Applied, thanks! Sergey Bugaev, le dim. 19 mars 2023 18:10:00 +0300, a ecrit: > This is a prelimenary version of intr-msg.h. I can't know whether or not > it works until we can test it.
Sure :) > 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. Not necessarily: this is only used for msg_report_wait, which is already extra cautious about what it's doing, at worse it will report dumb information, which should be fine enough for msg_report_wait. Possibly we could filter out by addresses of the functions known to perform an actual system call. Samuel > 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 > + <https://www.gnu.org/licenses/>. */ > + > + > +/* 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; > \ > +}) > -- > 2.39.2 > -- Samuel --- Pour une évaluation indépendante, transparente et rigoureuse ! Je soutiens la Commission d'Évaluation de l'Inria.
