[PATCH -tip v2 1/2] x86/ptrace: Use savesegment() in get_segment_reg() instead of inline asm

[Uros Bizjak <ubizjak@gmail.com>]

Replace direct 'movl' instructions for DS, ES, FS, and GS read in
get_segment_reg() with the savesegment() helper. This improves
readability, consistency, and ensures proper handling of
segment registers on x86_64.

No functional change intended.

Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
---
 arch/x86/kernel/ptrace.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 3dcadc13f09a..4cb00aa0645f 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -251,32 +251,31 @@ static u16 get_segment_reg(struct task_struct *task, unsigned long offset)
 	/*
 	 * Returning the value truncates it to 16 bits.
 	 */
-	unsigned int seg;
+	unsigned int retval;
 
 	switch (offset) {
 	case offsetof(struct user_regs_struct, fs):
 		if (task == current) {
-			/* Older gas can't assemble movq %?s,%r?? */
-			asm("movl %%fs,%0" : "=r" (seg));
-			return seg;
+			savesegment(fs, retval);
+			return retval;
 		}
 		return task->thread.fsindex;
 	case offsetof(struct user_regs_struct, gs):
 		if (task == current) {
-			asm("movl %%gs,%0" : "=r" (seg));
-			return seg;
+			savesegment(gs, retval);
+			return retval;
 		}
 		return task->thread.gsindex;
 	case offsetof(struct user_regs_struct, ds):
 		if (task == current) {
-			asm("movl %%ds,%0" : "=r" (seg));
-			return seg;
+			savesegment(ds, retval);
+			return retval;
 		}
 		return task->thread.ds;
 	case offsetof(struct user_regs_struct, es):
 		if (task == current) {
-			asm("movl %%es,%0" : "=r" (seg));
-			return seg;
+			savesegment(es, retval);
+			return retval;
 		}
 		return task->thread.es;
 
-- 
2.53.0