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[24.74.129.96]) by smtp.gmail.com with ESMTPSA id r13sm7141104qkk.73.2021.09.24.09.59.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Sep 2021 09:59:35 -0700 (PDT) From: Richard Henderson To: qemu-devel@nongnu.org Subject: [PATCH v3 10/27] linux-user/i386: Implement setup_sigtramp Date: Fri, 24 Sep 2021 12:59:09 -0400 Message-Id: <20210924165926.752809-11-richard.henderson@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210924165926.752809-1-richard.henderson@linaro.org> References: <20210924165926.752809-1-richard.henderson@linaro.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::834; envelope-from=richard.henderson@linaro.org; helo=mail-qt1-x834.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: peter.maydell@linaro.org, laurent@vivier.eu Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Create and record the two signal trampolines. Use them when the guest does not use SA_RESTORER. Note that x86_64 does not use this code. Signed-off-by: Richard Henderson --- linux-user/i386/target_signal.h | 2 ++ linux-user/x86_64/target_signal.h | 3 ++ linux-user/i386/signal.c | 56 +++++++++++++++++++++---------- 3 files changed, 43 insertions(+), 18 deletions(-) diff --git a/linux-user/i386/target_signal.h b/linux-user/i386/target_signal.h index 50361af874..64d09f2e75 100644 --- a/linux-user/i386/target_signal.h +++ b/linux-user/i386/target_signal.h @@ -22,4 +22,6 @@ typedef struct target_sigaltstack { #include "../generic/signal.h" #define TARGET_ARCH_HAS_SETUP_FRAME +#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1 + #endif /* I386_TARGET_SIGNAL_H */ diff --git a/linux-user/x86_64/target_signal.h b/linux-user/x86_64/target_signal.h index 4ea74f20dd..4673c5a886 100644 --- a/linux-user/x86_64/target_signal.h +++ b/linux-user/x86_64/target_signal.h @@ -21,4 +21,7 @@ typedef struct target_sigaltstack { #include "../generic/signal.h" +/* For x86_64, use of SA_RESTORER is mandatory. */ +#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 0 + #endif /* X86_64_TARGET_SIGNAL_H */ diff --git a/linux-user/i386/signal.c b/linux-user/i386/signal.c index 3b4b55fc0a..94ab6396a0 100644 --- a/linux-user/i386/signal.c +++ b/linux-user/i386/signal.c @@ -310,6 +310,22 @@ get_sigframe(struct target_sigaction *ka, CPUX86State *env, size_t frame_size) } #ifndef TARGET_X86_64 +static void install_sigtramp(void *tramp) +{ + /* This is popl %eax ; movl $syscall,%eax ; int $0x80 */ + __put_user(0xb858, (uint16_t *)(tramp + 0)); + __put_user(TARGET_NR_sigreturn, (int *)(tramp + 2)); + __put_user(0x80cd, (uint16_t *)(tramp + 6)); +} + +static void install_rt_sigtramp(void *tramp) +{ + /* This is movl $syscall,%eax ; int $0x80 */ + __put_user(0xb8, (char *)(tramp + 0)); + __put_user(TARGET_NR_rt_sigreturn, (int *)(tramp + 1)); + __put_user(0x80cd, (uint16_t *)(tramp + 5)); +} + /* compare linux/arch/i386/kernel/signal.c:setup_frame() */ void setup_frame(int sig, struct target_sigaction *ka, target_sigset_t *set, CPUX86State *env) @@ -338,16 +354,9 @@ void setup_frame(int sig, struct target_sigaction *ka, if (ka->sa_flags & TARGET_SA_RESTORER) { __put_user(ka->sa_restorer, &frame->pretcode); } else { - uint16_t val16; - abi_ulong retcode_addr; - retcode_addr = frame_addr + offsetof(struct sigframe, retcode); - __put_user(retcode_addr, &frame->pretcode); - /* This is popl %eax ; movl $,%eax ; int $0x80 */ - val16 = 0xb858; - __put_user(val16, (uint16_t *)(frame->retcode+0)); - __put_user(TARGET_NR_sigreturn, (int *)(frame->retcode+2)); - val16 = 0x80cd; - __put_user(val16, (uint16_t *)(frame->retcode+6)); + /* This is no longer used, but is retained for ABI compatibility. */ + install_sigtramp(frame->retcode); + __put_user(default_sigreturn, &frame->pretcode); } /* Set up registers for signal handler */ @@ -416,14 +425,9 @@ void setup_rt_frame(int sig, struct target_sigaction *ka, if (ka->sa_flags & TARGET_SA_RESTORER) { __put_user(ka->sa_restorer, &frame->pretcode); } else { - uint16_t val16; - addr = frame_addr + offsetof(struct rt_sigframe, retcode); - __put_user(addr, &frame->pretcode); - /* This is movl $,%eax ; int $0x80 */ - __put_user(0xb8, (char *)(frame->retcode+0)); - __put_user(TARGET_NR_rt_sigreturn, (int *)(frame->retcode+1)); - val16 = 0x80cd; - __put_user(val16, (uint16_t *)(frame->retcode+5)); + /* This is no longer used, but is retained for ABI compatibility. */ + install_rt_sigtramp(frame->retcode); + __put_user(default_rt_sigreturn, &frame->pretcode); } #else /* XXX: Would be slightly better to return -EFAULT here if test fails @@ -592,3 +596,19 @@ badframe: force_sig(TARGET_SIGSEGV); return -TARGET_QEMU_ESIGRETURN; } + +#ifndef TARGET_X86_64 +void setup_sigtramp(abi_ulong sigtramp_page) +{ + uint16_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 2 * 8, 0); + assert(tramp != NULL); + + default_sigreturn = sigtramp_page; + install_sigtramp(tramp); + + default_rt_sigreturn = sigtramp_page + 8; + install_rt_sigtramp(tramp + 8); + + unlock_user(tramp, sigtramp_page, 2 * 8); +} +#endif -- 2.25.1