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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 , Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv14 08/17] x86/mm: Reduce untagged_addr() overhead until the first LAM user Date: Wed, 11 Jan 2023 15:37:27 +0300 Message-Id: <20230111123736.20025-9-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.38.2 In-Reply-To: <20230111123736.20025-1-kirill.shutemov@linux.intel.com> References: <20230111123736.20025-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: CBDE240010 X-Stat-Signature: 3gwjbh3nf4h63y8btfei8czdek6triqh X-Rspam-User: X-HE-Tag: 1673443442-973342 X-HE-Meta: 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 PSytu/U4 cS2C7KzKF4s9fYwePNRZTTA9Pm5hVmt9JNh06 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 32c9dd052e43..f9f85d596581 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -24,6 +24,8 @@ static inline bool pagefault_disabled(void); #endif #ifdef CONFIG_ADDRESS_MASKING +DECLARE_STATIC_KEY_FALSE(tagged_addr_key); + /* * Mask out tag bits from the address. * @@ -32,8 +34,10 @@ static inline bool pagefault_disabled(void); */ #define __untagged_addr(untag_mask, addr) ({ \ u64 __addr = (__force u64)(addr); \ - s64 sign = (s64)__addr >> 63; \ - __addr &= untag_mask | sign; \ + if (static_branch_likely(&tagged_addr_key)) { \ + s64 sign = (s64)__addr >> 63; \ + __addr &= untag_mask | sign; \ + } \ (__force __typeof__(addr))__addr; \ }) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 88aae519c8f8..1b41c60ebf6e 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -745,6 +745,9 @@ static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr) #ifdef CONFIG_ADDRESS_MASKING +DEFINE_STATIC_KEY_FALSE(tagged_addr_key); +EXPORT_SYMBOL_GPL(tagged_addr_key); + #define LAM_U57_BITS 6 static int prctl_enable_tagged_addr(struct mm_struct *mm, unsigned long nr_bits) @@ -781,6 +784,7 @@ static int prctl_enable_tagged_addr(struct mm_struct *mm, unsigned long nr_bits) mmap_write_unlock(mm); + static_branch_enable(&tagged_addr_key); return 0; } #endif