJOVyDMxCNP2Ofh9 +kfd035HAz/KpEbC/gvlo7meJNdQzzHiwZWXoSa+fmvqtvV6joMrBQ2IZH467W94LZ GGl8LjdbntSXY0QNidTBtRQhT8EWfAm+yW18KN17/MRuk/M68H6Q+/CStu7Fri3RH7 NfBKPIgH7zZcRIO3vq56hMU9wWzmgsQUVlIqGgN8dByrwNAp41oZFBPD7bQIMNDJL+ AG7vLjZO95vqu588voAnQXLEuYeGtx+6N6HkO6+OSSO9eHWPrOqcKRP716KuwUx+tE 6Sx+o0dIM61BQ== Received: from rostedt by gandalf with local (Exim 4.98.2) (envelope-from ) id 1uYxoO-00000000DfW-0qoe; Mon, 07 Jul 2025 22:12:00 -0400 Message-ID: <20250708021200.058879671@kernel.org> User-Agent: quilt/0.68 Date: Mon, 07 Jul 2025 22:11:25 -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 v8 10/12] unwind_user/sframe: Enable debugging in uaccess regions References: <20250708021115.894007410@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 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 Signed-off-by: Steven Rostedt (Google) --- kernel/unwind/sframe.c | 60 ++++++++++++++++++++++++++++-------- kernel/unwind/sframe_debug.h | 31 +++++++++++++++++++ 2 files changed, 78 insertions(+), 13 deletions(-) diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index 66d3ba3c8389..3972bce40fc7 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; @@ -116,6 +125,7 @@ static __always_inline int __find_fde(struct sframe_section *sec, return 0; Efault: + dbg_sec_uaccess("fde usercopy failed\n"); return -EFAULT; } @@ -140,6 +150,8 @@ static __always_inline int __find_fde(struct sframe_section *sec, ____UNSAFE_GET_USER_INC(to, from, u_or_s##32, label); \ break; \ default: \ + dbg_sec_uaccess("%d: bad UNSAFE_GET_USER_INC size %u\n",\ + __LINE__, size); \ return -EFAULT; \ } \ }) @@ -174,24 +186,34 @@ 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); @@ -200,8 +222,10 @@ 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); } @@ -212,8 +236,10 @@ 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; @@ -224,6 +250,7 @@ static __always_inline int __read_fre(struct sframe_section *sec, return 0; Efault: + dbg_sec_uaccess("fre usercopy failed\n"); return -EFAULT; } @@ -257,13 +284,20 @@ 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 7794bf0bd78c..045e9c0b16c9 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; @@ -57,8 +86,10 @@ 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) {} -- 2.47.2