Re: [PATCH 10/10] acpi: bgrt: parse BGRT to obtain BMP address before it gets clobbered

Ard Biesheuvel
2019-02-05T23:27:51Z

On Tue, 5 Feb 2019 at 19:07, Ghannam, Yazen <Yazen.Ghannam@amd.com> wrote:
>
> > -----Original Message-----
> > From: linux-kernel-owner@vger.kernel.org <linux-kernel-
> > owner@vger.kernel.org> On Behalf Of Ard Biesheuvel
> > Sent: Saturday, February 2, 2019 3:41 AM
> > To: linux-efi@vger.kernel.org; Ingo Molnar <mingo@kernel.org>; Thomas
> > Gleixner <tglx@linutronix.de>
> > Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>; linux-kernel@vger.kernel.org;
> > AKASHI Takahiro <takahiro.akashi@linaro.org>; Alexander Graf
> > <agraf@suse.de>; Bjorn Andersson <bjorn.andersson@linaro.org>; Borislav
> > Petkov <bp@alien8.de>; Heinrich Schuchardt <xypron.glpk@gmx.de>; Jeffrey
> > Hugo <jhugo@codeaurora.org>; Lee Jones <lee.jones@linaro.org>; Leif
> > Lindholm <leif.lindholm@linaro.org>; Linus Torvalds <torvalds@linux-
> > foundation.org>; Peter Jones <pjones@redhat.com>; Peter Zijlstra
> > <peterz@infradead.org>; Sai Praneeth Prakhya
> > <sai.praneeth.prakhya@intel.com>
> > Subject: [PATCH 10/10] acpi: bgrt: parse BGRT to obtain BMP address before it
> > gets clobbered
> >
> > The bitmap left in the framebuffer by the firmware is described by an
> > ACPI table called "BGRT", which describes the size, pixel format and
> > the address of a BMP image in memory. While the BGRT ACPI table is
> > guaranteed to reside in a "ACPI reclaim" memory region, which is
> > never touched by Linux. The BMP image, however, typically resides
> > in EFI Boot Services Memory, which may have been overwritten by the
> > time the BGRT discovery routine runs.
> >
> > So instead, drop the handling from the ACPI init code, and call the
> > BGRT parsing code immediately after going over the EFI configuration
> > table array, at which time no memory has been touched yet except for
> > the .data/.bss regions covered by the static kernel image.
> >
> > Unfortunately, this involves a non-trivial amount of ACPI entry
> > point and root table parsing, but we cannot rely on the normal
> > ACPI infrastructure yet this early in the boot.
> >
> > Also note that we cannot take the 'acpi_disabled' global variable
> > into account, since it may not have assumed the correct value yet
> > (on arm64, the default value is '1' which is overridden to '0' if
> > no DT description has been made available by the firmware)
> >
> > Cc: Peter Jones <pjones@redhat.com>
> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > ---
>
> Hi Ard, et. al.,
>
> I'm trying out tip/master and I find that my system panics early during boot. Reverting
> this patch seems to resolve the issue. Please see the trace below.
>
> I've started debugging, but I'm not familiar with this code. Please let me know if you
> have any ideas or if there's anything you'd like me to try.
>

Hi Yazen,

Thanks for the report, you are the second person to flag this issue,
so in the mean time, I have asked Ingo to drop it from the efi/core
queue, and so the patch will be gone from -next as soon as it
refreshes.

I'll cc you on the updated version of this patch once I get around to
looking into it, which will probably be around early next week.

Thanks,
Ard.

>
> [ 0.000000] Kernel panic - not syncing: ERROR: Failed to allocate 0x0000000000000b40 bytes below 0x0000000000000000.
> [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.0.0-rc5-merged-bases+ #101
> [ 0.000000] Call Trace:
> [ 0.000000] dump_stack+0x63/0x85
> [ 0.000000] panic+0xfe/0x2a4
> [ 0.000000] memblock_alloc_base+0x33/0x35
> [ 0.000000] memblock_phys_alloc+0x10/0x12
> [ 0.000000] efi_memmap_alloc+0x62/0x65
> [ 0.000000] efi_arch_mem_reserve+0x10e/0x194
> [ 0.000000] efi_mem_reserve+0x31/0x36
> [ 0.000000] ? efi_mem_reserve+0x31/0x36
> [ 0.000000] efi_bgrt_init+0x2c6/0x2e0
> [ 0.000000] efi_config_parse_tables+0x1b2/0x1dd
> [ 0.000000] efi_config_init+0x7b/0x9f
> [ 0.000000] ? efi_config_init+0x7b/0x9f
> [ 0.000000] efi_init+0x366/0x465
> [ 0.000000] ? 0xffffffff87800000
> [ 0.000000] setup_arch+0x42f/0xcc9
> [ 0.000000] ? printk+0x52/0x6e
> [ 0.000000] start_kernel+0x6c/0x516
> [ 0.000000] x86_64_start_reservations+0x24/0x26
> [ 0.000000] x86_64_start_kernel+0x74/0x77
> [ 0.000000] secondary_startup_64+0xa4/0xb0
> [ 0.000000] ---[ end Kernel panic - not syncing: ERROR: Failed to allocate 0x0000000000000b40 bytes below 0x0000000000000000. ]---
>