[DTrace-devel] [PATCH 1/2 v3] Add support for the basename() action
Eugene Loh
eugene.loh at oracle.com
Wed Dec 1 19:25:40 UTC 2021
On 12/1/21 2:13 PM, Kris Van Hees wrote:
> Reviewed-by: Kris Van Hees <kris.van.hees at oracle.com>
>
> ... with the little changes below. I can apply them if you like as I do the
> integration on 'dev' since it is so minor.
Sounds great, thanks.
> On Fri, Nov 19, 2021 at 02:56:20PM -0500, eugene.loh--- via DTrace-devel wrote:
>> 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");
> s/str_of_str/path_helper/
>
>> + 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);
> No need to have the conditional - we do that in dt_cg_tstring_free().
>
>> +
>> + 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 ");
> s/str_of_str/path_helper/
>
>> +}
>> +
>> +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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