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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 , linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv8 06/11] x86/mm: Provide arch_prctl() interface for LAM Date: Tue, 30 Aug 2022 04:00:59 +0300 Message-Id: <20220830010104.1282-7-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220830010104.1282-1-kirill.shutemov@linux.intel.com> References: <20220830010104.1282-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1661821297; a=rsa-sha256; cv=none; b=l9ZI9Oo/0uBkNCMznbRs0+y4CrHtqmeFY/AaJqUQDqt5nkpatXKFaq/WMJUNiAnOPGzx6r O26GD1VTQvLz+3Dd9OsQpa9wKhIVFJ7LhuoEaxTGpxM3NCGEEocebsNiZFjqXJ1E7UGgTy yhqY4fDQL0JtGBcTv7MzTCdQy6JhTU8= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=ilwlbiyG; dmarc=fail reason="No valid SPF" header.from=intel.com (policy=none); spf=none (imf18.hostedemail.com: domain of kirill.shutemov@linux.intel.com has no SPF policy when checking 192.55.52.43) 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=1661821297; 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=gjgrFfjsqL4RUcsssh7Fcj0Rl9fhqB64ajPEVgRnofs=; b=qmeEJeHTeCYKImy4Sj2Hp2MUBVUN9LWiGobZNnxX/tpLMuZBfA1KLOku8UOl1/nhiQ5MxD lx5bieyb+yv9sWwJbJ5BT0cFFYZP1F9NYg+nnWYovaTE/DjjeV+crbwPRhwfJqvNbaaTB1 ZhJW2E9r+q7P5xCtLuPgUY8sWSoYSok= X-Stat-Signature: tbickfrnf6sh8sq3ayzeycb4u3zkphe5 X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: D8EC91C0010 Authentication-Results: imf18.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=ilwlbiyG; dmarc=fail reason="No valid SPF" header.from=intel.com (policy=none); spf=none (imf18.hostedemail.com: domain of kirill.shutemov@linux.intel.com has no SPF policy when checking 192.55.52.43) smtp.mailfrom=kirill.shutemov@linux.intel.com X-Rspam-User: X-HE-Tag: 1661821296-394787 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: Add a couple of arch_prctl() handles: - ARCH_ENABLE_TAGGED_ADDR enabled LAM. The argument is required number of tag bits. It is rounded up to the nearest LAM mode that can provide it. For now only LAM_U57 is supported, with 6 tag bits. - ARCH_GET_UNTAG_MASK returns untag mask. It can indicates where tag bits located in the address. - ARCH_GET_MAX_TAG_BITS returns the maximum tag bits user can request. Zero if LAM is not supported. Signed-off-by: Kirill A. Shutemov Tested-by: Alexander Potapenko Reviewed-by: Alexander Potapenko Acked-by: Peter Zijlstra (Intel) --- arch/x86/include/uapi/asm/prctl.h | 4 ++ arch/x86/kernel/process_64.c | 64 ++++++++++++++++++++++++++++++- 2 files changed, 67 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h index 500b96e71f18..a31e27b95b19 100644 --- a/arch/x86/include/uapi/asm/prctl.h +++ b/arch/x86/include/uapi/asm/prctl.h @@ -20,4 +20,8 @@ #define ARCH_MAP_VDSO_32 0x2002 #define ARCH_MAP_VDSO_64 0x2003 +#define ARCH_GET_UNTAG_MASK 0x4001 +#define ARCH_ENABLE_TAGGED_ADDR 0x4002 +#define ARCH_GET_MAX_TAG_BITS 0x4003 + #endif /* _ASM_X86_PRCTL_H */ diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 1962008fe743..455601a3cc3f 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -742,6 +742,59 @@ static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr) } #endif +static void enable_lam_func(void *mm) +{ + struct mm_struct *loaded_mm = this_cpu_read(cpu_tlbstate.loaded_mm); + unsigned long lam_mask; + unsigned long cr3; + + if (loaded_mm != mm) + return; + + lam_mask = READ_ONCE(loaded_mm->context.lam_cr3_mask); + + /* Update CR3 to get LAM active on the CPU */ + cr3 = __read_cr3(); + cr3 &= ~(X86_CR3_LAM_U48 | X86_CR3_LAM_U57); + cr3 |= lam_mask; + write_cr3(cr3); + set_tlbstate_cr3_lam_mask(lam_mask); +} + +#define LAM_U57_BITS 6 + +static int prctl_enable_tagged_addr(struct mm_struct *mm, unsigned long nr_bits) +{ + int ret = 0; + + if (!cpu_feature_enabled(X86_FEATURE_LAM)) + return -ENODEV; + + mutex_lock(&mm->context.lock); + + /* Already enabled? */ + if (mm->context.lam_cr3_mask) { + ret = -EBUSY; + goto out; + } + + if (!nr_bits) { + ret = -EINVAL; + goto out; + } else if (nr_bits <= LAM_U57_BITS) { + mm->context.lam_cr3_mask = X86_CR3_LAM_U57; + mm->context.untag_mask = ~GENMASK(62, 57); + } else { + ret = -EINVAL; + goto out; + } + + on_each_cpu_mask(mm_cpumask(mm), enable_lam_func, mm, true); +out: + mutex_unlock(&mm->context.lock); + return ret; +} + long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2) { int ret = 0; @@ -829,7 +882,16 @@ long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2) case ARCH_MAP_VDSO_64: return prctl_map_vdso(&vdso_image_64, arg2); #endif - + case ARCH_GET_UNTAG_MASK: + return put_user(task->mm->context.untag_mask, + (unsigned long __user *)arg2); + case ARCH_ENABLE_TAGGED_ADDR: + return prctl_enable_tagged_addr(task->mm, arg2); + case ARCH_GET_MAX_TAG_BITS: + if (!cpu_feature_enabled(X86_FEATURE_LAM)) + return put_user(0, (unsigned long __user *)arg2); + else + return put_user(LAM_U57_BITS, (unsigned long __user *)arg2); default: ret = -EINVAL; break; -- 2.35.1