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x86/entry/32: Remove leftover macros after stackprotector cleanups 

Now that nonlazy-GS mode is gone, remove the macros from entry_32.S
that obfuscated^Wabstracted GS handling.  The assembled output is
identical before and after this patch.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/b1543116f0f0e68f1763d90d5f7fcec27885dff5.1613243844.git.luto@kernel.org
This commit is contained in:
Andy Lutomirski 2021-02-13 11:19:45 -08:00 committed by Borislav Petkov
parent 3fb0fdb3bb
commit d0962f2b24
1 changed files with 2 additions and 41 deletions
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43
arch/x86/entry/entry_32.S
View File

@ -53,35 +53,6 @@
#define PTI_SWITCH_MASK (1 << PAGE_SHIFT)
/*
* User gs save/restore
*
* This is leftover junk from CONFIG_X86_32_LAZY_GS. A subsequent patch
* will remove it entirely.
*/
/* unfortunately push/pop can't be no-op */
.macro PUSH_GS
pushl $0
.endm
.macro POP_GS pop=0
addl $(4 + \pop), %esp
.endm
.macro POP_GS_EX
.endm
/* all the rest are no-op */
.macro PTGS_TO_GS
.endm
.macro PTGS_TO_GS_EX
.endm
.macro GS_TO_REG reg
.endm
.macro REG_TO_PTGS reg
.endm
.macro SET_KERNEL_GS reg
.endm
/* Unconditionally switch to user cr3 */
.macro SWITCH_TO_USER_CR3 scratch_reg:req
ALTERNATIVE "jmp .Lend_\@", "", X86_FEATURE_PTI
@ -234,7 +205,7 @@
.macro SAVE_ALL pt_regs_ax=%eax switch_stacks=0 skip_gs=0 unwind_espfix=0
cld
.if \skip_gs == 0
PUSH_GS
pushl $0
.endif
pushl %fs
@ -259,9 +230,6 @@
movl $(__USER_DS), %edx
movl %edx, %ds
movl %edx, %es
.if \skip_gs == 0
SET_KERNEL_GS %edx
.endif
/* Switch to kernel stack if necessary */
.if \switch_stacks > 0
SWITCH_TO_KERNEL_STACK
@ -300,7 +268,7 @@
1: popl %ds
2: popl %es
3: popl %fs
POP_GS \pop
addl $(4 + \pop), %esp /* pop the unused "gs" slot */
IRET_FRAME
.pushsection .fixup, "ax"
4: movl $0, (%esp)
@ -313,7 +281,6 @@
_ASM_EXTABLE(1b, 4b)
_ASM_EXTABLE(2b, 5b)
_ASM_EXTABLE(3b, 6b)
POP_GS_EX
.endm
.macro RESTORE_ALL_NMI cr3_reg:req pop=0
@ -928,7 +895,6 @@ SYM_FUNC_START(entry_SYSENTER_32)
movl PT_EIP(%esp), %edx /* pt_regs->ip */
movl PT_OLDESP(%esp), %ecx /* pt_regs->sp */
1: mov PT_FS(%esp), %fs
PTGS_TO_GS
popl %ebx /* pt_regs->bx */
addl $2*4, %esp /* skip pt_regs->cx and pt_regs->dx */
@ -964,7 +930,6 @@ SYM_FUNC_START(entry_SYSENTER_32)
jmp 1b
.popsection
_ASM_EXTABLE(1b, 2b)
PTGS_TO_GS_EX
.Lsysenter_fix_flags:
pushl $X86_EFLAGS_FIXED
@ -1106,11 +1071,7 @@ SYM_CODE_START_LOCAL_NOALIGN(handle_exception)
SAVE_ALL switch_stacks=1 skip_gs=1 unwind_espfix=1
ENCODE_FRAME_POINTER
/* fixup %gs */
GS_TO_REG %ecx
movl PT_GS(%esp), %edi # get the function address
REG_TO_PTGS %ecx
SET_KERNEL_GS %ecx
/* fixup orig %eax */
movl PT_ORIG_EAX(%esp), %edx # get the error code