lkml.org 
[lkml]   [2015]   [Dec]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: tboot: non-0 tboot_addr but it is not of type E820_RESERVED
Date

> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-
> owner@vger.kernel.org] On Behalf Of Elliott, Robert (Persistent Memory)
> Sent: Monday, November 23, 2015 7:58 PM
...
> Subject: tboot: non-0 tboot_addr but it is not of type E820_RESERVED
>
> I noticed this being reported on our UEFI-based machines booting
> with grub2 (and not using trusted boot):
> [    0.000000] tboot: non-0 tboot_addr but it is not of type E820_RESERVED
>
> The alleged address is:
>                 0x6b7369642065766f
> which is actually an ASCII string "ksid evo".
>
> That comes from arch/c86/kernel/tboot.c checking if the address is
> in the E820 table.
>
> Is that supposed to be initialized to 0 by the EFI boot stub
> in arch/x86/boot/compressed/eboot.c, and we're just lucky that it
> doesn't appear to be a valid address?
...

Per an hpa suggestion, I compared two versions of grub:

upstream grub (with "linux" in grub.cfg):
tboot_probe boot_params[0] = 0000008000000000 0000000000000070
tboot_probe boot_params[16] = 1000000400032000 0000009100003000
tboot_probe boot_params[32] = 3fa3001000100810 0808080008180000
tboot_probe boot_params[48] = 0000000000000000 0000000000000000
tboot probe boot_params[64] = 0000000000000000 0000000000000000
tboot_probe boot_params[80] = 0000000000000000 0000000000000000
tboot_probe boot_params[96] = 0000000000000000 0000000000000000
tboot_probe boot_params[112] = 0000000000000000 0000000000000000
tboot_probe boot_params[128] = 0000000000000000 0000000000000000
tboot_probe boot_params[144] = 0000000000000000 0000000000000000
tboot_probe boot_params[160] = 0000000000000000 0000000000000000
tboot_probe boot_params[176] = 0000000000000000 0000000000000000
tboot_probe boot_params[192] = 0000000000000000 0000000000000000
...
<no complaint about tboot_addr>

Fedora 22 grub (with "linuxefi" in grub.cfg):
tboot_probe boot_params[0] = 0000000000000000 0000000000000070
tboot_probe boot_params[16] = 0000000400032000 0000009100003000
tboot_probe boot_params[32] = 0000000000100810 0808080008180000
tboot_probe boot_params[48] = 0000010000000100 0000000000000000
tboot_probe boot_params[64] = 557365206120626f 6f74206c6f616465
tboot_probe boot_params[80] = 722e0d0a0a52656d 6f7665206469736b
tboot_probe boot_params[96] = 20616e6420707265 737320616e79206b
tboot_probe boot_params[112] = 657920746f207265 626f6f742e2e2e0d
tboot_probe boot_params[128] = 0a00504500006486 0400000000000000
tboot_probe boot_params[144] = 000001000000a000 06020b020214f017
tboot_probe boot_params[160] = 5c00000000001076 d200104600000002
tboot_probe boot_params[176] = 0000000000000000 0000200000002000
tboot_probe boot_params[192] = 0000000000000000 0000000000000000
...
[ 0.000000] tboot: non-0 tboot_addr 0x6b7369642065766f but it is not of type E820_RESERVED

In both cases, the kernel is compiled with CONFIG_EFI_STUB=y.

tboot_addr is at offset 88. Offset 64 is an ASCII string that says:
"Use a boot loader.

Remove disk and press any key to reboot..."

and is from arch/x86/boot/header.S, which is placing that string
at offset 64 (0x3c + 4) from .bstext (which precedes .bsdata) if
CONFIG_EFI_STUB is true.

#ifdef CONFIG_EFI_STUB
.org 0x3c
#
# Offset to the PE header.
#
.long pe_header
#endif /* CONFIG_EFI_STUB */

.section ".bsdata", "a"
bugger_off_msg:
.ascii "Use a boot loader.\r\n"
.ascii "\n"
.ascii "Remove disk and press any key to reboot...\r\n"
.byte 0




\
 
 \ /
  Last update: 2015-12-02 02:41    [W:0.045 / U:1.104 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site