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// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2019 Facebook
#include <linux/ptrace.h>
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
static volatile const struct {
unsigned a[4];
/*
* if the struct's size is multiple of 16, compiler will put it into
* .rodata.cst16 section, which is not recognized by libbpf; work
* around this by ensuring we don't have 16-aligned struct
*/
char _y;
} rdonly_values = { .a = {2, 3, 4, 5} };
static volatile struct {
unsigned did_run;
unsigned iters;
unsigned sum;
} res;
SEC("raw_tracepoint/sys_enter:skip_loop")
int skip_loop(struct pt_regs *ctx)
{
/* prevent compiler to optimize everything out */
unsigned * volatile p = (void *)&rdonly_values.a;
unsigned iters = 0, sum = 0;
/* we should never enter this loop */
while (*p & 1) {
iters++;
sum += *p;
p++;
}
res.did_run = 1;
res.iters = iters;
res.sum = sum;
return 0;
}
SEC("raw_tracepoint/sys_enter:part_loop")
int part_loop(struct pt_regs *ctx)
{
/* prevent compiler to optimize everything out */
unsigned * volatile p = (void *)&rdonly_values.a;
unsigned iters = 0, sum = 0;
/* validate verifier can derive loop termination */
while (*p < 5) {
iters++;
sum += *p;
p++;
}
res.did_run = 1;
res.iters = iters;
res.sum = sum;
return 0;
}
SEC("raw_tracepoint/sys_enter:full_loop")
int full_loop(struct pt_regs *ctx)
{
/* prevent compiler to optimize everything out */
unsigned * volatile p = (void *)&rdonly_values.a;
int i = sizeof(rdonly_values.a) / sizeof(rdonly_values.a[0]);
unsigned iters = 0, sum = 0;
/* validate verifier can allow full loop as well */
while (i > 0 ) {
iters++;
sum += *p;
p++;
i--;
}
res.did_run = 1;
res.iters = iters;
res.sum = sum;
return 0;
}
char _license[] SEC("license") = "GPL";
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