[DTrace-devel] [PATCH 1/2 v3] Add support for the basename() action
eugene.loh at oracle.com
eugene.loh at oracle.com
Fri Nov 19 19:56:20 UTC 2021
From: Eugene Loh <eugene.loh at oracle.com>
Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
---
bpf/Build | 1 +
bpf/basename.S | 125 ++++++++++++++++++++++++++++
libdtrace/dt_cg.c | 56 ++++++++++++-
libdtrace/dt_dlibs.c | 1 +
test/unittest/dif/basename.d | 1 -
test/unittest/funcs/tst.basename0.d | 38 +++++++++
test/unittest/funcs/tst.basename0.r | 21 +++++
7 files changed, 241 insertions(+), 2 deletions(-)
create mode 100644 bpf/basename.S
create mode 100644 test/unittest/funcs/tst.basename0.d
create mode 100644 test/unittest/funcs/tst.basename0.r
diff --git a/bpf/Build b/bpf/Build
index d8279411..e66e8dc9 100644
--- a/bpf/Build
+++ b/bpf/Build
@@ -23,6 +23,7 @@ bpf_dlib_DIR := $(current-dir)
bpf_dlib_SRCDEPS = $(objdir)/include/.dir.stamp
bpf_dlib_SOURCES = \
agg_lqbin.c agg_qbin.c \
+ basename.S \
get_bvar.c \
get_tvar.c set_tvar.c \
index.S \
diff --git a/bpf/basename.S b/bpf/basename.S
new file mode 100644
index 00000000..3ddb3bbf
--- /dev/null
+++ b/bpf/basename.S
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+ */
+
+#define DT_STRLEN_BYTES 2
+
+#define BPF_FUNC_probe_read_str 45
+
+/*
+ * void dt_basename(char *src, char *dst);
+ */
+ .text
+ .align 4
+ .global dt_basename
+ .type dt_basename, @function
+dt_basename :
+#define SRC %r6
+#define DST %r7
+#define BGN %r8
+#define LEN %r9
+
+ /* store copies of input arguments */
+ mov SRC, %r1
+ mov DST, %r2
+
+ /* ignore the string-length prefix */
+ add SRC, DT_STRLEN_BYTES
+
+ /* r0 = bpf_probe_read_str(dst, STRSZ + 1, src) */
+ mov %r1, DST
+ lddw %r2, STRSZ
+ add %r2, 1
+ mov %r3, SRC
+ call BPF_FUNC_probe_read_str
+
+ /* if (r0 s<= 1) goto Ldot */
+ jsle %r0, 1, .Ldot
+
+ /* len = r0 - 1 */
+ mov LEN, %r0
+ sub LEN, 1
+
+ /*
+ * Loop over len, backing it up to find a non-'/' char.
+ */
+.Lend:
+ /* len-- */
+ sub LEN, 1
+ /* if (len s< 0) goto Lslash */
+ jslt LEN, 0, .Lslash
+ /* if (src[len] == '/') goto Lend */
+ mov %r1, SRC
+ add %r1, LEN
+ ldxb %r1, [%r1+0]
+ and %r1, 0xff
+ jeq %r1, '/', .Lend
+
+ /*
+ * Loop over bgn, backing it up to find a '/' char.
+ */
+ /* bgn = len */
+ mov BGN, LEN
+.Lbgn:
+ /* bgn-- */
+ sub BGN, 1
+ /* if (bgn s< 0) goto Lcopy */
+ jslt BGN, 0, .Lcopy
+ /* if (src[bgn] != '/') goto Lbgn */
+ mov %r1, SRC
+ add %r1, BGN
+ ldxb %r1, [%r1+0]
+ and %r1, 0xff
+ jne %r1, '/', .Lbgn
+
+.Lcopy:
+ /*
+ * The output string is a copy of the designated substring.
+ */
+ /* len -= bgn (and help the BPF verifier) */
+ sub LEN, BGN
+ jsge LEN, 0, 1
+ mov LEN, 0
+ /* bgn++ */
+ add BGN, 1
+ /* bpf_probe_read_str(dst + DT_STRLEN_BYTES, len + 1, &src[bgn]) */
+ mov %r1, DST
+ add %r1, DT_STRLEN_BYTES
+ mov %r2, LEN
+ add %r2, 1
+ mov %r3, SRC
+ add %r3, BGN
+ call BPF_FUNC_probe_read_str
+
+.Lcoda:
+ /* dt_strlen_store(len, dst) */
+ mov %r1, LEN
+ mov %r2, DST
+ call dt_strlen_store
+
+ /* return */
+ exit
+
+.Ldot:
+ /*
+ * The output string is simply ".\0".
+ */
+ mov LEN, 1
+ stb [DST+DT_STRLEN_BYTES], '.'
+ stb [DST+(DT_STRLEN_BYTES+1)], '\0'
+ ja .Lcoda
+
+.Lslash:
+ /*
+ * The output string is simply "/\0".
+ */
+ mov LEN, 1
+ stb [DST+DT_STRLEN_BYTES], '/'
+ stb [DST+(DT_STRLEN_BYTES+1)], '\0'
+ ja .Lcoda
+#undef SRC
+#undef DST
+#undef BGN
+#undef LEN
+ .size dt_basename, .-dt_basename
diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
index 537e6706..ff28b748 100644
--- a/libdtrace/dt_cg.c
+++ b/libdtrace/dt_cg.c
@@ -3294,6 +3294,60 @@ dt_cg_array_op(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
emit(dlp, BPF_ALU64_REG((dnp->dn_flags & DT_NF_SIGNED) ? BPF_ARSH : BPF_RSH, dnp->dn_reg, n));
}
+/*
+ * This function is a helper function for subroutines that take a path
+ * argument and return the tstring resulting from applying a given BPF
+ * function (passed by name) on it.
+ */
+static void
+dt_cg_subr_path_helper(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp,
+ const char *fname)
+{
+ dt_ident_t *idp;
+ dt_node_t *str = dnp->dn_args;
+
+ TRACE_REGSET(" subr-str_of_str:Begin");
+ dt_cg_node(str, dlp, drp);
+ dt_cg_check_notnull(dlp, drp, str->dn_reg);
+
+ /*
+ * The result needs be be a temporary string, so we request one.
+ */
+ dnp->dn_reg = dt_regset_alloc(drp);
+ if (dnp->dn_reg == -1)
+ longjmp(yypcb->pcb_jmpbuf, EDT_NOREG);
+ dt_cg_tstring_alloc(yypcb, dnp);
+ emit(dlp, BPF_LOAD(BPF_DW, dnp->dn_reg, BPF_REG_FP, DT_STK_DCTX));
+ emit(dlp, BPF_LOAD(BPF_DW, dnp->dn_reg, dnp->dn_reg, DCTX_MEM));
+ emit(dlp, BPF_ALU64_IMM(BPF_ADD, dnp->dn_reg, dnp->dn_tstring->dn_value));
+
+ /* function call */
+ if (dt_regset_xalloc_args(drp) == -1)
+ longjmp(yypcb->pcb_jmpbuf, EDT_NOREG);
+
+ emit(dlp, BPF_MOV_REG(BPF_REG_1, str->dn_reg));
+ dt_regset_free(drp, str->dn_reg);
+ if (str->dn_tstring)
+ dt_cg_tstring_free(yypcb, str);
+
+ emit(dlp, BPF_MOV_REG(BPF_REG_2, dnp->dn_reg));
+
+ dt_regset_xalloc(drp, BPF_REG_0);
+ idp = dt_dlib_get_func(yypcb->pcb_hdl, fname);
+ assert(idp != NULL);
+ emite(dlp, BPF_CALL_FUNC(idp->di_id), idp);
+ dt_regset_free_args(drp);
+ dt_regset_free(drp, BPF_REG_0);
+
+ TRACE_REGSET(" subr-str_of_str:End ");
+}
+
+static void
+dt_cg_subr_basename(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
+{
+ dt_cg_subr_path_helper(dnp, dlp, drp, "dt_basename");
+}
+
/*
* Get and return a new speculation ID. These are unallocated entries in the
* specs map, obtained by calling dt_speculation(). Return zero if none is
@@ -3986,7 +4040,7 @@ static dt_cg_subr_f *_dt_cg_subr[DIF_SUBR_MAX + 1] = {
[DIF_SUBR_DDI_PATHNAME] = NULL,
[DIF_SUBR_STRJOIN] = dt_cg_subr_strjoin,
[DIF_SUBR_LLTOSTR] = &dt_cg_subr_lltostr,
- [DIF_SUBR_BASENAME] = NULL,
+ [DIF_SUBR_BASENAME] = &dt_cg_subr_basename,
[DIF_SUBR_DIRNAME] = NULL,
[DIF_SUBR_CLEANPATH] = NULL,
[DIF_SUBR_STRCHR] = &dt_cg_subr_strchr,
diff --git a/libdtrace/dt_dlibs.c b/libdtrace/dt_dlibs.c
index 50acc0dc..771eba64 100644
--- a/libdtrace/dt_dlibs.c
+++ b/libdtrace/dt_dlibs.c
@@ -54,6 +54,7 @@ static const dt_ident_t dt_bpf_symbols[] = {
/* BPF library (external) functions */
DT_BPF_SYMBOL(dt_agg_lqbin, DT_IDENT_SYMBOL),
DT_BPF_SYMBOL(dt_agg_qbin, DT_IDENT_SYMBOL),
+ DT_BPF_SYMBOL(dt_basename, DT_IDENT_SYMBOL),
DT_BPF_SYMBOL(dt_error, DT_IDENT_SYMBOL),
DT_BPF_SYMBOL(dt_get_bvar, DT_IDENT_SYMBOL),
DT_BPF_SYMBOL(dt_get_string, DT_IDENT_SYMBOL),
diff --git a/test/unittest/dif/basename.d b/test/unittest/dif/basename.d
index a4c50d7e..5e60b96d 100644
--- a/test/unittest/dif/basename.d
+++ b/test/unittest/dif/basename.d
@@ -1,4 +1,3 @@
-/* @@xfail: dtv2 */
BEGIN
{
exit(basename("/foo/bar") == "bar" ? 0 : 1);
diff --git a/test/unittest/funcs/tst.basename0.d b/test/unittest/funcs/tst.basename0.d
new file mode 100644
index 00000000..0f758996
--- /dev/null
+++ b/test/unittest/funcs/tst.basename0.d
@@ -0,0 +1,38 @@
+/*
+ * Oracle Linux DTrace.
+ * Copyright (c) 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.
+ */
+
+#pragma D option quiet
+
+BEGIN
+{
+ printf("|%s|\n", basename("/foo/bar/baz"));
+ printf("|%s|\n", basename("/foo/bar///baz/"));
+ printf("|%s|\n", basename("/foo/bar/baz/"));
+ printf("|%s|\n", basename("/foo/bar/baz//"));
+ printf("|%s|\n", basename("/foo/bar/baz/."));
+ printf("|%s|\n", basename("/foo/bar/baz/./"));
+ printf("|%s|\n", basename("/foo/bar/baz/.//"));
+ printf("|%s|\n", basename("foo/bar/baz/"));
+ printf("|%s|\n", basename("/"));
+ printf("|%s|\n", basename("./"));
+ printf("|%s|\n", basename("//"));
+ printf("|%s|\n", basename("/."));
+ printf("|%s|\n", basename("/./"));
+ printf("|%s|\n", basename("/./."));
+ printf("|%s|\n", basename("/.//"));
+ printf("|%s|\n", basename("."));
+ printf("|%s|\n", basename("f"));
+ printf("|%s|\n", basename("f/"));
+ printf("|%s|\n", basename("/////"));
+ printf("|%s|\n", basename(""));
+ exit(0);
+}
+
+ERROR
+{
+ exit(1);
+}
diff --git a/test/unittest/funcs/tst.basename0.r b/test/unittest/funcs/tst.basename0.r
new file mode 100644
index 00000000..37a96547
--- /dev/null
+++ b/test/unittest/funcs/tst.basename0.r
@@ -0,0 +1,21 @@
+|baz|
+|baz|
+|baz|
+|baz|
+|.|
+|.|
+|.|
+|baz|
+|/|
+|.|
+|/|
+|.|
+|.|
+|.|
+|.|
+|.|
+|f|
+|f|
+|/|
+|.|
+
--
2.18.4
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