[DTrace-devel] [PATCH v2 5/5] Add -xcpu support for general providers
eugene.loh at oracle.com
eugene.loh at oracle.com
Fri Dec 22 02:46:53 UTC 2023
From: Eugene Loh <eugene.loh at oracle.com>
Add code to dt_cg_tramp_prologue() to filter on the desired cpu.
Then call the new dt_cg_tramp_prologue_cpu() function, which
assumes a cpu has already been selected, if necessary.
Providers that handle -xcpu specially can bypass that filtering
by calling the new dt_cg_tramp_prologue_cpu() function.
The new function simply calls
dt_cg_tramp_prologue_act(pcb, DT_ACTIVITY_ACTIVE). The _act
function is called directly by only one provider: dtrace.
Signed-off-by: Eugene Loh <eugene.loh at oracle.com>
---
libdtrace/dt_cg.c | 28 ++++-
libdtrace/dt_cg.h | 1 +
libdtrace/dt_prov_cpc.c | 4 +-
libdtrace/dt_prov_profile.c | 4 +-
test/unittest/options/tst.cpu-syscall.sh | 151 +++++++++++++++++++++++
5 files changed, 181 insertions(+), 7 deletions(-)
create mode 100755 test/unittest/options/tst.cpu-syscall.sh
diff --git a/libdtrace/dt_cg.c b/libdtrace/dt_cg.c
index 7ae16db8..c8e80abb 100644
--- a/libdtrace/dt_cg.c
+++ b/libdtrace/dt_cg.c
@@ -356,10 +356,32 @@ dt_cg_tramp_prologue_act(dt_pcb_t *pcb, dt_activity_t act)
}
}
+void
+dt_cg_tramp_prologue_cpu(dt_pcb_t *pcb) {
+ dt_cg_tramp_prologue_act(pcb, DT_ACTIVITY_ACTIVE);
+}
+
void
dt_cg_tramp_prologue(dt_pcb_t *pcb)
{
- dt_cg_tramp_prologue_act(pcb, DT_ACTIVITY_ACTIVE);
+ dtrace_hdl_t *dtp = pcb->pcb_hdl;
+
+ /* Check if we are on the specified CPU (if any). */
+ if (dtp->dt_options[DTRACEOPT_CPU] != DTRACEOPT_UNSET) {
+ dt_irlist_t *dlp = &pcb->pcb_ir;
+
+ emit(dlp, BPF_MOV_REG(BPF_REG_8, BPF_REG_1));
+
+ emit(dlp, BPF_CALL_HELPER(BPF_FUNC_get_smp_processor_id));
+ emit(dlp, BPF_BRANCH_IMM(BPF_JNE, BPF_REG_0,
+ dtp->dt_options[DTRACEOPT_CPU],
+ pcb->pcb_exitlbl));
+
+ emit(dlp, BPF_MOV_REG(BPF_REG_1, BPF_REG_8));
+ }
+
+ /* Call the rest of the prologue code generation. */
+ dt_cg_tramp_prologue_cpu(pcb);
}
/*
@@ -506,8 +528,8 @@ dt_cg_tramp_copy_args_from_regs(dt_pcb_t *pcb, int called)
* So put the PC in both arg0 and arg1, test the PC, and then zero out
* either arg0 or arg1, as apropriate.
*
- * The caller must ensure that %r7 and %r8 contain the values set by
- * the dt_cg_tramp_prologue*() functions.
+ * The caller must ensure that %r7 and %r8 contain the values set by the
+ * dt_cg_tramp_prologue*() functions.
*/
void
dt_cg_tramp_copy_pc_from_regs(dt_pcb_t *pcb)
diff --git a/libdtrace/dt_cg.h b/libdtrace/dt_cg.h
index 95bf507f..50dd256b 100644
--- a/libdtrace/dt_cg.h
+++ b/libdtrace/dt_cg.h
@@ -21,6 +21,7 @@ extern void dt_cg(dt_pcb_t *, dt_node_t *);
extern void dt_cg_xsetx(dt_irlist_t *, dt_ident_t *, uint_t, int, uint64_t);
extern dt_irnode_t *dt_cg_node_alloc(uint_t, struct bpf_insn);
extern void dt_cg_tramp_prologue_act(dt_pcb_t *pcb, dt_activity_t act);
+extern void dt_cg_tramp_prologue_cpu(dt_pcb_t *pcb);
extern void dt_cg_tramp_prologue(dt_pcb_t *pcb);
extern void dt_cg_tramp_clear_regs(dt_pcb_t *pcb);
extern void dt_cg_tramp_copy_regs(dt_pcb_t *pcb);
diff --git a/libdtrace/dt_prov_cpc.c b/libdtrace/dt_prov_cpc.c
index 9e0f5542..93968950 100644
--- a/libdtrace/dt_prov_cpc.c
+++ b/libdtrace/dt_prov_cpc.c
@@ -395,10 +395,10 @@ static int trampoline(dt_pcb_t *pcb, uint_t exitlbl)
int i;
dt_irlist_t *dlp = &pcb->pcb_ir;
- dt_cg_tramp_prologue(pcb);
+ dt_cg_tramp_prologue_cpu(pcb);
/*
- * After the dt_cg_tramp_prologue() call, we have:
+ * After the dt_cg_tramp_prologue_cpu() call, we have:
* // (%r7 = dctx->mst)
* // (%r8 = dctx->ctx)
*/
diff --git a/libdtrace/dt_prov_profile.c b/libdtrace/dt_prov_profile.c
index f3f3bf23..967ca8c2 100644
--- a/libdtrace/dt_prov_profile.c
+++ b/libdtrace/dt_prov_profile.c
@@ -220,10 +220,10 @@ static int trampoline(dt_pcb_t *pcb, uint_t exitlbl)
int i;
dt_irlist_t *dlp = &pcb->pcb_ir;
- dt_cg_tramp_prologue(pcb);
+ dt_cg_tramp_prologue_cpu(pcb);
/*
- * After the dt_cg_tramp_prologue() call, we have:
+ * After the dt_cg_tramp_prologue_cpu() call, we have:
* // (%r7 = dctx->mst)
* // (%r8 = dctx->ctx)
*/
diff --git a/test/unittest/options/tst.cpu-syscall.sh b/test/unittest/options/tst.cpu-syscall.sh
new file mode 100755
index 00000000..8713e9d4
--- /dev/null
+++ b/test/unittest/options/tst.cpu-syscall.sh
@@ -0,0 +1,151 @@
+#!/bin/bash
+#
+# Oracle Linux DTrace.
+# Copyright (c) 2023, 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.
+#
+
+dtrace=$1
+
+DIRNAME="$tmpdir/cpu-syscall.$$.$RANDOM"
+mkdir -p $DIRNAME
+cd $DIRNAME
+
+#
+# Make trigger code and compile it.
+#
+
+cat << EOF > main.c
+#define _GNU_SOURCE
+#include <sched.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include <errno.h>
+
+int ncpus;
+cpu_set_t *mask;
+size_t size;
+
+/*
+ * Grow the CPU mask as needed.
+ *
+ * Other ways of determining the number of CPUs available on the system:
+ * - inspecting the contents of /proc/cpuinfo
+ * - using sysconf(3) to obtain _SC_NPROCESSORS_CONF and _SC_NPROCESSORS_ONLN
+ * - inspecting the list of CPU directories under /sys/devices/system/cpu/
+ */
+int grow_mask() {
+ ncpus = 1024;
+ while ((mask = CPU_ALLOC(ncpus)) != NULL &&
+ sched_getaffinity(0, CPU_ALLOC_SIZE(ncpus), mask) != 0 &&
+ errno == EINVAL) {
+ CPU_FREE(mask);
+ errno = 0;
+ ncpus *= 2;
+ }
+ if (mask == NULL || (errno != 0 && errno != EINVAL))
+ return 1;
+ size = CPU_ALLOC_SIZE(ncpus);
+ return 0;
+}
+
+int bind_to_cpu(size_t cpu) {
+ CPU_ZERO_S(size, mask);
+ CPU_SET_S(cpu, size, mask);
+ if (sched_setaffinity(0, size, mask) != 0)
+ return 1;
+ return 0;
+}
+
+int main(int c, char **v) {
+ int i, fd = open("/dev/null", O_WRONLY);
+
+ if (fd == -1)
+ return 1;
+
+ if (grow_mask() == -1)
+ return 1;
+
+ /* Loop over CPUs (in argv[]). */
+ for (i = 1; i < c; i++) {
+ /* Bind to CPU. */
+ if (bind_to_cpu(atol(v[i])) == -1)
+ return 1;
+
+ /* Call write() from CPU. */
+ write(fd, &i, sizeof(i));
+ }
+
+ close(fd);
+ CPU_FREE(mask);
+
+ return 0;
+}
+EOF
+
+gcc main.c
+if [ $? -ne 0 ]; then
+ echo ERROR compilation failed
+ exit 1
+fi
+
+#
+# Get CPU list and form expected-results file.
+#
+
+cpulist=`awk '/^processor[ ]: [0-9]*$/ { print $3 }' /proc/cpuinfo`
+echo $cpulist
+
+echo > expect.txt
+for cpu in $cpulist; do
+ echo $cpu >> expect.txt
+done
+
+#
+# Run DTrace (without -xcpu). Check that all CPUs appear.
+#
+
+$dtrace $dt_flags \
+ -qn 'syscall::write:entry { printf("%d\n", cpu); }' \
+ -c "./a.out $cpulist" | sort | uniq > actual.txt
+if [ $? -ne 0 ]; then
+ echo ERROR dtrace failed
+ exit 1
+fi
+
+if ! diff -q expect.txt actual.txt > /dev/null; then
+ echo ERROR did not see expected CPUs in baseline case
+ echo expect $cpulist
+ echo actual:
+ cat actual.txt
+ exit 1
+fi
+
+#
+# Run DTrace (with -xcpu). Check that only the specified CPU appears.
+#
+
+nerr=0
+for cpu0 in $cpulist; do
+ $dtrace $dt_flags -xcpu=$cpu0 \
+ -qn 'syscall::write:entry { printf("%d\n", cpu); }' \
+ -c "./a.out $cpulist" | sort | uniq > actual.txt
+ echo > expect.txt
+ echo $cpu0 >> expect.txt
+
+ if ! diff -q expect.txt actual.txt > /dev/null; then
+ echo ERROR did not see expected CPUs in cpu $cpu0 case, saw:
+ cat actual.txt
+ nerr=$(($nerr + 1))
+ fi
+done
+
+exit $nerr
--
2.18.4
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