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git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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24a6034acc
To reduce the reliance of trace samples (trace*_user) on bpf_load, move read_trace_pipe to trace_helpers. By moving this bpf_loader helper elsewhere, trace functions can be easily migrated to libbbpf. Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200321100424.1593964-2-danieltimlee@gmail.com
112 lines
1.9 KiB
C
112 lines
1.9 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <poll.h>
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#include <unistd.h>
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#include <linux/perf_event.h>
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#include <sys/mman.h>
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#include "trace_helpers.h"
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#define DEBUGFS "/sys/kernel/debug/tracing/"
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#define MAX_SYMS 300000
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static struct ksym syms[MAX_SYMS];
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static int sym_cnt;
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static int ksym_cmp(const void *p1, const void *p2)
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{
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return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
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}
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int load_kallsyms(void)
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{
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FILE *f = fopen("/proc/kallsyms", "r");
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char func[256], buf[256];
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char symbol;
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void *addr;
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int i = 0;
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if (!f)
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return -ENOENT;
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while (fgets(buf, sizeof(buf), f)) {
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if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3)
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break;
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if (!addr)
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continue;
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syms[i].addr = (long) addr;
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syms[i].name = strdup(func);
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i++;
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}
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fclose(f);
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sym_cnt = i;
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qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp);
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return 0;
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}
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struct ksym *ksym_search(long key)
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{
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int start = 0, end = sym_cnt;
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int result;
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/* kallsyms not loaded. return NULL */
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if (sym_cnt <= 0)
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return NULL;
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while (start < end) {
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size_t mid = start + (end - start) / 2;
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result = key - syms[mid].addr;
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if (result < 0)
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end = mid;
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else if (result > 0)
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start = mid + 1;
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else
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return &syms[mid];
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}
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if (start >= 1 && syms[start - 1].addr < key &&
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key < syms[start].addr)
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/* valid ksym */
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return &syms[start - 1];
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/* out of range. return _stext */
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return &syms[0];
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}
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long ksym_get_addr(const char *name)
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{
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int i;
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for (i = 0; i < sym_cnt; i++) {
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if (strcmp(syms[i].name, name) == 0)
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return syms[i].addr;
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}
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return 0;
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}
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void read_trace_pipe(void)
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{
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int trace_fd;
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trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
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if (trace_fd < 0)
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return;
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while (1) {
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static char buf[4096];
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ssize_t sz;
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sz = read(trace_fd, buf, sizeof(buf) - 1);
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if (sz > 0) {
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buf[sz] = 0;
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puts(buf);
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}
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}
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}
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