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 1A115371460; Sat, 28 Feb 2026 17:57:39 +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=1772301459; cv=none; b=tk/C0BOVfY0fDznRnaqQMi6FpkjT3eBI8cAWGM5J+wa7ol3I68YnOYky9VooAcBi+ajl6/2s1xTjAO4WNAb3skggxL/0MYXqQUixAlo7v65AOH8LiYlPC6S+Dyr2GYP4NL70NIraVh96VSBgzAUN2u8TxAPYfpIhO13a2iOr4Q4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772301459; c=relaxed/simple; bh=A1f1QShUP6lQqJ7k1RJjkakWAtceu7yz6XBz1K+AskQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DLmXs/fXXoLLwpFxFFretfftfr7sFmj3ZYpooji00YwTsAL0ppe34L5T3p/UlWX7Gbr08j7u6HrptKSQEvLNQk6a2Y2T3ez9A/FBeMD+VeCYeA6ZmaBHXiYkHvaWO3vJbkKl+nhIWiVQxro63QS0USlQ0cYFBp9VXUQM6reJE9M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=X2gOjI9E; 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="X2gOjI9E" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AAEC5C116D0; Sat, 28 Feb 2026 17:57:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772301459; bh=A1f1QShUP6lQqJ7k1RJjkakWAtceu7yz6XBz1K+AskQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=X2gOjI9ECiKwcs+H7GJsd6ozM2HqO9XqaK8SbZvsGOtJ6lihdpSUFbazUssuDW3gy EGNHFX9CFBcmHj6sJAcpfB0w+CNl8BLT2O3V/9XGq0I/zx970noRTbsTV9ub0vbDTD fsEZjIqJ6Gk9PTtMCt0Qda4SxqDhob+vc1IUov3f4V/oGThD3XIJ2dwyB/71oYSVLf Y+igb14dxOk2xMSh+AFKkEbkMHUSo4fC3L6enwT5b+uPflA212+eykvgVvpFavFTZ0 JhNYsu6wRMsX833zbTWNqFbeOGdtKa8KgC+hTEC32L5Mf0qujkwPelOw41umKCshE+ cCQRY3UYZ8BTQ== From: Sasha Levin To: patches@lists.linux.dev Cc: Li Chen , Baoquan He , Alexander Graf , Eric Biggers , Philipp Rudo , Ricardo Ribalda Delgado , Ross Zwisler , Sourabh Jain , Steven Rostedt , stable@vger.kernel.org, Andrew Morton , Sasha Levin Subject: [PATCH 6.18 644/752] kexec: derive purgatory entry from symbol Date: Sat, 28 Feb 2026 12:45:55 -0500 Message-ID: <20260228174750.1542406-644-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260228174750.1542406-1-sashal@kernel.org> References: <20260228174750.1542406-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit From: Li Chen [ Upstream commit 480e1d5c64bb14441f79f2eb9421d5e26f91ea3d ] kexec_load_purgatory() derives image->start by locating e_entry inside an SHF_EXECINSTR section. If the purgatory object contains multiple executable sections with overlapping sh_addr, the entrypoint check can match more than once and trigger a WARN. Derive the entry section from the purgatory_start symbol when present and compute image->start from its final placement. Keep the existing e_entry fallback for purgatories that do not expose the symbol. WARNING: kernel/kexec_file.c:1009 at kexec_load_purgatory+0x395/0x3c0, CPU#10: kexec/1784 Call Trace: bzImage64_load+0x133/0xa00 __do_sys_kexec_file_load+0x2b3/0x5c0 do_syscall_64+0x81/0x610 entry_SYSCALL_64_after_hwframe+0x76/0x7e [me@linux.beauty: move helper to avoid forward declaration, per Baoquan] Link: https://lkml.kernel.org/r/20260128043511.316860-1-me@linux.beauty Link: https://lkml.kernel.org/r/20260120124005.148381-1-me@linux.beauty Fixes: 8652d44f466a ("kexec: support purgatories with .text.hot sections") Signed-off-by: Li Chen Acked-by: Baoquan He Cc: Alexander Graf Cc: Eric Biggers Cc: Li Chen Cc: Philipp Rudo Cc: Ricardo Ribalda Delgado Cc: Ross Zwisler Cc: Sourabh Jain Cc: Steven Rostedt Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- kernel/kexec_file.c | 131 +++++++++++++++++++++++++------------------- 1 file changed, 74 insertions(+), 57 deletions(-) diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index eb62a97942428..2bfbb2d144e69 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -882,6 +882,60 @@ static int kexec_calculate_store_digests(struct kimage *image) } #ifdef CONFIG_ARCH_SUPPORTS_KEXEC_PURGATORY +/* + * kexec_purgatory_find_symbol - find a symbol in the purgatory + * @pi: Purgatory to search in. + * @name: Name of the symbol. + * + * Return: pointer to symbol in read-only symtab on success, NULL on error. + */ +static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi, + const char *name) +{ + const Elf_Shdr *sechdrs; + const Elf_Ehdr *ehdr; + const Elf_Sym *syms; + const char *strtab; + int i, k; + + if (!pi->ehdr) + return NULL; + + ehdr = pi->ehdr; + sechdrs = (void *)ehdr + ehdr->e_shoff; + + for (i = 0; i < ehdr->e_shnum; i++) { + if (sechdrs[i].sh_type != SHT_SYMTAB) + continue; + + if (sechdrs[i].sh_link >= ehdr->e_shnum) + /* Invalid strtab section number */ + continue; + strtab = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset; + syms = (void *)ehdr + sechdrs[i].sh_offset; + + /* Go through symbols for a match */ + for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) { + if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL) + continue; + + if (strcmp(strtab + syms[k].st_name, name) != 0) + continue; + + if (syms[k].st_shndx == SHN_UNDEF || + syms[k].st_shndx >= ehdr->e_shnum) { + pr_debug("Symbol: %s has bad section index %d.\n", + name, syms[k].st_shndx); + return NULL; + } + + /* Found the symbol we are looking for */ + return &syms[k]; + } + } + + return NULL; +} /* * kexec_purgatory_setup_kbuf - prepare buffer to load purgatory. * @pi: Purgatory to be loaded. @@ -960,6 +1014,10 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi, unsigned long offset; size_t sechdrs_size; Elf_Shdr *sechdrs; + const Elf_Sym *entry_sym; + u16 entry_shndx = 0; + unsigned long entry_off = 0; + bool start_fixed = false; int i; /* @@ -977,6 +1035,12 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi, bss_addr = kbuf->mem + kbuf->bufsz; kbuf->image->start = pi->ehdr->e_entry; + entry_sym = kexec_purgatory_find_symbol(pi, "purgatory_start"); + if (entry_sym) { + entry_shndx = entry_sym->st_shndx; + entry_off = entry_sym->st_value; + } + for (i = 0; i < pi->ehdr->e_shnum; i++) { unsigned long align; void *src, *dst; @@ -994,6 +1058,13 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi, offset = ALIGN(offset, align); + if (!start_fixed && entry_sym && i == entry_shndx && + (sechdrs[i].sh_flags & SHF_EXECINSTR) && + entry_off < sechdrs[i].sh_size) { + kbuf->image->start = kbuf->mem + offset + entry_off; + start_fixed = true; + } + /* * Check if the segment contains the entry point, if so, * calculate the value of image->start based on it. @@ -1004,13 +1075,14 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi, * is not set to the initial value, and warn the user so they * have a chance to fix their purgatory's linker script. */ - if (sechdrs[i].sh_flags & SHF_EXECINSTR && + if (!start_fixed && sechdrs[i].sh_flags & SHF_EXECINSTR && pi->ehdr->e_entry >= sechdrs[i].sh_addr && pi->ehdr->e_entry < (sechdrs[i].sh_addr + sechdrs[i].sh_size) && - !WARN_ON(kbuf->image->start != pi->ehdr->e_entry)) { + kbuf->image->start == pi->ehdr->e_entry) { kbuf->image->start -= sechdrs[i].sh_addr; kbuf->image->start += kbuf->mem + offset; + start_fixed = true; } src = (void *)pi->ehdr + sechdrs[i].sh_offset; @@ -1128,61 +1200,6 @@ int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf) return ret; } -/* - * kexec_purgatory_find_symbol - find a symbol in the purgatory - * @pi: Purgatory to search in. - * @name: Name of the symbol. - * - * Return: pointer to symbol in read-only symtab on success, NULL on error. - */ -static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi, - const char *name) -{ - const Elf_Shdr *sechdrs; - const Elf_Ehdr *ehdr; - const Elf_Sym *syms; - const char *strtab; - int i, k; - - if (!pi->ehdr) - return NULL; - - ehdr = pi->ehdr; - sechdrs = (void *)ehdr + ehdr->e_shoff; - - for (i = 0; i < ehdr->e_shnum; i++) { - if (sechdrs[i].sh_type != SHT_SYMTAB) - continue; - - if (sechdrs[i].sh_link >= ehdr->e_shnum) - /* Invalid strtab section number */ - continue; - strtab = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset; - syms = (void *)ehdr + sechdrs[i].sh_offset; - - /* Go through symbols for a match */ - for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) { - if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL) - continue; - - if (strcmp(strtab + syms[k].st_name, name) != 0) - continue; - - if (syms[k].st_shndx == SHN_UNDEF || - syms[k].st_shndx >= ehdr->e_shnum) { - pr_debug("Symbol: %s has bad section index %d.\n", - name, syms[k].st_shndx); - return NULL; - } - - /* Found the symbol we are looking for */ - return &syms[k]; - } - } - - return NULL; -} - void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name) { struct purgatory_info *pi = &image->purgatory_info; -- 2.51.0