x86/uprobes: Keep shadow stack in sync for emulated CALLs

Uprobe CALL emulation updates the normal user stack, but not the CET user
shadow stack. The subsequent RET then sees a stale shadow stack entry and
raises #CP.

Update the relative CALL emulation and XOL CALL fixup paths to keep the
shadow stack in sync.

Fixes: 488af8e ("x86/shstk: Wire in shadow stack interface")
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Link: https://patch.msgid.link/8b5b1c7407b98f31664ad7b6a6faf20d2d4a6cad.1782777969.git.dwindsor@gmail.com

Author: dwindsor

arch/x86/kernel/uprobes.c

@@ -1246,9 +1246,15 @@ static int default_post_xol_op(struct arch_uprobe *auprobe, struct pt_regs *regs
 		long correction = utask->vaddr - utask->xol_vaddr;
 		regs->ip += correction;
 	} else if (auprobe->defparam.fixups & UPROBE_FIX_CALL) {
+		unsigned long retaddr = utask->vaddr + auprobe->defparam.ilen;
+		int err;
+
 		regs->sp += sizeof_long(regs); /* Pop incorrect return address */
-		if (emulate_push_stack(regs, utask->vaddr + auprobe->defparam.ilen))
+		if (emulate_push_stack(regs, retaddr))
 			return -ERESTART;
+		err = shstk_update_last_frame(retaddr);
+		if (err)
+			return err;
 	}
 	/* popf; tell the caller to not touch TF */
 	if (auprobe->defparam.fixups & UPROBE_FIX_SETF)
@@ -1338,6 +1344,10 @@ static bool branch_emulate_op(struct arch_uprobe *auprobe, struct pt_regs *regs)
 		 */
 		if (emulate_push_stack(regs, new_ip))
 			return false;
+		if (shstk_push(new_ip) == -EFAULT) {
+			regs->sp += sizeof_long(regs);
+			return false;
+		}
 	} else if (!check_jmp_cond(auprobe, regs)) {
 		offs = 0;
 	}