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([2602:47:d490:6901:9d52:4fe8:10ce:5c3]) by smtp.gmail.com with ESMTPSA id c5-20020aa78c05000000b0066f37665a63sm456138pfd.73.2023.08.03.18.45.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Aug 2023 18:45:27 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Cc: joel@jms.id.au, akihiko.odaki@daynix.com, laurent@vivier.eu, deller@gmx.de Subject: [PATCH v8 12/17] linux-user: Use elf_et_dyn_base for ET_DYN with interpreter Date: Thu, 3 Aug 2023 18:45:12 -0700 Message-Id: <20230804014517.6361-13-richard.henderson@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230804014517.6361-1-richard.henderson@linaro.org> References: <20230804014517.6361-1-richard.henderson@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::42b; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x42b.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, T_SCC_BODY_TEXT_LINE=-0.01 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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Follow the lead of the linux kernel in fs/binfmt_elf.c, in which an ET_DYN executable which uses an interpreter (usually a PIE executable) is loaded away from where the interpreter itself will be loaded. Signed-off-by: Richard Henderson Reviewed-by: Akihiko Odaki Reviewed-by: Helge Deller --- linux-user/elfload.c | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 0c64aad8a5..a3aa08a13e 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -3106,6 +3106,8 @@ static void load_elf_image(const char *image_name, int image_fd, } } + load_addr = loaddr; + if (pinterp_name != NULL) { /* * This is the main executable. @@ -3135,11 +3137,32 @@ static void load_elf_image(const char *image_name, int image_fd, */ probe_guest_base(image_name, loaddr, hiaddr); } else { + abi_ulong align; + /* * The binary is dynamic, but we still need to * select guest_base. In this case we pass a size. */ probe_guest_base(image_name, 0, hiaddr - loaddr); + + /* + * Avoid collision with the loader by providing a different + * default load address. + */ + load_addr += elf_et_dyn_base; + + /* + * TODO: Better support for mmap alignment is desirable. + * Since we do not have complete control over the guest + * address space, we prefer the kernel to choose some address + * rather than force the use of LOAD_ADDR via MAP_FIXED. + * But without MAP_FIXED we cannot guarantee alignment, + * only suggest it. + */ + align = pow2ceil(info->alignment); + if (align) { + load_addr &= -align; + } } } @@ -3154,13 +3177,13 @@ static void load_elf_image(const char *image_name, int image_fd, * * Otherwise this is ET_DYN, and we are searching for a location * that can hold the memory space required. If the image is - * pre-linked, LOADDR will be non-zero, and the kernel should + * pre-linked, LOAD_ADDR will be non-zero, and the kernel should * honor that address if it happens to be free. * * In both cases, we will overwrite pages in this range with mappings * from the executable. */ - load_addr = target_mmap(loaddr, (size_t)hiaddr - loaddr + 1, PROT_NONE, + load_addr = target_mmap(load_addr, (size_t)hiaddr - loaddr + 1, PROT_NONE, MAP_PRIVATE | MAP_ANON | MAP_NORESERVE | (ehdr->e_type == ET_EXEC ? MAP_FIXED_NOREPLACE : 0), -1, 0);