1 /* Copyright (c) 2015-2018. The SimGrid Team.
2 * All rights reserved. */
4 /* This program is free software; you can redistribute it and/or modify it
5 * under the terms of the license (GNU LGPL) which comes with this package. */
11 #include <libunwind.h>
12 #include <libunwind-ptrace.h>
14 #include "src/mc/mc_unw.hpp"
15 #include "src/mc/remote/RemoteClient.hpp"
18 * Libunwind namespace implementation using process_vm_readv.
23 /** Partial structure of libunwind-ptrace context in order to get the PID
25 * HACK, The context type for libunwind-race is an opaque type.
26 * We need to get the PID which is the first field. This is a hack
27 * which might break if the libunwind-ptrace structure changes.
34 /** Get the PID of a `libunwind-ptrace` context
37 pid_t _UPT_getpid(void* arg)
39 _UPT_info* info = static_cast<_UPT_info*>(arg);
43 /** Read from the memory, avoid using `ptrace` (libunwind method)
45 static int access_mem(const unw_addr_space_t as,
46 const unw_word_t addr, unw_word_t* const valp,
47 const int write, void* const arg)
51 pid_t pid = _UPT_getpid(arg);
52 size_t size = sizeof(unw_word_t);
54 #if HAVE_PROCESS_VM_READV
55 // process_vm_read implementation.
56 // This is only available since Linux 3.2.
58 struct iovec local = { valp, size };
59 struct iovec remote = { (void*) addr, size };
60 ssize_t s = process_vm_readv(pid, &local, 1, &remote, 1, 0);
62 if ((size_t) s != size)
67 if (s < 0 && errno != ENOSYS)
71 // /proc/${pid}/mem implementation.
72 // On recent kernels, we do not need to ptrace the target process.
73 // On older kernels, it is necessary to ptrace the target process.
75 off_t off = (off_t) addr;
76 char* buf = (char*) valp;
77 int fd = simgrid::mc::open_vm(pid, O_RDONLY);
81 ssize_t s = pread(fd, buf, count, off);
98 // ptrace implementation.
99 // We need to have PTRACE_ATTACH-ed it before.
100 return _UPT_access_mem(as, addr, valp, write, arg);
106 /** Virtual table for our `libunwind-process_vm_readv` implementation.
108 * This implementation reuse most the code of `libunwind-ptrace` but
109 * does not use ptrace() to read the target process memory by
110 * `process_vm_readv()` or `/dev/${pid}/mem` if possible.
112 * Does not support any MC-specific behaviour (privatization, snapshots)
115 * It works with `void*` contexts allocated with `_UPT_create(pid)`.
117 // TODO, we could get rid of this if we properly stop the model-checked
118 // process before reading the memory.
119 static unw_accessors_t accessors = {
120 &_UPT_find_proc_info,
121 &_UPT_put_unwind_info,
122 &_UPT_get_dyn_info_list_addr,
130 unw_addr_space_t create_addr_space()
132 return unw_create_addr_space(&accessors, BYTE_ORDER);
135 void* create_context(unw_addr_space_t as, pid_t pid)
137 return _UPT_create(pid);