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From:   Yu-cheng Yu <yu-cheng.yu@intel.com>
To:     x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
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        linux-arch@vger.kernel.org, linux-api@vger.kernel.org,
        Arnd Bergmann <arnd@arndb.de>,
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        Balbir Singh <bsingharora@gmail.com>,
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        Dave Hansen <dave.hansen@linux.intel.com>,
        Florian Weimer <fweimer@redhat.com>,
        "H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
        Jonathan Corbet <corbet@lwn.net>,
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        Mike Kravetz <mike.kravetz@oracle.com>,
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        Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
        Peter Zijlstra <peterz@infradead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>
Cc:     Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [RFC PATCH v2 23/27] mm/mmap: Add IBT bitmap size to address space limit check
Date:   Tue, 10 Jul 2018 15:26:35 -0700
Message-Id: <20180710222639.8241-24-yu-cheng.yu@intel.com>
In-Reply-To: <20180710222639.8241-1-yu-cheng.yu@intel.com>
References: <20180710222639.8241-1-yu-cheng.yu@intel.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

The indirect branch tracking legacy bitmap takes a large address
space.  This causes may_expand_vm() failure on the address limit
check.  For a IBT-enabled task, add the bitmap size to the
address limit.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
---
 arch/x86/include/uapi/asm/resource.h |  5 +++++
 include/uapi/asm-generic/resource.h  |  3 +++
 mm/mmap.c                            | 12 +++++++++++-
 3 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/uapi/asm/resource.h b/arch/x86/include/uapi/asm/resource.h
index 04bc4db8921b..0741b2a6101a 100644
--- a/arch/x86/include/uapi/asm/resource.h
+++ b/arch/x86/include/uapi/asm/resource.h
@@ -1 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+#ifdef CONFIG_X86_INTEL_CET
+#define rlimit_as_extra() current->thread.cet.ibt_bitmap_size
+#endif
+
 #include <asm-generic/resource.h>
diff --git a/include/uapi/asm-generic/resource.h b/include/uapi/asm-generic/resource.h
index f12db7a0da64..8a7608a09700 100644
--- a/include/uapi/asm-generic/resource.h
+++ b/include/uapi/asm-generic/resource.h
@@ -58,5 +58,8 @@
 # define RLIM_INFINITY		(~0UL)
 #endif
 
+#ifndef rlimit_as_extra
+#define rlimit_as_extra() 0
+#endif
 
 #endif /* _UAPI_ASM_GENERIC_RESOURCE_H */
diff --git a/mm/mmap.c b/mm/mmap.c
index d1eb87ef4b1a..fad41b291ae1 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3242,7 +3242,17 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
  */
 bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
 {
-	if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
+	unsigned long as_limit = rlimit(RLIMIT_AS);
+	unsigned long as_limit_plus = as_limit + rlimit_as_extra();
+
+	/* as_limit_plus overflowed */
+	if (as_limit_plus < as_limit)
+		as_limit_plus = RLIM_INFINITY;
+
+	if (as_limit_plus > as_limit)
+		as_limit = as_limit_plus;
+
+	if (mm->total_vm + npages > as_limit >> PAGE_SHIFT)
 		return false;
 
 	if (is_data_mapping(flags) &&
-- 
2.17.1