From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?q?Manuel=20Sch=C3=B6lling?= Date: Sat, 23 Apr 2016 10:07:22 +0000 Subject: [PATCH] console: Add persistent scrollback buffers for all VGA consoles Message-Id: <1461406043-17741-1-git-send-email-manuel.schoelling@gmx.de> List-Id: References: <1401456425-15931-1-git-send-email-manuel.schoelling@gmx.de> In-Reply-To: <1401456425-15931-1-git-send-email-manuel.schoelling@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable To: plagnioj@jcrosoft.com Cc: tomi.valkeinen@ti.com, sfr@canb.auug.org.au, manuel.schoelling@gmx.de, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org 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. Use the escape sequence \e[3J instead for flushing the buffer. Signed-off-by: Manuel Sch=C3=B6lling --- drivers/video/console/Kconfig | 23 +++++- drivers/video/console/vgacon.c | 172 +++++++++++++++++++++++++++----------= ---- 2 files changed, 134 insertions(+), 61 deletions(-) diff --git a/drivers/video/console/Kconfig b/drivers/video/console/Kconfig index 38da6e2..67e52f0 100644 --- a/drivers/video/console/Kconfig +++ b/drivers/video/console/Kconfig @@ -43,9 +43,26 @@ 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 cause security issues. + Use the escape sequence \e[3J instead if this feature is activated. + + 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/vgacon.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 console dr= iver * * Created 28 Sep 1997 by Geert Uytterhoeven * @@ -106,12 +106,12 @@ static unsigned char vga_hardscroll_enabled __read_mo= stly; 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_data *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_CONSOLES]; +#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 reu= se 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, 1024, G= FP_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 count) { 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, int li= nes) #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