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Tue, 02 Jun 2020 11:03:09 -0700 (PDT) From: Andrei Vagin To: linux-arm-kernel@lists.infradead.org, Catalin Marinas , Will Deacon Subject: [PATCH 5/6] arm64/vdso: Restrict splitting VVAR VMA Date: Tue, 2 Jun 2020 11:02:58 -0700 Message-Id: <20200602180259.76361-6-avagin@gmail.com> X-Mailer: git-send-email 2.17.2 In-Reply-To: <20200602180259.76361-1-avagin@gmail.com> References: <20200602180259.76361-1-avagin@gmail.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200602_110311_787306_9432F70B X-CRM114-Status: GOOD ( 12.00 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:541 listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider [avagin[at]gmail.com] -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Dmitry Safonov , linux-kernel@vger.kernel.org, Andrei Vagin , Thomas Gleixner , Vincenzo Frascino MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Forbid splitting VVAR VMA resulting in a stricter ABI and reducing the amount of corner-cases to consider while working further on VDSO time namespace support. As the offset from timens to VVAR page is computed compile-time, the pages in VVAR should stay together and not being partically mremap()'ed. Reviewed-by: Vincenzo Frascino Signed-off-by: Andrei Vagin --- arch/arm64/kernel/vdso.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index f3baecd8edfb..8b17d7d10729 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -235,6 +235,17 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, return vmf_insert_pfn(vma, vmf->address, pfn); } +static int vvar_mremap(const struct vm_special_mapping *sm, + struct vm_area_struct *new_vma) +{ + unsigned long new_size = new_vma->vm_end - new_vma->vm_start; + + if (new_size != VVAR_NR_PAGES * PAGE_SIZE) + return -EINVAL; + + return 0; +} + static int __setup_additional_pages(enum arch_vdso_type arch_index, struct mm_struct *mm, struct linux_binprm *bprm, @@ -317,6 +328,7 @@ static struct vm_special_mapping aarch32_vdso_spec[C_PAGES] = { { .name = "[vvar]", .fault = vvar_fault, + .mremap = vvar_mremap, }, { .name = "[vdso]", @@ -488,6 +500,7 @@ static struct vm_special_mapping vdso_spec[A_PAGES] __ro_after_init = { { .name = "[vvar]", .fault = vvar_fault, + .mremap = vvar_mremap, }, { .name = "[vdso]",