[DTrace-devel] [PATCH v2 20/20] Support probeprov, probemod, probefunc, probename built-in variables
Kris Van Hees
kris.van.hees at oracle.com
Thu Jun 3 08:21:10 PDT 2021
THis patch adds support for the built-in variables that provide the
component names for the probe description of the current probe in a
D clause, i.e. the probe that triggered the execution of the clause.
Because clauses (compiled into BPF functions) can be linked into the
BPF programs for multiple probes, the value of these built-in variables
cannot be provided at compile time. Their value is obtained from a
new BPF hashmap named 'probes' that associates a probe id with the
constant strings that provide the components of the probe description.
This patch also introduces a new BPF constant (resolved at link time)
to hold the size of the string constant table. This value is needed
to satisfy BPF verifier expectations for map value access boundary
checking.
Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
---
bpf/get_bvar.c | 69 +++++++++++++++++++
libdtrace/dt_bpf.c | 35 +++++++++-
libdtrace/dt_bpf.h | 1 +
libdtrace/dt_bpf_maps.h | 12 ++--
libdtrace/dt_cc.c | 3 +
libdtrace/dt_cg.c | 46 ++++++++++++-
libdtrace/dt_dlibs.c | 4 ++
test/demo/builtin/probefunc.d | 1 -
test/demo/builtin/probemod.d | 1 -
test/demo/intro/trussrw.d | 3 +-
test/unittest/actions/system/tst.system-str.d | 3 +-
test/unittest/dif/strlen.d | 1 -
test/unittest/inline/tst.InlineKinds.d | 3 +-
test/unittest/providers/tst.beginprof.d | 3 +-
test/unittest/providers/tst.probattrs.d | 3 +-
test/unittest/providers/tst.probefunc.d | 3 +-
test/unittest/providers/tst.probemod.d | 3 +-
test/unittest/providers/tst.probename.d | 3 +-
test/unittest/providers/tst.probprov.d | 3 +-
19 files changed, 168 insertions(+), 32 deletions(-)
diff --git a/bpf/get_bvar.c b/bpf/get_bvar.c
index 7e7b25a3..ab4c2894 100644
--- a/bpf/get_bvar.c
+++ b/bpf/get_bvar.c
@@ -9,8 +9,10 @@
#include <dtrace/conf.h>
#include <dtrace/dif_defines.h>
#include <dtrace/faults_defines.h>
+#include <dt_bpf_maps.h>
#include <dt_dctx.h>
#include <dt_state.h>
+#include <dt_varint.h>
#include "probe_error.h"
@@ -19,8 +21,11 @@
#endif
extern struct bpf_map_def cpuinfo;
+extern struct bpf_map_def probes;
extern struct bpf_map_def state;
+extern uint64_t STBSZ;
+
#define error(dctx, fault, illval) \
({ \
dt_probe_error((dctx), -1, (fault), (illval)); \
@@ -52,6 +57,70 @@ noinline uint64_t dt_get_bvar(dt_dctx_t *dctx, uint32_t id)
/* FIXME: no stack() yet */
return 0;
}
+ case DIF_VAR_PROBEPROV: {
+ uint32_t key;
+ dt_bpf_probe_t *pinfo;
+ uint64_t off;
+
+ key = mst->prid;
+ pinfo = bpf_map_lookup_elem(&probes, &key);
+ if (pinfo == NULL)
+ return (uint64_t)dctx->strtab;
+
+ off = pinfo->prv;
+ if (off > (uint64_t)&STBSZ)
+ return (uint64_t)dctx->strtab;
+
+ return (uint64_t)(dctx->strtab + off);
+ }
+ case DIF_VAR_PROBEMOD: {
+ uint32_t key;
+ dt_bpf_probe_t *pinfo;
+ uint64_t off;
+
+ key = mst->prid;
+ pinfo = bpf_map_lookup_elem(&probes, &key);
+ if (pinfo == NULL)
+ return (uint64_t)dctx->strtab;
+
+ off = pinfo->mod;
+ if (off > (uint64_t)&STBSZ)
+ return (uint64_t)dctx->strtab;
+
+ return (uint64_t)(dctx->strtab + off);
+ }
+ case DIF_VAR_PROBEFUNC: {
+ uint32_t key;
+ dt_bpf_probe_t *pinfo;
+ uint64_t off;
+
+ key = mst->prid;
+ pinfo = bpf_map_lookup_elem(&probes, &key);
+ if (pinfo == NULL)
+ return (uint64_t)dctx->strtab;
+
+ off = pinfo->fun;
+ if (off > (uint64_t)&STBSZ)
+ return (uint64_t)dctx->strtab;
+
+ return (uint64_t)(dctx->strtab + off);
+ }
+ case DIF_VAR_PROBENAME: {
+ uint32_t key;
+ dt_bpf_probe_t *pinfo;
+ uint64_t off;
+
+ key = mst->prid;
+ pinfo = bpf_map_lookup_elem(&probes, &key);
+ if (pinfo == NULL)
+ return (uint64_t)dctx->strtab;
+
+ off = pinfo->prb;
+ if (off > (uint64_t)&STBSZ)
+ return (uint64_t)dctx->strtab;
+
+ return (uint64_t)(dctx->strtab + off);
+ }
case DIF_VAR_PID: {
uint64_t val = bpf_get_current_pid_tgid();
diff --git a/libdtrace/dt_bpf.c b/libdtrace/dt_bpf.c
index 7317abfc..3ef0b262 100644
--- a/libdtrace/dt_bpf.c
+++ b/libdtrace/dt_bpf.c
@@ -17,8 +17,10 @@
#include <dt_dctx.h>
#include <dt_probe.h>
#include <dt_state.h>
+#include <dt_strtab.h>
#include <dt_varint.h>
#include <dt_bpf.h>
+#include <dt_bpf_maps.h>
#include <port.h>
#include <bpf.h>
@@ -139,6 +141,24 @@ set_task_offsets(dtrace_hdl_t *dtp)
return 0;
}
+static void
+populate_probes_map(dtrace_hdl_t *dtp, int fd)
+{
+ dt_probe_t *prp;
+
+ for (prp = dt_list_next(&dtp->dt_enablings); prp != NULL;
+ prp = dt_list_next(prp)) {
+ dt_bpf_probe_t pinfo;
+
+ pinfo.prv = dt_strtab_index(dtp->dt_ccstab, prp->desc->prv);
+ pinfo.mod = dt_strtab_index(dtp->dt_ccstab, prp->desc->mod);
+ pinfo.fun = dt_strtab_index(dtp->dt_ccstab, prp->desc->fun);
+ pinfo.prb = dt_strtab_index(dtp->dt_ccstab, prp->desc->prb);
+
+ dt_bpf_map_update(fd, &prp->desc->id, &pinfo);
+ }
+}
+
/*
* Create the global BPF maps that are shared between all BPF programs in a
* single tracing session:
@@ -174,6 +194,10 @@ set_task_offsets(dtrace_hdl_t *dtp)
* consumer handle (dt_strlen), and increased by the maximum
* string size to ensure that the BPF verifier can validate all
* access requests for dynamic references to string constants.
+ * - probes: Probe information map. This is a global map indexed by probe
+ * ID. The value is a struct that contains static probe info.
+ * The map only contains entries for probes that are actually in
+ * use.
* - gvars: Global variables map. This is a global map with a singleton
* element (key 0) addressed by variable offset.
* - lvars: Local variables map. This is a per-CPU map with a singleton
@@ -201,7 +225,7 @@ int
dt_bpf_gmap_create(dtrace_hdl_t *dtp)
{
int stabsz, gvarsz, lvarsz, tvarc, aggsz;
- int ci_mapfd, st_mapfd;
+ int ci_mapfd, st_mapfd, pr_mapfd;
uint32_t key = 0;
/* If we already created the global maps, return success. */
@@ -275,6 +299,12 @@ dt_bpf_gmap_create(dtrace_hdl_t *dtp)
if (st_mapfd == -1)
return -1; /* dt_errno is set for us */
+ pr_mapfd = create_gmap(dtp, "probes", BPF_MAP_TYPE_HASH,
+ sizeof(uint32_t), sizeof(dt_bpf_probe_t),
+ dt_list_length(&dtp->dt_enablings));
+ if (pr_mapfd == -1)
+ return -1; /* dt_errno is set for us */
+
if (gvarsz > 0 &&
create_gmap(dtp, "gvars", BPF_MAP_TYPE_ARRAY,
sizeof(uint32_t), gvarsz, 1) == -1)
@@ -296,6 +326,9 @@ dt_bpf_gmap_create(dtrace_hdl_t *dtp)
/* Populate the 'strtab' map. */
dt_bpf_map_update(st_mapfd, &key, dtp->dt_strtab);
+ /* Populate the 'probes' map. */
+ populate_probes_map(dtp, pr_mapfd);
+
/* Set some task_struct offsets in state. */
if (set_task_offsets(dtp))
return dt_set_errno(dtp, EDT_CTF);
diff --git a/libdtrace/dt_bpf.h b/libdtrace/dt_bpf.h
index 4a9e598a..7fa9eed3 100644
--- a/libdtrace/dt_bpf.h
+++ b/libdtrace/dt_bpf.h
@@ -22,6 +22,7 @@ extern "C" {
#define DT_CONST_PRID 2
#define DT_CONST_CLID 3
#define DT_CONST_ARGC 4
+#define DT_CONST_STBSZ 5
extern int perf_event_open(struct perf_event_attr *attr, pid_t pid, int cpu,
int group_fd, unsigned long flags);
diff --git a/libdtrace/dt_bpf_maps.h b/libdtrace/dt_bpf_maps.h
index 12c2e8d8..aa088ce8 100644
--- a/libdtrace/dt_bpf_maps.h
+++ b/libdtrace/dt_bpf_maps.h
@@ -1,6 +1,6 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2021, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
@@ -8,22 +8,20 @@
#ifndef _DT_BPF_MAPS_H
#define _DT_BPF_MAPS_H
-#ifdef FIXME
#ifdef __cplusplus
extern "C" {
#endif
typedef struct dt_bpf_probe dt_bpf_probe_t;
struct dt_bpf_probe {
- uint_t prvv; /* probeprov string offset in strtab */
- uint_t mod; /* probemod string offset in strtab */
- uint_t fun; /* probefunc string offset in strtab */
- uint_t prb; /* probename string offset in strtab */
+ size_t prv; /* probeprov string offset in strtab */
+ size_t mod; /* probemod string offset in strtab */
+ size_t fun; /* probefunc string offset in strtab */
+ size_t prb; /* probename string offset in strtab */
};
#ifdef __cplusplus
}
#endif
-#endif
#endif /* _DT_BPF_FUNCS_H */
diff --git a/libdtrace/dt_cc.c b/libdtrace/dt_cc.c
index 66d93f3a..a374a747 100644
--- a/libdtrace/dt_cc.c
+++ b/libdtrace/dt_cc.c
@@ -2324,6 +2324,9 @@ dt_link_construct(dtrace_hdl_t *dtp, const dt_probe_t *prp, dtrace_difo_t *dp,
case DT_CONST_ARGC:
nrp->dofr_data = 0; /* FIXME */
continue;
+ case DT_CONST_STBSZ:
+ nrp->dofr_data = dtp->dt_strlen;
+ continue;
default:
/* probe name -> value is probe id */
if (strchr(idp->di_name, ':') != NULL)
diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
index 8bb01852..9d671071 100644
--- a/libdtrace/dt_cg.c
+++ b/libdtrace/dt_cg.c
@@ -54,6 +54,8 @@ dt_cg_tramp_prologue_act(dt_pcb_t *pcb, dt_activity_t act)
uint_t lbl_exit = pcb->pcb_exitlbl;
assert(mem != NULL);
+ assert(state != NULL);
+ assert(prid != NULL);
/*
* On input, %r1 is the BPF context.
@@ -753,13 +755,51 @@ dt_cg_store_val(dt_pcb_t *pcb, dt_node_t *dnp, dtrace_actkind_t kind,
return 0;
} else if (dt_node_is_string(dnp)) {
+ dt_ident_t *idp;
+ uint_t vcopy = dt_irlist_label(dlp);
+ int reg = dt_regset_alloc(drp);
+
off = dt_rec_add(pcb->pcb_hdl, dt_cg_fill_gap, kind,
size, 1, pfp, arg);
- emit(dlp, BPF_MOV_REG(BPF_REG_0, BPF_REG_9));
- emit(dlp, BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, off));
- dt_cg_memcpy(dlp, drp, BPF_REG_0, dnp->dn_reg, size);
+ /* Retrieve the length of the string. */
+ dt_cg_strlen(dlp, drp, reg, dnp->dn_reg);
+
+ if (dt_regset_xalloc_args(drp) == -1)
+ longjmp(yypcb->pcb_jmpbuf, EDT_NOREG);
+
+ /* Determine the number of bytes used for the length. */
+ emit(dlp, BPF_MOV_REG(BPF_REG_1, reg));
+ idp = dt_dlib_get_func(yypcb->pcb_hdl, "dt_vint_size");
+ assert(idp != NULL);
+ dt_regset_xalloc(drp, BPF_REG_0);
+ emite(dlp, BPF_CALL_FUNC(idp->di_id), idp);
+
+ /* Add length of the string (adjusted for terminating byte). */
+ emit(dlp, BPF_ALU64_IMM(BPF_ADD, reg, 1));
+ emit(dlp, BPF_ALU64_REG(BPF_ADD, BPF_REG_0, reg));
+ dt_regset_free(drp, reg);
+
+ /*
+ * Copy string data (varint length + string content) to the
+ * output buffer at [%r9 + off]. The amount of bytes copied is
+ * the lesser of the data size and the maximum string size.
+ */
+ emit(dlp, BPF_MOV_REG(BPF_REG_1, BPF_REG_9));
+ emit(dlp, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, off));
+ emit(dlp, BPF_MOV_REG(BPF_REG_2, dnp->dn_reg));
dt_regset_free(drp, dnp->dn_reg);
+ emit(dlp, BPF_MOV_REG(BPF_REG_3, BPF_REG_0));
+ dt_regset_free(drp, BPF_REG_0);
+ emit(dlp, BPF_BRANCH_IMM(BPF_JLT, BPF_REG_3, size, vcopy));
+ emit(dlp, BPF_MOV_IMM(BPF_REG_3, size));
+ idp = dt_dlib_get_func(yypcb->pcb_hdl, "dt_memcpy");
+ assert(idp != NULL);
+ dt_regset_xalloc(drp, BPF_REG_0);
+ emitle(dlp, vcopy,
+ BPF_CALL_FUNC(idp->di_id), idp);
+ dt_regset_free_args(drp);
+ dt_regset_free(drp, BPF_REG_0);
return 0;
}
diff --git a/libdtrace/dt_dlibs.c b/libdtrace/dt_dlibs.c
index 6dae65d5..fae58b1a 100644
--- a/libdtrace/dt_dlibs.c
+++ b/libdtrace/dt_dlibs.c
@@ -68,6 +68,7 @@ static const dt_ident_t dt_bpf_symbols[] = {
DT_BPF_SYMBOL(gvars, DT_IDENT_PTR),
DT_BPF_SYMBOL(lvars, DT_IDENT_PTR),
DT_BPF_SYMBOL(mem, DT_IDENT_PTR),
+ DT_BPF_SYMBOL(probes, DT_IDENT_PTR),
DT_BPF_SYMBOL(state, DT_IDENT_PTR),
DT_BPF_SYMBOL(strtab, DT_IDENT_PTR),
DT_BPF_SYMBOL(tvars, DT_IDENT_PTR),
@@ -76,6 +77,7 @@ static const dt_ident_t dt_bpf_symbols[] = {
DT_BPF_SYMBOL_ID(PRID, DT_IDENT_SCALAR, DT_CONST_PRID),
DT_BPF_SYMBOL_ID(CLID, DT_IDENT_SCALAR, DT_CONST_CLID),
DT_BPF_SYMBOL_ID(ARGC, DT_IDENT_SCALAR, DT_CONST_ARGC),
+ DT_BPF_SYMBOL_ID(STBSZ, DT_IDENT_SCALAR, DT_CONST_STBSZ),
/* End-of-list marker */
{ NULL, }
};
@@ -414,6 +416,8 @@ get_symbols(dtrace_hdl_t *dtp, Elf *elf, int syms_idx, int strs_idx,
idp = dt_dlib_get_map(dtp, name);
if (idp == NULL)
idp = dt_dlib_get_func(dtp, name);
+ if (idp == NULL)
+ idp = dt_dlib_get_var(dtp, name);
if (idp == NULL) {
dt_dlib_error(dtp, D_IDENT_UNDEF,
"undefined symbol %s in BPF dlib",
diff --git a/test/demo/builtin/probefunc.d b/test/demo/builtin/probefunc.d
index 9f9b9147..ed2bff00 100644
--- a/test/demo/builtin/probefunc.d
+++ b/test/demo/builtin/probefunc.d
@@ -1,4 +1,3 @@
-/* @@xfail: dtv2 */
BEGIN {
trace(probefunc);
exit(0);
diff --git a/test/demo/builtin/probemod.d b/test/demo/builtin/probemod.d
index eed55f10..5796bdc2 100644
--- a/test/demo/builtin/probemod.d
+++ b/test/demo/builtin/probemod.d
@@ -1,4 +1,3 @@
-/* @@xfail: dtv2 */
BEGIN {
trace(probemod);
exit(0);
diff --git a/test/demo/intro/trussrw.d b/test/demo/intro/trussrw.d
index 24cb5998..e1a17099 100644
--- a/test/demo/intro/trussrw.d
+++ b/test/demo/intro/trussrw.d
@@ -1,11 +1,10 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2005, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2021, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
-/* @@xfail: dtv2 */
/* @@trigger: mmap */
syscall::read:entry,
diff --git a/test/unittest/actions/system/tst.system-str.d b/test/unittest/actions/system/tst.system-str.d
index 70b67e2a..8f532ae6 100644
--- a/test/unittest/actions/system/tst.system-str.d
+++ b/test/unittest/actions/system/tst.system-str.d
@@ -1,10 +1,9 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2021, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
-/* @@xfail: dtv2 */
#pragma D option quiet
#pragma D option destructive
diff --git a/test/unittest/dif/strlen.d b/test/unittest/dif/strlen.d
index f801562d..b8f419d2 100644
--- a/test/unittest/dif/strlen.d
+++ b/test/unittest/dif/strlen.d
@@ -1,4 +1,3 @@
-/* @@xfail: dtv2 */
BEGIN
{
trace(strlen(probename));
diff --git a/test/unittest/inline/tst.InlineKinds.d b/test/unittest/inline/tst.InlineKinds.d
index 0b8bf8cd..5f2ec1b8 100644
--- a/test/unittest/inline/tst.InlineKinds.d
+++ b/test/unittest/inline/tst.InlineKinds.d
@@ -1,10 +1,9 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2021, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
-/* @@xfail: dtv2 */
/*
* Test the code generation and results of the various kinds of inlines.
diff --git a/test/unittest/providers/tst.beginprof.d b/test/unittest/providers/tst.beginprof.d
index c041dc34..2b97718a 100644
--- a/test/unittest/providers/tst.beginprof.d
+++ b/test/unittest/providers/tst.beginprof.d
@@ -1,10 +1,9 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2021, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
-/* @@xfail: dtv2 */
/*
* ASSERTION:
diff --git a/test/unittest/providers/tst.probattrs.d b/test/unittest/providers/tst.probattrs.d
index ed77fe5a..af42a6b0 100644
--- a/test/unittest/providers/tst.probattrs.d
+++ b/test/unittest/providers/tst.probattrs.d
@@ -1,10 +1,9 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2021, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
-/* @@xfail: dtv2 */
/*
* ASSERTION:
diff --git a/test/unittest/providers/tst.probefunc.d b/test/unittest/providers/tst.probefunc.d
index 86b8f7ea..0f4c7980 100644
--- a/test/unittest/providers/tst.probefunc.d
+++ b/test/unittest/providers/tst.probefunc.d
@@ -1,10 +1,9 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2021, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
-/* @@xfail: dtv2 */
/*
* ASSERTION:
diff --git a/test/unittest/providers/tst.probemod.d b/test/unittest/providers/tst.probemod.d
index 2dace056..fc20a4c7 100644
--- a/test/unittest/providers/tst.probemod.d
+++ b/test/unittest/providers/tst.probemod.d
@@ -1,10 +1,9 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2021, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
-/* @@xfail: dtv2 */
/*
* ASSERTION:
diff --git a/test/unittest/providers/tst.probename.d b/test/unittest/providers/tst.probename.d
index b486030b..462d07f4 100644
--- a/test/unittest/providers/tst.probename.d
+++ b/test/unittest/providers/tst.probename.d
@@ -1,10 +1,9 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2021, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
-/* @@xfail: dtv2 */
/*
* ASSERTION:
diff --git a/test/unittest/providers/tst.probprov.d b/test/unittest/providers/tst.probprov.d
index da5d67f0..faac3658 100644
--- a/test/unittest/providers/tst.probprov.d
+++ b/test/unittest/providers/tst.probprov.d
@@ -1,10 +1,9 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2006, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2021, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
-/* @@xfail: dtv2 */
/*
* ASSERTION:
--
2.31.1
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