linux-kernel - Re: [PATCH] x86/PCI: setup data may be in highmem

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Date:	Fri, 24 May 2013 08:38:10 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Matt Fleming <matt@...sole-pimps.org>
Cc:	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	Matt Fleming <matt.fleming@...el.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Seth Forshee <seth.forshee@...onical.com>,
	Jesse Barnes <jbarnes@...tuousgeek.org>, stable@...r.kernel.org
Subject: Re: [PATCH] x86/PCI: setup data may be in highmem

On Wed, May 22, 2013 at 3:43 AM, Matt Fleming <matt@...sole-pimps.org> wrote:
> From: Matt Fleming <matt.fleming@...el.com>
>
> pcibios_add_device() assumes that the physical addresses stored in
> setup_data are accessible via the direct kernel mapping, and that
> calling phys_to_virt() is valid. This isn't guaranteed to be true on x86
> where the direct mapping range is much smaller than on x86-64.
>
> Calling phys_to_virt() on a highmem address results in the following,
>
>  BUG: unable to handle kernel paging request at 39a3c198
>  IP: [<c262be0f>] pcibios_add_device+0x2f/0x90
>  *pde = 00000000
>  Oops: 0000 [#1] SMP
>  Modules linked in:
>  Pid: 1, comm: swapper/0 Tainted: G        W I  3.9.0-rc2+ #280
>  EIP: 0060:[<c262be0f>] EFLAGS: 00010206 CPU: 1
>  EIP is at pcibios_add_device+0x2f/0x90
>  EAX: f6258800 EBX: f6258800 ECX: 79a3c190 EDX: 39a3c190
>  ESI: f62d9814 EDI: f6258864 EBP: f60add38 ESP: f60add2c
>   DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
>  CR0: 8005003b CR2: 39a3c198 CR3: 02b91000 CR4: 001007d0
>  DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
>  DR6: ffff0ff0 DR7: 00000400
>  Process swapper/0 (pid: 1, ti=f60ac000 task=f60b0000 task.ti=f60ac000)
>  Stack:
>   f6258800 f62d9814 f6258864 f60add4c c2370c73 00000000 f62d9800 00000000
>   f60add6c c274640b 0000ea60 f6258800 0f008086 f62d9800 f62d9800 00000000
>   f60add84 c2370d08 00000000 00000008 f62d9800 00000000 f60adda4 c2371904
>  Call Trace:
>   [<c2370c73>] pci_device_add+0xe3/0x130
>   [<c274640b>] pci_scan_single_device+0x8b/0xb0
>   [<c2370d08>] pci_scan_slot+0x48/0x100
>   [<c2371904>] pci_scan_child_bus+0x24/0xc0
>   [<c262a7b0>] pci_acpi_scan_root+0x2c0/0x490
>   [<c23b7203>] acpi_pci_root_add+0x312/0x42f
>   [<c23b29d7>] ? acpi_device_notify_fixed+0x1d/0x1d
>   [<c23b36a8>] acpi_bus_device_attach+0x77/0xdd
>   [<c23cb6be>] acpi_ns_walk_namespace+0xb1/0x163
>   [<c23b3631>] ? acpi_bus_type_and_status+0x82/0x82
>   [<c23cbd4e>] acpi_walk_namespace+0x7e/0xa8
>   [<c23b3631>] ? acpi_bus_type_and_status+0x82/0x82
>   [<c23b46e0>] acpi_bus_scan+0x9a/0xa6
>   [<c23b3631>] ? acpi_bus_type_and_status+0x82/0x82
>   [<c2b17ec9>] acpi_scan_init+0x51/0x144
>   [<c2b252a2>] ? pci_mmcfg_late_init+0x49/0x4b
>   [<c2b17cdc>] acpi_init+0x224/0x28c
>   [<c2001144>] do_one_initcall+0x34/0x170
>   [<c2b17ab8>] ? acpi_sleep_proc_init+0x2e/0x2e
>   [<c2aeeb83>] kernel_init_freeable+0x119/0x1b6
>   [<c2aee4da>] ? do_early_param+0x74/0x74
>   [<c2743f10>] kernel_init+0x10/0xd0
>   [<c2765697>] ret_from_kernel_thread+0x1b/0x28
>   [<c2743f00>] ? rest_init+0x60/0x60
>
> The most reliable way to trigger this crash seems to be booting a 32-bit
> kernel via the EFI boot stub.
>
> The solution is to use early_ioremap() instead of phys_to_virt() to map
> the setup data into the kernel address space.
>
> Tested-by: Jani Nikula <jani.nikula@...el.com>
> Cc: Matthew Garrett <mjg59@...f.ucam.org>
> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: Seth Forshee <seth.forshee@...onical.com>
> Cc: Jesse Barnes <jbarnes@...tuousgeek.org>
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Matt Fleming <matt.fleming@...el.com>
> ---
>  arch/x86/pci/common.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
> index 305c68b..7ae6671 100644
> --- a/arch/x86/pci/common.c
> +++ b/arch/x86/pci/common.c
> @@ -628,7 +628,7 @@ int pcibios_add_device(struct pci_dev *dev)
>
>         pa_data = boot_params.hdr.setup_data;
>         while (pa_data) {
> -               data = phys_to_virt(pa_data);
> +               data = early_ioremap(pa_data, sizeof(*rom));

pcibios_add_device() is mostly called at boot-time, when
early_ioremap() probably works well.  But it's also called when we
hot-add devices later, and it looks like early_ioremap() will then
generate warnings because "system_state != SYSTEM_BOOTING".

>                 if (data->type == SETUP_PCI) {
>                         rom = (struct pci_setup_rom *)data;
> @@ -645,6 +645,7 @@ int pcibios_add_device(struct pci_dev *dev)
>                         }
>                 }
>                 pa_data = data->next;
> +               early_iounmap(data, sizeof(*rom));
>         }
>         return 0;
>  }
> --
> 1.8.1.4
>
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