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[187.189.51.144]) by smtp.gmail.com with ESMTPSA id i11sm1953966otp.76.2021.03.20.09.57.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 20 Mar 2021 09:57:23 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Subject: [PATCH v3 for-6.0 1/2] tcg: Do not set guard pages on the rx portion of code_gen_buffer Date: Sat, 20 Mar 2021 10:57:19 -0600 Message-Id: <20210320165720.1813545-2-richard.henderson@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210320165720.1813545-1-richard.henderson@linaro.org> References: <20210320165720.1813545-1-richard.henderson@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::c2b; envelope-from=richard.henderson@linaro.org; helo=mail-oo1-xc2b.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: r.bolshakov@yadro.com, j@getutm.app Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" The rw portion of the buffer is the only one in which overruns can be generated. Allow the rx portion to be more completely covered by huge pages. Signed-off-by: Richard Henderson --- tcg/tcg.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/tcg/tcg.c b/tcg/tcg.c index de91bb6e9e..88c9e6f8a4 100644 --- a/tcg/tcg.c +++ b/tcg/tcg.c @@ -828,7 +828,6 @@ void tcg_region_init(void) size_t region_size; size_t n_regions; size_t i; - uintptr_t splitwx_diff; n_regions = tcg_n_regions(); @@ -858,8 +857,11 @@ void tcg_region_init(void) /* account for that last guard page */ region.end -= page_size; - /* set guard pages */ - splitwx_diff = tcg_splitwx_diff; + /* + * 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. + */ for (i = 0; i < region.n; i++) { void *start, *end; int rc; @@ -867,10 +869,6 @@ void tcg_region_init(void) tcg_region_bounds(i, &start, &end); rc = qemu_mprotect_none(end, page_size); g_assert(!rc); - if (splitwx_diff) { - rc = qemu_mprotect_none(end + splitwx_diff, page_size); - g_assert(!rc); - } } tcg_region_trees_init(); -- 2.25.1