1 /*===- InstrProfilingPlatformFuchsia.c - Profile data Fuchsia platform ----===*\
2 |*
3 |* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 |* See https://llvm.org/LICENSE.txt for license information.
5 |* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 |*
7 \*===----------------------------------------------------------------------===*/
8 /*
9  * This file implements the profiling runtime for Fuchsia and defines the
10  * shared profile runtime interface. Each module (executable or DSO) statically
11  * links in the whole profile runtime to satisfy the calls from its
12  * instrumented code. Several modules in the same program might be separately
13  * compiled and even use different versions of the instrumentation ABI and data
14  * format. All they share in common is the VMO and the offset, which live in
15  * exported globals so that exactly one definition will be shared across all
16  * modules. Each module has its own independent runtime that registers its own
17  * atexit hook to append its own data into the shared VMO which is published
18  * via the data sink hook provided by Fuchsia's dynamic linker.
19  */
20 
21 #if defined(__Fuchsia__)
22 
23 #include <inttypes.h>
24 #include <stdarg.h>
25 #include <stdbool.h>
26 #include <stdlib.h>
27 
28 #include <zircon/process.h>
29 #include <zircon/sanitizer.h>
30 #include <zircon/status.h>
31 #include <zircon/syscalls.h>
32 
33 #include "InstrProfiling.h"
34 #include "InstrProfilingInternal.h"
35 #include "InstrProfilingUtil.h"
36 
37 /* VMO that contains the coverage data shared across all modules. This symbol
38  * has default visibility and is exported in each module (executable or DSO)
39  * that statically links in the profiling runtime.
40  */
41 zx_handle_t __llvm_profile_vmo;
42 /* Current offset within the VMO where data should be written next. This symbol
43  * has default visibility and is exported in each module (executable or DSO)
44  * that statically links in the profiling runtime.
45  */
46 uint64_t __llvm_profile_offset;
47 
48 static const char ProfileSinkName[] = "llvm-profile";
49 
50 static inline void lprofWrite(const char *fmt, ...) {
51   char s[256];
52 
53   va_list ap;
54   va_start(ap, fmt);
55   int ret = vsnprintf(s, sizeof(s), fmt, ap);
56   va_end(ap);
57 
58   __sanitizer_log_write(s, ret + 1);
59 }
60 
61 static void createVMO() {
62   /* Don't create VMO if it has been alread created. */
63   if (__llvm_profile_vmo != ZX_HANDLE_INVALID)
64     return;
65 
66   /* Get information about the current process. */
67   zx_info_handle_basic_t Info;
68   zx_status_t Status =
69       _zx_object_get_info(_zx_process_self(), ZX_INFO_HANDLE_BASIC, &Info,
70                           sizeof(Info), NULL, NULL);
71   if (Status != ZX_OK) {
72     lprofWrite("LLVM Profile: cannot get info about current process: %s\n",
73                _zx_status_get_string(Status));
74     return;
75   }
76 
77   /* Create VMO to hold the profile data. */
78   Status = _zx_vmo_create(0, ZX_VMO_RESIZABLE, &__llvm_profile_vmo);
79   if (Status != ZX_OK) {
80     lprofWrite("LLVM Profile: cannot create VMO: %s\n",
81                _zx_status_get_string(Status));
82     return;
83   }
84 
85   /* Give the VMO a name including our process KOID so it's easy to spot. */
86   char VmoName[ZX_MAX_NAME_LEN];
87   snprintf(VmoName, sizeof(VmoName), "%s.%" PRIu64, ProfileSinkName, Info.koid);
88   _zx_object_set_property(__llvm_profile_vmo, ZX_PROP_NAME, VmoName,
89                           strlen(VmoName));
90 
91   /* Duplicate the handle since __sanitizer_publish_data consumes it. */
92   zx_handle_t Handle;
93   Status =
94       _zx_handle_duplicate(__llvm_profile_vmo, ZX_RIGHT_SAME_RIGHTS, &Handle);
95   if (Status != ZX_OK) {
96     lprofWrite("LLVM Profile: cannot duplicate VMO handle: %s\n",
97                _zx_status_get_string(Status));
98     _zx_handle_close(__llvm_profile_vmo);
99     __llvm_profile_vmo = ZX_HANDLE_INVALID;
100     return;
101   }
102 
103   /* Publish the VMO which contains profile data to the system. */
104   __sanitizer_publish_data(ProfileSinkName, Handle);
105 
106   /* Use the dumpfile symbolizer markup element to write the name of VMO. */
107   lprofWrite("LLVM Profile: {{{dumpfile:%s:%s}}}\n", ProfileSinkName, VmoName);
108 }
109 
110 static uint32_t lprofVMOWriter(ProfDataWriter *This, ProfDataIOVec *IOVecs,
111                                uint32_t NumIOVecs) {
112   /* Compute the total length of data to be written. */
113   size_t Length = 0;
114   for (uint32_t I = 0; I < NumIOVecs; I++)
115     Length += IOVecs[I].ElmSize * IOVecs[I].NumElm;
116 
117   /* Resize the VMO to ensure there's sufficient space for the data. */
118   zx_status_t Status =
119       _zx_vmo_set_size(__llvm_profile_vmo, __llvm_profile_offset + Length);
120   if (Status != ZX_OK)
121     return -1;
122 
123   /* Copy the data into VMO. */
124   for (uint32_t I = 0; I < NumIOVecs; I++) {
125     size_t Length = IOVecs[I].ElmSize * IOVecs[I].NumElm;
126     if (IOVecs[I].Data) {
127       Status = _zx_vmo_write(__llvm_profile_vmo, IOVecs[I].Data,
128                              __llvm_profile_offset, Length);
129       if (Status != ZX_OK)
130         return -1;
131     }
132     __llvm_profile_offset += Length;
133   }
134 
135   return 0;
136 }
137 
138 static void initVMOWriter(ProfDataWriter *This) {
139   This->Write = lprofVMOWriter;
140   This->WriterCtx = NULL;
141 }
142 
143 static int dump(void) {
144   if (lprofProfileDumped()) {
145     lprofWrite("LLVM Profile: data not published: already written.\n");
146     return 0;
147   }
148 
149   /* Check if there is llvm/runtime version mismatch. */
150   if (GET_VERSION(__llvm_profile_get_version()) != INSTR_PROF_RAW_VERSION) {
151     lprofWrite("LLVM Profile: runtime and instrumentation version mismatch: "
152                "expected %d, but got %d\n",
153                INSTR_PROF_RAW_VERSION,
154                (int)GET_VERSION(__llvm_profile_get_version()));
155     return -1;
156   }
157 
158   /* Write the profile data into the mapped region. */
159   ProfDataWriter VMOWriter;
160   initVMOWriter(&VMOWriter);
161   if (lprofWriteData(&VMOWriter, lprofGetVPDataReader(), 0) != 0)
162     return -1;
163 
164   return 0;
165 }
166 
167 COMPILER_RT_VISIBILITY
168 int __llvm_profile_dump(void) {
169   int rc = dump();
170   lprofSetProfileDumped();
171   return rc;
172 }
173 
174 static void dumpWithoutReturn(void) { dump(); }
175 
176 /* This method is invoked by the runtime initialization hook
177  * InstrProfilingRuntime.o if it is linked in.
178  */
179 COMPILER_RT_VISIBILITY
180 void __llvm_profile_initialize_file(void) { createVMO(); }
181 
182 COMPILER_RT_VISIBILITY
183 int __llvm_profile_register_write_file_atexit(void) {
184   static bool HasBeenRegistered = false;
185 
186   if (HasBeenRegistered)
187     return 0;
188 
189   lprofSetupValueProfiler();
190 
191   HasBeenRegistered = true;
192   return atexit(dumpWithoutReturn);
193 }
194 
195 #endif
196