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[174.21.70.228]) by smtp.gmail.com with ESMTPSA id q23sm6139829pgm.31.2021.06.11.16.42.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Jun 2021 16:42:01 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Subject: [PULL 27/34] tcg: Merge buffer protection and guard page protection Date: Fri, 11 Jun 2021 16:41:37 -0700 Message-Id: <20210611234144.653682-28-richard.henderson@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210611234144.653682-1-richard.henderson@linaro.org> References: <20210611234144.653682-1-richard.henderson@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::1035; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x1035.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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Luis Pires , =?UTF-8?q?Alex=20Benn=C3=A9e?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Do not handle protections on a case-by-case basis in the various alloc_code_gen_buffer instances; do it within a single loop in tcg_region_init. Reviewed-by: Alex Bennée Reviewed-by: Luis Pires Signed-off-by: Richard Henderson --- tcg/region.c | 45 +++++++++++++++++++++++++++++++-------------- 1 file changed, 31 insertions(+), 14 deletions(-) diff --git a/tcg/region.c b/tcg/region.c index e1790ce1e4..294cbd8e65 100644 --- a/tcg/region.c +++ b/tcg/region.c @@ -535,11 +535,6 @@ static int alloc_code_gen_buffer(size_t tb_size, int splitwx, Error **errp) } #endif - if (qemu_mprotect_rwx(buf, size)) { - error_setg_errno(errp, errno, "mprotect of jit buffer"); - return false; - } - region.start_aligned = buf; region.total_size = size; @@ -823,8 +818,7 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus) { const size_t page_size = qemu_real_host_page_size; size_t region_size; - size_t i; - int have_prot; + int have_prot, need_prot; /* Size the buffer. */ if (tb_size == 0) { @@ -884,18 +878,41 @@ void tcg_region_init(size_t tb_size, int splitwx, unsigned max_cpus) * Set guard pages in the rw buffer, as that's the one into which * buffer overruns could occur. Do not set guard pages in the rx * buffer -- let that one use hugepages throughout. + * Work with the page protections set up with the initial mapping. */ - for (i = 0; i < region.n; i++) { + need_prot = PAGE_READ | PAGE_WRITE; +#ifndef CONFIG_TCG_INTERPRETER + if (tcg_splitwx_diff == 0) { + need_prot |= PAGE_EXEC; + } +#endif + for (size_t i = 0, n = region.n; i < n; i++) { void *start, *end; tcg_region_bounds(i, &start, &end); + if (have_prot != need_prot) { + int rc; - /* - * macOS 11.2 has a bug (Apple Feedback FB8994773) in which mprotect - * rejects a permission change from RWX -> NONE. Guard pages are - * nice for bug detection but are not essential; ignore any failure. - */ - (void)qemu_mprotect_none(end, page_size); + if (need_prot == (PAGE_READ | PAGE_WRITE | PAGE_EXEC)) { + rc = qemu_mprotect_rwx(start, end - start); + } else if (need_prot == (PAGE_READ | PAGE_WRITE)) { + rc = qemu_mprotect_rw(start, end - start); + } else { + g_assert_not_reached(); + } + if (rc) { + error_setg_errno(&error_fatal, errno, + "mprotect of jit buffer"); + } + } + if (have_prot != 0) { + /* + * macOS 11.2 has a bug (Apple Feedback FB8994773) in which mprotect + * rejects a permission change from RWX -> NONE. Guard pages are + * nice for bug detection but are not essential; ignore any failure. + */ + (void)qemu_mprotect_none(end, page_size); + } } tcg_region_trees_init(); -- 2.25.1