1 /* Machine-dependent details of interruptible RPC messaging. x86_64 version.
2 Copyright (C) 1995-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19
20 /* Note that we must mark OPTION and TIMEOUT as outputs of this operation,
21 to indicate that the signal thread might mutate them as part
22 of sending us to a signal handler. */
23
24 #define INTR_MSG_TRAP(msg, option, send_size, rcv_size, rcv_name, timeout, notify, cancel_p, intr_port_p) \
25 ({ \
26 error_t err; \
27 register uintptr_t rcv_size_r10 asm ("r10") = rcv_size; \
28 register uintptr_t rcv_name_r8 asm ("r8") = rcv_name; \
29 register uintptr_t timeout_r9 asm ("r9") = timeout; \
30 asm volatile ( \
31 ".globl _hurd_intr_rpc_msg_about_to\n" \
32 ".globl _hurd_intr_rpc_msg_setup_done\n" \
33 ".globl _hurd_intr_rpc_msg_in_trap\n" \
34 /* Clear rax before we do the check for cancel below. This is to
35 detect rax being set to non-zero (actually MACH_SEND_INTERRUPTED)
36 from the outside (namely, _hurdsig_abort_rpcs), which signals us
37 to skip the trap we were about to enter. */ \
38 " xor %[err], %[err]\n" \
39 "_hurd_intr_rpc_msg_about_to:" \
40 /* We need to make a last check of cancel, in case we got interrupted
41 right before _hurd_intr_rpc_msg_about_to. */ \
42 " cmpl $0, %[cancel]\n" \
43 " jz _hurd_intr_rpc_msg_do\n" \
44 /* We got interrupted, note so and return EINTR. */ \
45 " movl $0, %[intr_port]\n" \
46 " movl %[eintr], %[err]\n" \
47 " jmp _hurd_intr_rpc_msg_sp_restored\n" \
48 "_hurd_intr_rpc_msg_do:" \
49 /* Ok, prepare the mach_msg_trap arguments. We pass the first 6 args
50 in registers, and push the last one and a fake return address. */ \
51 " pushq %[notify]\n" \
52 " pushq $0\n" \
53 "_hurd_intr_rpc_msg_setup_done:" \
54 /* From here on, it is safe to make us jump over the syscall. Now
55 check if we have been told to skip the syscall while running
56 the above. */ \
57 " test %[err], %[err]\n" \
58 " jnz _hurd_intr_rpc_msg_in_trap\n" \
59 /* Do the actual syscall. */ \
60 " movq $-25, %%rax\n" \
61 "_hurd_intr_rpc_msg_do_trap: syscall # status in %[err]\n" \
62 "_hurd_intr_rpc_msg_in_trap:" \
63 /* Clean the arguments. */ \
64 " addq $16, %%rsp\n" \
65 "_hurd_intr_rpc_msg_sp_restored:" \
66 : [err] "=&a" (err), "+S" (option), [intr_port] "=m" (*intr_port_p), \
67 "+r" (timeout_r9) \
68 : "D" (msg), "d" (send_size), "r" (rcv_size_r10), "r" (rcv_name_r8), \
69 [notify] "rm" ((uintptr_t) notify), [cancel] "m" (*cancel_p), \
70 [eintr] "i" (EINTR) \
71 : "rcx", "r11"); \
72 timeout = timeout_r9; \
73 err; \
74 })
75
76 #include "hurdfault.h"
77
78 /* This cannot be an inline function because it calls setjmp. */
79 #define SYSCALL_EXAMINE(state, callno) \
80 ({ \
81 struct { unsigned char c[2]; } *p = (void *) ((state)->rip - 2); \
82 int result; \
83 if (_hurdsig_catch_memory_fault (p)) \
84 return 0; \
85 if (result = p->c[0] == 0xf && p->c[1] == 0x5) \
86 /* The PC appears to be just after a `syscall' instruction. \
87 This is a system call in progress; %rax holds the call number. */ \
88 *(callno) = (state)->rax; \
89 _hurdsig_end_catch_fault (); \
90 result; \
91 })
92
93
94 /* This cannot be an inline function because it calls setjmp. */
95 #define MSG_EXAMINE(state, msgid, rcvname, send_name, opt, tmout) \
96 ({ \
97 int ret = 0; \
98 const struct machine_thread_state *s = (state); \
99 const mach_msg_header_t *msg = (const void *) s->rdi; \
100 *(rcvname) = s->r8; \
101 *(opt) = s->rsi; \
102 *(tmout) = s->r9; \
103 if (msg == 0) \
104 { \
105 *(send_name) = MACH_PORT_NULL; \
106 *(msgid) = 0; \
107 } \
108 else \
109 { \
110 ret = _hurdsig_catch_memory_fault (msg) ? -1 : 0; \
111 if (ret == 0) \
112 { \
113 *(send_name) = msg->msgh_remote_port; \
114 *(msgid) = msg->msgh_id; \
115 _hurdsig_end_catch_fault (); \
116 } \
117 } \
118 ret; \
119 })