| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <1402788275.4561.6.camel@schoellingm.dzne.de>
Date: Sun, 15 Jun 2014 01:24:35 +0200
From: Manuel Schoelling <manuel.schoelling@....de>
To: plagnioj@...osoft.com
Cc: tomi.valkeinen@...com, geert@...ux-m68k.org, broonie@...aro.org,
rdunlap@...radead.org, hans.verkuil@...co.com,
dh.herrmann@...il.com, tiwai@...e.de, gregkh@...uxfoundation.org,
airlied@...hat.com, mtosatti@...hat.com,
linux-fbdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND v2] console: Add persistent scrollback buffers
for all VGA consoles
This version reuses an "old" scrollback buffer of the previous console
if memory allocation fails.
However, the issue of clearing the console using the 'clear_console'
commnad [1,2] is still unsolved. I'd prefer implementing it using a
ioctl() call but it's open for discussion ;)
[1] https://sources.debian.net/src/bash/4.2%
2Bdfsg-0.1/debian/clear_console.c
[2] http://manpages.debian.org/cgi-bin/man.cgi?query=clear_console
On So, 2014-06-15 at 01:15 +0200, Manuel Schölling wrote:
> 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.
>
> Signed-off-by: Manuel Schölling <manuel.schoelling@....de>
> ---
> drivers/video/console/Kconfig | 19 ++++-
> drivers/video/console/vgacon.c | 159 +++++++++++++++++++++++++++-------------
> 2 files changed, 124 insertions(+), 54 deletions(-)
>
> diff --git a/drivers/video/console/Kconfig b/drivers/video/console/Kconfig
> index fe1cd01..05fdc2c 100644
> --- a/drivers/video/console/Kconfig
> +++ b/drivers/video/console/Kconfig
> @@ -43,9 +43,22 @@ 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 y
> + 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.
> +
> + If you use a RAM-constrained system, say N here.
>
> config MDA_CONSOLE
> depends on !M68K && !PARISC && ISA
> diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
> index 9d8feac..652131d 100644
> --- a/drivers/video/console/vgacon.c
> +++ b/drivers/video/console/vgacon.c
> @@ -181,70 +181,126 @@ static inline void vga_set_mem_top(struct vc_data *c)
>
> #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_CONSOLES];
> +#else
> +static struct vgacon_scrollback_info vgacon_scrollbacks[1];
> +#endif
> +
> +static void vgacon_scrollback_reset(size_t reset_size)
> {
> - int rows = CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024/pitch;
> -
> - if (vgacon_scrollback) {
> - vgacon_scrollback_cnt = 0;
> - vgacon_scrollback_tail = 0;
> - vgacon_scrollback_cur = 0;
> - vgacon_scrollback_rows = rows - 1;
> - vgacon_scrollback_size = rows * pitch;
> + if (vgacon_scrollback_cur->data && reset_size > 0)
> + memset(vgacon_scrollback_cur->data, 0, reset_size);
> +
> + vgacon_scrollback_cur->cnt = 0;
> + vgacon_scrollback_cur->tail = 0;
> + vgacon_scrollback_cur->cur = 0;
> +}
> +
> +static void vgacon_scrollback_init(int vc_num)
> +{
> + int pitch = vga_video_num_columns * 2;
> + size_t size = CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024;
> + int rows = size/pitch;
> + void *data;
> +
> + data = kcalloc(CONFIG_VGACON_SOFT_SCROLLBACK_SIZE, 1024, GFP_NOWAIT);
> + if (data) {
> + vgacon_scrollbacks[vc_num].data = data;
> + vgacon_scrollback_cur = &vgacon_scrollbacks[vc_num];
> +
> + vgacon_scrollback_cur->rows = rows - 1;
> + vgacon_scrollback_cur->size = 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);
> }
> }
>
> +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 = &vgacon_scrollbacks[vc_num];
> +#else
> + vc_num = 0;
> +
> + if (!vgacon_scrollbacks[vc_num].data)
> + vgacon_scrollback_init(vc_num);
> + else {
> + size_t size = CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024;
> +
> + vgacon_scrollback_reset(size);
> + }
> +#endif
> +}
> +
> static void vgacon_scrollback_startup(void)
> {
> - vgacon_scrollback = kcalloc(CONFIG_VGACON_SOFT_SCROLLBACK_SIZE, 1024, GFP_NOWAIT);
> - vgacon_scrollback_init(vga_video_num_columns * 2);
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(vgacon_scrollbacks); ++i)
> + vgacon_scrollbacks[i].data = NULL;
> +
> + vgacon_scrollback_cur = &vgacon_scrollbacks[0];
> + vgacon_scrollback_init(0);
> }
>
> static void vgacon_scrollback_update(struct vc_data *c, int t, int count)
> {
> void *p;
>
> - if (!vgacon_scrollback_size || c->vc_num != fg_console)
> + if (!vgacon_scrollback_cur->data || !vgacon_scrollback_cur->size)
> return;
>
> p = (void *) (c->vc_origin + t * c->vc_size_row);
>
> 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 += c->vc_size_row;
> - vgacon_scrollback_tail += c->vc_size_row;
> + vgacon_scrollback_cur->tail += c->vc_size_row;
>
> - if (vgacon_scrollback_tail >= vgacon_scrollback_size)
> - vgacon_scrollback_tail = 0;
> + if (vgacon_scrollback_cur->tail >= vgacon_scrollback_cur->size)
> + vgacon_scrollback_cur->tail = 0;
>
> - if (vgacon_scrollback_cnt > vgacon_scrollback_rows)
> - vgacon_scrollback_cnt = vgacon_scrollback_rows;
> + if (vgacon_scrollback_cur->cnt > vgacon_scrollback_cur->rows)
> + vgacon_scrollback_cur->cnt = vgacon_scrollback_cur->rows;
>
> - vgacon_scrollback_cur = vgacon_scrollback_cnt;
> + vgacon_scrollback_cur->cur = vgacon_scrollback_cur->cnt;
> }
> }
>
> static void vgacon_restore_screen(struct vc_data *c)
> {
> - vgacon_scrollback_save = 0;
> + vgacon_scrollback_cur->save = 0;
>
> - 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 = 1;
> - vgacon_scrollback_cur = vgacon_scrollback_cnt;
> + vgacon_scrollback_cur->restore = 1;
> + vgacon_scrollback_cur->cur = vgacon_scrollback_cur->cnt;
> }
> }
>
> @@ -258,41 +314,41 @@ static int vgacon_scrolldelta(struct vc_data *c, int lines)
> return 1;
> }
>
> - if (!vgacon_scrollback)
> + if (!vgacon_scrollback_cur->data)
> return 1;
>
> - if (!vgacon_scrollback_save) {
> + if (!vgacon_scrollback_cur->save) {
> vgacon_cursor(c, CM_ERASE);
> vgacon_save_screen(c);
> - vgacon_scrollback_save = 1;
> + vgacon_scrollback_cur->save = 1;
> }
>
> - vgacon_scrollback_restore = 0;
> - start = vgacon_scrollback_cur + lines;
> + vgacon_scrollback_cur->restore = 0;
> + start = vgacon_scrollback_cur->cur + lines;
> end = start + abs(lines);
>
> if (start < 0)
> start = 0;
>
> - if (start > vgacon_scrollback_cnt)
> - start = vgacon_scrollback_cnt;
> + if (start > vgacon_scrollback_cur->cnt)
> + start = vgacon_scrollback_cur->cnt;
>
> if (end < 0)
> end = 0;
>
> - if (end > vgacon_scrollback_cnt)
> - end = vgacon_scrollback_cnt;
> + if (end > vgacon_scrollback_cur->cnt)
> + end = vgacon_scrollback_cur->cnt;
>
> - vgacon_scrollback_cur = start;
> + vgacon_scrollback_cur->cur = start;
> count = end - start;
> - soff = vgacon_scrollback_tail - ((vgacon_scrollback_cnt - end) *
> - c->vc_size_row);
> + soff = vgacon_scrollback_cur->tail -
> + ((vgacon_scrollback_cur->cnt - end) * c->vc_size_row);
> soff -= count * c->vc_size_row;
>
> if (soff < 0)
> - soff += vgacon_scrollback_size;
> + soff += vgacon_scrollback_cur->size;
>
> - count = vgacon_scrollback_cnt - start;
> + count = vgacon_scrollback_cur->cnt - start;
>
> if (count > c->vc_rows)
> count = c->vc_rows;
> @@ -306,13 +362,13 @@ static int vgacon_scrolldelta(struct vc_data *c, int lines)
>
> count *= c->vc_size_row;
> /* how much memory to end of buffer left? */
> - copysize = min(count, vgacon_scrollback_size - soff);
> - scr_memcpyw(d, vgacon_scrollback + soff, copysize);
> + copysize = min(count, vgacon_scrollback_cur->size - soff);
> + scr_memcpyw(d, vgacon_scrollback_cur->data + soff, copysize);
> d += copysize;
> count -= copysize;
>
> if (count) {
> - scr_memcpyw(d, vgacon_scrollback, count);
> + scr_memcpyw(d, vgacon_scrollback_cur->data, count);
> d += count;
> }
>
> @@ -327,6 +383,7 @@ static int vgacon_scrolldelta(struct vc_data *c, int 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)
>
> static void vgacon_restore_screen(struct vc_data *c)
> {
> @@ -842,7 +899,7 @@ static int vgacon_switch(struct vc_data *c)
> vgacon_doresize(c, c->vc_cols, c->vc_rows);
> }
>
> - vgacon_scrollback_init(c->vc_size_row);
> + vgacon_switch_scrollback(c->vc_num);
> return 0; /* Redrawing not needed */
> }
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists