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 B37C3200A5 for ; Mon, 6 Nov 2023 13:06:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="WwNVjo81" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2C22DC433C7; Mon, 6 Nov 2023 13:06:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1699276010; bh=pkoH3EDZmq83zqC/93i9WQdW9Nuwq3jKoifn61uRNRQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WwNVjo81QXjmHHx63kUb1MEXJOsTa+QtK6FSmomIIvYP5il44kqNTm8G18hlQnDwq 2TgSkPAeQfYFhzgiWctr7QjXmdvkb11pWC8urUaRUqB0/tH/H0hBmo8bUzDJDCt0I6 Wj4ryjytBOT9Yef+Ic5D+36Lj9h8vVr6fd+nd7no= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Josh Poimboeuf , "Peter Zijlstra (Intel)" , Borislav Petkov , Nathan Chancellor Subject: [PATCH 4.14 21/48] x86/mm: Simplify RESERVE_BRK() Date: Mon, 6 Nov 2023 14:03:12 +0100 Message-ID: <20231106130258.599336089@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231106130257.862199836@linuxfoundation.org> References: <20231106130257.862199836@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Josh Poimboeuf commit a1e2c031ec3949b8c039b739c0b5bf9c30007b00 upstream. RESERVE_BRK() reserves data in the .brk_reservation section. The data is initialized to zero, like BSS, so the macro specifies 'nobits' to prevent the data from taking up space in the vmlinux binary. The only way to get the compiler to do that (without putting the variable in .bss proper) is to use inline asm. The macro also has a hack which encloses the inline asm in a discarded function, which allows the size to be passed (global inline asm doesn't allow inputs). Remove the need for the discarded function hack by just stringifying the size rather than supplying it as an input to the inline asm. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov Reviewed-by: Borislav Petkov Link: https://lore.kernel.org/r/20220506121631.133110232@infradead.org [nathan: Fix conflict due to lack of 2b6ff7dea670 and 33def8498fdd] Signed-off-by: Nathan Chancellor Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/setup.h | 30 +++++++++++------------------- 1 file changed, 11 insertions(+), 19 deletions(-) --- a/arch/x86/include/asm/setup.h +++ b/arch/x86/include/asm/setup.h @@ -91,27 +91,19 @@ extern unsigned long _brk_end; void *extend_brk(size_t size, size_t align); /* - * Reserve space in the brk section. The name must be unique within - * the file, and somewhat descriptive. The size is in bytes. Must be - * used at file scope. + * Reserve space in the brk section. The name must be unique within the file, + * and somewhat descriptive. The size is in bytes. * - * (This uses a temp function to wrap the asm so we can pass it the - * size parameter; otherwise we wouldn't be able to. We can't use a - * "section" attribute on a normal variable because it always ends up - * being @progbits, which ends up allocating space in the vmlinux - * executable.) + * The allocation is done using inline asm (rather than using a section + * attribute on a normal variable) in order to allow the use of @nobits, so + * that it doesn't take up any space in the vmlinux file. */ -#define RESERVE_BRK(name,sz) \ - static void __section(.discard.text) __used notrace \ - __brk_reservation_fn_##name##__(void) { \ - asm volatile ( \ - ".pushsection .brk_reservation,\"aw\",@nobits;" \ - ".brk." #name ":" \ - " 1:.skip %c0;" \ - " .size .brk." #name ", . - 1b;" \ - " .popsection" \ - : : "i" (sz)); \ - } +#define RESERVE_BRK(name, size) \ + asm(".pushsection .brk_reservation,\"aw\",@nobits\n\t" \ + ".brk." #name ":\n\t" \ + ".skip " __stringify(size) "\n\t" \ + ".size .brk." #name ", " __stringify(size) "\n\t" \ + ".popsection\n\t") /* Helper for reserving space for arrays of things */ #define RESERVE_BRK_ARRAY(type, name, entries) \