From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D084147B439 for ; Tue, 28 Apr 2026 18:37:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777401450; cv=none; b=WwZI+06ECDVKlCOXlZPqD/iAEGl+Wp5Lhsrbk6uQJMuvppoz8vnxCTHvgL1gE3oKW4LNxZIcKLfInCJBlcYIfv44FbegC0Sgwujt2mrYYm99Or40zSahZTm3akSATT++mOkCBL5bRT6V1GNlaYsGOCUicDXXC6o3R9as1yQgP+8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777401450; c=relaxed/simple; bh=wm8fmz57HEth2J1hN6vgXStLpyz5KgZ/vbS889B0dtc=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=BAmK2R27V7u48aaFi7WTUru81F7v2eN6Tmb7eQxapEZwySDnvG7W1oh0D3rsbBxz+ZTZmFEcmvWXBR4TYs4ZIeSNPxJdBgEwR0ElsvA9aixdKzkL5DLUPoAFJdyaVPzGSwf0nMnGS+ixIUKxeMSGg96kFJH4DKZAk/MQnWM0u8E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--dylanbhatch.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=uRZkCkQg; arc=none smtp.client-ip=209.85.214.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--dylanbhatch.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="uRZkCkQg" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-2b2ed279eedso82047535ad.0 for ; Tue, 28 Apr 2026 11:37:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1777401448; x=1778006248; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=Goh3F7XcpkTSr7iRpzcfIAl6DDNpb912M5nWLNqSnmg=; b=uRZkCkQgy1PKvqXpmzO4WYWxYJLJbamh9mliJPRtSNHvwF907HMdmgAXWVhvINHonG jYPPNcBRkqHuOJ2+zoKypMm+LA7rWzEpgG3dI0O2jMJnRkJ6oKykwYofV3fWzA7bmebN j0+f6hP9wdQx1GWEkKmWRk4ja7H1WV1rIvK84anqqdmt8z95XsnqZTBOg93wvOdUASwU +i+z8d92fjSoNUTNi1ETzgwOnTCx6yPOyffCtQgkx/FTzYXjHjoAV4SlwiDrrY7fLuc8 DZqF6uEZquvvETjiRANAIoWdVAtA7Ng2gE996+0RoZBk+M2ZiZTEQp0QRJoQQ33tWA/N 7T8w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777401448; x=1778006248; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Goh3F7XcpkTSr7iRpzcfIAl6DDNpb912M5nWLNqSnmg=; b=f6zzQOTUaYV0dGDycpAOWNzCI/lR6jh2YepSV7POTPvPb7jMqEwPUiGx8tQHFh10dV SNP534Afwa60VrPCtlXCdpn2hasBIZ5BR5IZMAtfMrjqEfNfHv6bwTbnAkUSnUU35Y3T JSnDqU1F8gLjnvgx0PvkcIW/7cWf0MN6U9i1XUFeqlfVu2Xy5mg6BsTPZzfILpblDSn8 s6eCBb7SxKcnaEY+ju3UGv3SH1HxYxDfheTd+CW6BK1HPyWc0D74ool0OXtg4Xnstjo6 1paP46s46Fm5Qmv+gIoQsLTwLuuKVzTNd9RpdutEBMMM7OB3YcVE81kDJuUEinyNEwK5 5MsA== X-Forwarded-Encrypted: i=1; AFNElJ+2MYrq4pPOUH2zbiFbK87U6vLRNvZkbmbi5ibylQN0lOmolm+dPLPCENOROT13Xg/ePR8kvPfxQf4gT/c=@vger.kernel.org X-Gm-Message-State: AOJu0Yw7ahDsX5ueL8G5u8Fr2s1R//DsLj8gb6rY8DqmaZB1aycjnNun /SLdWszETYdDC2GkzBucfjhiwzAxHCx0k2y0lvRDe/lCHjOPvlgfvQWTdSDnlfS8tFgsjTURnsa TkpOqjG1lmddZvgBLS1+Pw8fMSg== X-Received: from plbkg3.prod.google.com ([2002:a17:903:603:b0:2b4:5fd0:a45d]) (user=dylanbhatch job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:3583:b0:2b0:59c4:e9dc with SMTP id d9443c01a7336-2b987407cfamr4803655ad.22.1777401447910; Tue, 28 Apr 2026 11:37:27 -0700 (PDT) Date: Tue, 28 Apr 2026 18:36:42 +0000 In-Reply-To: <20260428183643.3796063-1-dylanbhatch@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260428183643.3796063-1-dylanbhatch@google.com> X-Mailer: git-send-email 2.54.0.545.g6539524ca2-goog Message-ID: <20260428183643.3796063-8-dylanbhatch@google.com> Subject: [PATCH v5 7/8] sframe: Introduce in-kernel SFRAME_VALIDATION From: Dylan Hatch To: Roman Gushchin , Weinan Liu , Will Deacon , Josh Poimboeuf , Indu Bhagat , Peter Zijlstra , Steven Rostedt , Catalin Marinas , Jiri Kosina , Jens Remus Cc: Dylan Hatch , Mark Rutland , Prasanna Kumar T S M , Puranjay Mohan , Song Liu , joe.lawrence@redhat.com, linux-toolchains@vger.kernel.org, linux-kernel@vger.kernel.org, live-patching@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Randy Dunlap Content-Type: text/plain; charset="UTF-8" Generalize the __safe* helpers to support a non-user-access code path. This requires arch-specific function address validation. This is because arm64 vmlinux keeps .exit.text (normally discarded), and .rodata.text sections both of which lie outside the bounds of the normal .text. .rodata.text contains code that is never executed by the kernel mapping, but for which the toolchain nonetheless generates sframe data, and needs to be considered valid for a PC lookup. Additionally .init.text lies outside .text for all arches and must be accounted for as well. Suggested-by: Jens Remus Reviewed-by: Jens Remus Signed-off-by: Dylan Hatch --- arch/Kconfig | 2 +- arch/arm64/include/asm/sections.h | 1 + arch/arm64/include/asm/unwind_sframe.h | 47 ++++++++++++++++++++++++++ arch/arm64/kernel/vmlinux.lds.S | 2 ++ include/linux/sframe.h | 2 ++ kernel/unwind/sframe.c | 25 ++++++++++++-- 6 files changed, 76 insertions(+), 3 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index 8d27b3249e7a..a528f5b23647 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -503,7 +503,7 @@ config HAVE_UNWIND_USER_SFRAME config SFRAME_VALIDATION bool "Enable .sframe section debugging" - depends on HAVE_UNWIND_USER_SFRAME + depends on UNWIND_SFRAME_LOOKUP depends on DYNAMIC_DEBUG help When adding an .sframe section for a task, validate the entire diff --git a/arch/arm64/include/asm/sections.h b/arch/arm64/include/asm/sections.h index 51b0d594239e..5edb4304f661 100644 --- a/arch/arm64/include/asm/sections.h +++ b/arch/arm64/include/asm/sections.h @@ -23,6 +23,7 @@ extern char __irqentry_text_start[], __irqentry_text_end[]; extern char __mmuoff_data_start[], __mmuoff_data_end[]; extern char __entry_tramp_text_start[], __entry_tramp_text_end[]; extern char __relocate_new_kernel_start[], __relocate_new_kernel_end[]; +extern char _srodatatext[], _erodatatext[]; static inline size_t entry_tramp_text_size(void) { diff --git a/arch/arm64/include/asm/unwind_sframe.h b/arch/arm64/include/asm/unwind_sframe.h index 876412881196..66ebe5f38bd0 100644 --- a/arch/arm64/include/asm/unwind_sframe.h +++ b/arch/arm64/include/asm/unwind_sframe.h @@ -2,7 +2,54 @@ #ifndef _ASM_ARM64_UNWIND_SFRAME_H #define _ASM_ARM64_UNWIND_SFRAME_H +#include +#include +#include + #define SFRAME_REG_SP 31 #define SFRAME_REG_FP 29 +static inline bool sframe_func_start_addr_valid(struct sframe_section *sec, + unsigned long func_addr) +{ + /* Common case for unwinding */ + if (sec->text_start <= func_addr && func_addr < sec->text_end) + return true; + + if (sec->sec_type != SFRAME_KERNEL) + return false; + + /* + * Account for vmlinux and module code outside the normal .text section. + * The toolchain still generates sframe data for these functions, so + * sframe lookups on them should be allowed. + */ + if (sec == &kernel_sfsec) { + if (is_kernel_inittext(func_addr)) + return true; + + /* .exit.text is retained in vmlinux on arm64. */ + if (func_addr >= (unsigned long)__exittext_begin && + func_addr < (unsigned long)__exittext_end) + return true; + + + /* + * .rodata.text is never executed from the kernel mapping, but + * still has sframe data + */ + if (func_addr >= (unsigned long)_srodatatext && + func_addr < (unsigned long)_erodatatext) + return true; + } else { + struct module *mod = container_of(sec, struct module, + arch.sframe_sec); + if (within_module_mem_type(func_addr, mod, MOD_INIT_TEXT)) + return true; + } + + return false; +} +#define sframe_func_start_addr_valid sframe_func_start_addr_valid + #endif /* _ASM_ARM64_UNWIND_SFRAME_H */ diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 2964aad0362e..8c2dae6e7a86 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -213,12 +213,14 @@ SECTIONS /* code sections that are never executed via the kernel mapping */ .rodata.text : { + _srodatatext = .; TRAMP_TEXT HIBERNATE_TEXT KEXEC_TEXT IDMAP_TEXT . = ALIGN(PAGE_SIZE); } + _erodatatext = .; idmap_pg_dir = .; . += PAGE_SIZE; diff --git a/include/linux/sframe.h b/include/linux/sframe.h index 27f5a66190af..ac3aa9db7d91 100644 --- a/include/linux/sframe.h +++ b/include/linux/sframe.h @@ -34,6 +34,8 @@ struct sframe_section { signed char fp_off; }; +extern struct sframe_section kernel_sfsec __ro_after_init; + #endif /* CONFIG_UNWIND_SFRAME_LOOKUP */ #ifdef CONFIG_HAVE_UNWIND_USER_SFRAME diff --git a/kernel/unwind/sframe.c b/kernel/unwind/sframe.c index 70001c8e586d..99c2a39c51ce 100644 --- a/kernel/unwind/sframe.c +++ b/kernel/unwind/sframe.c @@ -21,10 +21,18 @@ #include "sframe.h" #include "sframe_debug.h" +#ifndef sframe_func_start_addr_valid +static inline bool sframe_func_start_addr_valid(struct sframe_section *sec, + unsigned long func_addr) +{ + return (sec->text_start <= func_addr && func_addr < sec->text_end); +} +#endif + #ifdef CONFIG_HAVE_UNWIND_KERNEL_SFRAME static bool sframe_init __ro_after_init; -static struct sframe_section kernel_sfsec __ro_after_init; +struct sframe_section kernel_sfsec __ro_after_init; #endif /* CONFIG_HAVE_UNWIND_KERNEL_SFRAME */ @@ -152,7 +160,7 @@ static __always_inline int __read_fde(struct sframe_section *sec, sizeof(struct sframe_fde_v3), Efault); func_addr = fde_addr + _fde.func_start_off; - if (func_addr < sec->text_start || func_addr > sec->text_end) + if (!sframe_func_start_addr_valid(sec, func_addr)) return -EINVAL; fda_addr = sec->fres_start + _fde.fres_off; @@ -636,6 +644,9 @@ static int safe_read_fde(struct sframe_section *sec, { int ret; + if (sec->sec_type == SFRAME_KERNEL) + return __read_fde(sec, fde_num, fde); + if (!user_read_access_begin((void __user *)sec->sframe_start, sec->sframe_end - sec->sframe_start)) return -EFAULT; @@ -651,6 +662,9 @@ static int safe_read_fre(struct sframe_section *sec, { int ret; + if (sec->sec_type == SFRAME_KERNEL) + return __read_fre(sec, fde, fre_addr, fre); + if (!user_read_access_begin((void __user *)sec->sframe_start, sec->sframe_end - sec->sframe_start)) return -EFAULT; @@ -665,6 +679,9 @@ static int safe_read_fre_datawords(struct sframe_section *sec, { int ret; + if (sec->sec_type == SFRAME_KERNEL) + return __read_fre_datawords(sec, fde, fre); + if (!user_read_access_begin((void __user *)sec->sframe_start, sec->sframe_end - sec->sframe_start)) return -EFAULT; @@ -1013,6 +1030,8 @@ void __init init_sframe_table(void) if (WARN_ON(sframe_read_header(&kernel_sfsec))) return; + if (WARN_ON(sframe_validate_section(&kernel_sfsec))) + return; sframe_init = true; } @@ -1031,6 +1050,8 @@ void sframe_module_init(struct module *mod, void *sframe, size_t sframe_size, if (WARN_ON(sframe_read_header(&sec))) return; + if (WARN_ON(sframe_validate_section(&sec))) + return; mod->arch.sframe_sec = sec; mod->arch.sframe_init = true; -- 2.54.0.545.g6539524ca2-goog