[PATCH 2/6] selftests/x86/xstate: Pre-allocate ptracee XSAVE buffer

["Chang S. Bae" <chang.seok.bae@intel.com>]

Currently, the ptrace test does not handle XSAVE buffer allocation
failures in the child process. But such a failure can lead to an
unexpected exit path, complicating error handling.

Instead, allocate the buffer in the parent process so that
allocation and error handling are handled before forking the child.

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
---
 tools/testing/selftests/x86/xstate.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/x86/xstate.c b/tools/testing/selftests/x86/xstate.c
index c26dbe33622f..240567e79e96 100644
--- a/tools/testing/selftests/x86/xstate.c
+++ b/tools/testing/selftests/x86/xstate.c
@@ -236,6 +236,8 @@ static void test_context_switch(void)
 	free(finfo);
 }
 
+static struct xsave_buffer *stashed_xbuf;
+
 /*
  * Ptrace test for the ABI format as described in arch/x86/include/asm/user.h
  */
@@ -247,14 +249,8 @@ static void test_context_switch(void)
  */
 static inline void ptracee_touch_xstate(void)
 {
-	struct xsave_buffer *xbuf;
-
-	xbuf = alloc_xbuf();
-
-	load_rand_xstate(&xstate, xbuf);
-	load_init_xstate(&xstate, xbuf);
-
-	free(xbuf);
+	load_rand_xstate(&xstate, stashed_xbuf);
+	load_init_xstate(&xstate, stashed_xbuf);
 }
 
 static bool validate_ptracer_xstate(pid_t target, struct iovec iov,
@@ -335,6 +331,10 @@ static void test_ptrace(void)
 	pid_t child;
 	int status;
 
+	stashed_xbuf = alloc_xbuf();
+	if (!stashed_xbuf)
+		ksft_exit_fail_msg("unable to allocate XSAVE buffer\n");
+
 	child = fork();
 	if (child < 0) {
 		ksft_exit_fail_msg("fork() failed\n");
@@ -358,6 +358,8 @@ static void test_ptrace(void)
 	wait(&status);
 	if (!WIFEXITED(status) || WEXITSTATUS(status))
 		ksft_exit_fail_msg("ptracee exit error\n");
+
+	free(stashed_xbuf);
 }
 
 /*
@@ -391,8 +393,6 @@ static inline void sig_print_fail(char *msg)
 	sig_print(msg);
 }
 
-static struct xsave_buffer *stashed_xbuf;
-
 static void validate_sigfpstate(int sig, siginfo_t *si, void *ctx_void)
 {
 	ucontext_t *ctx = (ucontext_t *)ctx_void;
-- 
2.53.0