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([2a00:1370:818c:4a57:577a:76f4:df43:5e66]) by smtp.gmail.com with ESMTPSA id m19-20020ac24253000000b004e90dee5469sm1274089lfl.157.2023.03.19.08.11.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Mar 2023 08:11:11 -0700 (PDT) To: libc-alpha@sourceware.org, bug-hurd@gnu.org Cc: Samuel Thibault , Sergey Bugaev Subject: [RFC PATCH glibc 17/34] hurd: Implement x86_64/intr-msg.h Date: Sun, 19 Mar 2023 18:10:00 +0300 Message-Id: <20230319151017.531737-18-bugaevc@gmail.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230319151017.531737-1-bugaevc@gmail.com> References: <20230319151017.531737-1-bugaevc@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-11.4 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Sergey Bugaev via Libc-alpha From: Sergey Bugaev Reply-To: Sergey Bugaev Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" Signed-off-by: Sergey Bugaev --- This is a prelimenary version of intr-msg.h. I can't know whether or not it works until we can test it. The code relies on syscall preserving values of the registers used to pass syscall arguments. The code in SYSCALL_EXAMINE that just compares two bytes to the encoded syscall instruction is sure to give many false positives; we're going to need to come up with a more reliable scheme. sysdeps/mach/hurd/x86_64/intr-msg.h | 119 ++++++++++++++++++++++++++++ 1 file changed, 119 insertions(+) create mode 100644 sysdeps/mach/hurd/x86_64/intr-msg.h diff --git a/sysdeps/mach/hurd/x86_64/intr-msg.h b/sysdeps/mach/hurd/x86_64/intr-msg.h new file mode 100644 index 00000000..5d94c85f --- /dev/null +++ b/sysdeps/mach/hurd/x86_64/intr-msg.h @@ -0,0 +1,119 @@ +/* Machine-dependent details of interruptible RPC messaging. x86_64 version. + Copyright (C) 1995-2023 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + + +/* Note that we must mark OPTION and TIMEOUT as outputs of this operation, + to indicate that the signal thread might mutate them as part + of sending us to a signal handler. */ + +#define INTR_MSG_TRAP(msg, option, send_size, rcv_size, rcv_name, timeout, notify, cancel_p, intr_port_p) \ +({ \ + error_t err; \ + register uintptr_t rcv_size_r10 asm ("r10") = rcv_size; \ + register uintptr_t rcv_name_r8 asm ("r8") = rcv_name; \ + register uintptr_t timeout_r9 asm ("r9") = timeout; \ + asm volatile ( \ + ".globl _hurd_intr_rpc_msg_about_to\n" \ + ".globl _hurd_intr_rpc_msg_setup_done\n" \ + ".globl _hurd_intr_rpc_msg_in_trap\n" \ + /* Clear rax before we do the check for cancel below. This is to + detect rax being set to non-zero (actually MACH_SEND_INTERRUPTED) + from the outside (namely, _hurdsig_abort_rpcs), which signals us + to skip the trap we were about to enter. */ \ + " xor %[err], %[err]\n" \ + "_hurd_intr_rpc_msg_about_to:" \ + /* We need to make a last check of cancel, in case we got interrupted + right before _hurd_intr_rpc_msg_about_to. */ \ + " cmpl $0, %[cancel]\n" \ + " jz _hurd_intr_rpc_msg_do\n" \ + /* We got interrupted, note so and return EINTR. */ \ + " movl $0, %[intr_port]\n" \ + " movl %[eintr], %[err]\n" \ + " jmp _hurd_intr_rpc_msg_sp_restored\n" \ + "_hurd_intr_rpc_msg_do:" \ + /* Ok, prepare the mach_msg_trap arguments. We pass the first 6 args + in registers, and push the last one and a fake return address. */ \ + " pushq %[notify]\n" \ + " pushq $0\n" \ + "_hurd_intr_rpc_msg_setup_done:" \ + /* From here on, it is safe to make us jump over the syscall. Now + check if we have been told to skip the syscall while running + the above. */ \ + " test %[err], %[err]\n" \ + " jnz _hurd_intr_rpc_msg_in_trap\n" \ + /* Do the actual syscall. */ \ + " movq $-25, %%rax\n" \ + "_hurd_intr_rpc_msg_do_trap: syscall # status in %[err]\n" \ + "_hurd_intr_rpc_msg_in_trap:" \ + /* Clean the arguments. */ \ + " addq $16, %%rsp\n" \ + "_hurd_intr_rpc_msg_sp_restored:" \ + : [err] "=&a" (err), "+S" (option), [intr_port] "=m" (*intr_port_p), \ + "+r" (timeout_r9) \ + : "D" (msg), "d" (send_size), "r" (rcv_size_r10), "r" (rcv_name_r8), \ + [notify] "rm" ((uintptr_t) notify), [cancel] "m" (*cancel_p), \ + [eintr] "i" (EINTR) \ + : "rcx", "r11"); \ + timeout = timeout_r9; \ + err; \ +}) + +#include "hurdfault.h" + +/* This cannot be an inline function because it calls setjmp. */ +#define SYSCALL_EXAMINE(state, callno) \ +({ \ + struct { unsigned char c[2]; } *p = (void *) ((state)->rip - 2); \ + int result; \ + if (_hurdsig_catch_memory_fault (p)) \ + return 0; \ + if (result = p->c[0] == 0xf && p->c[1] == 0x5) \ + /* The PC appears to be just after a `syscall' instruction. \ + This is a system call in progress; %rax holds the call number. */ \ + *(callno) = (state)->rax; \ + _hurdsig_end_catch_fault (); \ + result; \ +}) + + +/* This cannot be an inline function because it calls setjmp. */ +#define MSG_EXAMINE(state, msgid, rcvname, send_name, opt, tmout) \ +({ \ + int ret = 0; \ + const struct machine_thread_state *s = (state); \ + const mach_msg_header_t *msg = (const void *) s->rdi; \ + *(rcvname) = s->r8; \ + *(opt) = s->rsi; \ + *(tmout) = s->r9; \ + if (msg == 0) \ + { \ + *(send_name) = MACH_PORT_NULL; \ + *(msgid) = 0; \ + } \ + else \ + { \ + ret = _hurdsig_catch_memory_fault (msg) ? -1 : 0; \ + if (ret == 0) \ + { \ + *(send_name) = msg->msgh_remote_port; \ + *(msgid) = msg->msgh_id; \ + _hurdsig_end_catch_fault (); \ + } \ + } \ + ret; \ +})