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Tue, 15 Jun 2021 06:39:15 -0700 (PDT) Received: from avogadro.lan ([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id r17sm11843769edt.33.2021.06.15.06.39.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Jun 2021 06:39:14 -0700 (PDT) From: Paolo Bonzini To: qemu-devel@nongnu.org Subject: [PULL 18/33] util/mmap-alloc: Factor out calculation of the pagesize for the guard page Date: Tue, 15 Jun 2021 15:38:40 +0200 Message-Id: <20210615133855.775687-19-pbonzini@redhat.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210615133855.775687-1-pbonzini@redhat.com> References: <20210615133855.775687-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2a00:1450:4864:20::52f; envelope-from=paolo.bonzini@gmail.com; helo=mail-ed1-x52f.google.com X-Spam_score_int: -14 X-Spam_score: -1.5 X-Spam_bar: - X-Spam_report: (-1.5 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FORGED_FROMDOMAIN=0.25, FREEMAIL_FROM=0.001, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Igor Kotrasinski , Murilo Opsfelder Araujo , Eduardo Habkost , Peter Xu , David Hildenbrand Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" From: David Hildenbrand Let's factor out calculating the size of the guard page and rename the variable to make it clearer that this pagesize only applies to the guard page. Reviewed-by: Peter Xu Acked-by: Murilo Opsfelder Araujo Acked-by: Eduardo Habkost for memory backend and machine core Cc: Igor Kotrasinski Signed-off-by: David Hildenbrand Message-Id: <20210510114328.21835-2-david@redhat.com> Signed-off-by: Paolo Bonzini --- util/mmap-alloc.c | 31 ++++++++++++++++--------------- 1 file changed, 16 insertions(+), 15 deletions(-) diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index e6fa8b598b..24854064b4 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -82,6 +82,16 @@ size_t qemu_mempath_getpagesize(const char *mem_path) return qemu_real_host_page_size; } +static inline size_t mmap_guard_pagesize(int fd) +{ +#if defined(__powerpc64__) && defined(__linux__) + /* Mappings in the same segment must share the same page size */ + return qemu_fd_getpagesize(fd); +#else + return qemu_real_host_page_size; +#endif +} + void *qemu_ram_mmap(int fd, size_t size, size_t align, @@ -90,12 +100,12 @@ void *qemu_ram_mmap(int fd, bool is_pmem, off_t map_offset) { + const size_t guard_pagesize = mmap_guard_pagesize(fd); int prot; int flags; int map_sync_flags = 0; int guardfd; size_t offset; - size_t pagesize; size_t total; void *guardptr; void *ptr; @@ -116,8 +126,7 @@ void *qemu_ram_mmap(int fd, * anonymous memory is OK. */ flags = MAP_PRIVATE; - pagesize = qemu_fd_getpagesize(fd); - if (fd == -1 || pagesize == qemu_real_host_page_size) { + if (fd == -1 || guard_pagesize == qemu_real_host_page_size) { guardfd = -1; flags |= MAP_ANONYMOUS; } else { @@ -126,7 +135,6 @@ void *qemu_ram_mmap(int fd, } #else guardfd = -1; - pagesize = qemu_real_host_page_size; flags = MAP_PRIVATE | MAP_ANONYMOUS; #endif @@ -138,7 +146,7 @@ void *qemu_ram_mmap(int fd, assert(is_power_of_2(align)); /* Always align to host page size */ - assert(align >= pagesize); + assert(align >= guard_pagesize); flags = MAP_FIXED; flags |= fd == -1 ? MAP_ANONYMOUS : 0; @@ -193,8 +201,8 @@ void *qemu_ram_mmap(int fd, * a guard page guarding against potential buffer overflows. */ total -= offset; - if (total > size + pagesize) { - munmap(ptr + size + pagesize, total - size - pagesize); + if (total > size + guard_pagesize) { + munmap(ptr + size + guard_pagesize, total - size - guard_pagesize); } return ptr; @@ -202,15 +210,8 @@ void *qemu_ram_mmap(int fd, void qemu_ram_munmap(int fd, void *ptr, size_t size) { - size_t pagesize; - if (ptr) { /* Unmap both the RAM block and the guard page */ -#if defined(__powerpc64__) && defined(__linux__) - pagesize = qemu_fd_getpagesize(fd); -#else - pagesize = qemu_real_host_page_size; -#endif - munmap(ptr, size + pagesize); + munmap(ptr, size + mmap_guard_pagesize(fd)); } } -- 2.31.1