| Message ID | nycvar.YSQ.7.76.1901101131090.6027@knanqh.ubzr |
|---|---|
| State | Accepted |
| Commit | bfd8d8fe98b8792f362cd210a7873969f8d2fc04 |
| Headers | show |
| Series | vgacon: unconfuse vc_origin when using soft scrollback | expand |
On Thu, 10 Jan 2019, Nicolas Pitre wrote: > When CONFIG_VGACON_SOFT_SCROLLBACK is selected, the VGA display memory > index and vc_visible_origin don't change when scrollback is activated. > The actual screen content is saved away and the scrollbackdata is copied > over it. However the vt code, and /dev/vcs devices in particular, still > expect vc_origin to always point at the actual screen content not the > displayed scrollback content. > > So adjust vc_origin to point at the saved screen content when scrollback > is active and set it back to vc_visible_origin when restoring the screen. > > This fixes /dev/vcsa<n> that return scrollback content when they > shouldn't (onli /dev/vcsa without a number should), and also fixes > /dev/vcsu that should return scrollback content when scrollback is > active but currently doesn't. The vt code is just a frigging mess of integer variables and pointer variables referring to the same thing. It is therefore littered with casts all over the place. And of course I missed one in this patch. Here's a revised patch to quiet a warning: ----- >8 Subject: [PATCH] vgacon: unconfuse vc_origin when using soft scrollback When CONFIG_VGACON_SOFT_SCROLLBACK is selected, the VGA display memory index and vc_visible_origin don't change when scrollback is activated. The actual screen content is saved away and the scrollbackdata is copied over it. However the vt code, and /dev/vcs devices in particular, still expect vc_origin to always point at the actual screen content not the displayed scrollback content. So adjust vc_origin to point at the saved screen content when scrollback is active and set it back to vc_visible_origin when restoring the screen. This fixes /dev/vcsa<n> that return scrollback content when they shouldn't (onli /dev/vcsa without a number should), and also fixes /dev/vcsu that should return scrollback content when scrollback is active but currently doesn't. An unnecessary call to vga_set_mem_top() is also removed. Signed-off-by: Nicolas Pitre <nico@linaro.org> Cc: stable@vger.kernel.org # v4.19+ --- I tagged it for stable starting with v4.19 as this is the kernel that introduced /dev/vcsu* which is directly affected. Users of earlier kernels most likely won't care. diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c index 09731b2f68..a3353a9970 100644 --- a/drivers/video/console/vgacon.c +++ b/drivers/video/console/vgacon.c @@ -271,6 +271,7 @@ static void vgacon_scrollback_update(struct vc_data *c, int t, int count) static void vgacon_restore_screen(struct vc_data *c) { + c->vc_origin = c->vc_visible_origin; vgacon_scrollback_cur->save = 0; if (!vga_is_gfx && !vgacon_scrollback_cur->restore) { @@ -287,8 +288,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines) int start, end, count, soff; if (!lines) { - c->vc_visible_origin = c->vc_origin; - vga_set_mem_top(c); + vgacon_restore_screen(c); return; } @@ -298,6 +298,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines) if (!vgacon_scrollback_cur->save) { vgacon_cursor(c, CM_ERASE); vgacon_save_screen(c); + c->vc_origin = c->vc_screenbuf; vgacon_scrollback_cur->save = 1; } @@ -335,7 +336,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines) int copysize; int diff = c->vc_rows - count; - void *d = (void *) c->vc_origin; + void *d = (void *) c->vc_visible_origin; void *s = (void *) c->vc_screenbuf; count *= c->vc_size_row;
On Thu, 10 Jan 2019, Nicolas Pitre wrote: > The vt code is just a frigging mess of integer variables and pointer > variables referring to the same thing. It is therefore littered with > casts all over the place. And of course I missed one in this patch. > > Here's a revised patch to quiet a warning: And of course I forgot to commit and reposted the same patch with the missing cast. So here it is again: ----- >8 Subject: [PATCH] vgacon: unconfuse vc_origin when using soft scrollback When CONFIG_VGACON_SOFT_SCROLLBACK is selected, the VGA display memory index and vc_visible_origin don't change when scrollback is activated. The actual screen content is saved away and the scrollbackdata is copied over it. However the vt code, and /dev/vcs devices in particular, still expect vc_origin to always point at the actual screen content not the displayed scrollback content. So adjust vc_origin to point at the saved screen content when scrollback is active and set it back to vc_visible_origin when restoring the screen. This fixes /dev/vcsa<n> that return scrollback content when they shouldn't (onli /dev/vcsa without a number should), and also fixes /dev/vcsu that should return scrollback content when scrollback is active but currently doesn't. An unnecessary call to vga_set_mem_top() is also removed. Signed-off-by: Nicolas Pitre <nico@linaro.org> Cc: stable@vger.kernel.org # v4.19+ --- I tagged it for stable starting with v4.19 as this is the kernel that introduced /dev/vcsu* which is directly affected. Users of earlier kernels most likely won't care. diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c index 09731b2f68..c6b3bdbbdb 100644 --- a/drivers/video/console/vgacon.c +++ b/drivers/video/console/vgacon.c @@ -271,6 +271,7 @@ static void vgacon_scrollback_update(struct vc_data *c, int t, int count) static void vgacon_restore_screen(struct vc_data *c) { + c->vc_origin = c->vc_visible_origin; vgacon_scrollback_cur->save = 0; if (!vga_is_gfx && !vgacon_scrollback_cur->restore) { @@ -287,8 +288,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines) int start, end, count, soff; if (!lines) { - c->vc_visible_origin = c->vc_origin; - vga_set_mem_top(c); + vgacon_restore_screen(c); return; } @@ -298,6 +298,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines) if (!vgacon_scrollback_cur->save) { vgacon_cursor(c, CM_ERASE); vgacon_save_screen(c); + c->vc_origin = (unsigned long)c->vc_screenbuf; vgacon_scrollback_cur->save = 1; } @@ -335,7 +336,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines) int copysize; int diff = c->vc_rows - count; - void *d = (void *) c->vc_origin; + void *d = (void *) c->vc_visible_origin; void *s = (void *) c->vc_screenbuf; count *= c->vc_size_row;
diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c index 09731b2f68..a3353a9970 100644 --- a/drivers/video/console/vgacon.c +++ b/drivers/video/console/vgacon.c @@ -271,6 +271,7 @@ static void vgacon_scrollback_update(struct vc_data *c, int t, int count) static void vgacon_restore_screen(struct vc_data *c) { + c->vc_origin = c->vc_visible_origin; vgacon_scrollback_cur->save = 0; if (!vga_is_gfx && !vgacon_scrollback_cur->restore) { @@ -287,8 +288,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines) int start, end, count, soff; if (!lines) { - c->vc_visible_origin = c->vc_origin; - vga_set_mem_top(c); + vgacon_restore_screen(c); return; } @@ -298,6 +298,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines) if (!vgacon_scrollback_cur->save) { vgacon_cursor(c, CM_ERASE); vgacon_save_screen(c); + c->vc_origin = c->vc_screenbuf; vgacon_scrollback_cur->save = 1; } @@ -335,7 +336,7 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines) int copysize; int diff = c->vc_rows - count; - void *d = (void *) c->vc_origin; + void *d = (void *) c->vc_visible_origin; void *s = (void *) c->vc_screenbuf; count *= c->vc_size_row;
When CONFIG_VGACON_SOFT_SCROLLBACK is selected, the VGA display memory index and vc_visible_origin don't change when scrollback is activated. The actual screen content is saved away and the scrollbackdata is copied over it. However the vt code, and /dev/vcs devices in particular, still expect vc_origin to always point at the actual screen content not the displayed scrollback content. So adjust vc_origin to point at the saved screen content when scrollback is active and set it back to vc_visible_origin when restoring the screen. This fixes /dev/vcsa<n> that return scrollback content when they shouldn't (onli /dev/vcsa without a number should), and also fixes /dev/vcsu that should return scrollback content when scrollback is active but currently doesn't. An unnecessary call to vga_set_mem_top() is also removed. Signed-off-by: Nicolas Pitre <nico@linaro.org> Cc: stable@vger.kernel.org # v4.19+ --- I tagged it for stable starting with v4.19 as this is the kernel that introduced /dev/vcsu* which is directly affected. Users of earlier kernels most likely won't care.