From: Andy Shevchenko andriy.shevchenko@linux.intel.com
[ Upstream commit b418d660bb9798d2249ac6a46c844389ef50b6a5 ]
When commit:
69c1f396f25b ("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: 69c1f396f25b ("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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/firmware/efi/earlycon.c | 40 +++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+)
diff --git a/drivers/firmware/efi/earlycon.c b/drivers/firmware/efi/earlycon.c index c9a0efca17b0..d4077db6dc97 100644 --- a/drivers/firmware/efi/earlycon.c +++ b/drivers/firmware/efi/earlycon.c @@ -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);