From patchwork Tue Mar 24 10:03:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Vivier X-Patchwork-Id: 1260548 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=vivier.eu 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 ozlabs.org (Postfix) with ESMTPS id 48mn3W5bvFz9sP7 for ; Tue, 24 Mar 2020 21:07:03 +1100 (AEDT) Received: from localhost ([::1]:45334 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jGgSb-0000uf-NU for incoming@patchwork.ozlabs.org; Tue, 24 Mar 2020 06:07:01 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49471) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jGgPC-00069n-IA for qemu-devel@nongnu.org; Tue, 24 Mar 2020 06:03:32 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jGgPA-0000ep-NE for qemu-devel@nongnu.org; Tue, 24 Mar 2020 06:03:30 -0400 Received: from mout.kundenserver.de ([212.227.17.13]:60365) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1jGgPA-0000eK-Do for qemu-devel@nongnu.org; Tue, 24 Mar 2020 06:03:28 -0400 Received: from localhost.localdomain ([82.252.135.106]) by mrelayeu.kundenserver.de (mreue109 [212.227.15.183]) with ESMTPSA (Nemesis) id 1M2fDl-1jFqvM2Xdf-004FkX; Tue, 24 Mar 2020 11:03:15 +0100 From: Laurent Vivier To: qemu-devel@nongnu.org Subject: [PULL 3/5] linux-user/i386: Emulate x86_64 vsyscalls Date: Tue, 24 Mar 2020 11:03:09 +0100 Message-Id: <20200324100311.588288-4-laurent@vivier.eu> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200324100311.588288-1-laurent@vivier.eu> References: <20200324100311.588288-1-laurent@vivier.eu> MIME-Version: 1.0 X-Provags-ID: V03:K1:OXu2EBDMcXnv46HrJDbKY9A+52Hd7vrYXjTaMleT9EevKzQ9qQz S+hP+E4rNj/+ixO+fkI0HJYwx/fN/NCEaijyE+J1zIPF84DRLw438FvX0ynC4uD7QMIzA9d XfQq8PA1pyAfqJv+tlcy2U2YIkmHrB5EF4ZJl/Ou8fuX19cBwtPR1VcTQhskzTBSG87sIDQ FiqkDE47YA4xHeo2zwSlw== X-UI-Out-Filterresults: notjunk:1; V03:K0:Hufkybbf2n0=:P6v+ihT7h5V+5U0sD3zBG8 8ndo1lru968ESMimuGlAE/xUd3MfXyuGNUMJedDb+i3/BCjXaH00YDyomi4KQqn/owSuXgGmJ 1CkUwfjW8uy9zCEN6qQcy7D2TwgLsoix9+9jUEst8pHh1Sc4p92n8hDAMk7wev2EaecqIRcD1 tVxaEUPw4MvIb/jAHPsahT/QW+WVvuorl7qZ2vSTPC00g10lk5/QkMwaMnh3+jctRmlg09U0K 8fVG/1kWj6mJATi/s9ewJg3TkHT7sIsZ8mFMIG0+jCkNiSIwnrKFC95ubK+fhBcaGYvW1yuF0 2grKY9jM3INpUjI8X1NIqs7UP/HBppCl/zjCDsYpm/sYpcc1UtolDXc0RzK5ZuR6lfTIufX2E Dj0ilrSfwEmn6tUXbaPHrZjmgCgMLKMwR9iFJT4Ox0tqhUzVbDN517cgVUDW0x02XOL/+nG7w fBb2xzk5ulSYmkrW//Y7goDaL4GA7ITy2mAO9Y/9+k4D5Q4HBFiZFQ1c1Q0bwiatJnqFecSis oGwhuuggZRgIdrkpQTmSbkNPt4SomBgyNoj6bU/S2k30n1sa4LfXDmdvzStNC5EZKUdz2dvZo 0SnEdaiIsasFRix4RTMv+dQn08wzHE+aYBMHEq8bzDarwtRln6RDW7ccYMvyEf9d6Va4tgyQB CJvHZQTsJ1XtMwevGawQj8iRH7Ge9LKYQnX1bXSwvyj+HQyrjT42Y6ch+IPKoIOY62QA3c6VD 6xPUIoVzifItTeO7RDzRg00dSlCUrgiSRRv3FHyQSIx3EXTAjT1KcUEqKRQmVLKQL7T9VxQ0X FYXYtBo7Z8jvI2mz5QyzPhAvNQGrNLlOE/pWc6CIlAsR40RdptAxgPyCZThpcFhWrTs9e9C X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 212.227.17.13 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+incoming=patchwork.ozlabs.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