[DTrace-devel] [PATCH 4/4] Add support for strrchr() subroutine
eugene.loh at oracle.com
eugene.loh at oracle.com
Tue Sep 7 17:06:42 PDT 2021
From: Eugene Loh <eugene.loh at oracle.com>
Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
---
bpf/Build | 1 +
bpf/strrchr.S | 113 +++++++++++++++++++++++++++++++
libdtrace/dt_cg.c | 53 ++++++++++++++-
libdtrace/dt_dlibs.c | 1 +
test/unittest/funcs/tst.strchr.d | 1 -
5 files changed, 167 insertions(+), 2 deletions(-)
create mode 100644 bpf/strrchr.S
diff --git a/bpf/Build b/bpf/Build
index 1aa9dd62..6e9ffa20 100644
--- a/bpf/Build
+++ b/bpf/Build
@@ -29,6 +29,7 @@ bpf_dlib_SOURCES = \
strchr.S \
strcmp.S \
strjoin.S \
+ strrchr.S \
substr.S \
strlen.c
diff --git a/bpf/strrchr.S b/bpf/strrchr.S
new file mode 100644
index 00000000..6a527ea0
--- /dev/null
+++ b/bpf/strrchr.S
@@ -0,0 +1,113 @@
+// 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 4
+#define BPF_FUNC_probe_read_str 45
+
+/*
+ * char *dt_strrchr(char *src, uint64_t c, char *dst) {
+ *
+ * c <<= 56;
+ *
+ * [%fp-8]=src
+ * [%fp-16]=c
+ * [%fp-24]=dst
+ *
+ * r6 = bpf_probe_read_str(dst, STRSZ, src + DT_STRLEN_BYTES);
+ * r6--;
+ *
+ * r8 = r6;
+ * Lloop:
+ * r8--;
+ * r3 = src[DT_STRLEN_BYTES + r8];
+ * r3 <<= 56;
+ * if (r3 == c) goto Lfound;
+ * if (r8 > 0) goto Lloop;
+ *
+ * return -1;
+ *
+ * Lfound:
+ * r6 -= r8;
+ * dt_strlen_store(r6, dst);
+ * r8 += DT_STRLEN_BYTES;
+ * bpf_probe_read(dst + DT_STRLEN_BYTES, r6, src + r8);
+ *
+ * r6 += DT_STRLEN_BYTES;
+ * dst[r6] = '\0';
+ *
+ * return 0;
+ * }
+ */
+ .text
+ .align 4
+ .global dt_strrchr
+dt_strrchr :
+ lsh %r2, 56 /* c <<= 56 */
+
+ stxdw [%fp+-8], %r1 /* Spill src */
+ stxdw [%fp+-16], %r2 /* Spill c */
+ stxdw [%fp+-24], %r3 /* Spill dst */
+
+ ldxdw %r1, [%fp+-24]
+ lddw %r2, STRSZ
+ ldxdw %r3, [%fp+-8]
+ add %r3, DT_STRLEN_BYTES
+ call BPF_FUNC_probe_read_str /* r6 = bpf_probe_read_str(dst, STRSZ, src + DT_STRLEN_BYTES) */
+ jsle %r0, 0, .Lerror
+ mov %r6, %r0
+
+ sub %r6, 1 /* r6-- */
+
+ mov %r8, %r6 /* r8 = r6 */
+
+ ldxdw %r5, [%fp+-16]
+ lddw %r1, STRSZ
+ jsle %r8, 0, .Lnone
+.Lloop:
+ sub %r8, 1 /* r8-- */
+ mov %r4, %r8
+ add %r4, DT_STRLEN_BYTES
+ ldxdw %r3, [%fp+-8]
+ add %r3, %r4
+ ldxb %r3, [%r3+0] /* r3 = src[DT_STRLEN_BYTES+ r8] */
+ lsh %r3, 56 /* r3 <<= 56 */
+ jeq %r3, %r5, .Lfound /* if (r3 == c) goto Lfound */
+ jgt %r8, 0, .Lloop /* if (r8 > 0) goto Lloop */
+
+.Lnone:
+ mov %r0, -1 /* return -1 */
+ exit
+
+.Lfound:
+ sub %r6, %r8 /* r6 -= r8 */
+ jsle %r6, 0, .Lerror
+
+ mov %r1, %r6
+ ldxdw %r2, [%fp+-24]
+ call dt_strlen_store /* dt_strlen_store(r6, dst) */
+
+ add %r8, DT_STRLEN_BYTES /* r8 += DT_STRLEN_BYTES */
+
+ ldxdw %r1, [%fp+-24]
+ add %r1, DT_STRLEN_BYTES
+ mov %r2, %r6
+ ldxdw %r3, [%fp+-8]
+ add %r3, %r8
+ call BPF_FUNC_probe_read /* bpf_probe_read(dst + DT_STRLEN_BYTES, r6, src + r8) */
+
+ add %r6, DT_STRLEN_BYTES /* r6 += DT_STRLEN_BYTES */
+ ldxdw %r1, [%fp+-24]
+ add %r1, %r6 /* dst[r6] = '\0' */
+ mov %r2, 0
+ stxb [%r1+0], %r2
+
+ mov %r0, 0 /* return 0 */
+ exit
+
+.Lerror:
+ mov %r0, -1
+ exit
diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
index bf88c862..d71ce6fd 100644
--- a/libdtrace/dt_cg.c
+++ b/libdtrace/dt_cg.c
@@ -3223,6 +3223,57 @@ dt_cg_subr_strchr(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
TRACE_REGSET(" subr-strchr:End ");
}
+static void
+dt_cg_subr_strrchr(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
+{
+ dt_ident_t *idp;
+ dt_node_t *str = dnp->dn_args;
+ dt_node_t *chr = str->dn_list;
+ uint_t Lfound = dt_irlist_label(dlp);
+
+ TRACE_REGSET(" subr-strrchr:Begin");
+ dt_cg_node(str, dlp, drp);
+ dt_cg_check_notnull(dlp, drp, str->dn_reg);
+ dt_cg_node(chr, dlp, drp);
+
+ 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, chr->dn_reg));
+ dt_regset_free(drp, chr->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));
+ emit(dlp, BPF_MOV_REG(BPF_REG_3, dnp->dn_reg));
+
+ dt_regset_xalloc(drp, BPF_REG_0);
+ idp = dt_dlib_get_func(yypcb->pcb_hdl, "dt_strrchr");
+ assert(idp != NULL);
+ emite(dlp, BPF_CALL_FUNC(idp->di_id), idp);
+ dt_regset_free_args(drp);
+
+ emit (dlp, BPF_BRANCH_IMM(BPF_JEQ, BPF_REG_0, 0, Lfound));
+ emit (dlp, BPF_MOV_IMM(dnp->dn_reg, 0));
+ emitl(dlp, Lfound,
+ BPF_NOP());
+ dt_regset_free(drp, BPF_REG_0);
+
+ TRACE_REGSET(" subr-strrchr:End ");
+}
+
static void
dt_cg_subr_strlen(dt_node_t *dnp, dt_irlist_t *dlp, dt_regset_t *drp)
{
@@ -3370,7 +3421,7 @@ static dt_cg_subr_f *_dt_cg_subr[DIF_SUBR_MAX + 1] = {
[DIF_SUBR_DIRNAME] = NULL,
[DIF_SUBR_CLEANPATH] = NULL,
[DIF_SUBR_STRCHR] = dt_cg_subr_strchr,
- [DIF_SUBR_STRRCHR] = NULL,
+ [DIF_SUBR_STRRCHR] = &dt_cg_subr_strrchr,
[DIF_SUBR_STRSTR] = NULL,
[DIF_SUBR_STRTOK] = NULL,
[DIF_SUBR_SUBSTR] = &dt_cg_subr_substr,
diff --git a/libdtrace/dt_dlibs.c b/libdtrace/dt_dlibs.c
index c4e495e0..d9836f40 100644
--- a/libdtrace/dt_dlibs.c
+++ b/libdtrace/dt_dlibs.c
@@ -62,6 +62,7 @@ static const dt_ident_t dt_bpf_symbols[] = {
DT_BPF_SYMBOL(dt_strchr, DT_IDENT_SYMBOL),
DT_BPF_SYMBOL(dt_strcmp, DT_IDENT_SYMBOL),
DT_BPF_SYMBOL(dt_strjoin, DT_IDENT_SYMBOL),
+ DT_BPF_SYMBOL(dt_strrchr, DT_IDENT_SYMBOL),
DT_BPF_SYMBOL(dt_substr, DT_IDENT_SYMBOL),
/* BPF maps */
DT_BPF_SYMBOL(aggs, DT_IDENT_PTR),
diff --git a/test/unittest/funcs/tst.strchr.d b/test/unittest/funcs/tst.strchr.d
index 9d8262df..a562b72e 100644
--- a/test/unittest/funcs/tst.strchr.d
+++ b/test/unittest/funcs/tst.strchr.d
@@ -4,7 +4,6 @@
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
-/* @@xfail: dtv2 */
#pragma D option quiet
--
2.18.4
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