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efi/earlycon: Remap entire framebuffer after page initialization

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When commit:

  69c1f396f2 ("efi/x86: Convert x86 EFI earlyprintk into generic earlycon implementation")

moved the x86 specific EFI earlyprintk implementation to a shared location,
it also tweaked the behaviour. In particular, it dropped a trick with full
framebuffer remapping after page initialization, leading to two regressions:

  1) very slow scrolling after page initialization,
  2) kernel hang when the 'keep_bootcon' command line argument is passed.

Putting the tweak back fixes #2 and mitigates #1, i.e., it limits the slow
behavior to the early boot stages, presumably due to eliminating heavy
map()/unmap() operations per each pixel line on the screen.

 [ ardb: ensure efifb is unmapped again unless keep_bootcon is in effect. ]
 [ mingo: speling fixes. ]

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Cc: linux-efi@vger.kernel.org
Fixes: 69c1f396f2 ("efi/x86: Convert x86 EFI earlyprintk into generic earlycon implementation")
Link: https://lkml.kernel.org/r/20191206165542.31469-7-ardb@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Shevchenko 2019-12-06 16:55:42 +00:00 committed by Ingo Molnar
parent 9fa76ca7b8
commit b418d660bb
1 changed files with 40 additions and 0 deletions
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40
drivers/firmware/efi/earlycon.c
View File

@ -13,18 +13,57 @@
#include <asm/early_ioremap.h>
static const struct console *earlycon_console __initdata;
static const struct font_desc *font;
static u32 efi_x, efi_y;
static u64 fb_base;
static pgprot_t fb_prot;
static void *efi_fb;
/*
* EFI earlycon needs to use early_memremap() to map the framebuffer.
* But early_memremap() is not usable for 'earlycon=efifb keep_bootcon',
* memremap() should be used instead. memremap() will be available after
* paging_init() which is earlier than initcall callbacks. Thus adding this
* early initcall function early_efi_map_fb() to map the whole EFI framebuffer.
*/
static int __init efi_earlycon_remap_fb(void)
{
/* bail if there is no bootconsole or it has been disabled already */
if (!earlycon_console || !(earlycon_console->flags & CON_ENABLED))
return 0;
if (pgprot_val(fb_prot) == pgprot_val(PAGE_KERNEL))
efi_fb = memremap(fb_base, screen_info.lfb_size, MEMREMAP_WB);
else
efi_fb = memremap(fb_base, screen_info.lfb_size, MEMREMAP_WC);
return efi_fb ? 0 : -ENOMEM;
}
early_initcall(efi_earlycon_remap_fb);
static int __init efi_earlycon_unmap_fb(void)
{
/* unmap the bootconsole fb unless keep_bootcon has left it enabled */
if (efi_fb && !(earlycon_console->flags & CON_ENABLED))
memunmap(efi_fb);
return 0;
}
late_initcall(efi_earlycon_unmap_fb);
static __ref void *efi_earlycon_map(unsigned long start, unsigned long len)
{
if (efi_fb)
return efi_fb + start;
return early_memremap_prot(fb_base + start, len, pgprot_val(fb_prot));
}
static __ref void efi_earlycon_unmap(void *addr, unsigned long len)
{
if (efi_fb)
return;
early_memunmap(addr, len);
}
@ -201,6 +240,7 @@ static int __init efi_earlycon_setup(struct earlycon_device *device,
efi_earlycon_scroll_up();
device->con->write = efi_earlycon_write;
earlycon_console = device->con;
return 0;
}
EARLYCON_DECLARE(efifb, efi_earlycon_setup);