* [PATCH 1/2] console: Add persistent scrollback buffers for all VGA consoles
2016-04-18 19:56 [PATCH 0/2] Persistent scrollback buffers for all VGA consoles Manuel Schölling
@ 2016-04-18 19:56 ` Manuel Schölling
2016-04-18 19:56 ` [PATCH 2/2] console: Add ioctl for flushing the scrollback buffer Manuel Schölling
[not found] ` <1461009418-1795-1-git-send-email-manuel.schoelling-Mmb7MZpHnFY@public.gmane.org>
2 siblings, 0 replies; 6+ messages in thread
From: Manuel Schölling @ 2016-04-18 19:56 UTC (permalink / raw)
To: gregkh
Cc: jslaby, thomas, plagnioj, tomi.valkeinen, jejb, deller,
manuel.schoelling, sfr, linux-kernel, linux-usb, linux-fbdev,
linux-parisc
Add a scrollback buffers for each VGA console. The benefit is that
the scrollback history is not flushed when switching between consoles
but is persistent.
The buffers are allocated on demand when a new console is opened.
This breaks tools like clear_console that rely on flushing the
scrollback history by switching back and forth between consoles
which is why this feature is disabled by default.
Signed-off-by: Manuel Sch=C3=B6lling <manuel.schoelling@gmx.de>
---
drivers/video/console/Kconfig | 22 +++++-
drivers/video/console/vgacon.c | 172 +++++++++++++++++++++++++++------=
--------
2 files changed, 133 insertions(+), 61 deletions(-)
diff --git a/drivers/video/console/Kconfig b/drivers/video/console/Kcon=
fig
index 38da6e2..f101a63 100644
--- a/drivers/video/console/Kconfig
+++ b/drivers/video/console/Kconfig
@@ -43,9 +43,25 @@ config VGACON_SOFT_SCROLLBACK_SIZE
range 1 1024
default "64"
help
- Enter the amount of System RAM to allocate for the scrollback
- buffer. Each 64KB will give you approximately 16 80x25
- screenfuls of scrollback buffer
+ Enter the amount of System RAM to allocate for scrollback
+ buffers of VGA consoles. Each 64KB will give you approximately
+ 16 80x25 screenfuls of scrollback buffer.
+
+config VGACON_SOFT_SCROLLBACK_FOR_EACH_CONSOLE
+ bool "Persistent Scrollback History for each console"
+ depends on VGACON_SOFT_SCROLLBACK
+ default n
+ help
+ Say Y here if for each VGA console a scrollback buffer should
+ be allocated. The scrollback history will persist when switching
+ between consoles. If you say N here, scrollback is only supported
+ for the active VGA console and scrollback history will be flushed
+ when switching between consoles.
+
+ This breaks legacy versions of tools like clear_console which
+ might raise security issues.
+
+ If you use a RAM-constrained system, say N here.
=20
config MDA_CONSOLE
depends on !M68K && !PARISC && ISA
diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vga=
con.c
index 517f565..6c0b9ba 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -1,5 +1,5 @@
/*
- * linux/drivers/video/vgacon.c -- Low level VGA based console driver
+ * linux/drivers/video/console/vgacon.c -- Low level VGA based consol=
e driver
*
* Created 28 Sep 1997 by Geert Uytterhoeven
*
@@ -106,12 +106,12 @@ static unsigned char vga_hardscroll_enabled __rea=
d_mostly;
static unsigned char vga_hardscroll_user_enable __read_mostly =3D 1;
static unsigned char vga_font_is_default =3D 1;
static int vga_vesa_blanked;
-static int vga_palette_blanked;
-static int vga_is_gfx;
-static int vga_512_chars;
-static int vga_video_font_height;
-static int vga_scan_lines __read_mostly;
-static unsigned int vga_rolled_over;
+static int vga_palette_blanked;
+static int vga_is_gfx;
+static int vga_512_chars;
+static int vga_video_font_height;
+static int vga_scan_lines __read_mostly;
+static unsigned int vga_rolled_over;
=20
static int vgacon_text_mode_force;
=20
@@ -182,70 +182,125 @@ static inline void vga_set_mem_top(struct vc_dat=
a *c)
=20
#ifdef CONFIG_VGACON_SOFT_SCROLLBACK
/* software scrollback */
-static void *vgacon_scrollback;
-static int vgacon_scrollback_tail;
-static int vgacon_scrollback_size;
-static int vgacon_scrollback_rows;
-static int vgacon_scrollback_cnt;
-static int vgacon_scrollback_cur;
-static int vgacon_scrollback_save;
-static int vgacon_scrollback_restore;
-
-static void vgacon_scrollback_init(int pitch)
+struct vgacon_scrollback_info {
+ void *data;
+ int tail;
+ int size;
+ int rows;
+ int cnt;
+ int cur;
+ int save;
+ int restore;
+};
+static struct vgacon_scrollback_info *vgacon_scrollback_cur;
+#ifdef CONFIG_VGACON_SOFT_SCROLLBACK_FOR_EACH_CONSOLE
+static struct vgacon_scrollback_info vgacon_scrollbacks[MAX_NR_CONSOLE=
S];
+#else
+static struct vgacon_scrollback_info vgacon_scrollbacks[1];
+#endif
+
+static void vgacon_scrollback_reset(size_t reset_size)
{
- int rows =3D CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024/pitch;
-
- if (vgacon_scrollback) {
- vgacon_scrollback_cnt =3D 0;
- vgacon_scrollback_tail =3D 0;
- vgacon_scrollback_cur =3D 0;
- vgacon_scrollback_rows =3D rows - 1;
- vgacon_scrollback_size =3D rows * pitch;
+ if (vgacon_scrollback_cur->data && reset_size > 0)
+ memset(vgacon_scrollback_cur->data, 0, reset_size);
+
+ vgacon_scrollback_cur->cnt =3D 0;
+ vgacon_scrollback_cur->tail =3D 0;
+ vgacon_scrollback_cur->cur =3D 0;
+}
+
+static void vgacon_scrollback_init(int vc_num)
+{
+ int pitch =3D vga_video_num_columns * 2;
+ size_t size =3D CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024;
+ int rows =3D size/pitch;
+ void *data;
+
+ data =3D kcalloc(CONFIG_VGACON_SOFT_SCROLLBACK_SIZE, 1024, GFP_NOWAIT=
);
+ if (data) {
+ vgacon_scrollbacks[vc_num].data =3D data;
+ vgacon_scrollback_cur =3D &vgacon_scrollbacks[vc_num];
+
+ vgacon_scrollback_cur->rows =3D rows - 1;
+ vgacon_scrollback_cur->size =3D rows * pitch;
+
+ vgacon_scrollback_reset(0);
+ } else {
+ pr_warn("VGAcon: failed to allocate memory for scrollback. Trying to=
reuse previous buffer.\n");
+ /* Leave vgacon_scrollback_cur untouched but reset its content */
+ vgacon_scrollback_reset(size);
}
}
=20
+static void vgacon_switch_scrollback(int vc_num)
+{
+#ifdef CONFIG_VGACON_SOFT_SCROLLBACK_FOR_EACH_CONSOLE
+ if (!vgacon_scrollbacks[vc_num].data)
+ vgacon_scrollback_init(vc_num);
+ else
+ vgacon_scrollback_cur =3D &vgacon_scrollbacks[vc_num];
+#else
+ vc_num =3D 0;
+
+ if (!vgacon_scrollbacks[vc_num].data)
+ vgacon_scrollback_init(vc_num);
+ else {
+ size_t size =3D CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024;
+
+ vgacon_scrollback_reset(size);
+ }
+#endif
+}
+
static void vgacon_scrollback_startup(void)
{
- vgacon_scrollback =3D kcalloc(CONFIG_VGACON_SOFT_SCROLLBACK_SIZE, 102=
4, GFP_NOWAIT);
- vgacon_scrollback_init(vga_video_num_columns * 2);
+ int i;
+
+ for (i =3D 0; i < ARRAY_SIZE(vgacon_scrollbacks); ++i)
+ vgacon_scrollbacks[i].data =3D NULL;
+
+ vgacon_scrollback_cur =3D &vgacon_scrollbacks[0];
+ vgacon_scrollback_init(0);
}
=20
static void vgacon_scrollback_update(struct vc_data *c, int t, int cou=
nt)
{
void *p;
=20
- if (!vgacon_scrollback_size || c->vc_num !=3D fg_console)
+ if (!vgacon_scrollback_cur->data || !vgacon_scrollback_cur->size)
return;
=20
p =3D (void *) (c->vc_origin + t * c->vc_size_row);
=20
while (count--) {
- scr_memcpyw(vgacon_scrollback + vgacon_scrollback_tail,
+ scr_memcpyw(vgacon_scrollback_cur->data +
+ vgacon_scrollback_cur->tail,
p, c->vc_size_row);
- vgacon_scrollback_cnt++;
+
+ vgacon_scrollback_cur->cnt++;
p +=3D c->vc_size_row;
- vgacon_scrollback_tail +=3D c->vc_size_row;
+ vgacon_scrollback_cur->tail +=3D c->vc_size_row;
=20
- if (vgacon_scrollback_tail >=3D vgacon_scrollback_size)
- vgacon_scrollback_tail =3D 0;
+ if (vgacon_scrollback_cur->tail >=3D vgacon_scrollback_cur->size)
+ vgacon_scrollback_cur->tail =3D 0;
=20
- if (vgacon_scrollback_cnt > vgacon_scrollback_rows)
- vgacon_scrollback_cnt =3D vgacon_scrollback_rows;
+ if (vgacon_scrollback_cur->cnt > vgacon_scrollback_cur->rows)
+ vgacon_scrollback_cur->cnt =3D vgacon_scrollback_cur->rows;
=20
- vgacon_scrollback_cur =3D vgacon_scrollback_cnt;
+ vgacon_scrollback_cur->cur =3D vgacon_scrollback_cur->cnt;
}
}
=20
static void vgacon_restore_screen(struct vc_data *c)
{
- vgacon_scrollback_save =3D 0;
+ vgacon_scrollback_cur->save =3D 0;
=20
- if (!vga_is_gfx && !vgacon_scrollback_restore) {
+ if (!vga_is_gfx && !vgacon_scrollback_cur->restore) {
scr_memcpyw((u16 *) c->vc_origin, (u16 *) c->vc_screenbuf,
c->vc_screenbuf_size > vga_vram_size ?
vga_vram_size : c->vc_screenbuf_size);
- vgacon_scrollback_restore =3D 1;
- vgacon_scrollback_cur =3D vgacon_scrollback_cnt;
+ vgacon_scrollback_cur->restore =3D 1;
+ vgacon_scrollback_cur->cur =3D vgacon_scrollback_cur->cnt;
}
}
=20
@@ -259,41 +314,41 @@ static int vgacon_scrolldelta(struct vc_data *c, =
int lines)
return 1;
}
=20
- if (!vgacon_scrollback)
+ if (!vgacon_scrollback_cur->data)
return 1;
=20
- if (!vgacon_scrollback_save) {
+ if (!vgacon_scrollback_cur->save) {
vgacon_cursor(c, CM_ERASE);
vgacon_save_screen(c);
- vgacon_scrollback_save =3D 1;
+ vgacon_scrollback_cur->save =3D 1;
}
=20
- vgacon_scrollback_restore =3D 0;
- start =3D vgacon_scrollback_cur + lines;
+ vgacon_scrollback_cur->restore =3D 0;
+ start =3D vgacon_scrollback_cur->cur + lines;
end =3D start + abs(lines);
=20
if (start < 0)
start =3D 0;
=20
- if (start > vgacon_scrollback_cnt)
- start =3D vgacon_scrollback_cnt;
+ if (start > vgacon_scrollback_cur->cnt)
+ start =3D vgacon_scrollback_cur->cnt;
=20
if (end < 0)
end =3D 0;
=20
- if (end > vgacon_scrollback_cnt)
- end =3D vgacon_scrollback_cnt;
+ if (end > vgacon_scrollback_cur->cnt)
+ end =3D vgacon_scrollback_cur->cnt;
=20
- vgacon_scrollback_cur =3D start;
+ vgacon_scrollback_cur->cur =3D start;
count =3D end - start;
- soff =3D vgacon_scrollback_tail - ((vgacon_scrollback_cnt - end) *
- c->vc_size_row);
+ soff =3D vgacon_scrollback_cur->tail;
+ soff -=3D ((vgacon_scrollback_cur->cnt - end) * c->vc_size_row);
soff -=3D count * c->vc_size_row;
=20
if (soff < 0)
- soff +=3D vgacon_scrollback_size;
+ soff +=3D vgacon_scrollback_cur->size;
=20
- count =3D vgacon_scrollback_cnt - start;
+ count =3D vgacon_scrollback_cur->cnt - start;
=20
if (count > c->vc_rows)
count =3D c->vc_rows;
@@ -307,13 +362,13 @@ static int vgacon_scrolldelta(struct vc_data *c, =
int lines)
=20
count *=3D c->vc_size_row;
/* how much memory to end of buffer left? */
- copysize =3D min(count, vgacon_scrollback_size - soff);
- scr_memcpyw(d, vgacon_scrollback + soff, copysize);
+ copysize =3D min(count, vgacon_scrollback_cur->size - soff);
+ scr_memcpyw(d, vgacon_scrollback_cur->data + soff, copysize);
d +=3D copysize;
count -=3D copysize;
=20
if (count) {
- scr_memcpyw(d, vgacon_scrollback, count);
+ scr_memcpyw(d, vgacon_scrollback_cur->data, count);
d +=3D count;
}
=20
@@ -328,6 +383,7 @@ static int vgacon_scrolldelta(struct vc_data *c, in=
t lines)
#define vgacon_scrollback_startup(...) do { } while (0)
#define vgacon_scrollback_init(...) do { } while (0)
#define vgacon_scrollback_update(...) do { } while (0)
+#define vgacon_switch_scrollback(...) do { } while (0)
=20
static void vgacon_restore_screen(struct vc_data *c)
{
@@ -843,7 +899,7 @@ static int vgacon_switch(struct vc_data *c)
vgacon_doresize(c, c->vc_cols, c->vc_rows);
}
=20
- vgacon_scrollback_init(c->vc_size_row);
+ vgacon_switch_scrollback(c->vc_num);
return 0; /* Redrawing not needed */
}
=20
--=20
2.1.4
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^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 2/2] console: Add ioctl for flushing the scrollback buffer
2016-04-18 19:56 [PATCH 0/2] Persistent scrollback buffers for all VGA consoles Manuel Schölling
2016-04-18 19:56 ` [PATCH 1/2] console: Add persistent " Manuel Schölling
@ 2016-04-18 19:56 ` Manuel Schölling
[not found] ` <1461009418-1795-3-git-send-email-manuel.schoelling-Mmb7MZpHnFY@public.gmane.org>
[not found] ` <1461009418-1795-1-git-send-email-manuel.schoelling-Mmb7MZpHnFY@public.gmane.org>
2 siblings, 1 reply; 6+ messages in thread
From: Manuel Schölling @ 2016-04-18 19:56 UTC (permalink / raw)
To: gregkh
Cc: jslaby, thomas, plagnioj, tomi.valkeinen, jejb, deller,
manuel.schoelling, sfr, linux-kernel, linux-usb, linux-fbdev,
linux-parisc
Tools like clear_console rely on the fact that scrollback history is
flushed when switching back and forth between consoles.
Persistent scrollback buffers for each console breaks this, so this
patch adds a ioctl() callf for flushing the scrollback history.
Signed-off-by: Manuel Sch=C3=B6lling <manuel.schoelling@gmx.de>
---
drivers/tty/vt/vt_ioctl.c | 20 ++++++++++++++++++++
drivers/usb/misc/sisusbvga/sisusb_con.c | 1 +
drivers/video/console/dummycon.c | 1 +
drivers/video/console/mdacon.c | 6 ++++++
drivers/video/console/newport_con.c | 1 +
drivers/video/console/sticon.c | 7 +++++++
drivers/video/console/vgacon.c | 23 +++++++++++++++++++++++
include/linux/console.h | 1 +
include/uapi/linux/vt.h | 1 +
9 files changed, 61 insertions(+)
diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index 97d5a74..18adc23 100644
--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -903,6 +903,26 @@ int vt_ioctl(struct tty_struct *tty,
break;
}
=20
+ /*
+ * flush the specified VT's scollback buffer
+ */
+ case VT_FLUSH_SCROLLBACK: {
+ if (!perm)
+ return -EPERM;
+ if (arg =3D=3D 0 || arg > MAX_NR_CONSOLES)
+ ret =3D -ENXIO;
+ else {
+ struct vc_data *data =3D vc_cons[arg-1].d;
+
+ if (!data)
+ ret =3D -ENXIO;
+ else
+ ret =3D data->vc_sw->con_flush_scrollback(data);
+ }
+
+ break;
+ }
+
case PIO_FONT: {
if (!perm)
return -EPERM;
diff --git a/drivers/usb/misc/sisusbvga/sisusb_con.c b/drivers/usb/misc=
/sisusbvga/sisusb_con.c
index ace3430..cc5fc10 100644
--- a/drivers/usb/misc/sisusbvga/sisusb_con.c
+++ b/drivers/usb/misc/sisusbvga/sisusb_con.c
@@ -1442,6 +1442,7 @@ static const struct consw sisusb_dummy_con =3D {
.con_font_copy =3D SISUSBCONDUMMY,
.con_set_palette =3D SISUSBCONDUMMY,
.con_scrolldelta =3D SISUSBCONDUMMY,
+ .con_flush_scrollback =3D SISUSBCONDUMMY,
};
=20
int
diff --git a/drivers/video/console/dummycon.c b/drivers/video/console/d=
ummycon.c
index 0efc52f..d2888e5 100644
--- a/drivers/video/console/dummycon.c
+++ b/drivers/video/console/dummycon.c
@@ -73,5 +73,6 @@ const struct consw dummy_con =3D {
.con_font_copy =3D DUMMY,
.con_set_palette =3D DUMMY,
.con_scrolldelta =3D DUMMY,
+ .con_flush_scrollback =3D DUMMY,
};
EXPORT_SYMBOL_GPL(dummy_con);
diff --git a/drivers/video/console/mdacon.c b/drivers/video/console/mda=
con.c
index 296e945..10ebcbe 100644
--- a/drivers/video/console/mdacon.c
+++ b/drivers/video/console/mdacon.c
@@ -510,6 +510,11 @@ static int mdacon_scrolldelta(struct vc_data *c, i=
nt lines)
return 0;
}
=20
+static int mdacon_flush_scrollback(struct vc_data *c)
+{
+ return 0;
+}
+
static void mdacon_cursor(struct vc_data *c, int mode)
{
if (mode =3D=3D CM_ERASE) {
@@ -579,6 +584,7 @@ static const struct consw mda_con =3D {
.con_blank =3D mdacon_blank,
.con_set_palette =3D mdacon_set_palette,
.con_scrolldelta =3D mdacon_scrolldelta,
+ .con_flush_scrollback =3D mdacon_flush_scrollback,
.con_build_attr =3D mdacon_build_attr,
.con_invert_region =3D mdacon_invert_region,
};
diff --git a/drivers/video/console/newport_con.c b/drivers/video/consol=
e/newport_con.c
index bb4e962..d04183c 100644
--- a/drivers/video/console/newport_con.c
+++ b/drivers/video/console/newport_con.c
@@ -738,6 +738,7 @@ const struct consw newport_con =3D {
.con_scrolldelta =3D newport_scrolldelta,
.con_set_origin =3D DUMMY,
.con_save_screen =3D DUMMY
+ .con_flush_scrollback =3D DUMMY,
};
=20
static int newport_probe(struct gio_device *dev,
diff --git a/drivers/video/console/sticon.c b/drivers/video/console/sti=
con.c
index 026fd12..46046d6 100644
--- a/drivers/video/console/sticon.c
+++ b/drivers/video/console/sticon.c
@@ -345,6 +345,12 @@ static void sticon_save_screen(struct vc_data *con=
p)
{
}
=20
+static int sticon_flush_scrollback(struct vc_data *c)
+{
+ return 0;
+}
+
+
static const struct consw sti_con =3D {
.owner =3D THIS_MODULE,
.con_startup =3D sticon_startup,
@@ -360,6 +366,7 @@ static const struct consw sti_con =3D {
.con_blank =3D sticon_blank,
.con_set_palette =3D sticon_set_palette,
.con_scrolldelta =3D sticon_scrolldelta,
+ .con_flush_scrollback =3D sticon_flush_scrollback,
.con_set_origin =3D sticon_set_origin,
.con_save_screen =3D sticon_save_screen,=20
.con_build_attr =3D sticon_build_attr,
diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vga=
con.c
index 6c0b9ba..b5ea94f 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -379,12 +379,34 @@ static int vgacon_scrolldelta(struct vc_data *c, =
int lines)
=20
return 1;
}
+
+/* flush the scrollback buffer of a console */
+static int vgacon_flush_scrollback(struct vc_data *c)
+{
+ size_t size =3D CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024;
+ struct vgacon_scrollback_info *vgacon_scrollback_prev;
+
+ vgacon_scrollback_prev =3D vgacon_scrollback_cur;
+ vgacon_scrollback_cur =3D &vgacon_scrollbacks[c->vc_num];
+
+ if (vgacon_scrollback_cur !=3D NULL)
+ vgacon_scrollback_reset(size);
+
+ vgacon_scrollback_cur =3D vgacon_scrollback_prev;
+
+ return 0;
+}
#else
#define vgacon_scrollback_startup(...) do { } while (0)
#define vgacon_scrollback_init(...) do { } while (0)
#define vgacon_scrollback_update(...) do { } while (0)
#define vgacon_switch_scrollback(...) do { } while (0)
=20
+static int vgacon_flush_scrollback(struct vc_data *c)
+{
+ return 0;
+}
+
static void vgacon_restore_screen(struct vc_data *c)
{
if (c->vc_origin !=3D c->vc_visible_origin)
@@ -1492,6 +1514,7 @@ const struct consw vga_con =3D {
.con_resize =3D vgacon_resize,
.con_set_palette =3D vgacon_set_palette,
.con_scrolldelta =3D vgacon_scrolldelta,
+ .con_flush_scrollback =3D vgacon_flush_scrollback,
.con_set_origin =3D vgacon_set_origin,
.con_save_screen =3D vgacon_save_screen,
.con_build_attr =3D vgacon_build_attr,
diff --git a/include/linux/console.h b/include/linux/console.h
index e49cc1e..946ff20 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -49,6 +49,7 @@ struct consw {
unsigned int);
int (*con_set_palette)(struct vc_data *, unsigned char *);
int (*con_scrolldelta)(struct vc_data *, int);
+ int (*con_flush_scrollback)(struct vc_data *);
int (*con_set_origin)(struct vc_data *);
void (*con_save_screen)(struct vc_data *);
u8 (*con_build_attr)(struct vc_data *, u8, u8, u8, u8, u8, u8);
diff --git a/include/uapi/linux/vt.h b/include/uapi/linux/vt.h
index 978578b..b799541 100644
--- a/include/uapi/linux/vt.h
+++ b/include/uapi/linux/vt.h
@@ -83,5 +83,6 @@ struct vt_setactivate {
};
=20
#define VT_SETACTIVATE 0x560F /* Activate and set the mode of a consol=
e */
+#define VT_FLUSH_SCROLLBACK 0x5610 /* Flush the scrollback buffer */
=20
#endif /* _UAPI_LINUX_VT_H */
--=20
2.1.4
^ permalink raw reply related [flat|nested] 6+ messages in thread