PATCH 1/2] Subject: vt: selection: allow functions to be called from inside kernel

[Gregory Nowak]

Forwarding to the list as Okash requested.

Greg


----- Forwarded message from Okash Khawaja <okash.khawaja at gmail.com> -----

Date: Fri, 29 Mar 2019 11:31:03 +0000
From: Okash Khawaja <okash.khawaja at gmail.com>
To: Samuel Thibault <samuel.thibault at ens-lyon.org>
Cc: William Hubbs <w.d.hubbs at gmail.com>, Chris Brannon
	<chris at the-brannons.com>, Kirk Reiser <kirk at reisers.ca>, John Covici
	<covici at ccs.covici.com>, Gregory Nowak <greg at gregn.net>, Tom Fowle
	<wa6ivgtf at fastmail.fm>, speakup at linux-speakup.org, Okash Khawaja
	<okash.khawaja at gmail.com>
Subject: [PATCH 1/2] Subject: vt: selection: allow functions to be called from
	inside kernel

This patch breaks set_selection() into two functions so that when
called from kernel, copy_from_user() can be avoided. It also exports
set_selection() and paste_selection().

These changes are used the following patch where speakup's selection
functionality calls into the above functions, thereby doing away with
parallel implementation.

Signed-off-by: Okash Khawaja <okash.khawaja at gmail.com>
---
 drivers/tty/vt/selection.c | 37 ++++++++++++++++++++++++-------------
 include/linux/selection.h  |  3 +--
 2 files changed, 25 insertions(+), 15 deletions(-)

diff --git a/drivers/tty/vt/selection.c b/drivers/tty/vt/selection.c
index 07496c7..a43f9cd9 100644
--- a/drivers/tty/vt/selection.c
+++ b/drivers/tty/vt/selection.c
@@ -80,6 +80,7 @@ void clear_selection(void)
 		sel_start = -1;
 	}
 }
+EXPORT_SYMBOL_GPL(clear_selection);
 
 /*
  * User settable table: what characters are to be considered alphabetic?
@@ -165,33 +166,41 @@ static int store_utf8(u32 c, char *p)
  */
 int set_selection(const struct tiocl_selection __user *sel, struct tty_struct *tty)
 {
+	struct tiocl_selection v;
+
+	if (copy_from_user(&v, sel, sizeof(*sel)))
+		return -EFAULT;
+
+	return do_set_selection(&v, tty);
+}
+
+int do_set_selection(struct tiocl_selection *v, struct tty_struct *tty)
+{
 	struct vc_data *vc = vc_cons[fg_console].d;
 	int new_sel_start, new_sel_end, spc;
-	struct tiocl_selection v;
 	char *bp, *obp;
 	int i, ps, pe, multiplier;
 	u32 c;
 	int mode;
 
 	poke_blanked_console();
-	if (copy_from_user(&v, sel, sizeof(*sel)))
-		return -EFAULT;
 
-	v.xs = min_t(u16, v.xs - 1, vc->vc_cols - 1);
-	v.ys = min_t(u16, v.ys - 1, vc->vc_rows - 1);
-	v.xe = min_t(u16, v.xe - 1, vc->vc_cols - 1);
-	v.ye = min_t(u16, v.ye - 1, vc->vc_rows - 1);
-	ps = v.ys * vc->vc_size_row + (v.xs << 1);
-	pe = v.ye * vc->vc_size_row + (v.xe << 1);
+	v->xs = min_t(u16, v->xs - 1, vc->vc_cols - 1);
+	v->ys = min_t(u16, v->ys - 1, vc->vc_rows - 1);
+	v->xe = min_t(u16, v->xe - 1, vc->vc_cols - 1);
+	v->ye = min_t(u16, v->ye - 1, vc->vc_rows - 1);
+	ps = v->ys * vc->vc_size_row + (v->xs << 1);
+	pe = v->ye * vc->vc_size_row + (v->xe << 1);
 
-	if (v.sel_mode == TIOCL_SELCLEAR) {
+	if (v->sel_mode == TIOCL_SELCLEAR) {
 		/* useful for screendump without selection highlights */
 		clear_selection();
 		return 0;
 	}
 
-	if (mouse_reporting() && (v.sel_mode & TIOCL_SELMOUSEREPORT)) {
-		mouse_report(tty, v.sel_mode & TIOCL_SELBUTTONMASK, v.xs, v.ys);
+	if (mouse_reporting() && (v->sel_mode & TIOCL_SELMOUSEREPORT)) {
+		mouse_report(tty, v->sel_mode & TIOCL_SELBUTTONMASK, v->xs,
+			     v->ys);
 		return 0;
 	}
 
@@ -208,7 +217,7 @@ int set_selection(const struct tiocl_selection __user *sel, struct tty_struct *t
 	else
 		use_unicode = 0;
 
-	switch (v.sel_mode)
+	switch (v->sel_mode)
 	{
 		case TIOCL_SELCHAR:	/* character-by-character selection */
 			new_sel_start = ps;
@@ -322,6 +331,7 @@ int set_selection(const struct tiocl_selection __user *sel, struct tty_struct *t
 	sel_buffer_lth = bp - sel_buffer;
 	return 0;
 }
+EXPORT_SYMBOL_GPL(do_set_selection);
 
 /* Insert the contents of the selection buffer into the
  * queue of the tty associated with the current console.
@@ -367,3 +377,4 @@ int paste_selection(struct tty_struct *tty)
 	tty_ldisc_deref(ld);
 	return 0;
 }
+EXPORT_SYMBOL_GPL(paste_selection);
diff --git a/include/linux/selection.h b/include/linux/selection.h
index a8f5b97..171d77d 100644
--- a/include/linux/selection.h
+++ b/include/linux/selection.h
@@ -11,13 +11,12 @@
 #include <linux/tiocl.h>
 #include <linux/vt_buffer.h>
 
-struct tty_struct;
-
 extern struct vc_data *sel_cons;
 struct tty_struct;
 
 extern void clear_selection(void);
 extern int set_selection(const struct tiocl_selection __user *sel, struct tty_struct *tty);
+extern int do_set_selection(struct tiocl_selection *v, struct tty_struct *tty);
 extern int paste_selection(struct tty_struct *tty);
 extern int sel_loadlut(char __user *p);
 extern int mouse_reporting(void);
-- 
1.8.3.1


----- End forwarded message -----

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