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x86/boot: Remove KEEP_SEGMENTS support

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Commit a24e785111a3 ("i386: paravirt boot sequence") added this flag for
use by paravirtualized environments such as Xen. However, Xen never made
use of this flag [1], and it was only ever used by lguest [2].

Commit ecda85e70277 ("x86/lguest: Remove lguest support") removed
lguest, so KEEP_SEGMENTS has lost its last user.

[1] https://lore.kernel.org/lkml/4D4B097C.5050405@goop.org
[2] https://www.mail-archive.com/lguest@lists.ozlabs.org/msg00469.html

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Link: https://lore.kernel.org/r/20200202171353.3736319-2-nivedita@alum.mit.edu
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Arvind Sankar 2020-02-02 12:13:47 -05:00 committed by Ard Biesheuvel
parent 9f9223778e
commit 67a6af7ad1
4 changed files with 2 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
Documentation/x86/boot.rst
View File

@ -490,15 +490,11 @@ Protocol: 2.00+
kernel) to not write early messages that require kernel) to not write early messages that require
accessing the display hardware directly. accessing the display hardware directly.
Bit 6 (write): KEEP_SEGMENTS Bit 6 (obsolete): KEEP_SEGMENTS
Protocol: 2.07+ Protocol: 2.07+
- If 0, reload the segment registers in the 32bit entry point. - This flag is obsolete.
- If 1, do not reload the segment registers in the 32bit entry point.
Assume that %cs %ds %ss %es are all set to flat segments with
a base of 0 (or the equivalent for their environment).
Bit 7 (write): CAN_USE_HEAP Bit 7 (write): CAN_USE_HEAP

8
arch/x86/boot/compressed/head_32.S
View File

@ -63,13 +63,6 @@
__HEAD __HEAD
SYM_FUNC_START(startup_32) SYM_FUNC_START(startup_32)
cld cld
/*
* Test KEEP_SEGMENTS flag to see if the bootloader is asking
* us to not reload segments
*/
testb $KEEP_SEGMENTS, BP_loadflags(%esi)
jnz 1f
cli cli
movl $__BOOT_DS, %eax movl $__BOOT_DS, %eax
movl %eax, %ds movl %eax, %ds
@ -77,7 +70,6 @@ SYM_FUNC_START(startup_32)
movl %eax, %fs movl %eax, %fs
movl %eax, %gs movl %eax, %gs
movl %eax, %ss movl %eax, %ss
1:
/* /*
* Calculate the delta between where we were compiled to run * Calculate the delta between where we were compiled to run

8
arch/x86/boot/compressed/head_64.S
View File

@ -53,19 +53,11 @@ SYM_FUNC_START(startup_32)
* all need to be under the 4G limit. * all need to be under the 4G limit.
*/ */
cld cld
/*
* Test KEEP_SEGMENTS flag to see if the bootloader is asking
* us to not reload segments
*/
testb $KEEP_SEGMENTS, BP_loadflags(%esi)
jnz 1f
cli cli
movl $(__BOOT_DS), %eax movl $(__BOOT_DS), %eax
movl %eax, %ds movl %eax, %ds
movl %eax, %es movl %eax, %es
movl %eax, %ss movl %eax, %ss
1:
/* /*
* Calculate the delta between where we were compiled to run * Calculate the delta between where we were compiled to run

6
arch/x86/kernel/head_32.S
View File

@ -67,11 +67,6 @@ __HEAD
SYM_CODE_START(startup_32) SYM_CODE_START(startup_32)
movl pa(initial_stack),%ecx movl pa(initial_stack),%ecx
/* test KEEP_SEGMENTS flag to see if the bootloader is asking
us to not reload segments */
testb $KEEP_SEGMENTS, BP_loadflags(%esi)
jnz 2f
/* /*
* Set segments to known values. * Set segments to known values.
*/ */
@ -82,7 +77,6 @@ SYM_CODE_START(startup_32)
movl %eax,%fs movl %eax,%fs
movl %eax,%gs movl %eax,%gs
movl %eax,%ss movl %eax,%ss
2:
leal -__PAGE_OFFSET(%ecx),%esp leal -__PAGE_OFFSET(%ecx),%esp
/* /*