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Diffstat (limited to 'android-utils/cpu-features.c')
| -rw-r--r-- | android-utils/cpu-features.c | 555 |
1 files changed, 555 insertions, 0 deletions
diff --git a/android-utils/cpu-features.c b/android-utils/cpu-features.c new file mode 100644 index 0000000..70f5545 --- /dev/null +++ b/android-utils/cpu-features.c @@ -0,0 +1,555 @@ +/* + * 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; +} |
