[LTP] [PATCH] hugemmap41: Migrate ptrace-write-hugepage from libhugetlbfs v3

[Pavithra]

This test verifies that ptrace POKEDATA and PEEKDATA operations work
correctly on hugepage-backed memory regions. The test creates a child
process that maps a hugepage, then the parent process uses ptrace to
attach to the child and perform write/read operations on the child's
hugepage memory.

Signed-off-by: Pavithra <pavrampu@linux.ibm.com>
---
 runtest/hugetlb                               |   1 +
 testcases/kernel/mem/.gitignore               |   1 +
 .../kernel/mem/hugetlb/hugemmap/hugemmap41.c  | 140 ++++++++++++++++++
 3 files changed, 142 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap41.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index 0896d3c94..14ca64018 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -36,6 +36,7 @@ hugemmap30 hugemmap30
 hugemmap31 hugemmap31
 hugemmap32 hugemmap32
 hugemmap34 hugemmap34
+hugemmap41 hugemmap41
 hugemmap05_1 hugemmap05 -m
 hugemmap05_2 hugemmap05 -s
 hugemmap05_3 hugemmap05 -s -m
diff --git a/testcases/kernel/mem/.gitignore b/testcases/kernel/mem/.gitignore
index b4455de51..4bd7481b0 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -36,6 +36,7 @@
 /hugetlb/hugemmap/hugemmap31
 /hugetlb/hugemmap/hugemmap32
 /hugetlb/hugemmap/hugemmap34
+/hugetlb/hugemmap/hugemmap41
 /hugetlb/hugeshmat/hugeshmat01
 /hugetlb/hugeshmat/hugeshmat02
 /hugetlb/hugeshmat/hugeshmat03
diff --git a/testcases/kernel/mem/hugetlb/hugemmap/hugemmap41.c b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap41.c
new file mode 100644
index 000000000..98b9909be
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap41.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2005-2006 David Gibson & Adam Litke, IBM Corporation.
+ * Copyright (c) 2026 Pavithra <pavrampu@linux.ibm.com>
+ */
+
+/*
+ * Test ptrace write to hugepage memory.
+ *
+ * This test verifies that ptrace POKEDATA and PEEKDATA work correctly
+ * on hugepage-backed memory regions. A child process maps a hugepage,
+ * and the parent uses ptrace to write and read data from the child's
+ * hugepage memory, ensuring that ptrace operations function properly
+ * with hugepage mappings.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/ptrace.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "tst_test.h"
+#include "hugetlb.h"
+
+#define CONST	0xdeadbeefL
+#define MNTPOINT "hugetlbfs/"
+
+static long hpage_size;
+static int fd = -1;
+
+static void child(int hugefd, int pipefd[2])
+{
+	void *p;
+
+	SAFE_CLOSE(pipefd[0]);
+
+	p = SAFE_MMAP(NULL, hpage_size, PROT_READ|PROT_WRITE, MAP_SHARED,
+		      hugefd, 0);
+
+	memset(p, 0, hpage_size);
+
+	tst_res(TINFO, "Child mapped data at %p", p);
+
+	SAFE_WRITE(SAFE_WRITE_ALL, pipefd[1], &p, sizeof(p));
+	SAFE_CLOSE(pipefd[1]);
+
+	pause();
+	/* Child is killed by parent via PTRACE_KILL, so cleanup is not reached */
+}
+
+static void do_poke(pid_t pid, void *p)
+{
+	long err;
+
+	tst_res(TINFO, "Poking at %p...", p);
+	err = ptrace(PTRACE_POKEDATA, pid, p, (void *)CONST);
+	if (err)
+		tst_brk(TFAIL | TERRNO, "ptrace(POKEDATA) failed");
+
+	tst_res(TINFO, "Peeking at %p...", p);
+	errno = 0;
+	err = ptrace(PTRACE_PEEKDATA, pid, p, NULL);
+	if (err == -1 && errno)
+		tst_brk(TFAIL | TERRNO, "ptrace(PEEKDATA) failed");
+
+	if (err != CONST)
+		tst_brk(TFAIL, "Value mismatch: got %lx, expected %lx", err, CONST);
+}
+
+static void run_test(void)
+{
+	int pipefd[2];
+	long err;
+	pid_t cpid;
+	void *p;
+	int status;
+
+	fd = tst_creat_unlinked(MNTPOINT, 0, 0600);
+
+	SAFE_PIPE(pipefd);
+
+	cpid = SAFE_FORK();
+
+	if (cpid == 0) {
+		child(fd, pipefd);
+		exit(0);
+	}
+
+	/* Parent */
+	SAFE_CLOSE(pipefd[1]);
+	SAFE_READ(1, pipefd[0], &p, sizeof(p));
+	SAFE_CLOSE(pipefd[0]);
+
+	tst_res(TINFO, "Parent received address %p", p);
+
+	err = ptrace(PTRACE_ATTACH, cpid, NULL, NULL);
+	if (err)
+		tst_brk(TFAIL | TERRNO, "ptrace(ATTACH) failed");
+
+	TST_PROCESS_STATE_WAIT(cpid, 't', 0);
+
+	do_poke(cpid, p);
+	do_poke(cpid, p + getpagesize());
+
+	SAFE_PTRACE(PTRACE_KILL, cpid, NULL, NULL);
+	SAFE_WAITPID(cpid, &status, 0);
+
+	SAFE_CLOSE(fd);
+	fd = -1;
+
+	tst_res(TPASS, "ptrace write to hugepage succeeded");
+}
+
+static void setup(void)
+{
+	hpage_size = tst_get_hugepage_size();
+}
+
+static void cleanup(void)
+{
+	if (fd != -1)
+		SAFE_CLOSE(fd);
+}
+
+static struct tst_test test = {
+	.tags = (struct tst_tag[]) {
+		{"linux-git", "ebed4bfc8da8"},
+		{}
+	},
+	.needs_root = 1,
+	.mntpoint = MNTPOINT,
+	.needs_hugetlbfs = 1,
+	.hugepages = {4, TST_NEEDS},
+	.forks_child = 1,
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = run_test,
+};
-- 
2.53.0