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Shutemov" To: Dave Hansen , Andy Lutomirski , Peter Zijlstra Cc: x86@kernel.org, Kostya Serebryany , Andrey Ryabinin , Andrey Konovalov , Alexander Potapenko , Taras Madan , Dmitry Vyukov , "H . J . Lu" , Andi Kleen , Rick Edgecombe , Bharata B Rao , Jacob Pan , Ashok Raj , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv11 08/16] x86/mm: Reduce untagged_addr() overhead until the first LAM user Date: Tue, 25 Oct 2022 03:17:14 +0300 Message-Id: <20221025001722.17466-9-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.38.0 In-Reply-To: <20221025001722.17466-1-kirill.shutemov@linux.intel.com> References: <20221025001722.17466-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1666657062; a=rsa-sha256; cv=none; b=nFm5orjc8CNEkPX7kOhFpPJGp9p11turYoAvCovW5Ztj00D2WPIMvICD+s8nVRdRIKKOCf 5Xpcg3G+Zokt4FzkWP+SLukdD8XH87m79XromiYDHWag1yM6492NJZlqcXEFg0yyRAT9/+ 45fEfari4QDTayxXN7KicU0IoFBzRAo= ARC-Authentication-Results: i=1; imf11.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=QQQj9Lg3; dmarc=fail reason="No valid SPF" header.from=intel.com (policy=none); spf=none (imf11.hostedemail.com: domain of kirill.shutemov@linux.intel.com has no SPF policy when checking 134.134.136.20) smtp.mailfrom=kirill.shutemov@linux.intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1666657062; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=HGH62+uFEu8c6UZDAvYEhOO+nimuGapexta/TJtDuPw=; b=1ywEvJcl3E8+zTtjC41cy2/QZs7IvklUZtYJZc2UGOGqGNUkICy8uVR0TxdD/tCvOWF49Z hxorBtnhGi0EX9LyhzKuW3cUiXJPNpcB5jFuIko293jvXgp6zQfIHER3urNjgP0FDuUVkd +MIptTnUNLIMviap02nmWNoY4RQ0Vj8= X-Rspamd-Queue-Id: 4E2A740019 Authentication-Results: imf11.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=QQQj9Lg3; dmarc=fail reason="No valid SPF" header.from=intel.com (policy=none); spf=none (imf11.hostedemail.com: domain of kirill.shutemov@linux.intel.com has no SPF policy when checking 134.134.136.20) smtp.mailfrom=kirill.shutemov@linux.intel.com X-Rspamd-Server: rspam12 X-Rspam-User: X-Stat-Signature: 186pc3m3oa3fqpku1ig9jzy75mn8kzfi X-HE-Tag: 1666657062-568317 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Use static key to reduce untagged_addr() overhead. The key only gets enabled when the first process enables LAM. Signed-off-by: Kirill A. Shutemov --- arch/x86/include/asm/uaccess.h | 8 ++++++-- arch/x86/kernel/process_64.c | 4 ++++ 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index c6062c07ccd2..820234f1f750 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -23,6 +23,8 @@ static inline bool pagefault_disabled(void); #endif #ifdef CONFIG_X86_64 +DECLARE_STATIC_KEY_FALSE(tagged_addr_key); + /* * Mask out tag bits from the address. * @@ -31,8 +33,10 @@ static inline bool pagefault_disabled(void); */ #define untagged_addr(mm, addr) ({ \ u64 __addr = (__force u64)(addr); \ - s64 sign = (s64)__addr >> 63; \ - __addr &= (mm)->context.untag_mask | sign; \ + if (static_branch_likely(&tagged_addr_key)) { \ + s64 sign = (s64)__addr >> 63; \ + __addr &= (mm)->context.untag_mask | sign; \ + } \ (__force __typeof__(addr))__addr; \ }) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index a98536101447..9952e9f517ec 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -743,6 +743,9 @@ static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr) } #endif +DEFINE_STATIC_KEY_FALSE(tagged_addr_key); +EXPORT_SYMBOL_GPL(tagged_addr_key); + static void enable_lam_func(void *mm) { struct mm_struct *loaded_mm = this_cpu_read(cpu_tlbstate.loaded_mm); @@ -792,6 +795,7 @@ static int prctl_enable_tagged_addr(struct mm_struct *mm, unsigned long nr_bits) } on_each_cpu_mask(mm_cpumask(mm), enable_lam_func, mm, true); + static_branch_enable(&tagged_addr_key); out: mmap_write_unlock(mm); return ret; -- 2.38.0