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doubango/android-utils/cpu-features.c

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/*
* Copyright (C) 2010 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/* ChangeLog for this library:
*
* NDK r7c: Fix CPU count computation. The old method only reported the
* number of _active_ CPUs when the library was initialized,
* which could be less than the real total.
*
* NDK r5: Handle buggy kernels which report a CPU Architecture number of 7
* for an ARMv6 CPU (see below).
*
* Handle kernels that only report 'neon', and not 'vfpv3'
* (VFPv3 is mandated by the ARM architecture is Neon is implemented)
*
* Handle kernels that only report 'vfpv3d16', and not 'vfpv3'
*
* Fix x86 compilation. Report ANDROID_CPU_FAMILY_X86 in
* android_getCpuFamily().
*
* NDK r4: Initial release
*/
#include <sys/system_properties.h>
#ifdef __arm__
#include <machine/cpu-features.h>
#endif
#include <pthread.h>
#include "cpu-features.h"
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
static pthread_once_t g_once;
static AndroidCpuFamily g_cpuFamily;
static uint64_t g_cpuFeatures;
static int g_cpuCount;
static const int android_cpufeatures_debug = 0;
#ifdef __arm__
# define DEFAULT_CPU_FAMILY ANDROID_CPU_FAMILY_ARM
#elif defined __i386__
# define DEFAULT_CPU_FAMILY ANDROID_CPU_FAMILY_X86
#else
# define DEFAULT_CPU_FAMILY ANDROID_CPU_FAMILY_UNKNOWN
#endif
#define D(...) \
do { \
if (android_cpufeatures_debug) { \
printf(__VA_ARGS__); fflush(stdout); \
} \
} while (0)
#ifdef __i386__
static __inline__ void x86_cpuid(int func, int values[4])
{
int a, b, c, d;
/* We need to preserve ebx since we're compiling PIC code */
/* this means we can't use "=b" for the second output register */
__asm__ __volatile__ ( \
"push %%ebx\n"
"cpuid\n" \
"mov %1, %%ebx\n"
"pop %%ebx\n"
: "=a" (a), "=r" (b), "=c" (c), "=d" (d) \
: "a" (func) \
);
values[0] = a;
values[1] = b;
values[2] = c;
values[3] = d;
}
#endif
/* 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;
}
/* 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;
}
/* Parse an decimal integer starting from 'input', but not going further
* than 'limit'. Return the value into '*result'.
*
* NOTE: Does not skip over leading spaces, or deal with sign characters.
* NOTE: Ignores overflows.
*
* The function returns NULL in case of error (bad format), or the new
* position after the decimal number in case of success (which will always
* be <= 'limit').
*/
static const char*
parse_decimal(const char* input, const char* limit, int* result)
{
const char* p = input;
int val = 0;
while (p < limit) {
int d = (*p - '0');
if ((unsigned)d >= 10U) {
break;
}
val = val*10 + d;
p++;
}
if (p == input) {
return NULL;
}
*result = val;
return p;
}
/* This small data type is used to represent a CPU list / mask, as read
* from sysfs on Linux. See http://www.kernel.org/doc/Documentation/cputopology.txt
*
* For now, we don't expect more than 32 cores on mobile devices, so keep
* everything simple.
*/
typedef struct {
uint32_t mask;
} CpuList;
static __inline__ void
cpulist_init(CpuList* list)
{
list->mask = 0;
}
static __inline__ void
cpulist_and(CpuList* list1, CpuList* list2)
{
list1->mask &= list2->mask;
}
static __inline__ void
cpulist_set(CpuList* list, int index)
{
if ((unsigned)index < 32) {
list->mask |= (uint32_t)(1U << index);
}
}
static __inline__ int
cpulist_count(CpuList* list)
{
return __builtin_popcount(list->mask);
}
/* Parse a textual list of cpus and store the result inside a CpuList object.
* Input format is the following:
* - comma-separated list of items (no spaces)
* - each item is either a single decimal number (cpu index), or a range made
* of two numbers separated by a single dash (-). Ranges are inclusive.
*
* Examples: 0
* 2,4-127,128-143
* 0-1
*/
static void
cpulist_parse(CpuList* list, const char* line, int line_len)
{
const char* p = line;
const char* end = p + line_len;
const char* q;
/* NOTE: the input line coming from sysfs typically contains a
* trailing newline, so take care of it in the code below
*/
while (p < end && *p != '\n') {
int val, start_value, end_value;
/* Find the end of current item, and put it into 'q' */
q = memchr(p, ',', end-p);
if (q == NULL) {
q = end;
}
/* Get first value */
p = parse_decimal(p, q, &start_value);
if (p == NULL) {
goto BAD_FORMAT;
}
end_value = start_value;
/* If we're not at the end of the item, expect a dash and
* and integer; extract end value.
*/
if (p < q && *p == '-') {
p = parse_decimal(p+1, q, &end_value);
if (p == NULL) {
goto BAD_FORMAT;
}
}
/* Set bits CPU list bits */
for (val = start_value; val <= end_value; val++) {
cpulist_set(list, val);
}
/* Jump to next item */
p = q;
if (p < end) {
p++;
}
}
BAD_FORMAT:
;
}
/* Read a CPU list from one sysfs file */
static void
cpulist_read_from(CpuList* list, const char* filename)
{
char file[64];
int filelen;
cpulist_init(list);
filelen = read_file(filename, file, sizeof file);
if (filelen < 0) {
D("Could not read %s: %s\n", filename, strerror(errno));
return;
}
cpulist_parse(list, file, filelen);
}
/* Return the number of cpus present on a given device.
*
* To handle all weird kernel configurations, we need to compute the
* intersection of the 'present' and 'possible' CPU lists and count
* the result.
*/
static int
get_cpu_count(void)
{
CpuList cpus_present[1];
CpuList cpus_possible[1];
cpulist_read_from(cpus_present, "/sys/devices/system/cpu/present");
cpulist_read_from(cpus_possible, "/sys/devices/system/cpu/possible");
/* Compute the intersection of both sets to get the actual number of
* CPU cores that can be used on this device by the kernel.
*/
cpulist_and(cpus_present, cpus_possible);
return cpulist_count(cpus_present);
}
static void
android_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 = get_cpu_count();
if (g_cpuCount == 0) {
g_cpuCount = 1;
}
D("found cpuCount = %d\n", g_cpuCount);
#ifdef __ARM_ARCH__
{
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!
*
* See http://code.google.com/p/android/issues/detail?id=10812
*
* 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 |= ANDROID_CPU_ARM_FEATURE_ARMv7;
}
/* The LDREX / STREX instructions are available from ARMv6 */
if (archNumber >= 6) {
g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_LDREX_STREX;
}
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 |= ANDROID_CPU_ARM_FEATURE_VFPv3;
}
else if (has_list_item(cpuFeatures, "vfpv3d16")) {
g_cpuFeatures |= ANDROID_CPU_ARM_FEATURE_VFPv3;
}
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 |= ANDROID_CPU_ARM_FEATURE_NEON |
ANDROID_CPU_ARM_FEATURE_VFPv3;
}
free(cpuFeatures);
}
}
#endif /* __ARM_ARCH__ */
#ifdef __i386__
g_cpuFamily = ANDROID_CPU_FAMILY_X86;
int regs[4];
/* According to http://en.wikipedia.org/wiki/CPUID */
#define VENDOR_INTEL_b 0x756e6547
#define VENDOR_INTEL_c 0x6c65746e
#define VENDOR_INTEL_d 0x49656e69
x86_cpuid(0, regs);
int vendorIsIntel = (regs[1] == VENDOR_INTEL_b &&
regs[2] == VENDOR_INTEL_c &&
regs[3] == VENDOR_INTEL_d);
x86_cpuid(1, regs);
if ((regs[2] & (1 << 9)) != 0) {
g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_SSSE3;
}
if ((regs[2] & (1 << 23)) != 0) {
g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_POPCNT;
}
if (vendorIsIntel && (regs[2] & (1 << 22)) != 0) {
g_cpuFeatures |= ANDROID_CPU_X86_FEATURE_MOVBE;
}
#endif
#ifdef _MIPS_ARCH
g_cpuFamily = ANDROID_CPU_FAMILY_MIPS;
#endif /* _MIPS_ARCH */
}
AndroidCpuFamily
android_getCpuFamily(void)
{
pthread_once(&g_once, android_cpuInit);
return g_cpuFamily;
}
uint64_t
android_getCpuFeatures(void)
{
pthread_once(&g_once, android_cpuInit);
return g_cpuFeatures;
}
int
android_getCpuCount(void)
{
pthread_once(&g_once, android_cpuInit);
return g_cpuCount;
}
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