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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: [PATCHv13 06/16] x86/mm: Provide arch_prctl() interface for LAM Date: Tue, 27 Dec 2022 06:08:19 +0300 Message-Id: <20221227030829.12508-7-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.38.2 In-Reply-To: <20221227030829.12508-1-kirill.shutemov@linux.intel.com> References: <20221227030829.12508-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 1995440015 X-Stat-Signature: 43kske6khfjkothr8zzz7zp91wke5fpd X-HE-Tag: 1672110534-611237 X-HE-Meta: U2FsdGVkX191IAq1JuSpbffQDay21IK9Fra9GPIH0s9yr08pkDq6cbYk3dCARhcIDQuKaffUyFdmJbiZhuHlLWCBh4ZCdcdLH7e6sljASjB8hADUqSF6lJMnuGcXtmiEa/Nv7QuuRuSVsNiJC1Pmlvi9c9h88btQNDI6p3GKh0kkvQUA3BVpPi50Vry4o3IweMDVMVwa/IQMfcoOzAAhqB/BgSbnUOEnNwqGa0e4RWvBayDxQhx2Z0Lzd2KE5C02acZjNqIesGECmrQg5LXSUQrZt05EGc/bvZGjwBJnTejPWXikURUCKyK819wPo1DO/edXJRnnqsYgGJo3oC5DkOTuJHIo6fjEAoxX7LL4Vt3p/vPAyoI7sLZEfqyZaKtjRv6E+9JKwVHwJrUn5hSbVLnD112bDNHVz2eCMMICAQYacn9xsobAFh4yMYiIERvS4Q5dJRX8HM/8umdVN2KGUwThoRpfM3l78g6RpLcHxhuELyUU5TA/P9vUKqaIgjMsOso+M/jLnglvWuTkbantLATdqZP6/QZ94K0PWt+MGXvnXWcLHgeL2OOaQzNs98/PY5Q4xPpBOeU1fvXCVZPLpZa5arAleVYp5ber8h9AxtzP9nFQugFjlvdMyJZhSj+m0bEs5T2pcHXUDvfc9MjDOyxjaxLS/kaZtHGX476siFAe53ScEpjD3NUQ+2mh19eynVpVbOswcC4hCobkGbYEptGpUN8GxpvUHZn+q35zwz06+2Jcr0jsEPVFet7iAYMWtEVXyZMnEHu6mkG20nqEnj2IoiDQKXWjWfqp+PbcckwkMrCqZ4kTQdNWh4kRyMp3NPqCOjo9dl3RJ+y6Mzohj6GIoiLfW+Sf/tBNjy+hTzKU7VcHyEkzylpdeHt969BpLf/CBfVs+HMZ0w5Pe3JqihCnCVQmdhQ4qBCE2OjHiFLodmcI4Fg5/HuiBeWf7xXkpRYwOI3Ly/JxHh59rd4 hsdvS9QS zxccqO+6U2V/2fjV44hBt54XXZIgeLifoSMIb 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 --- arch/x86/include/asm/mmu.h | 2 ++ arch/x86/include/uapi/asm/prctl.h | 4 +++ arch/x86/kernel/process.c | 3 +++ arch/x86/kernel/process_64.c | 44 ++++++++++++++++++++++++++++++- 4 files changed, 52 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/mmu.h b/arch/x86/include/asm/mmu.h index ed72fcd2292d..54e4a3e9b5c5 100644 --- a/arch/x86/include/asm/mmu.h +++ b/arch/x86/include/asm/mmu.h @@ -12,6 +12,8 @@ #define MM_CONTEXT_UPROBE_IA32 0 /* vsyscall page is accessible on this MM */ #define MM_CONTEXT_HAS_VSYSCALL 1 +/* Do not allow changing LAM mode */ +#define MM_CONTEXT_LOCK_LAM 2 /* * x86 has arch-specific MMU state beyond what lives in mm_struct. 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.c b/arch/x86/kernel/process.c index ef6bde1d40d8..cc0677f58f42 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -162,6 +162,9 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) savesegment(es, p->thread.es); savesegment(ds, p->thread.ds); + + if (p->mm && (clone_flags & (CLONE_VM | CLONE_VFORK)) == CLONE_VM) + set_bit(MM_CONTEXT_LOCK_LAM, &p->mm->context.flags); #else p->thread.sp0 = (unsigned long) (childregs + 1); savesegment(gs, p->thread.gs); diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 8b06034e8c70..fef127ed79b6 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -743,6 +743,39 @@ static long prctl_map_vdso(const struct vdso_image *image, unsigned long addr) } #endif +#define LAM_U57_BITS 6 + +static int prctl_enable_tagged_addr(struct mm_struct *mm, unsigned long nr_bits) +{ + if (!cpu_feature_enabled(X86_FEATURE_LAM)) + return -ENODEV; + + if (test_bit(MM_CONTEXT_LOCK_LAM, &mm->context.flags)) + return -EBUSY; + + if (mmap_write_lock_killable(mm)) + return -EINTR; + + if (!nr_bits) { + mmap_write_unlock(mm); + return -EINVAL; + } else if (nr_bits <= LAM_U57_BITS) { + mm->context.lam_cr3_mask = X86_CR3_LAM_U57; + mm->context.untag_mask = ~GENMASK(62, 57); + } else { + mmap_write_unlock(mm); + return -EINVAL; + } + + write_cr3(__read_cr3() | mm->context.lam_cr3_mask); + set_tlbstate_cr3_lam_mask(mm->context.lam_cr3_mask); + set_bit(MM_CONTEXT_LOCK_LAM, &mm->context.flags); + + mmap_write_unlock(mm); + + return 0; +} + long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2) { int ret = 0; @@ -830,7 +863,16 @@ 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;