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libbpf-tools: Allow tools to run on old kernels #4546

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libbpf-tools: Allow tools to run on old kernels #4546

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18 changes: 18 additions & 0 deletions libbpf-tools/biosnoop.bpf.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,24 @@ int BPF_PROG(blk_account_io_start, struct request *rq)
return trace_pid(rq);
}

SEC("kprobe/blk_account_io_start")
int BPF_KPROBE(kprobe_blk_account_io_start, struct request *rq)
{
if (filter_cg && !bpf_current_task_under_cgroup(&cgroup_map, 0))
return 0;

return trace_pid(rq);
}

SEC("kprobe/__blk_account_io_start")
int BPF_KPROBE(kprobe___blk_account_io_start, struct request *rq)
{
if (filter_cg && !bpf_current_task_under_cgroup(&cgroup_map, 0))
return 0;

return trace_pid(rq);
}

SEC("kprobe/blk_account_io_merge_bio")
int BPF_KPROBE(blk_account_io_merge_bio, struct request *rq)
{
Expand Down
58 changes: 46 additions & 12 deletions libbpf-tools/biosnoop.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -197,6 +197,8 @@ int main(int argc, char **argv)
int err;
int idx, cg_map_fd;
int cgfd = -1;
bool blk_account_io_start_symbol;
bool blk_account_io_start_fentry;

err = argp_parse(&argp, argc, argv, 0, NULL, NULL);
if (err)
Expand Down Expand Up @@ -229,12 +231,32 @@ int main(int argc, char **argv)
obj->rodata->targ_queued = env.queued;
obj->rodata->filter_cg = env.cg;

if (fentry_can_attach("blk_account_io_start", NULL))
bpf_program__set_attach_target(obj->progs.blk_account_io_start, 0,
"blk_account_io_start");
else
bpf_program__set_attach_target(obj->progs.blk_account_io_start, 0,
"__blk_account_io_start");

if (kprobe_exists("blk_account_io_start")) {
if (fentry_can_attach("blk_account_io_start", NULL)) {
bpf_program__set_attach_target(obj->progs.blk_account_io_start, 0,
"blk_account_io_start");
bpf_program__set_autoload(obj->progs.kprobe_blk_account_io_start, false);
blk_account_io_start_fentry = true;
} else {
bpf_program__set_autoload(obj->progs.blk_account_io_start, false);
blk_account_io_start_fentry = false;
}
bpf_program__set_autoload(obj->progs.kprobe___blk_account_io_start, false);
blk_account_io_start_symbol = true;
} else {
if (fentry_can_attach("__blk_account_io_start", NULL)) {
bpf_program__set_attach_target(obj->progs.blk_account_io_start, 0,
"__blk_account_io_start");
bpf_program__set_autoload(obj->progs.kprobe___blk_account_io_start, false);
blk_account_io_start_fentry = true;
} else {
bpf_program__set_autoload(obj->progs.blk_account_io_start, false);
blk_account_io_start_fentry = false;
}
bpf_program__set_autoload(obj->progs.kprobe_blk_account_io_start, false);
blk_account_io_start_symbol = false;
}

err = biosnoop_bpf__load(obj);
if (err) {
Expand All @@ -257,12 +279,24 @@ int main(int argc, char **argv)
}
}

obj->links.blk_account_io_start = bpf_program__attach(obj->progs.blk_account_io_start);
if (!obj->links.blk_account_io_start) {
err = -errno;
fprintf(stderr, "failed to attach blk_account_io_start: %s\n",
strerror(-err));
goto cleanup;

if (blk_account_io_start_fentry)
obj->links.blk_account_io_start = bpf_program__attach(
obj->progs.blk_account_io_start);
else
if (blk_account_io_start_symbol)
obj->links.kprobe_blk_account_io_start = bpf_program__attach(
obj->progs.kprobe_blk_account_io_start);
else
obj->links.kprobe___blk_account_io_start = bpf_program__attach(
obj->progs.kprobe___blk_account_io_start);
if (!obj->links.blk_account_io_start &&
!obj->links.kprobe_blk_account_io_start &&
!obj->links.kprobe___blk_account_io_start) {
err = -errno;
fprintf(stderr, "failed to attach blk_account_io_start: %s\n",
strerror(-err));
goto cleanup;
}
ksyms = ksyms__load();
if (!ksyms) {
Expand Down
59 changes: 45 additions & 14 deletions libbpf-tools/biostacks.bpf.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -67,20 +67,8 @@ int trace_start(void *ctx, struct request *rq, bool merge_bio)
return 0;
}

SEC("fentry/blk_account_io_start")
int BPF_PROG(blk_account_io_start, struct request *rq)
{
return trace_start(ctx, rq, false);
}

SEC("kprobe/blk_account_io_merge_bio")
int BPF_KPROBE(blk_account_io_merge_bio, struct request *rq)
{
return trace_start(ctx, rq, true);
}

SEC("fentry/blk_account_io_done")
int BPF_PROG(blk_account_io_done, struct request *rq)
static __always_inline
int trace_done(void *ctx, struct request *rq)
Comment on lines +70 to +71
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Collaborator

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The reason will be displayed to describe this comment to others. Learn more.

Keep this in single line. We don't need __always_inline here.

{
u64 slot, ts = bpf_ktime_get_ns();
struct internal_rqinfo *i_rqinfop;
Expand Down Expand Up @@ -110,4 +98,47 @@ int BPF_PROG(blk_account_io_done, struct request *rq)
return 0;
}


SEC("fentry/blk_account_io_start")
int BPF_PROG(blk_account_io_start, struct request *rq)
{
return trace_start(ctx, rq, false);
}

SEC("fentry/blk_account_io_done")
int BPF_PROG(blk_account_io_done, struct request *rq)
{
return trace_done(ctx, rq);
}

SEC("kprobe/blk_account_io_start")
int BPF_KPROBE(kprobe_blk_account_io_start, struct request *rq)
{
return trace_start(ctx, rq, false);
}

SEC("kprobe/blk_account_io_done")
int BPF_KPROBE(kprobe_blk_account_io_done, struct request *rq)
{
return trace_done(ctx, rq);
}

SEC("kprobe/__blk_account_io_start")
int BPF_KPROBE(kprobe___blk_account_io_start, struct request *rq)
{
return trace_start(ctx, rq, false);
}

SEC("kprobe/__blk_account_io_done")
int BPF_KPROBE(kprobe___blk_account_io_done, struct request *rq)
{
return trace_done(ctx, rq);
}

SEC("kprobe/blk_account_io_merge_bio")
int BPF_KPROBE(blk_account_io_merge_bio, struct request *rq)
{
return trace_start(ctx, rq, true);
}

char LICENSE[] SEC("license") = "GPL";
64 changes: 34 additions & 30 deletions libbpf-tools/biostacks.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -172,52 +172,56 @@ int main(int argc, char **argv)

obj->rodata->targ_ms = env.milliseconds;

if (fentry_can_attach("blk_account_io_start", NULL)) {
bpf_program__set_attach_target(obj->progs.blk_account_io_start, 0,
"blk_account_io_start");
bpf_program__set_attach_target(obj->progs.blk_account_io_done, 0,
"blk_account_io_done");
if (kprobe_exists("blk_account_io_start")) {
if (fentry_can_attach("blk_account_io_start", NULL)) {
bpf_program__set_attach_target(obj->progs.blk_account_io_start, 0,
"blk_account_io_start");
bpf_program__set_attach_target(obj->progs.blk_account_io_done, 0,
"blk_account_io_done");
bpf_program__set_autoload(obj->progs.kprobe_blk_account_io_start, false);
bpf_program__set_autoload(obj->progs.kprobe_blk_account_io_done, false);
} else {
bpf_program__set_autoload(obj->progs.blk_account_io_start, false);
bpf_program__set_autoload(obj->progs.blk_account_io_done, false);
}
bpf_program__set_autoload(obj->progs.kprobe___blk_account_io_start, false);
bpf_program__set_autoload(obj->progs.kprobe___blk_account_io_done, false);
} else {
bpf_program__set_attach_target(obj->progs.blk_account_io_start, 0,
"__blk_account_io_start");
bpf_program__set_attach_target(obj->progs.blk_account_io_done, 0,
"__blk_account_io_done");
if (fentry_can_attach("__blk_account_io_start", NULL)) {
bpf_program__set_attach_target(obj->progs.blk_account_io_start, 0,
"__blk_account_io_start");
bpf_program__set_attach_target(obj->progs.blk_account_io_done, 0,
"__blk_account_io_done");
bpf_program__set_autoload(obj->progs.kprobe___blk_account_io_start, false);
bpf_program__set_autoload(obj->progs.kprobe___blk_account_io_done, false);
} else {
bpf_program__set_autoload(obj->progs.blk_account_io_start, false);
bpf_program__set_autoload(obj->progs.blk_account_io_done, false);
}
bpf_program__set_autoload(obj->progs.kprobe_blk_account_io_start, false);
bpf_program__set_autoload(obj->progs.kprobe_blk_account_io_done, false);
}

if (!kprobe_exists("blk_account_io_merge_bio"))
bpf_program__set_autoload(obj->progs.blk_account_io_merge_bio, false);

err = biostacks_bpf__load(obj);
if (err) {
fprintf(stderr, "failed to load BPF object: %d\n", err);
goto cleanup;
}

obj->links.blk_account_io_start = bpf_program__attach(obj->progs.blk_account_io_start);
if (!obj->links.blk_account_io_start) {
err = -errno;
fprintf(stderr, "failed to attach blk_account_io_start: %s\n", strerror(-err));
err = biostacks_bpf__attach(obj);
if (err) {
fprintf(stderr, "failed to attach BPF programs\n");
goto cleanup;
}

ksyms = ksyms__load();
if (!ksyms) {
fprintf(stderr, "failed to load kallsyms\n");
goto cleanup;
}
if (ksyms__get_symbol(ksyms, "blk_account_io_merge_bio")) {
obj->links.blk_account_io_merge_bio =
bpf_program__attach(obj->progs.blk_account_io_merge_bio);
if (!obj->links.blk_account_io_merge_bio) {
err = -errno;
fprintf(stderr, "failed to attach blk_account_io_merge_bio: %s\n",
strerror(-err));
goto cleanup;
}
}
obj->links.blk_account_io_done = bpf_program__attach(obj->progs.blk_account_io_done);
if (!obj->links.blk_account_io_done) {
err = -errno;
fprintf(stderr, "failed to attach blk_account_io_done: %s\n",
strerror(-err));
goto cleanup;
}

signal(SIGINT, sig_handler);

Expand Down
106 changes: 83 additions & 23 deletions libbpf-tools/readahead.bpf.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -24,18 +24,8 @@ struct {

struct hist hist = {};

SEC("fentry/do_page_cache_ra")
int BPF_PROG(do_page_cache_ra)
{
u32 pid = bpf_get_current_pid_tgid();
u64 one = 1;

bpf_map_update_elem(&in_readahead, &pid, &one, 0);
return 0;
}

SEC("fexit/__page_cache_alloc")
int BPF_PROG(page_cache_alloc_ret, gfp_t gfp, struct page *ret)
static __always_inline
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Ditto.

int do_page_cache_alloc_ret(struct page *ret)
{
u32 pid = bpf_get_current_pid_tgid();
u64 ts;
Expand All @@ -51,17 +41,8 @@ int BPF_PROG(page_cache_alloc_ret, gfp_t gfp, struct page *ret)
return 0;
}

SEC("fexit/do_page_cache_ra")
int BPF_PROG(do_page_cache_ra_ret)
{
u32 pid = bpf_get_current_pid_tgid();

bpf_map_delete_elem(&in_readahead, &pid);
return 0;
}

SEC("fentry/mark_page_accessed")
int BPF_PROG(mark_page_accessed, struct page *page)
static __always_inline
int do_mark_page_accessed(struct page *page)
{
u64 *tsp, slot, ts = bpf_ktime_get_ns();
s64 delta;
Expand All @@ -84,4 +65,83 @@ int BPF_PROG(mark_page_accessed, struct page *page)
return 0;
}

static __always_inline
int do_page_cache_ra(void)
{
u32 pid = bpf_get_current_pid_tgid();
u64 one = 1;

bpf_map_update_elem(&in_readahead, &pid, &one, 0);
return 0;
}

static __always_inline
int do_page_cache_ra_ret(void)
{
u32 pid = bpf_get_current_pid_tgid();

bpf_map_delete_elem(&in_readahead, &pid);
return 0;
}

SEC("fentry/do_page_cache_ra")
int BPF_PROG(fentry_do_page_cache_ra)
{
return do_page_cache_ra();
}

SEC("fexit/__page_cache_alloc")
int BPF_PROG(fexit_page_cache_alloc, gfp_t gfp, struct page *ret)
{
return do_page_cache_alloc_ret(ret);
}

SEC("fexit/do_page_cache_ra")
int BPF_PROG(fexit_do_page_cache_ra)
{
return do_page_cache_ra_ret();
}

SEC("fentry/mark_page_accessed")
int BPF_PROG(fentry_mark_page_accessed, struct page *page)
{
return do_mark_page_accessed(page);
}

SEC("kprobe/do_page_cache_ra")
int BPF_KPROBE(kprobe_do_page_cache_ra)
{
return do_page_cache_ra();
}

SEC("kretprobe/do_page_cache_ra")
int BPF_KRETPROBE(kretprobe_do_page_cache_ra)
{
return do_page_cache_ra_ret();
}

SEC("kprobe/__do_page_cache_readahead")
int BPF_KPROBE(kprobe___do_page_cache_readahead)
{
return do_page_cache_ra();
}

SEC("kretprobe/__do_page_cache_readahead")
int BPF_KRETPROBE(kretprobe___do_page_cache_readahead)
{
return do_page_cache_ra_ret();
}

SEC("kretprobe/__page_cache_alloc")
int BPF_KRETPROBE(kretprobe_page_cache_alloc, struct page *ret)
{
return do_page_cache_alloc_ret(ret);
}

SEC("kprobe/mark_page_accessed")
int BPF_KPROBE(kprobe_mark_page_accessed, struct page *page)
{
return do_mark_page_accessed(page);
}

char LICENSE[] SEC("license") = "GPL";
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