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-rw-r--r--tools/testing/selftests/bpf/trace_helpers.c755
1 files changed, 755 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
new file mode 100644
index 000000000000..eeaab7013ca2
--- /dev/null
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -0,0 +1,755 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <pthread.h>
+#include <unistd.h>
+#include <linux/perf_event.h>
+#include <linux/fs.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include "trace_helpers.h"
+#include <linux/limits.h>
+#include <libelf.h>
+#include <gelf.h>
+#include "bpf/hashmap.h"
+#include "bpf/libbpf_internal.h"
+#include "bpf_util.h"
+
+#define TRACEFS_PIPE "/sys/kernel/tracing/trace_pipe"
+#define DEBUGFS_PIPE "/sys/kernel/debug/tracing/trace_pipe"
+
+struct ksyms {
+ struct ksym *syms;
+ size_t sym_cap;
+ size_t sym_cnt;
+};
+
+static struct ksyms *ksyms;
+static pthread_mutex_t ksyms_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static int ksyms__add_symbol(struct ksyms *ksyms, const char *name,
+ unsigned long addr)
+{
+ void *tmp;
+
+ tmp = strdup(name);
+ if (!tmp)
+ return -ENOMEM;
+ ksyms->syms[ksyms->sym_cnt].addr = addr;
+ ksyms->syms[ksyms->sym_cnt].name = tmp;
+ ksyms->sym_cnt++;
+ return 0;
+}
+
+void free_kallsyms_local(struct ksyms *ksyms)
+{
+ unsigned int i;
+
+ if (!ksyms)
+ return;
+
+ if (!ksyms->syms) {
+ free(ksyms);
+ return;
+ }
+
+ for (i = 0; i < ksyms->sym_cnt; i++)
+ free(ksyms->syms[i].name);
+ free(ksyms->syms);
+ free(ksyms);
+}
+
+static struct ksyms *load_kallsyms_local_common(ksym_cmp_t cmp_cb)
+{
+ FILE *f;
+ char func[256], buf[256];
+ char symbol;
+ void *addr;
+ int ret;
+ struct ksyms *ksyms;
+
+ f = fopen("/proc/kallsyms", "r");
+ if (!f)
+ return NULL;
+
+ ksyms = calloc(1, sizeof(struct ksyms));
+ if (!ksyms) {
+ fclose(f);
+ return NULL;
+ }
+
+ while (fgets(buf, sizeof(buf), f)) {
+ if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3)
+ break;
+ if (!addr)
+ continue;
+
+ ret = libbpf_ensure_mem((void **) &ksyms->syms, &ksyms->sym_cap,
+ sizeof(struct ksym), ksyms->sym_cnt + 1);
+ if (ret)
+ goto error;
+ ret = ksyms__add_symbol(ksyms, func, (unsigned long)addr);
+ if (ret)
+ goto error;
+ }
+ fclose(f);
+ qsort(ksyms->syms, ksyms->sym_cnt, sizeof(struct ksym), cmp_cb);
+ return ksyms;
+
+error:
+ fclose(f);
+ free_kallsyms_local(ksyms);
+ return NULL;
+}
+
+static int ksym_cmp(const void *p1, const void *p2)
+{
+ return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
+}
+
+struct ksyms *load_kallsyms_local(void)
+{
+ return load_kallsyms_local_common(ksym_cmp);
+}
+
+struct ksyms *load_kallsyms_custom_local(ksym_cmp_t cmp_cb)
+{
+ return load_kallsyms_local_common(cmp_cb);
+}
+
+int load_kallsyms(void)
+{
+ pthread_mutex_lock(&ksyms_mutex);
+ if (!ksyms)
+ ksyms = load_kallsyms_local();
+ pthread_mutex_unlock(&ksyms_mutex);
+ return ksyms ? 0 : 1;
+}
+
+struct ksym *ksym_search_local(struct ksyms *ksyms, long key)
+{
+ int start = 0, end = ksyms->sym_cnt;
+ int result;
+
+ /* kallsyms not loaded. return NULL */
+ if (ksyms->sym_cnt <= 0)
+ return NULL;
+
+ while (start < end) {
+ size_t mid = start + (end - start) / 2;
+
+ result = key - ksyms->syms[mid].addr;
+ if (result < 0)
+ end = mid;
+ else if (result > 0)
+ start = mid + 1;
+ else
+ return &ksyms->syms[mid];
+ }
+
+ if (start >= 1 && ksyms->syms[start - 1].addr < key &&
+ key < ksyms->syms[start].addr)
+ /* valid ksym */
+ return &ksyms->syms[start - 1];
+
+ /* out of range. return _stext */
+ return &ksyms->syms[0];
+}
+
+struct ksym *search_kallsyms_custom_local(struct ksyms *ksyms, const void *p,
+ ksym_search_cmp_t cmp_cb)
+{
+ int start = 0, mid, end = ksyms->sym_cnt;
+ struct ksym *ks;
+ int result;
+
+ while (start < end) {
+ mid = start + (end - start) / 2;
+ ks = &ksyms->syms[mid];
+ result = cmp_cb(p, ks);
+ if (result < 0)
+ end = mid;
+ else if (result > 0)
+ start = mid + 1;
+ else
+ return ks;
+ }
+
+ return NULL;
+}
+
+struct ksym *ksym_search(long key)
+{
+ if (!ksyms)
+ return NULL;
+ return ksym_search_local(ksyms, key);
+}
+
+long ksym_get_addr_local(struct ksyms *ksyms, const char *name)
+{
+ int i;
+
+ for (i = 0; i < ksyms->sym_cnt; i++) {
+ if (strcmp(ksyms->syms[i].name, name) == 0)
+ return ksyms->syms[i].addr;
+ }
+
+ return 0;
+}
+
+long ksym_get_addr(const char *name)
+{
+ if (!ksyms)
+ return 0;
+ return ksym_get_addr_local(ksyms, name);
+}
+
+/* open kallsyms and read symbol addresses on the fly. Without caching all symbols,
+ * this is faster than load + find.
+ */
+int kallsyms_find(const char *sym, unsigned long long *addr)
+{
+ char type, name[500], *match;
+ unsigned long long value;
+ int err = 0;
+ FILE *f;
+
+ f = fopen("/proc/kallsyms", "r");
+ if (!f)
+ return -EINVAL;
+
+ while (fscanf(f, "%llx %c %499s%*[^\n]\n", &value, &type, name) > 0) {
+ /* If CONFIG_LTO_CLANG_THIN is enabled, static variable/function
+ * symbols could be promoted to global due to cross-file inlining.
+ * For such cases, clang compiler will add .llvm.<hash> suffix
+ * to those symbols to avoid potential naming conflict.
+ * Let us ignore .llvm.<hash> suffix during symbol comparison.
+ */
+ if (type == 'd') {
+ match = strstr(name, ".llvm.");
+ if (match)
+ *match = '\0';
+ }
+ if (strcmp(name, sym) == 0) {
+ *addr = value;
+ goto out;
+ }
+ }
+ err = -ENOENT;
+
+out:
+ fclose(f);
+ return err;
+}
+
+#ifdef PROCMAP_QUERY
+int env_verbosity __weak = 0;
+
+static int procmap_query(int fd, const void *addr, __u32 query_flags, size_t *start, size_t *offset, int *flags)
+{
+ char path_buf[PATH_MAX], build_id_buf[20];
+ struct procmap_query q;
+ int err;
+
+ memset(&q, 0, sizeof(q));
+ q.size = sizeof(q);
+ q.query_flags = query_flags;
+ q.query_addr = (__u64)addr;
+ q.vma_name_addr = (__u64)path_buf;
+ q.vma_name_size = sizeof(path_buf);
+ q.build_id_addr = (__u64)build_id_buf;
+ q.build_id_size = sizeof(build_id_buf);
+
+ err = ioctl(fd, PROCMAP_QUERY, &q);
+ if (err < 0) {
+ err = -errno;
+ if (err == -ENOTTY)
+ return -EOPNOTSUPP; /* ioctl() not implemented yet */
+ if (err == -ENOENT)
+ return -ESRCH; /* vma not found */
+ return err;
+ }
+
+ if (env_verbosity >= 1) {
+ printf("VMA FOUND (addr %08lx): %08lx-%08lx %c%c%c%c %08lx %02x:%02x %ld %s (build ID: %s, %d bytes)\n",
+ (long)addr, (long)q.vma_start, (long)q.vma_end,
+ (q.vma_flags & PROCMAP_QUERY_VMA_READABLE) ? 'r' : '-',
+ (q.vma_flags & PROCMAP_QUERY_VMA_WRITABLE) ? 'w' : '-',
+ (q.vma_flags & PROCMAP_QUERY_VMA_EXECUTABLE) ? 'x' : '-',
+ (q.vma_flags & PROCMAP_QUERY_VMA_SHARED) ? 's' : 'p',
+ (long)q.vma_offset, q.dev_major, q.dev_minor, (long)q.inode,
+ q.vma_name_size ? path_buf : "",
+ q.build_id_size ? "YES" : "NO",
+ q.build_id_size);
+ }
+
+ *start = q.vma_start;
+ *offset = q.vma_offset;
+ *flags = q.vma_flags;
+ return 0;
+}
+#else
+# ifndef PROCMAP_QUERY_VMA_EXECUTABLE
+# define PROCMAP_QUERY_VMA_EXECUTABLE 0x04
+# endif
+
+static int procmap_query(int fd, const void *addr, __u32 query_flags, size_t *start, size_t *offset, int *flags)
+{
+ return -EOPNOTSUPP;
+}
+#endif
+
+ssize_t get_uprobe_offset(const void *addr)
+{
+ size_t start, base, end;
+ FILE *f;
+ char buf[256];
+ int err, flags;
+
+ f = fopen("/proc/self/maps", "r");
+ if (!f)
+ return -errno;
+
+ /* requested executable VMA only */
+ err = procmap_query(fileno(f), addr, PROCMAP_QUERY_VMA_EXECUTABLE, &start, &base, &flags);
+ if (err == -EOPNOTSUPP) {
+ bool found = false;
+
+ while (fscanf(f, "%zx-%zx %s %zx %*[^\n]\n", &start, &end, buf, &base) == 4) {
+ if (buf[2] == 'x' && (uintptr_t)addr >= start && (uintptr_t)addr < end) {
+ found = true;
+ break;
+ }
+ }
+ if (!found) {
+ fclose(f);
+ return -ESRCH;
+ }
+ } else if (err) {
+ fclose(f);
+ return err;
+ }
+ fclose(f);
+
+#if defined(__powerpc64__) && defined(_CALL_ELF) && _CALL_ELF == 2
+
+#define OP_RT_RA_MASK 0xffff0000UL
+#define LIS_R2 0x3c400000UL
+#define ADDIS_R2_R12 0x3c4c0000UL
+#define ADDI_R2_R2 0x38420000UL
+
+ /*
+ * A PPC64 ABIv2 function may have a local and a global entry
+ * point. We need to use the local entry point when patching
+ * functions, so identify and step over the global entry point
+ * sequence.
+ *
+ * The global entry point sequence is always of the form:
+ *
+ * addis r2,r12,XXXX
+ * addi r2,r2,XXXX
+ *
+ * A linker optimisation may convert the addis to lis:
+ *
+ * lis r2,XXXX
+ * addi r2,r2,XXXX
+ */
+ {
+ const __u32 *insn = (const __u32 *)(uintptr_t)addr;
+
+ if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
+ ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
+ ((*(insn + 1) & OP_RT_RA_MASK) == ADDI_R2_R2))
+ return (uintptr_t)(insn + 2) - start + base;
+ }
+#endif
+ return (uintptr_t)addr - start + base;
+}
+
+ssize_t get_rel_offset(uintptr_t addr)
+{
+ size_t start, end, offset;
+ char buf[256];
+ FILE *f;
+ int err, flags;
+
+ f = fopen("/proc/self/maps", "r");
+ if (!f)
+ return -errno;
+
+ err = procmap_query(fileno(f), (const void *)addr, 0, &start, &offset, &flags);
+ if (err == 0) {
+ fclose(f);
+ return (size_t)addr - start + offset;
+ } else if (err != -EOPNOTSUPP) {
+ fclose(f);
+ return err;
+ } else if (err) {
+ while (fscanf(f, "%zx-%zx %s %zx %*[^\n]\n", &start, &end, buf, &offset) == 4) {
+ if (addr >= start && addr < end) {
+ fclose(f);
+ return (size_t)addr - start + offset;
+ }
+ }
+ }
+
+ fclose(f);
+ return -EINVAL;
+}
+
+static int
+parse_build_id_buf(const void *note_start, Elf32_Word note_size, char *build_id)
+{
+ Elf32_Word note_offs = 0;
+
+ while (note_offs + sizeof(Elf32_Nhdr) < note_size) {
+ Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs);
+
+ if (nhdr->n_type == 3 && nhdr->n_namesz == sizeof("GNU") &&
+ !strcmp((char *)(nhdr + 1), "GNU") && nhdr->n_descsz > 0 &&
+ nhdr->n_descsz <= BPF_BUILD_ID_SIZE) {
+ memcpy(build_id, note_start + note_offs +
+ ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), nhdr->n_descsz);
+ memset(build_id + nhdr->n_descsz, 0, BPF_BUILD_ID_SIZE - nhdr->n_descsz);
+ return (int) nhdr->n_descsz;
+ }
+
+ note_offs = note_offs + sizeof(Elf32_Nhdr) +
+ ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4);
+ }
+
+ return -ENOENT;
+}
+
+/* Reads binary from *path* file and returns it in the *build_id* buffer
+ * with *size* which is expected to be at least BPF_BUILD_ID_SIZE bytes.
+ * Returns size of build id on success. On error the error value is
+ * returned.
+ */
+int read_build_id(const char *path, char *build_id, size_t size)
+{
+ int fd, err = -EINVAL;
+ Elf *elf = NULL;
+ GElf_Ehdr ehdr;
+ size_t max, i;
+
+ if (size < BPF_BUILD_ID_SIZE)
+ return -EINVAL;
+
+ fd = open(path, O_RDONLY | O_CLOEXEC);
+ if (fd < 0)
+ return -errno;
+
+ (void)elf_version(EV_CURRENT);
+
+ elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+ if (!elf)
+ goto out;
+ if (elf_kind(elf) != ELF_K_ELF)
+ goto out;
+ if (!gelf_getehdr(elf, &ehdr))
+ goto out;
+
+ for (i = 0; i < ehdr.e_phnum; i++) {
+ GElf_Phdr mem, *phdr;
+ char *data;
+
+ phdr = gelf_getphdr(elf, i, &mem);
+ if (!phdr)
+ goto out;
+ if (phdr->p_type != PT_NOTE)
+ continue;
+ data = elf_rawfile(elf, &max);
+ if (!data)
+ goto out;
+ if (phdr->p_offset + phdr->p_memsz > max)
+ goto out;
+ err = parse_build_id_buf(data + phdr->p_offset, phdr->p_memsz, build_id);
+ if (err > 0)
+ break;
+ }
+
+out:
+ if (elf)
+ elf_end(elf);
+ close(fd);
+ return err;
+}
+
+int read_trace_pipe_iter(void (*cb)(const char *str, void *data), void *data, int iter)
+{
+ size_t buflen, n;
+ char *buf = NULL;
+ FILE *fp = NULL;
+
+ if (access(TRACEFS_PIPE, F_OK) == 0)
+ fp = fopen(TRACEFS_PIPE, "r");
+ else
+ fp = fopen(DEBUGFS_PIPE, "r");
+ if (!fp)
+ return -1;
+
+ /* We do not want to wait forever when iter is specified. */
+ if (iter)
+ fcntl(fileno(fp), F_SETFL, O_NONBLOCK);
+
+ while ((n = getline(&buf, &buflen, fp) >= 0) || errno == EAGAIN) {
+ if (n > 0)
+ cb(buf, data);
+ if (iter && !(--iter))
+ break;
+ }
+
+ free(buf);
+ if (fp)
+ fclose(fp);
+ return 0;
+}
+
+static void trace_pipe_cb(const char *str, void *data)
+{
+ printf("%s", str);
+}
+
+void read_trace_pipe(void)
+{
+ read_trace_pipe_iter(trace_pipe_cb, NULL, 0);
+}
+
+static size_t symbol_hash(long key, void *ctx __maybe_unused)
+{
+ return str_hash((const char *) key);
+}
+
+static bool symbol_equal(long key1, long key2, void *ctx __maybe_unused)
+{
+ return strcmp((const char *) key1, (const char *) key2) == 0;
+}
+
+static bool is_invalid_entry(char *buf, bool kernel)
+{
+ if (kernel && strchr(buf, '['))
+ return true;
+ if (!kernel && !strchr(buf, '['))
+ return true;
+ return false;
+}
+
+static const char * const trace_blacklist[] = {
+ "migrate_disable",
+ "migrate_enable",
+ "rcu_read_unlock_strict",
+ "preempt_count_add",
+ "preempt_count_sub",
+ "__rcu_read_lock",
+ "__rcu_read_unlock",
+ "bpf_get_numa_node_id",
+};
+
+static bool skip_entry(char *name)
+{
+ int i;
+
+ /*
+ * We attach to almost all kernel functions and some of them
+ * will cause 'suspicious RCU usage' when fprobe is attached
+ * to them. Filter out the current culprits - arch_cpu_idle
+ * default_idle and rcu_* functions.
+ */
+ if (!strcmp(name, "arch_cpu_idle"))
+ return true;
+ if (!strcmp(name, "default_idle"))
+ return true;
+ if (!strncmp(name, "rcu_", 4))
+ return true;
+ if (!strcmp(name, "bpf_dispatcher_xdp_func"))
+ return true;
+ if (!strncmp(name, "__ftrace_invalid_address__",
+ sizeof("__ftrace_invalid_address__") - 1))
+ return true;
+
+ for (i = 0; i < ARRAY_SIZE(trace_blacklist); i++) {
+ if (!strcmp(name, trace_blacklist[i]))
+ return true;
+ }
+
+ return false;
+}
+
+/* Do comparison by ignoring '.llvm.<hash>' suffixes. */
+static int compare_name(const char *name1, const char *name2)
+{
+ const char *res1, *res2;
+ int len1, len2;
+
+ res1 = strstr(name1, ".llvm.");
+ res2 = strstr(name2, ".llvm.");
+ len1 = res1 ? res1 - name1 : strlen(name1);
+ len2 = res2 ? res2 - name2 : strlen(name2);
+
+ if (len1 == len2)
+ return strncmp(name1, name2, len1);
+ if (len1 < len2)
+ return strncmp(name1, name2, len1) <= 0 ? -1 : 1;
+ return strncmp(name1, name2, len2) >= 0 ? 1 : -1;
+}
+
+static int load_kallsyms_compare(const void *p1, const void *p2)
+{
+ return compare_name(((const struct ksym *)p1)->name, ((const struct ksym *)p2)->name);
+}
+
+static int search_kallsyms_compare(const void *p1, const struct ksym *p2)
+{
+ return compare_name(p1, p2->name);
+}
+
+int bpf_get_ksyms(char ***symsp, size_t *cntp, bool kernel)
+{
+ size_t cap = 0, cnt = 0;
+ char *name = NULL, *ksym_name, **syms = NULL;
+ struct hashmap *map;
+ struct ksyms *ksyms;
+ struct ksym *ks;
+ char buf[256];
+ FILE *f;
+ int err = 0;
+
+ ksyms = load_kallsyms_custom_local(load_kallsyms_compare);
+ if (!ksyms)
+ return -EINVAL;
+
+ /*
+ * The available_filter_functions contains many duplicates,
+ * but other than that all symbols are usable to trace.
+ * Filtering out duplicates by using hashmap__add, which won't
+ * add existing entry.
+ */
+
+ if (access("/sys/kernel/tracing/trace", F_OK) == 0)
+ f = fopen("/sys/kernel/tracing/available_filter_functions", "r");
+ else
+ f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
+
+ if (!f)
+ return -EINVAL;
+
+ map = hashmap__new(symbol_hash, symbol_equal, NULL);
+ if (IS_ERR(map)) {
+ err = libbpf_get_error(map);
+ goto error;
+ }
+
+ while (fgets(buf, sizeof(buf), f)) {
+ if (is_invalid_entry(buf, kernel))
+ continue;
+
+ free(name);
+ if (sscanf(buf, "%ms$*[^\n]\n", &name) != 1)
+ continue;
+ if (skip_entry(name))
+ continue;
+
+ ks = search_kallsyms_custom_local(ksyms, name, search_kallsyms_compare);
+ if (!ks) {
+ err = -EINVAL;
+ goto error;
+ }
+
+ ksym_name = ks->name;
+ err = hashmap__add(map, ksym_name, 0);
+ if (err == -EEXIST) {
+ err = 0;
+ continue;
+ }
+ if (err)
+ goto error;
+
+ err = libbpf_ensure_mem((void **) &syms, &cap,
+ sizeof(*syms), cnt + 1);
+ if (err)
+ goto error;
+
+ syms[cnt++] = ksym_name;
+ }
+
+ *symsp = syms;
+ *cntp = cnt;
+
+error:
+ free(name);
+ fclose(f);
+ hashmap__free(map);
+ if (err)
+ free(syms);
+ return err;
+}
+
+int bpf_get_addrs(unsigned long **addrsp, size_t *cntp, bool kernel)
+{
+ unsigned long *addr, *addrs, *tmp_addrs;
+ int err = 0, max_cnt, inc_cnt;
+ char *name = NULL;
+ size_t cnt = 0;
+ char buf[256];
+ FILE *f;
+
+ if (access("/sys/kernel/tracing/trace", F_OK) == 0)
+ f = fopen("/sys/kernel/tracing/available_filter_functions_addrs", "r");
+ else
+ f = fopen("/sys/kernel/debug/tracing/available_filter_functions_addrs", "r");
+
+ if (!f)
+ return -ENOENT;
+
+ /* In my local setup, the number of entries is 50k+ so Let us initially
+ * allocate space to hold 64k entries. If 64k is not enough, incrementally
+ * increase 1k each time.
+ */
+ max_cnt = 65536;
+ inc_cnt = 1024;
+ addrs = malloc(max_cnt * sizeof(long));
+ if (addrs == NULL) {
+ err = -ENOMEM;
+ goto error;
+ }
+
+ while (fgets(buf, sizeof(buf), f)) {
+ if (is_invalid_entry(buf, kernel))
+ continue;
+
+ free(name);
+ if (sscanf(buf, "%p %ms$*[^\n]\n", &addr, &name) != 2)
+ continue;
+ if (skip_entry(name))
+ continue;
+
+ if (cnt == max_cnt) {
+ max_cnt += inc_cnt;
+ tmp_addrs = realloc(addrs, max_cnt * sizeof(long));
+ if (!tmp_addrs) {
+ err = -ENOMEM;
+ goto error;
+ }
+ addrs = tmp_addrs;
+ }
+
+ addrs[cnt++] = (unsigned long)addr;
+ }
+
+ *addrsp = addrs;
+ *cntp = cnt;
+
+error:
+ free(name);
+ fclose(f);
+ if (err)
+ free(addrs);
+ return err;
+}
generated by cgit (git 2.34.1) at 2025-12-21 23:50:54 +0000