From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762851AbcINP1Q (ORCPT ); Wed, 14 Sep 2016 11:27:16 -0400 Received: from mout.gmx.net ([212.227.17.22]:52432 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756348AbcINP1O (ORCPT ); Wed, 14 Sep 2016 11:27:14 -0400 From: =?UTF-8?q?Manuel=20Sch=C3=B6lling?= To: plagnioj@jcrosoft.com, tomi.valkeinen@ti.com Cc: manuel.schoelling@gmx.de, jslaby@suse.cz, gregkh@linuxfoundation.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3] console: Add persistent scrollback buffers for all VGA consoles Date: Wed, 14 Sep 2016 17:27:00 +0200 Message-Id: <1473866820-24040-1-git-send-email-manuel.schoelling@gmx.de> X-Mailer: git-send-email 2.1.4 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Provags-ID: V03:K0:trdUCv+zom8aDF4HgMQtPPO+/zThuHiEDuujwi+MFsLQdNOMEWO ZuzF/ZZNu1pZvrvI+cOrkrcQAKlybL2ZaFcZ/xx9wwrTPSWKrui+sCGKlNV9072j8rVBNiG Na9c9HHDedohHcDwx7tQ0UDTNQHhZWQt8jiZ8DC7bY1k2dxEf/n2rPCvbCA/elJM1LiwKOA Rxzf4WY2y8uUjZoSPyIFQ== X-UI-Out-Filterresults: notjunk:1;V01:K0:8wyiAycdDY4=:/UzHHDku4rfYF/kNIWpU3e nKJHRD1hdc5BQkBeYkhb8MvuqMfHaR4859FAjeB5/zj3QcVevgj0yFYgdFeHGIhOGbglUn1xc yJD6ntuFG16TbFf9fx9CgytBiKHcM82ZtffYhTDCdxtjlOxu6V10OYuxokcmKiwagQsmD9Dw+ dnvGylzxBcIj82Cp4L5vTVKdxpCNDykopgmYUWzp5BudUwh45TRHHITjDfc0prw4l1e9ZwVhK DuKyfMJgtc0ocytHavCne9q2xSEW2e9eUSNxHcwIWP9nRUs99pfyFiYKSgSmVtUMrP+iqVhdK 07mHyTS1vv8RMlKbpSn3Z2BNjk+h7DDafLVFhrmAVvxO6k/CUCbJX6fYKX5yxRzMg2IL//Boo g7cOiJsjR198Fm0NqLBR+dZiynpEBXYFA5QpfKdDWB1WqElPfQUDeexmqsqvupsGbxUQk7/Dq 0m4e6o0OMs+xIoK8b9HNai3fC9QhZW/EGwf2GUC7WyIroc+rWHyzAjLatYYgZvbr+NWAN7WnS l8+odAO5t4ZKhdYMcBwPfN4iZjB6WIjIIArv0GfzE+87rIJcS9o7CdPmgjGJRyHupPcwax4Wz o9Pm+xNUbwO9QfreqajU7i4yT/ShJFZU0nxEzVGhgF/5V8a4IALt1gN2igZXm/nlmgdWSN9qG 5rwta9pV32lDlp2AoK/QRuvMh6WRzN3ib5Icn55LlbehlEVVakIK75ypuUGDi0fkP/j0hs3l1 z5O6PUUMibHiqFATDnjzaI+4bciycLeaPPjXZ+52h14YHOmevJAFjZ/R7JXlIvBW+iCgpZrS8 wiN3Lhr Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: 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. It always annoys me when I switch back to a console and I can just read half of an error backtrace. This should fix issues like these. 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 Schölling --- Changes in v3: - Add config option for this feature - Fallback to old scrollback buffer if kcalloc() fails - Remove ioctl() call again and add documentation about existing escape sequence to flush the scrollback buffer Changes in v2: - Add ioctl() call to flush scrollback buffer - (Patch v2 was not labeled as such, sorry) --- drivers/video/console/Kconfig | 23 +++++- drivers/video/console/vgacon.c | 160 +++++++++++++++++++++++++++-------------- 2 files changed, 128 insertions(+), 55 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. config MDA_CONSOLE depends on !M68K && !PARISC && ISA diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c index 1157661..e70e8fe 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 driver * * Created 28 Sep 1997 by Geert Uytterhoeven * @@ -181,70 +181,125 @@ 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 +313,41 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines) return; } - if (!vgacon_scrollback) + if (!vgacon_scrollback_cur->data) return; - 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 - (c->vc_size_row * + (vgacon_scrollback_cur->cnt - end)); 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 +361,13 @@ static void 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; } @@ -325,6 +380,7 @@ static void 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) { @@ -839,7 +895,7 @@ 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 */ } -- 2.1.4