Add -xcpu support for general providers

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@oracle.com>
Reviewed-by: Kris Van Hees <kris.van.hees@oracle.com>

libdtrace/dt_cg.c

@@ -391,10 +391,32 @@ 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);
 }
 
 /*
@@ -541,8 +563,8 @@ 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)

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);

libdtrace/dt_prov_cpc.c

@@ -397,10 +397,10 @@ 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)
 	 */

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)
 	 */

test/stress/options/tst.cpu-syscall.sh

@@ -0,0 +1,151 @@
+#!/bin/bash
+#
+# Oracle Linux DTrace.
+# Copyright (c) 2024, 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 -n | 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 -n | 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

test/unittest/options/tst.cpu-syscall.sh

@@ -0,0 +1,156 @@
+#!/bin/bash
+#
+# Oracle Linux DTrace.
+# Copyright (c) 2024, 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 -n | 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
+
+#
+# Pick a CPU at random.
+#
+
+cpus=( $cpulist )
+ncpus=${#cpus[@]}
+cpu0=${cpus[$((RANDOM % $ncpus))]}
+
+#
+# Run DTrace (with -xcpu).  Check that only the specified CPU appears.
+#
+
+$dtrace $dt_flags -xcpu=$cpu0 \
+    -qn 'syscall::write:entry { printf("%d\n", cpu); }' \
+    -c "./a.out $cpulist" | sort -n | 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
+	exit 1
+fi
+
+exit 0