LXR linux/tools/testing/selftests/bpf/progs/test_rdonly

   1// SPDX-License-Identifier: GPL-2.0
   2// Copyright (c) 2019 Facebook
   3
   4#include <linux/ptrace.h>
   5#include <linux/bpf.h>
   6#include <bpf/bpf_helpers.h>
   7
   8const struct {
   9        unsigned a[4];
  10        /*
  11         * if the struct's size is multiple of 16, compiler will put it into
  12         * .rodata.cst16 section, which is not recognized by libbpf; work
  13         * around this by ensuring we don't have 16-aligned struct
  14         */
  15        char _y;
  16} rdonly_values = { .a = {2, 3, 4, 5} };
  17
  18struct {
  19        unsigned did_run;
  20        unsigned iters;
  21        unsigned sum;
  22} res = {};
  23
  24SEC("raw_tracepoint/sys_enter:skip_loop")
  25int skip_loop(struct pt_regs *ctx)
  26{
  27        /* prevent compiler to optimize everything out */
  28        unsigned * volatile p = (void *)&rdonly_values.a;
  29        unsigned iters = 0, sum = 0;
  30
  31        /* we should never enter this loop */
  32        while (*p & 1) {
  33                iters++;
  34                sum += *p;
  35                p++;
  36        }
  37        res.did_run = 1;
  38        res.iters = iters;
  39        res.sum = sum;
  40        return 0;
  41}
  42
  43SEC("raw_tracepoint/sys_enter:part_loop")
  44int part_loop(struct pt_regs *ctx)
  45{
  46        /* prevent compiler to optimize everything out */
  47        unsigned * volatile p = (void *)&rdonly_values.a;
  48        unsigned iters = 0, sum = 0;
  49
  50        /* validate verifier can derive loop termination */
  51        while (*p < 5) {
  52                iters++;
  53                sum += *p;
  54                p++;
  55        }
  56        res.did_run = 1;
  57        res.iters = iters;
  58        res.sum = sum;
  59        return 0;
  60}
  61
  62SEC("raw_tracepoint/sys_enter:full_loop")
  63int full_loop(struct pt_regs *ctx)
  64{
  65        /* prevent compiler to optimize everything out */
  66        unsigned * volatile p = (void *)&rdonly_values.a;
  67        int i = sizeof(rdonly_values.a) / sizeof(rdonly_values.a[0]);
  68        unsigned iters = 0, sum = 0;
  69
  70        /* validate verifier can allow full loop as well */
  71        while (i > 0 ) {
  72                iters++;
  73                sum += *p;
  74                p++;
  75                i--;
  76        }
  77        res.did_run = 1;
  78        res.iters = iters;
  79        res.sum = sum;
  80        return 0;
  81}
  82
  83char _license[] SEC("license") = "GPL";
  84