Commit 5e2ac390 authored by Daniel Borkmann's avatar Daniel Borkmann

Merge branch 'bpf-libbpf-num-cpus'

Hechao Li says:

====================
Getting number of possible CPUs is commonly used for per-CPU BPF maps
and perf_event_maps. Add a new API libbpf_num_possible_cpus() that
helps user with per-CPU related operations and remove duplicate
implementations in bpftool and selftests.

v2: Save errno before calling pr_warning in case it is changed.
v3: Make sure libbpf_num_possible_cpus never returns 0 so that user only
    has to check if ret value < 0.
v4: Fix error code when reading 0 bytes from possible CPU file.
v5: Fix selftests compliation issue.
v6: Split commit to reuse libbpf_num_possible_cpus() into two commits:
    One commit to remove bpf_util.h from test BPF C programs.
    One commit to reuse libbpf_num_possible_cpus() in bpftools
    and bpf_util.h.
====================
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parents 89cceaa9 4c587c19
......@@ -21,6 +21,7 @@
#include <sys/vfs.h>
#include <bpf.h>
#include <libbpf.h> /* libbpf_num_possible_cpus */
#include "main.h"
......@@ -439,57 +440,13 @@ unsigned int get_page_size(void)
unsigned int get_possible_cpus(void)
{
static unsigned int result;
char buf[128];
long int n;
char *ptr;
int fd;
if (result)
return result;
fd = open("/sys/devices/system/cpu/possible", O_RDONLY);
if (fd < 0) {
p_err("can't open sysfs possible cpus");
exit(-1);
}
n = read(fd, buf, sizeof(buf));
if (n < 2) {
p_err("can't read sysfs possible cpus");
exit(-1);
}
close(fd);
int cpus = libbpf_num_possible_cpus();
if (n == sizeof(buf)) {
p_err("read sysfs possible cpus overflow");
if (cpus < 0) {
p_err("Can't get # of possible cpus: %s", strerror(-cpus));
exit(-1);
}
ptr = buf;
n = 0;
while (*ptr && *ptr != '\n') {
unsigned int a, b;
if (sscanf(ptr, "%u-%u", &a, &b) == 2) {
n += b - a + 1;
ptr = strchr(ptr, '-') + 1;
} else if (sscanf(ptr, "%u", &a) == 1) {
n++;
} else {
assert(0);
}
while (isdigit(*ptr))
ptr++;
if (*ptr == ',')
ptr++;
}
result = n;
return result;
return cpus;
}
static char *
......
......@@ -3827,3 +3827,60 @@ void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear)
desc->array_offset, addr);
}
}
int libbpf_num_possible_cpus(void)
{
static const char *fcpu = "/sys/devices/system/cpu/possible";
int len = 0, n = 0, il = 0, ir = 0;
unsigned int start = 0, end = 0;
static int cpus;
char buf[128];
int error = 0;
int fd = -1;
if (cpus > 0)
return cpus;
fd = open(fcpu, O_RDONLY);
if (fd < 0) {
error = errno;
pr_warning("Failed to open file %s: %s\n",
fcpu, strerror(error));
return -error;
}
len = read(fd, buf, sizeof(buf));
close(fd);
if (len <= 0) {
error = len ? errno : EINVAL;
pr_warning("Failed to read # of possible cpus from %s: %s\n",
fcpu, strerror(error));
return -error;
}
if (len == sizeof(buf)) {
pr_warning("File %s size overflow\n", fcpu);
return -EOVERFLOW;
}
buf[len] = '\0';
for (ir = 0, cpus = 0; ir <= len; ir++) {
/* Each sub string separated by ',' has format \d+-\d+ or \d+ */
if (buf[ir] == ',' || buf[ir] == '\0') {
buf[ir] = '\0';
n = sscanf(&buf[il], "%u-%u", &start, &end);
if (n <= 0) {
pr_warning("Failed to get # CPUs from %s\n",
&buf[il]);
return -EINVAL;
} else if (n == 1) {
end = start;
}
cpus += end - start + 1;
il = ir + 1;
}
}
if (cpus <= 0) {
pr_warning("Invalid #CPUs %d from %s\n", cpus, fcpu);
return -EINVAL;
}
return cpus;
}
......@@ -454,6 +454,22 @@ bpf_program__bpil_addr_to_offs(struct bpf_prog_info_linear *info_linear);
LIBBPF_API void
bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear);
/*
* A helper function to get the number of possible CPUs before looking up
* per-CPU maps. Negative errno is returned on failure.
*
* Example usage:
*
* int ncpus = libbpf_num_possible_cpus();
* if (ncpus < 0) {
* // error handling
* }
* long values[ncpus];
* bpf_map_lookup_elem(per_cpu_map_fd, key, values);
*
*/
LIBBPF_API int libbpf_num_possible_cpus(void);
#ifdef __cplusplus
} /* extern "C" */
#endif
......
......@@ -172,4 +172,5 @@ LIBBPF_0.0.4 {
btf_dump__new;
btf__parse_elf;
bpf_object__load_xattr;
libbpf_num_possible_cpus;
} LIBBPF_0.0.3;
......@@ -2,6 +2,7 @@
#ifndef __BPF_ENDIAN__
#define __BPF_ENDIAN__
#include <linux/stddef.h>
#include <linux/swab.h>
/* LLVM's BPF target selects the endianness of the CPU
......
......@@ -6,44 +6,17 @@
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <libbpf.h> /* libbpf_num_possible_cpus */
static inline unsigned int bpf_num_possible_cpus(void)
{
static const char *fcpu = "/sys/devices/system/cpu/possible";
unsigned int start, end, possible_cpus = 0;
char buff[128];
FILE *fp;
int len, n, i, j = 0;
int possible_cpus = libbpf_num_possible_cpus();
fp = fopen(fcpu, "r");
if (!fp) {
printf("Failed to open %s: '%s'!\n", fcpu, strerror(errno));
if (possible_cpus < 0) {
printf("Failed to get # of possible cpus: '%s'!\n",
strerror(-possible_cpus));
exit(1);
}
if (!fgets(buff, sizeof(buff), fp)) {
printf("Failed to read %s!\n", fcpu);
exit(1);
}
len = strlen(buff);
for (i = 0; i <= len; i++) {
if (buff[i] == ',' || buff[i] == '\0') {
buff[i] = '\0';
n = sscanf(&buff[j], "%u-%u", &start, &end);
if (n <= 0) {
printf("Failed to retrieve # possible CPUs!\n");
exit(1);
} else if (n == 1) {
end = start;
}
possible_cpus += end - start + 1;
j = i + 1;
}
}
fclose(fp);
return possible_cpus;
}
......
#include <linux/bpf.h>
#include "bpf_helpers.h"
#include "bpf_util.h"
#include "bpf_endian.h"
int _version SEC("version") = 1;
......
#include <linux/bpf.h>
#include "bpf_helpers.h"
#include "bpf_util.h"
#include "bpf_endian.h"
int _version SEC("version") = 1;
......
#include <linux/bpf.h>
#include "bpf_helpers.h"
#include "bpf_util.h"
#include "bpf_endian.h"
int _version SEC("version") = 1;
......
......@@ -8,7 +8,6 @@
#include <linux/bpf.h>
#include "bpf_helpers.h"
#include "bpf_util.h"
/* Max supported length of a string with unsigned long in base 10 (pow2 - 1). */
#define MAX_ULONG_STR_LEN 0xF
......@@ -16,6 +15,10 @@
/* Max supported length of sysctl value string (pow2). */
#define MAX_VALUE_STR_LEN 0x40
#ifndef ARRAY_SIZE
#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
#endif
static __always_inline int is_tcp_mem(struct bpf_sysctl *ctx)
{
char tcp_mem_name[] = "net/ipv4/tcp_mem";
......
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