[PATCH v2 10/11] tools/nolibc: add ptrace support

Benjamin Berg
2025-09-19T15:36:13Z

From: Benjamin Berg <benjamin.berg@intel.com>

Add ptrace support, as it will be useful in UML.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
---
tools/include/nolibc/Makefile | 1 +
tools/include/nolibc/nolibc.h | 1 +
tools/include/nolibc/sys/ptrace.h | 52 ++++++++++++++++++++
tools/testing/selftests/nolibc/nolibc-test.c | 2 +
4 files changed, 56 insertions(+)
create mode 100644 tools/include/nolibc/sys/ptrace.h

diff --git a/tools/include/nolibc/Makefile b/tools/include/nolibc/Makefile
index 9bbbba32dac6..8e0cac3ac522 100644
--- a/tools/include/nolibc/Makefile
+++ b/tools/include/nolibc/Makefile
@@ -53,6 +53,7 @@ all_files := \
sys/mman.h \
sys/mount.h \
sys/prctl.h \
+ sys/ptrace.h \
sys/random.h \
sys/reboot.h \
sys/resource.h \
diff --git a/tools/include/nolibc/nolibc.h b/tools/include/nolibc/nolibc.h
index b4bc1c9b883d..590eef545ca6 100644
--- a/tools/include/nolibc/nolibc.h
+++ b/tools/include/nolibc/nolibc.h
@@ -101,6 +101,7 @@
#include "sys/mman.h"
#include "sys/mount.h"
#include "sys/prctl.h"
+#include "sys/ptrace.h"
#include "sys/random.h"
#include "sys/reboot.h"
#include "sys/resource.h"
diff --git a/tools/include/nolibc/sys/ptrace.h b/tools/include/nolibc/sys/ptrace.h
new file mode 100644
index 000000000000..3119abdeeecb
--- /dev/null
+++ b/tools/include/nolibc/sys/ptrace.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * ptrace for NOLIBC
+ * Copyright (C) 2017-2021 Willy Tarreau <w@1wt.eu>
+ * Copyright (C) 2025 Intel Corporation
+ */
+
+/* make sure to include all global symbols */
+#include "../nolibc.h"
+
+#ifndef _NOLIBC_SYS_PTRACE_H
+#define _NOLIBC_SYS_PTRACE_H
+
+#include "../sys.h"
+#include "uio.h"
+
+
+#include <linux/ptrace.h>
+
+/*
+ * long ptrace(int op, pid_t pid, void *addr, void *data);
+ *
+ * However, addr may also be an integer in some cases.
+ */
+static __attribute__((unused))
+long sys_vptrace(int op, pid_t pid, va_list args)
+{
+ return my_syscall4(__NR_ptrace, op, pid,
+ va_arg(args, void *), va_arg(args, void *));
+}
+
+static __attribute__((unused))
+ssize_t sys_ptrace(int op, pid_t pid, ...)
+{
+ va_list args;
+
+ va_start(args, pid);
+ return sys_vptrace(op, pid, args);
+ va_end(args);
+}
+
+static __attribute__((unused))
+ssize_t ptrace(int op, pid_t pid, ...)
+{
+ va_list args;
+
+ va_start(args, pid);
+ return __sysret(sys_vptrace(op, pid, args));
+ va_end(args);
+}
+
+#endif /* _NOLIBC_SYS_PTRACE_H */
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 1907128bc3f6..4c1b9ee32b7d 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -17,6 +17,7 @@
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/prctl.h>
+#include <sys/ptrace.h>
#include <sys/random.h>
#include <sys/reboot.h>
#include <sys/resource.h>
@@ -1404,6 +1405,7 @@ int run_syscall(int min, int max)
CASE_TEST(readv_zero); EXPECT_SYSZR(1, readv(1, NULL, 0)); break;
CASE_TEST(writev_badf); EXPECT_SYSER(1, writev(-1, &iov_one, 1), -1, EBADF); break;
CASE_TEST(writev_zero); EXPECT_SYSZR(1, writev(1, NULL, 0)); break;
+ CASE_TEST(ptrace); EXPECT_SYSER(1, ptrace(PTRACE_CONT, getpid(), NULL, NULL), -1, ESRCH); break;
CASE_TEST(syscall_noargs); EXPECT_SYSEQ(1, syscall(__NR_getpid), getpid()); break;
CASE_TEST(syscall_args); EXPECT_SYSER(1, syscall(__NR_statx, 0, NULL, 0, 0, NULL), -1, EFAULT); break;
CASE_TEST(namespace); EXPECT_SYSZR(euid0 && proc, test_namespace()); break;
--
2.51.0