[LTP] [PATCH v6] hugemmap/hugemmap41: Migrate ptrace-write-hugepage from libhugetlbfs

[Pavithra <pavrampu@linux.ibm.com>]

This test verifies that ptrace POKEDATA and PEEKDATA operations work
correctly on hugepage-backed memory regions. Migrating it to LTP as
libhugetlbfs is not actively maintained.

Signed-off-by: Pavithra <pavrampu@linux.ibm.com>
---
v5 -> v6:
- Use TST_EXP_EQ_LU((unsigned long)TST_RET, CONST) instead of TST_EXP_EQ_LI() to preserve unsigned long semantics and prevent sign-extension failure on 32-bit targets.
link to v5: https://lore.kernel.org/ltp/20260808150238.1526150-1-pavrampu@linux.ibm.com/
---
 runtest/hugetlb                               |   1 +
 testcases/kernel/mem/.gitignore               |   1 +
 .../kernel/mem/hugetlb/hugemmap/hugemmap41.c  | 136 ++++++++++++++++++
 3 files changed, 138 insertions(+)
 create mode 100644 testcases/kernel/mem/hugetlb/hugemmap/hugemmap41.c

diff --git a/runtest/hugetlb b/runtest/hugetlb
index 6b35c1f42..621c9718a 100644
--- a/runtest/hugetlb
+++ b/runtest/hugetlb
@@ -40,6 +40,7 @@ hugemmap35 hugemmap35
 hugemmap36 hugemmap36
 hugemmap37 hugemmap37
 hugemmap38 hugemmap38
+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 e63a6dde7..9e706e1c8 100644
--- a/testcases/kernel/mem/.gitignore
+++ b/testcases/kernel/mem/.gitignore
@@ -40,6 +40,7 @@
 /hugetlb/hugemmap/hugemmap36
 /hugetlb/hugemmap/hugemmap37
 /hugetlb/hugemmap/hugemmap38
+/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..70f29edb8
--- /dev/null
+++ b/testcases/kernel/mem/hugetlb/hugemmap/hugemmap41.c
@@ -0,0 +1,136 @@
+// 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 :manpage:`ptrace(2)` write to hugepage memory.
+ *
+ * A child process maps a hugepage via hugetlbfs, zeroes it, and sends
+ * the mapped address to the parent. The parent attaches with
+ * :manpage:`ptrace(2)`, then uses PTRACE_POKEDATA and PTRACE_PEEKDATA
+ * to write and read back a known value at two different offsets within
+ * the hugepage, verifying that ptrace operates correctly on
+ * hugepage-backed memory regions.
+ *
+ * Requires root to mount hugetlbfs and for :manpage:`ptrace(2)`
+ * PTRACE_ATTACH to work across processes when ptrace_scope is
+ * restrictive.
+ */
+
+#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 SIGKILL, so cleanup is not reached */
+}
+
+static void do_poke(pid_t pid, void *p)
+{
+	tst_res(TINFO, "Poking at %p...", p);
+	SAFE_PTRACE(PTRACE_POKEDATA, pid, p, (void *)CONST);
+
+	tst_res(TINFO, "Peeking at %p...", p);
+	TEST(ptrace(PTRACE_PEEKDATA, pid, p, NULL));
+	if (TST_ERR)
+		tst_brk(TFAIL | TTERRNO, "ptrace(PEEKDATA) failed");
+
+	TST_EXP_EQ_LU((unsigned long)TST_RET, CONST);
+}
+
+static void run_test(void)
+{
+	int pipefd[2];
+	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);
+	}
+
+	SAFE_CLOSE(pipefd[1]);
+	SAFE_READ(1, pipefd[0], &p, sizeof(p));
+	SAFE_CLOSE(pipefd[0]);
+
+	tst_res(TINFO, "Parent received address %p", p);
+
+	SAFE_PTRACE(PTRACE_ATTACH, cpid, NULL, NULL);
+
+	SAFE_WAITPID(cpid, &status, 0);
+	if (!WIFSTOPPED(status))
+		tst_brk(TBROK, "Child %d was not stopped", cpid);
+
+	do_poke(cpid, p);
+	do_poke(cpid, p + getpagesize());
+
+	SAFE_KILL(cpid, SIGKILL);
+	SAFE_WAITPID(cpid, &status, 0);
+
+	SAFE_CLOSE(fd);
+
+	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 = {1, TST_NEEDS},
+	.forks_child = 1,
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = run_test,
+};
-- 
2.55.0


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