[DTrace-devel] [PATCH 2/2] cc, bpf: separate final BPF program creation from linking and loading
Kris Van Hees
kris.van.hees at oracle.com
Thu Aug 24 15:13:28 UTC 2023
Some providers may need to do more complex code generaetion for the
probe BPF program trampoline. The generation of trampoline code was
being done after BPF map creation, making it impossible for trampoline
code to use constructs that require data to be added to BPF maps.
The final BPF program handling has been changed to first create the
final programs, then create the BPF maps, and finally link and load the
BPF programs (performing the final relocations) and attaching them to
their probes.
Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
---
libdtrace/dt_bpf.c | 48 ++++++++++++++++++++++++++++++--------------
libdtrace/dt_bpf.h | 1 +
libdtrace/dt_cc.c | 4 ++--
libdtrace/dt_impl.h | 4 ++++
libdtrace/dt_probe.c | 3 +++
libdtrace/dt_probe.h | 1 +
libdtrace/dt_work.c | 4 ++++
7 files changed, 48 insertions(+), 17 deletions(-)
diff --git a/libdtrace/dt_bpf.c b/libdtrace/dt_bpf.c
index 9688c444..5ae5f55f 100644
--- a/libdtrace/dt_bpf.c
+++ b/libdtrace/dt_bpf.c
@@ -1085,12 +1085,11 @@ dt_bpf_reloc_error_prog(dtrace_hdl_t *dtp, dtrace_difo_t *dp)
}
int
-dt_bpf_load_progs(dtrace_hdl_t *dtp, uint_t cflags)
+dt_bpf_make_progs(dtrace_hdl_t *dtp, uint_t cflags)
{
dt_probe_t *prp;
dtrace_difo_t *dp;
dt_ident_t *idp = dt_dlib_get_func(dtp, "dt_error");
- dtrace_optval_t dest_ok = DTRACEOPT_UNSET;
assert(idp != NULL);
@@ -1108,19 +1107,11 @@ dt_bpf_load_progs(dtrace_hdl_t *dtp, uint_t cflags)
idp->di_flags |= DT_IDFLG_CGREG; /* mark it as inline-ready */
dt_bpf_reloc_error_prog(dtp, dp);
- /*
- * Determine whether we can allow destructive actions.
- */
- dtrace_getopt(dtp, "destructive", &dest_ok);
-
/*
* Now construct all the other programs.
*/
for (prp = dt_list_next(&dtp->dt_enablings); prp != NULL;
prp = dt_list_next(prp)) {
- int fd;
- int rc = -1;
-
/* Already done. */
if (prp == dtp->dt_error)
continue;
@@ -1132,19 +1123,46 @@ dt_bpf_load_progs(dtrace_hdl_t *dtp, uint_t cflags)
if (prp->prov->impl->prog_type == BPF_PROG_TYPE_UNSPEC)
continue;
- dp = dt_program_construct(dtp, prp, cflags, NULL);
+ dp = dt_construct(dtp, prp, cflags, NULL);
if (dp == NULL)
return -1;
- if (dp->dtdo_flags & DIFOFLG_DESTRUCTIVE &&
+
+ prp->difo = dp;
+ }
+
+ return 0;
+}
+
+int
+dt_bpf_load_progs(dtrace_hdl_t *dtp, uint_t cflags)
+{
+ dt_probe_t *prp;
+ dtrace_optval_t dest_ok = DTRACEOPT_UNSET;
+
+ /*
+ * Determine whether we can allow destructive actions.
+ */
+ dtrace_getopt(dtp, "destructive", &dest_ok);
+
+ for (prp = dt_list_next(&dtp->dt_enablings); prp != NULL;
+ prp = dt_list_next(prp)) {
+ int fd;
+ int rc = -1;
+
+ if (prp->difo == NULL)
+ continue;
+
+ if (dt_link(dtp, prp, prp->difo, NULL) == -1)
+ return -1;
+
+ if (prp->difo->dtdo_flags & DIFOFLG_DESTRUCTIVE &&
dest_ok == DTRACEOPT_UNSET)
return dt_set_errno(dtp, EDT_DESTRUCTIVE);
- fd = dt_bpf_load_prog(dtp, prp, dp, cflags);
+ fd = dt_bpf_load_prog(dtp, prp, prp->difo, cflags);
if (fd == -1)
return -1;
- dt_difo_free(dtp, dp);
-
if (prp->prov->impl->attach)
rc = prp->prov->impl->attach(dtp, prp, fd);
diff --git a/libdtrace/dt_bpf.h b/libdtrace/dt_bpf.h
index 578b7cf9..0fee533b 100644
--- a/libdtrace/dt_bpf.h
+++ b/libdtrace/dt_bpf.h
@@ -63,6 +63,7 @@ extern int dt_bpf_prog_load(enum bpf_prog_type prog_type,
const dtrace_difo_t *dp, uint32_t log_level,
char *log_buf, size_t log_buf_sz);
extern int dt_bpf_raw_tracepoint_open(const void *tp, int fd);
+extern int dt_bpf_make_progs(struct dtrace_hdl *, uint_t);
extern int dt_bpf_load_progs(struct dtrace_hdl *, uint_t);
extern void dt_bpf_init_helpers(struct dtrace_hdl *dtp);
diff --git a/libdtrace/dt_cc.c b/libdtrace/dt_cc.c
index 86807caa..a42109f1 100644
--- a/libdtrace/dt_cc.c
+++ b/libdtrace/dt_cc.c
@@ -775,7 +775,7 @@ out:
return err ? NULL : rv;
}
-static dtrace_difo_t *
+dtrace_difo_t *
dt_construct(dtrace_hdl_t *dtp, dt_probe_t *prp, uint_t cflags, dt_ident_t *idp)
{
dt_pcb_t pcb;
@@ -1264,7 +1264,7 @@ dt_link_resolve(dtrace_hdl_t *dtp, dtrace_difo_t *dp)
}
}
-static int
+int
dt_link(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
dt_ident_t *idp)
{
diff --git a/libdtrace/dt_impl.h b/libdtrace/dt_impl.h
index de46d3db..674905b9 100644
--- a/libdtrace/dt_impl.h
+++ b/libdtrace/dt_impl.h
@@ -803,6 +803,10 @@ extern int dt_load_libs(dtrace_hdl_t *dtp);
extern void *dt_compile(dtrace_hdl_t *dtp, int context,
dtrace_probespec_t pspec, void *arg, uint_t cflags,
int argc, char *const argv[], FILE *fp, const char *s);
+extern dtrace_difo_t *dt_construct(dtrace_hdl_t *dtp, struct dt_probe *prp,
+ uint_t cflags, dt_ident_t *idp);
+extern int dt_link(dtrace_hdl_t *dtp, const struct dt_probe *prp,
+ dtrace_difo_t *dp, dt_ident_t *idp);
extern dtrace_difo_t *dt_program_construct(dtrace_hdl_t *dtp,
struct dt_probe *prp, uint_t cflags,
dt_ident_t *idp);
diff --git a/libdtrace/dt_probe.c b/libdtrace/dt_probe.c
index 8f32adce..93266ff7 100644
--- a/libdtrace/dt_probe.c
+++ b/libdtrace/dt_probe.c
@@ -477,6 +477,9 @@ dt_probe_destroy(dt_probe_t *prp)
else
dtp = yypcb->pcb_hdl;
+ if (prp->difo)
+ dt_difo_free(dtp, prp->difo);
+
if (prp->desc) {
dtp->dt_probes[prp->desc->id] = NULL;
diff --git a/libdtrace/dt_probe.h b/libdtrace/dt_probe.h
index 4b9396a7..c9839124 100644
--- a/libdtrace/dt_probe.h
+++ b/libdtrace/dt_probe.h
@@ -54,6 +54,7 @@ typedef struct dt_probe {
dtrace_typeinfo_t *argv; /* output argument types */
int argc; /* output argument count */
dt_probe_instance_t *pr_inst; /* list of functions and offsets */
+ dtrace_difo_t *difo; /* BPF probe program */
} dt_probe_t;
extern dt_probe_t *dt_probe_lookup2(dt_provider_t *, const char *);
diff --git a/libdtrace/dt_work.c b/libdtrace/dt_work.c
index 4492f563..1bb6104c 100644
--- a/libdtrace/dt_work.c
+++ b/libdtrace/dt_work.c
@@ -150,6 +150,10 @@ dtrace_go(dtrace_hdl_t *dtp, uint_t cflags)
setrlimit(RLIMIT_MEMLOCK, &rl);
}
+ /* Create the BPF programs. */
+ if (dt_bpf_make_progs(dtp, cflags) == -1)
+ return -1;
+
/* Create the global BPF maps. */
if (dt_bpf_gmap_create(dtp) == -1)
return -1;
--
2.40.1
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