Commit d0962f2b authored by Andy Lutomirski's avatar Andy Lutomirski Committed by Borislav Petkov
Browse files

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: default avatarAndy Lutomirski <luto@kernel.org>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/b1543116f0f0e68f1763d90d5f7fcec27885dff5.1613243844.git.luto@kernel.org
parent 3fb0fdb3

arch/x86/entry/entry_32.S

+2 −41
Original line number Diff line number Diff line
@@ -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