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([2602:47:d49d:ec01:bbf3:9914:aa9c:3b4e]) by smtp.gmail.com with ESMTPSA id g184-20020a6252c1000000b00535d19c46d7sm2199904pfb.203.2022.08.18.20.26.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 18 Aug 2022 20:26:19 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Cc: laurent@vivier.eu, iii@linux.ibm.com, dramforever@live.com, alistair.francis@wdc.com, alex.bennee@linaro.org Subject: [PATCH v6 02/21] linux-user/hppa: Allocate page zero as a commpage Date: Thu, 18 Aug 2022 20:25:56 -0700 Message-Id: <20220819032615.884847-3-richard.henderson@linaro.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220819032615.884847-1-richard.henderson@linaro.org> References: <20220819032615.884847-1-richard.henderson@linaro.org> MIME-Version: 1.0 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, 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" We're about to start validating PAGE_EXEC, which means that we've got to mark page zero executable. We had been special casing this entirely within translate. Signed-off-by: Richard Henderson --- linux-user/elfload.c | 34 +++++++++++++++++++++++++++++++--- 1 file changed, 31 insertions(+), 3 deletions(-) diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 3e3dc02499..29d910c4cc 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -1646,6 +1646,34 @@ static inline void init_thread(struct target_pt_regs *regs, regs->gr[31] = infop->entry; } +#define LO_COMMPAGE 0 + +static bool init_guest_commpage(void) +{ + void *want = g2h_untagged(LO_COMMPAGE); + void *addr = mmap(want, qemu_host_page_size, PROT_NONE, + MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, -1, 0); + + if (addr == MAP_FAILED) { + perror("Allocating guest commpage"); + exit(EXIT_FAILURE); + } + if (addr != want) { + return false; + } + + /* + * On Linux, page zero is normally marked execute only + gateway. + * Normal read or write is supposed to fail (thus PROT_NONE above), + * but specific offsets have kernel code mapped to raise permissions + * and implement syscalls. Here, simply mark the page executable. + * Special case the entry points during translation (see do_page_zero). + */ + page_set_flags(LO_COMMPAGE, LO_COMMPAGE + TARGET_PAGE_SIZE, + PAGE_EXEC | PAGE_VALID); + return true; +} + #endif /* TARGET_HPPA */ #ifdef TARGET_XTENSA @@ -2326,12 +2354,12 @@ static abi_ulong create_elf_tables(abi_ulong p, int argc, int envc, } #if defined(HI_COMMPAGE) -#define LO_COMMPAGE 0 +#define LO_COMMPAGE -1 #elif defined(LO_COMMPAGE) #define HI_COMMPAGE 0 #else #define HI_COMMPAGE 0 -#define LO_COMMPAGE 0 +#define LO_COMMPAGE -1 #define init_guest_commpage() true #endif @@ -2555,7 +2583,7 @@ static void pgb_static(const char *image_name, abi_ulong orig_loaddr, } else { offset = -(HI_COMMPAGE & -align); } - } else if (LO_COMMPAGE != 0) { + } else if (LO_COMMPAGE != -1) { loaddr = MIN(loaddr, LO_COMMPAGE & -align); }