From nobody Wed Oct 8 00:04:17 2025 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 D8B5630205F; Fri, 4 Jul 2025 13:50:03 +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=1751637004; cv=none; b=X4XZIUoaw67DtMDntP+Zi+H55jMEwmmdpVWoP9+BYHwwBmKU7w9auCKwuVXoti3YMBqgGbu9hzTvBanfxMIXPyATEWXnz0C7yYHWdBVdn4RHEqeHgo7wLI61OiHnxz3Zdly+HbQTaXsEikr/p0H9JVgEaXwcn882h7R7gJS2dvE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751637004; c=relaxed/simple; bh=NrvBoIv7ihWz3msr5ucNgQMNcZ4XLlRn/Kum2bPi/3o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KO6REvpDUpqDvRNVEyvCgKNgknQkduGgL+a3TcuS+eYtGHs9dhMoxX/pmA/XWgQLQho0n0Xjscb9hAd3JPFlAG0yX2J+ske9cMcgy/j4nlKI4xU9RB0QmyYhP8Ft67yWXokRlelgEGHGQk5KOdoYl1lyUGcGBQMnnyMNo8autZg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=du9mSzGa; 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="du9mSzGa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 79C19C4CEE3; Fri, 4 Jul 2025 13:49:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751637003; bh=NrvBoIv7ihWz3msr5ucNgQMNcZ4XLlRn/Kum2bPi/3o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=du9mSzGaCObmMu4AJfvOoggVAr+IvAH88kHSLClKN/Mfwta17SYcXTn/8LmevqoGx AcvO1HVvuNnHtYa2S3cTeJpP/UAadzyjKs+bueQhrshFpa73GQXfrPqjv/3xZAl5oJ ZuHXPvfRdopM8RuzgkMy1C4gekeUHMofMNM79RXoQkBZ19n34qDLy1rE3DU/u18JZ9 ajmTCNtxJpyfh9oBrBWU0N1CsaKDxgBBnnqkQUC5tMFeaaxSfXsni9oXxgiycthABl whmMPdoAKby8UIZBKLXZUi6axYTd9YPeIGG9ZyGSxn9RkmCzQgrPDQawnEKDvsGZVC 0+BAZ5kPr6WrA== From: Mike Rapoport To: Andrew Morton Cc: Andy Lutomirski , Borislav Petkov , Daniel Gomez , Dave Hansen , Ingo Molnar , Luis Chamberlain , Mark Rutland , Masami Hiramatsu , Mike Rapoport , "H. Peter Anvin" , Peter Zijlstra , Petr Pavlu , Sami Tolvanen , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org Subject: [PATCH 2/8] execmem: introduce execmem_alloc_rw() Date: Fri, 4 Jul 2025 16:49:37 +0300 Message-ID: <20250704134943.3524829-3-rppt@kernel.org> X-Mailer: git-send-email 2.47.2 In-Reply-To: <20250704134943.3524829-1-rppt@kernel.org> References: <20250704134943.3524829-1-rppt@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: "Mike Rapoport (Microsoft)" Some callers of execmem_alloc() require the memory to be temporarily writable even when it is allocated from ROX cache. These callers use execemem_make_temp_rw() right after the call to execmem_alloc(). Wrap this sequence in execmem_alloc_rw() API. Signed-off-by: Mike Rapoport (Microsoft) --- arch/x86/kernel/alternative.c | 3 +-- include/linux/execmem.h | 38 ++++++++++++++++++++--------------- kernel/module/main.c | 13 ++---------- mm/execmem.c | 27 ++++++++++++++++++++++++- 4 files changed, 51 insertions(+), 30 deletions(-) diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index ea1d984166cd..526a5fef93ab 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -120,7 +120,7 @@ struct its_array its_pages; =20 static void *__its_alloc(struct its_array *pages) { - void *page __free(execmem) =3D execmem_alloc(EXECMEM_MODULE_TEXT, PAGE_SI= ZE); + void *page __free(execmem) =3D execmem_alloc_rw(EXECMEM_MODULE_TEXT, PAGE= _SIZE); if (!page) return NULL; =20 @@ -237,7 +237,6 @@ static void *its_alloc(void) if (!page) return NULL; =20 - execmem_make_temp_rw(page, PAGE_SIZE); if (pages =3D=3D &its_pages) set_memory_x((unsigned long)page, 1); =20 diff --git a/include/linux/execmem.h b/include/linux/execmem.h index 734fbe83d98e..4e510d1c609c 100644 --- a/include/linux/execmem.h +++ b/include/linux/execmem.h @@ -67,21 +67,6 @@ enum execmem_range_flags { */ void execmem_fill_trapping_insns(void *ptr, size_t size, bool writable); =20 -/** - * execmem_make_temp_rw - temporarily remap region with read-write - * permissions - * @ptr: address of the region to remap - * @size: size of the region to remap - * - * Remaps a part of the cached large page in the ROX cache in the range - * [@ptr, @ptr + @size) as writable and not executable. The caller must - * have exclusive ownership of this range and ensure nothing will try to - * execute code in this range. - * - * Return: 0 on success or negative error code on failure. - */ -int execmem_make_temp_rw(void *ptr, size_t size); - /** * execmem_restore_rox - restore read-only-execute permissions * @ptr: address of the region to remap @@ -95,7 +80,6 @@ int execmem_make_temp_rw(void *ptr, size_t size); */ int execmem_restore_rox(void *ptr, size_t size); #else -static inline int execmem_make_temp_rw(void *ptr, size_t size) { return 0;= } static inline int execmem_restore_rox(void *ptr, size_t size) { return 0; } #endif =20 @@ -165,6 +149,28 @@ struct execmem_info *execmem_arch_setup(void); */ void *execmem_alloc(enum execmem_type type, size_t size); =20 +/** + * execmem_alloc_rw - allocate writatble executable memory + * @type: type of the allocation + * @size: how many bytes of memory are required + * + * Allocates memory that will contain executable code, either generated or + * loaded from kernel modules. + * + * Allocates memory that will contain data coupled with executable code, + * like data sections in kernel modules. + * + * Forces writable permissions on the allocated memory and the caller is + * responsible to manage the permissions afterwards. + * + * For architectures that use ROX cache the permissions will be set to R+W. + * For architectures that don't use ROX cache the default permissions for = @type + * will be used as they must be writable. + * + * Return: a pointer to the allocated memory or %NULL + */ +void *execmem_alloc_rw(enum execmem_type type, size_t size); + /** * execmem_free - free executable memory * @ptr: pointer to the memory that should be freed diff --git a/kernel/module/main.c b/kernel/module/main.c index 413ac6ea3702..d009326ef7bb 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -1292,20 +1292,11 @@ static int module_memory_alloc(struct module *mod, = enum mod_mem_type type) else execmem_type =3D EXECMEM_MODULE_TEXT; =20 - ptr =3D execmem_alloc(execmem_type, size); + ptr =3D execmem_alloc_rw(execmem_type, size); if (!ptr) return -ENOMEM; =20 - if (execmem_is_rox(execmem_type)) { - int err =3D execmem_make_temp_rw(ptr, size); - - if (err) { - execmem_free(ptr); - return -ENOMEM; - } - - mod->mem[type].is_rox =3D true; - } + mod->mem[type].is_rox =3D execmem_is_rox(execmem_type); =20 /* * The pointer to these blocks of memory are stored on the module diff --git a/mm/execmem.c b/mm/execmem.c index 0712ebb4eb77..6b040fbc5f4f 100644 --- a/mm/execmem.c +++ b/mm/execmem.c @@ -336,7 +336,7 @@ static bool execmem_cache_free(void *ptr) return true; } =20 -int execmem_make_temp_rw(void *ptr, size_t size) +static int execmem_force_rw(void *ptr, size_t size) { unsigned int nr =3D PAGE_ALIGN(size) >> PAGE_SHIFT; unsigned long addr =3D (unsigned long)ptr; @@ -358,6 +358,16 @@ int execmem_restore_rox(void *ptr, size_t size) } =20 #else /* CONFIG_ARCH_HAS_EXECMEM_ROX */ +/* + * when ROX cache is not used the permissions defined by architectures for + * execmem ranges that are updated before use (e.g. EXECMEM_MODULE_TEXT) m= ust + * be writable anyway + */ +static inline int execmem_force_rw(void *ptr, size_t size) +{ + return 0; +} + static void *execmem_cache_alloc(struct execmem_range *range, size_t size) { return NULL; @@ -387,6 +397,21 @@ void *execmem_alloc(enum execmem_type type, size_t siz= e) return kasan_reset_tag(p); } =20 +void *execmem_alloc_rw(enum execmem_type type, size_t size) +{ + void *p __free(execmem) =3D execmem_alloc(type, size); + int err; + + if (!p) + return NULL; + + err =3D execmem_force_rw(p, size); + if (err) + return NULL; + + return no_free_ptr(p); +} + void execmem_free(void *ptr) { /* --=20 2.47.2