fa7f17d066
Add a writable bare tracepoint in bpf_testmod module, and trigger its calling when reading /sys/kernel/bpf_testmod with a specific buffer length. The reading will return the value in writable context if the early return flag is enabled in writable context. Signed-off-by: Hou Tao <houtao1@huawei.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20211004094857.30868-4-hotforest@gmail.com
121 lines
3.0 KiB
C
121 lines
3.0 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2020 Facebook */
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#include <linux/btf.h>
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#include <linux/btf_ids.h>
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#include <linux/error-injection.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/percpu-defs.h>
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#include <linux/sysfs.h>
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#include <linux/tracepoint.h>
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#include "bpf_testmod.h"
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#define CREATE_TRACE_POINTS
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#include "bpf_testmod-events.h"
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DEFINE_PER_CPU(int, bpf_testmod_ksym_percpu) = 123;
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noinline void
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bpf_testmod_test_mod_kfunc(int i)
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{
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*(int *)this_cpu_ptr(&bpf_testmod_ksym_percpu) = i;
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}
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noinline int bpf_testmod_loop_test(int n)
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{
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int i, sum = 0;
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/* the primary goal of this test is to test LBR. Create a lot of
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* branches in the function, so we can catch it easily.
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*/
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for (i = 0; i < n; i++)
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sum += i;
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return sum;
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}
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noinline ssize_t
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bpf_testmod_test_read(struct file *file, struct kobject *kobj,
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struct bin_attribute *bin_attr,
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char *buf, loff_t off, size_t len)
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{
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struct bpf_testmod_test_read_ctx ctx = {
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.buf = buf,
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.off = off,
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.len = len,
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};
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/* This is always true. Use the check to make sure the compiler
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* doesn't remove bpf_testmod_loop_test.
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*/
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if (bpf_testmod_loop_test(101) > 100)
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trace_bpf_testmod_test_read(current, &ctx);
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/* Magic number to enable writable tp */
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if (len == 64) {
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struct bpf_testmod_test_writable_ctx writable = {
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.val = 1024,
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};
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trace_bpf_testmod_test_writable_bare(&writable);
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if (writable.early_ret)
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return snprintf(buf, len, "%d\n", writable.val);
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}
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return -EIO; /* always fail */
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}
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EXPORT_SYMBOL(bpf_testmod_test_read);
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ALLOW_ERROR_INJECTION(bpf_testmod_test_read, ERRNO);
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noinline ssize_t
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bpf_testmod_test_write(struct file *file, struct kobject *kobj,
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struct bin_attribute *bin_attr,
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char *buf, loff_t off, size_t len)
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{
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struct bpf_testmod_test_write_ctx ctx = {
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.buf = buf,
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.off = off,
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.len = len,
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};
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trace_bpf_testmod_test_write_bare(current, &ctx);
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return -EIO; /* always fail */
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}
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EXPORT_SYMBOL(bpf_testmod_test_write);
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ALLOW_ERROR_INJECTION(bpf_testmod_test_write, ERRNO);
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static struct bin_attribute bin_attr_bpf_testmod_file __ro_after_init = {
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.attr = { .name = "bpf_testmod", .mode = 0666, },
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.read = bpf_testmod_test_read,
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.write = bpf_testmod_test_write,
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};
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BTF_SET_START(bpf_testmod_kfunc_ids)
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BTF_ID(func, bpf_testmod_test_mod_kfunc)
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BTF_SET_END(bpf_testmod_kfunc_ids)
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static DEFINE_KFUNC_BTF_ID_SET(&bpf_testmod_kfunc_ids, bpf_testmod_kfunc_btf_set);
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static int bpf_testmod_init(void)
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{
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int ret;
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ret = sysfs_create_bin_file(kernel_kobj, &bin_attr_bpf_testmod_file);
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if (ret)
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return ret;
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register_kfunc_btf_id_set(&prog_test_kfunc_list, &bpf_testmod_kfunc_btf_set);
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return 0;
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}
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static void bpf_testmod_exit(void)
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{
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unregister_kfunc_btf_id_set(&prog_test_kfunc_list, &bpf_testmod_kfunc_btf_set);
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return sysfs_remove_bin_file(kernel_kobj, &bin_attr_bpf_testmod_file);
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}
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module_init(bpf_testmod_init);
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module_exit(bpf_testmod_exit);
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MODULE_AUTHOR("Andrii Nakryiko");
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MODULE_DESCRIPTION("BPF selftests module");
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MODULE_LICENSE("Dual BSD/GPL");
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