* [PATCH 5.4 066/222] x86/efistub: Disable paging at mixed mode entry
[not found] <20200122092833.339495161@linuxfoundation.org>
@ 2020-01-22 9:27 ` Greg Kroah-Hartman
2020-01-22 9:27 ` [PATCH 5.4 072/222] efi/earlycon: Fix write-combine mapping on x86 Greg Kroah-Hartman
1 sibling, 0 replies; 2+ messages in thread
From: Greg Kroah-Hartman @ 2020-01-22 9:27 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Ard Biesheuvel, Arvind Sankar,
Hans de Goede, Linus Torvalds, Peter Zijlstra, Thomas Gleixner,
linux-efi, Ingo Molnar
From: Ard Biesheuvel <ardb@kernel.org>
commit 4911ee401b7ceff8f38e0ac597cbf503d71e690c upstream.
The EFI mixed mode entry code goes through the ordinary startup_32()
routine before jumping into the kernel's EFI boot code in 64-bit
mode. The 32-bit startup code must be entered with paging disabled,
but this is not documented as a requirement for the EFI handover
protocol, and so we should disable paging explicitly when entering
the kernel from 32-bit EFI firmware.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Cc: <stable@vger.kernel.org>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: https://lkml.kernel.org/r/20191224132909.102540-4-ardb@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/boot/compressed/head_64.S | 5 +++++
1 file changed, 5 insertions(+)
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -244,6 +244,11 @@ ENTRY(efi32_stub_entry)
leal efi32_config(%ebp), %eax
movl %eax, efi_config(%ebp)
+ /* Disable paging */
+ movl %cr0, %eax
+ btrl $X86_CR0_PG_BIT, %eax
+ movl %eax, %cr0
+
jmp startup_32
ENDPROC(efi32_stub_entry)
#endif
^ permalink raw reply [flat|nested] 2+ messages in thread
* [PATCH 5.4 072/222] efi/earlycon: Fix write-combine mapping on x86
[not found] <20200122092833.339495161@linuxfoundation.org>
2020-01-22 9:27 ` [PATCH 5.4 066/222] x86/efistub: Disable paging at mixed mode entry Greg Kroah-Hartman
@ 2020-01-22 9:27 ` Greg Kroah-Hartman
1 sibling, 0 replies; 2+ messages in thread
From: Greg Kroah-Hartman @ 2020-01-22 9:27 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Arvind Sankar, Ard Biesheuvel,
Hans de Goede, Linus Torvalds, Peter Zijlstra, Thomas Gleixner,
linux-efi, Ingo Molnar
From: Arvind Sankar <nivedita@alum.mit.edu>
commit d92b54570d24d017d2630e314b525ed792f5aa6c upstream.
On x86, until PAT is initialized, WC translates into UC-. Since we
calculate and store pgprot_writecombine(PAGE_KERNEL) when earlycon is
initialized, this means we actually use UC- mappings instead of WC
mappings, which makes scrolling very slow.
Instead store a boolean flag to indicate whether we want to use
writeback or write-combine mappings, and recalculate the actual pgprot_t
we need on every mapping. Once PAT is initialized, we will start using
write-combine mappings, which speeds up the scrolling considerably.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Fixes: 69c1f396f25b ("efi/x86: Convert x86 EFI earlyprintk into generic earlycon implementation")
Link: https://lkml.kernel.org/r/20191224132909.102540-2-ardb@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/firmware/efi/earlycon.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
--- a/drivers/firmware/efi/earlycon.c
+++ b/drivers/firmware/efi/earlycon.c
@@ -17,7 +17,7 @@ static const struct console *earlycon_co
static const struct font_desc *font;
static u32 efi_x, efi_y;
static u64 fb_base;
-static pgprot_t fb_prot;
+static bool fb_wb;
static void *efi_fb;
/*
@@ -33,10 +33,8 @@ static int __init efi_earlycon_remap_fb(
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);
+ efi_fb = memremap(fb_base, screen_info.lfb_size,
+ fb_wb ? MEMREMAP_WB : MEMREMAP_WC);
return efi_fb ? 0 : -ENOMEM;
}
@@ -53,9 +51,12 @@ late_initcall(efi_earlycon_unmap_fb);
static __ref void *efi_earlycon_map(unsigned long start, unsigned long len)
{
+ pgprot_t fb_prot;
+
if (efi_fb)
return efi_fb + start;
+ fb_prot = fb_wb ? PAGE_KERNEL : pgprot_writecombine(PAGE_KERNEL);
return early_memremap_prot(fb_base + start, len, pgprot_val(fb_prot));
}
@@ -215,10 +216,7 @@ static int __init efi_earlycon_setup(str
if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
fb_base |= (u64)screen_info.ext_lfb_base << 32;
- if (opt && !strcmp(opt, "ram"))
- fb_prot = PAGE_KERNEL;
- else
- fb_prot = pgprot_writecombine(PAGE_KERNEL);
+ fb_wb = opt && !strcmp(opt, "ram");
si = &screen_info;
xres = si->lfb_width;
^ permalink raw reply [flat|nested] 2+ messages in thread