From patchwork Tue Mar 24 11:16:58 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Vivier X-Patchwork-Id: 11455213 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 86F761392 for ; Tue, 24 Mar 2020 11:21:21 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 66D5A20786 for ; Tue, 24 Mar 2020 11:21:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 66D5A20786 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=vivier.eu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:46938 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jGhcW-0008HR-Jx for patchwork-qemu-devel@patchwork.kernel.org; Tue, 24 Mar 2020 07:21:20 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:33415) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jGhYg-0002GG-K1 for qemu-devel@nongnu.org; Tue, 24 Mar 2020 07:17:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jGhYd-0007M2-Oj for qemu-devel@nongnu.org; Tue, 24 Mar 2020 07:17:22 -0400 Received: from mout.kundenserver.de ([212.227.126.187]:58085) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1jGhYd-0007Lb-GZ for qemu-devel@nongnu.org; Tue, 24 Mar 2020 07:17:19 -0400 Received: from localhost.localdomain ([82.252.135.106]) by mrelayeu.kundenserver.de (mreue011 [212.227.15.167]) with ESMTPSA (Nemesis) id 1MKKER-1iyCR33L8Z-00Lm0m; Tue, 24 Mar 2020 12:17:07 +0100 From: Laurent Vivier To: qemu-devel@nongnu.org Subject: [PULL v2 3/5] linux-user/i386: Emulate x86_64 vsyscalls Date: Tue, 24 Mar 2020 12:16:58 +0100 Message-Id: <20200324111700.595531-4-laurent@vivier.eu> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200324111700.595531-1-laurent@vivier.eu> References: <20200324111700.595531-1-laurent@vivier.eu> MIME-Version: 1.0 X-Provags-ID: V03:K1:r9JZFDzHesbtdtjjLFO5e8F/goXYNKkaI25sGWvvho31XKg365x 1AS7MiJIEQrC+Y3yXUa+kBdVcdJy3ouC3IRNsm5hmi4t6p14diEGEvKGmSNm0z2rwxxIMzZ H6MLWiQMZ2v//B6EOzSIQWI+O+wgnES490hop+LwHdetUH1wDjiqIqBT0GKb1X3tzJTm1bW 6DLIY6Uo0eSHvZDexTYAg== X-UI-Out-Filterresults: notjunk:1;V03:K0:dnkYpM5ijW0=:eZphKNc94bqgjwwFsHSHsr iau5gIhsrLDWh/Rr7ona2aXKH1PNINk/QrpxPPn3nd4RwmuAmFO5lPfvJ4a9Ch0ZwtoBxpzTi UF1dJuMG3JP5osk5HBUuwoIuX7pu6f9UUYIbEnqzA5s2FygVWZKmH0dOr/bC3/dE5Za+J7BkI xvVxkF9wz6S0JkBGILFhTpoofJ/O751ZSof1oav+SSX/yNvDUt+dGxLR6J79tVUY5HKk45IW5 hGEtqqFReRdO5vfyI/aP26r93h8O1wS0xna5sIRVLh7KJXDPVGjoUdAfYvK+HpDOYrxRpfrJ/ c7NH4YHre46Px1lpQczh980ungR7R5lOtLFo5ojW//fRY5TTKkLI8yDmeUWcuaRG7sQzkqWzF UoIciW+BK/pufcqh9zAaQkIQ4DMThLJQKZAcq+8h/XIjOrhn4HRWI5TwqMhVJ+QcqWrPQM4Kv QPP3VB2Pb01cc8MsNGxZwELoN/ySt65j2oJxwZRhi7r01wQcYCHIiZCmfUlz41hzrFYVVuEnS PFjLWWGhagsEwVh1i1zV6UFTV8rNf6euMVuVYnfSzKnAVb53TMTvRGKMzyRAGSNL8rEc4b2WV 5B5o3j4donOU/ZWnhc4S2g1OesuCabRnm/CscVoAXHKZk6vB0aAAvCy+xAvc5WoD6AiZ5HQ+e rbNUZw0Jp9OcP5ng+ECs2E7+T8vr7lFgomwsVX8nU9hdPIPpSn6h/snLYvooVc22BUyevt/Df 9+olJwF1Qo/lP3LbdgI9heXfll0tfl8t2KDxVbe0IfBqzWgdSqqiyD2gTQnhtRUJZK45mlB7S VkUStpF5RABZbZBnPs1DLPiL2oNqrmT9828GZ2TDThU36E/PKdWTqK8qSEjZUi+ZZLM21FH X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 212.227.126.187 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: Paolo Bonzini , Riku Voipio , Richard Henderson , Laurent Vivier Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" From: Richard Henderson Notice the magic page during translate, much like we already do for the arm32 commpage. At runtime, raise an exception to return cpu_loop for emulation. Reviewed-by: Paolo Bonzini Signed-off-by: Richard Henderson Message-Id: <20200213032223.14643-4-richard.henderson@linaro.org> Signed-off-by: Laurent Vivier --- linux-user/i386/cpu_loop.c | 108 +++++++++++++++++++++++++++++++++++++ target/i386/cpu.h | 7 +++ target/i386/translate.c | 14 ++++- 3 files changed, 128 insertions(+), 1 deletion(-) diff --git a/linux-user/i386/cpu_loop.c b/linux-user/i386/cpu_loop.c index e217cca5ee1e..70cde417e605 100644 --- a/linux-user/i386/cpu_loop.c +++ b/linux-user/i386/cpu_loop.c @@ -92,6 +92,109 @@ static void gen_signal(CPUX86State *env, int sig, int code, abi_ptr addr) queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info); } +#ifdef TARGET_X86_64 +static bool write_ok_or_segv(CPUX86State *env, abi_ptr addr, size_t len) +{ + /* + * For all the vsyscalls, NULL means "don't write anything" not + * "write it at address 0". + */ + if (addr == 0 || access_ok(VERIFY_WRITE, addr, len)) { + return true; + } + + env->error_code = PG_ERROR_W_MASK | PG_ERROR_U_MASK; + gen_signal(env, TARGET_SIGSEGV, TARGET_SEGV_MAPERR, addr); + return false; +} + +/* + * Since v3.1, the kernel traps and emulates the vsyscall page. + * Entry points other than the official generate SIGSEGV. + */ +static void emulate_vsyscall(CPUX86State *env) +{ + int syscall; + abi_ulong ret; + uint64_t caller; + + /* + * Validate the entry point. We have already validated the page + * during translation to get here; now verify the offset. + */ + switch (env->eip & ~TARGET_PAGE_MASK) { + case 0x000: + syscall = TARGET_NR_gettimeofday; + break; + case 0x400: + syscall = TARGET_NR_time; + break; + case 0x800: + syscall = TARGET_NR_getcpu; + break; + default: + goto sigsegv; + } + + /* + * Validate the return address. + * Note that the kernel treats this the same as an invalid entry point. + */ + if (get_user_u64(caller, env->regs[R_ESP])) { + goto sigsegv; + } + + /* + * Validate the the pointer arguments. + */ + switch (syscall) { + case TARGET_NR_gettimeofday: + if (!write_ok_or_segv(env, env->regs[R_EDI], + sizeof(struct target_timeval)) || + !write_ok_or_segv(env, env->regs[R_ESI], + sizeof(struct target_timezone))) { + return; + } + break; + case TARGET_NR_time: + if (!write_ok_or_segv(env, env->regs[R_EDI], sizeof(abi_long))) { + return; + } + break; + case TARGET_NR_getcpu: + if (!write_ok_or_segv(env, env->regs[R_EDI], sizeof(uint32_t)) || + !write_ok_or_segv(env, env->regs[R_ESI], sizeof(uint32_t))) { + return; + } + break; + default: + g_assert_not_reached(); + } + + /* + * Perform the syscall. None of the vsyscalls should need restarting. + */ + ret = do_syscall(env, syscall, env->regs[R_EDI], env->regs[R_ESI], + env->regs[R_EDX], env->regs[10], env->regs[8], + env->regs[9], 0, 0); + g_assert(ret != -TARGET_ERESTARTSYS); + g_assert(ret != -TARGET_QEMU_ESIGRETURN); + if (ret == -TARGET_EFAULT) { + goto sigsegv; + } + env->regs[R_EAX] = ret; + + /* Emulate a ret instruction to leave the vsyscall page. */ + env->eip = caller; + env->regs[R_ESP] += 8; + return; + + sigsegv: + /* Like force_sig(SIGSEGV). */ + gen_signal(env, TARGET_SIGSEGV, TARGET_SI_KERNEL, 0); +} +#endif + void cpu_loop(CPUX86State *env) { CPUState *cs = env_cpu(env); @@ -141,6 +244,11 @@ void cpu_loop(CPUX86State *env) env->regs[R_EAX] = ret; } break; +#endif +#ifdef TARGET_X86_64 + case EXCP_VSYSCALL: + emulate_vsyscall(env); + break; #endif case EXCP0B_NOSEG: case EXCP0C_STACK: diff --git a/target/i386/cpu.h b/target/i386/cpu.h index 49ecc23104c9..9af1b0c12e8e 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -1003,6 +1003,7 @@ typedef uint64_t FeatureWordArray[FEATURE_WORDS]; #define EXCP_VMEXIT 0x100 /* only for system emulation */ #define EXCP_SYSCALL 0x101 /* only for user emulation */ +#define EXCP_VSYSCALL 0x102 /* only for user emulation */ /* i386-specific interrupt pending bits. */ #define CPU_INTERRUPT_POLL CPU_INTERRUPT_TGT_EXT_1 @@ -2218,4 +2219,10 @@ static inline bool hyperv_feat_enabled(X86CPU *cpu, int feat) return !!(cpu->hyperv_features & BIT(feat)); } +#if defined(TARGET_X86_64) && \ + defined(CONFIG_USER_ONLY) && \ + defined(CONFIG_LINUX) +# define TARGET_VSYSCALL_PAGE (UINT64_C(-10) << 20) +#endif + #endif /* I386_CPU_H */ diff --git a/target/i386/translate.c b/target/i386/translate.c index d9af8f4078b3..5e5dbb41b0ce 100644 --- a/target/i386/translate.c +++ b/target/i386/translate.c @@ -8555,7 +8555,19 @@ static bool i386_tr_breakpoint_check(DisasContextBase *dcbase, CPUState *cpu, static void i386_tr_translate_insn(DisasContextBase *dcbase, CPUState *cpu) { DisasContext *dc = container_of(dcbase, DisasContext, base); - target_ulong pc_next = disas_insn(dc, cpu); + target_ulong pc_next; + +#ifdef TARGET_VSYSCALL_PAGE + /* + * Detect entry into the vsyscall page and invoke the syscall. + */ + if ((dc->base.pc_next & TARGET_PAGE_MASK) == TARGET_VSYSCALL_PAGE) { + gen_exception(dc, EXCP_VSYSCALL, dc->base.pc_next); + return; + } +#endif + + pc_next = disas_insn(dc, cpu); if (dc->tf || (dc->base.tb->flags & HF_INHIBIT_IRQ_MASK)) { /* if single step mode, we generate only one instruction and