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([2602:ae:1541:f901:b714:1fce:85fa:2fc7]) by smtp.gmail.com with ESMTPSA id a17-20020a170902ee9100b001a24cded097sm2360122pld.236.2023.03.31.21.51.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 31 Mar 2023 21:51:08 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Cc: alex.bennee@linaro.org Subject: [PATCH 1/3] Revert "linux-user/arm: Take more care allocating commpage" Date: Fri, 31 Mar 2023 21:51:04 -0700 Message-Id: <20230401045106.3885562-2-richard.henderson@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230401045106.3885562-1-richard.henderson@linaro.org> References: <20230401045106.3885562-1-richard.henderson@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::1032; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x1032.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org This reverts commit 4f5c67f8df7f26e559509c68c45e652709edd23f. This exposes bugs in target_mmap et al with respect to overflow with the final page of the guest address space. To be fixed in the next development cycle. Signed-off-by: Richard Henderson --- linux-user/elfload.c | 37 ++++++++++--------------------------- 1 file changed, 10 insertions(+), 27 deletions(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index b96b3e566b..f1370a7a8b 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -423,32 +423,12 @@ enum { static bool init_guest_commpage(void) { - ARMCPU *cpu = ARM_CPU(thread_cpu); - abi_ptr want = HI_COMMPAGE & TARGET_PAGE_MASK; - abi_ptr addr; + abi_ptr commpage = HI_COMMPAGE & -qemu_host_page_size; + void *want = g2h_untagged(commpage); + void *addr = mmap(want, qemu_host_page_size, PROT_READ | PROT_WRITE, + MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0); - /* - * M-profile allocates maximum of 2GB address space, so can never - * allocate the commpage. Skip it. - */ - if (arm_feature(&cpu->env, ARM_FEATURE_M)) { - return true; - } - - /* - * If reserved_va does not cover the commpage, we get an assert - * in page_set_flags. Produce an intelligent error instead. - */ - if (reserved_va != 0 && want + TARGET_PAGE_SIZE - 1 > reserved_va) { - error_report("Allocating guest commpage: -R 0x%" PRIx64 " too small", - (uint64_t)reserved_va + 1); - exit(EXIT_FAILURE); - } - - addr = target_mmap(want, TARGET_PAGE_SIZE, PROT_READ | PROT_WRITE, - MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0); - - if (addr == -1) { + if (addr == MAP_FAILED) { perror("Allocating guest commpage"); exit(EXIT_FAILURE); } @@ -457,12 +437,15 @@ static bool init_guest_commpage(void) } /* Set kernel helper versions; rest of page is 0. */ - put_user_u32(5, 0xffff0ffcu); + __put_user(5, (uint32_t *)g2h_untagged(0xffff0ffcu)); - if (target_mprotect(addr, qemu_host_page_size, PROT_READ | PROT_EXEC)) { + if (mprotect(addr, qemu_host_page_size, PROT_READ)) { perror("Protecting guest commpage"); exit(EXIT_FAILURE); } + + page_set_flags(commpage, commpage | ~qemu_host_page_mask, + PAGE_READ | PAGE_EXEC | PAGE_VALID); return true; } -- 2.34.1