On Wed, Mar 04, 2020 at 05:59:17PM +0100, Ard Biesheuvel wrote:
> Commit 3a6b6c6fb23667fa ("efi: Make EFI_MEMORY_ATTRIBUTES_TABLE
> initialization common across all architectures") moved the call to
> efi_memattr_init() from ARM specific to generic EFI init code, in
> order to be able to apply the restricted permissions described in
> that table on x86 as well.
>
> We never enabled this feature fully on i386, and so mapping and
> reserving this table is pointless. However, due to the early call to
> memblock_reserve(), the memory bookkeeping gets confused to the point
> where it produces the splat below when we try to map the memory later
> on:
>
> ------------[ cut here ]------------
> ioremap on RAM at 0x3f251000 - 0x3fa1afff
> WARNING: CPU: 0 PID: 0 at arch/x86/mm/ioremap.c:166 __ioremap_caller ...
> Modules linked in:
> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.20.0 #48
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015
> EIP: __ioremap_caller.constprop.0+0x249/0x260
> Code: 90 0f b7 05 4e 38 40 de 09 45 e0 e9 09 ff ff ff 90 8d 45 ec c6 05 ...
> EAX: 00000029 EBX: 00000000 ECX: de59c228 EDX: 00000001
> ESI: 3f250fff EDI: 00000000 EBP: de3edf20 ESP: de3edee0
> DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 EFLAGS: 00200296
> CR0: 80050033 CR2: ffd17000 CR3: 1e58c000 CR4: 00040690
> Call Trace:
> ioremap_cache+0xd/0x10
> ? old_map_region+0x72/0x9d
> old_map_region+0x72/0x9d
> efi_map_region+0x8/0xa
> efi_enter_virtual_mode+0x260/0x43b
> start_kernel+0x329/0x3aa
> i386_start_kernel+0xa7/0xab
> startup_32_smp+0x164/0x168
> ---[ end trace e15ccf6b9f356833 ]---
>
> Let's work around this by disregarding the memory attributes table
> altogether on i386, which does not result in a loss of functionality
> or protection, given that we never consumed the contents.
>
> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Thanks!
Tested-by: Arvind Sankar <nivedita@xxxxxxxxxxxx>
> ---
> drivers/firmware/efi/efi.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index d1746a579c99..34bca039fca0 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -543,7 +543,7 @@ int __init efi_config_parse_tables(const efi_config_table_t *config_tables,
> }
> }
>
> - if (efi_enabled(EFI_MEMMAP))
> + if (!IS_ENABLED(CONFIG_X86_32) && efi_enabled(EFI_MEMMAP))
> efi_memattr_init();
>
> efi_tpm_eventlog_init();
> --
> 2.17.1
>
