/*
* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
// This file is derived from Android's NDK package r7, located at
// <ndk>/sources/android/cpufeatures/ (downloadable from
// http://developer.android.com/sdk/ndk/index.html).
#include "cpu_features_wrapper.h"
#include <fcntl.h>
#include <errno.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
// Define CPU family.
typedef enum {
CPU_FAMILY_UNKNOWN = 0,
CPU_FAMILY_ARM,
CPU_FAMILY_X86,
CPU_FAMILY_MAX // Do not remove.
} CpuFamily;
static pthread_once_t g_once;
static CpuFamily g_cpuFamily;
static uint64_t g_cpuFeatures;
static int g_cpuCount;
static const int cpufeatures_debug = 0;
#ifdef __arm__
# define DEFAULT_CPU_FAMILY CPU_FAMILY_ARM
#elif defined __i386__
# define DEFAULT_CPU_FAMILY CPU_FAMILY_X86
#else
# define DEFAULT_CPU_FAMILY CPU_FAMILY_UNKNOWN
#endif
#define D(...) \
do { \
if (cpufeatures_debug) { \
printf(__VA_ARGS__); fflush(stdout); \
} \
} while (0)
/* Read the content of /proc/cpuinfo into a user-provided buffer.
* Return the length of the data, or -1 on error. Does *not*
* zero-terminate the content. Will not read more
* than 'buffsize' bytes.
*/
static int read_file(const char* pathname, char* buffer, size_t buffsize) {
int fd, len;
fd = open(pathname, O_RDONLY);
if (fd < 0)
return -1;
do {
len = read(fd, buffer, buffsize);
} while (len < 0 && errno == EINTR);
close(fd);
return len;
}
/* Extract the content of a the first occurence of a given field in
* the content of /proc/cpuinfo and return it as a heap-allocated
* string that must be freed by the caller.
*
* Return NULL if not found
*/
static char* extract_cpuinfo_field(char* buffer, int buflen, const char* field) {
int fieldlen = strlen(field);
char* bufend = buffer + buflen;
char* result = NULL;
int len, ignore;
const char* p, *q;
/* Look for first field occurence, and ensures it starts the line.
*/
p = buffer;
bufend = buffer + buflen;
for (;;) {
p = memmem(p, bufend - p, field, fieldlen);
if (p == NULL)
goto EXIT;
if (p == buffer || p[-1] == '\n')
break;
p += fieldlen;
}
/* Skip to the first column followed by a space */
p += fieldlen;
p = memchr(p, ':', bufend - p);
if (p == NULL || p[1] != ' ')
goto EXIT;
/* Find the end of the line */
p += 2;
q = memchr(p, '\n', bufend - p);
if (q == NULL)
q = bufend;
/* Copy the line into a heap-allocated buffer */
len = q - p;
result = malloc(len + 1);
if (result == NULL)
goto EXIT;
memcpy(result, p, len);
result[len] = '\0';
EXIT:
return result;
}
/* Count the number of occurences of a given field prefix in /proc/cpuinfo.
*/
static int count_cpuinfo_field(char* buffer, int buflen, const char* field) {
int fieldlen = strlen(field);
const char* p = buffer;
const char* bufend = buffer + buflen;
const char* q;
int count = 0;
for (;;) {
const char* q;
p = memmem(p, bufend - p, field, fieldlen);
if (p == NULL)
break;
/* Ensure that the field is at the start of a line */
if (p > buffer && p[-1] != '\n') {
p += fieldlen;
continue;
}
/* skip any whitespace */
q = p + fieldlen;
while (q < bufend && (*q == ' ' || *q == '\t'))
q++;
/* we must have a colon now */
if (q < bufend && *q == ':') {
count += 1;
q ++;
}
p = q;
}
return count;
}
/* Like strlen(), but for constant string literals */
#define STRLEN_CONST(x) ((sizeof(x)-1)
/* Checks that a space-separated list of items contains one given 'item'.
* Returns 1 if found, 0 otherwise.
*/
static int has_list_item(const char* list, const char* item) {
const char* p = list;
int itemlen = strlen(item);
if (list == NULL)
return 0;
while (*p) {
const char* q;
/* skip spaces */
while (*p == ' ' || *p == '\t')
p++;
/* find end of current list item */
q = p;
while (*q && *q != ' ' && *q != '\t')
q++;
if (itemlen == q - p && !memcmp(p, item, itemlen))
return 1;
/* skip to next item */
p = q;
}
return 0;
}
static void cpuInit(void) {
char cpuinfo[4096];
int cpuinfo_len;
g_cpuFamily = DEFAULT_CPU_FAMILY;
g_cpuFeatures = 0;
g_cpuCount = 1;
cpuinfo_len = read_file("/proc/cpuinfo", cpuinfo, sizeof cpuinfo);
D("cpuinfo_len is (%d):\n%.*s\n", cpuinfo_len,
cpuinfo_len >= 0 ? cpuinfo_len : 0, cpuinfo);
if (cpuinfo_len < 0) { /* should not happen */
return;
}
/* Count the CPU cores, the value may be 0 for single-core CPUs */
g_cpuCount = count_cpuinfo_field(cpuinfo, cpuinfo_len, "processor");
if (g_cpuCount == 0) {
g_cpuCount = count_cpuinfo_field(cpuinfo, cpuinfo_len, "Processor");
if (g_cpuCount == 0) {
g_cpuCount = 1;
}
}
D("found cpuCount = %d\n", g_cpuCount);
#ifdef __arm__
{
char* features = NULL;
char* architecture = NULL;
/* Extract architecture from the "CPU Architecture" field.
* The list is well-known, unlike the the output of
* the 'Processor' field which can vary greatly.
*
* See the definition of the 'proc_arch' array in
* $KERNEL/arch/arm/kernel/setup.c and the 'c_show' function in
* same file.
*/
char* cpuArch = extract_cpuinfo_field(cpuinfo, cpuinfo_len,
"CPU architecture");
if (cpuArch != NULL) {
char* end;
long archNumber;
int hasARMv7 = 0;
D("found cpuArch = '%s'\n", cpuArch);
/* read the initial decimal number, ignore the rest */
archNumber = strtol(cpuArch, &end, 10);
/* Here we assume that ARMv8 will be upwards compatible with v7
* in the future. Unfortunately, there is no 'Features' field to
* indicate that Thumb-2 is supported.
*/
if (end > cpuArch && archNumber >= 7) {
hasARMv7 = 1;
}
/* Unfortunately, it seems that certain ARMv6-based CPUs
* report an incorrect architecture number of 7!
*
* We try to correct this by looking at the 'elf_format'
* field reported by the 'Processor' field, which is of the
* form of "(v7l)" for an ARMv7-based CPU, and "(v6l)" for
* an ARMv6-one.
*/
if (hasARMv7) {
char* cpuProc = extract_cpuinfo_field(cpuinfo, cpuinfo_len,
"Processor");
if (cpuProc != NULL) {
D("found cpuProc = '%s'\n", cpuProc);
if (has_list_item(cpuProc, "(v6l)")) {
D("CPU processor and architecture mismatch!!\n");
hasARMv7 = 0;
}
free(cpuProc);
}
}
if (hasARMv7) {
g_cpuFeatures |= kCPUFeatureARMv7;
}
/* The LDREX / STREX instructions are available from ARMv6 */
if (archNumber >= 6) {
g_cpuFeatures |= kCPUFeatureLDREXSTREX;
}
free(cpuArch);
}
/* Extract the list of CPU features from 'Features' field */
char* cpuFeatures = extract_cpuinfo_field(cpuinfo, cpuinfo_len,
"Features");
if (cpuFeatures != NULL) {
D("found cpuFeatures = '%s'\n", cpuFeatures);
if (has_list_item(cpuFeatures, "vfpv3"))
g_cpuFeatures |= kCPUFeatureVFPv3;
else if (has_list_item(cpuFeatures, "vfpv3d16"))
g_cpuFeatures |= kCPUFeatureVFPv3;
if (has_list_item(cpuFeatures, "neon")) {
/* Note: Certain kernels only report neon but not vfpv3
* in their features list. However, ARM mandates
* that if Neon is implemented, so must be VFPv3
* so always set the flag.
*/
g_cpuFeatures |= kCPUFeatureNEON |
kCPUFeatureVFPv3;
}
free(cpuFeatures);
}
}
#endif // __arm__
#ifdef __i386__
g_cpuFamily = CPU_FAMILY_X86;
#endif
}
uint64_t WebRtc_GetCPUFeaturesARM(void) {
pthread_once(&g_once, cpuInit);
return g_cpuFeatures;
}