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Commit 1eeb207f authored by Denys Vlasenko's avatar Denys Vlasenko Committed by Ingo Molnar
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x86/asm/entry/64: Move 'save_paranoid' and 'ret_from_fork' closer to their users 



For some odd reason, these two functions are at the very top of
the file. "save_paranoid"'s caller is approximately in the middle
of it, move it there. Move 'ret_from_fork' to be right after
fork/exec helpers.

This is a pure block move, nothing is changed in the function
bodies.

Signed-off-by: default avatarDenys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: default avatarAndy Lutomirski <luto@amacapital.net>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/6446bbfe4094532623a5b83779b7015fec167a9d.1424989793.git.luto@amacapital.net


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent b87cf63e

arch/x86/kernel/entry_64.S

+53 −53
Original line number Diff line number Diff line
@@ -202,59 +202,6 @@ ENDPROC(native_usergs_sysret64) 
	CFI_REL_OFFSET r15, R15+\offset

	.endm



ENTRY(save_paranoid)

	XCPT_FRAME 1 RDI+8

	cld

	SAVE_C_REGS 8

	SAVE_EXTRA_REGS 8

	movl $1,%ebx

	movl $MSR_GS_BASE,%ecx

	rdmsr

	testl %edx,%edx

	js 1f	/* negative -> in kernel */

	SWAPGS

	xorl %ebx,%ebx

1:	ret

	CFI_ENDPROC

END(save_paranoid)



/*

 * A newly forked process directly context switches into this address.

 *

 * rdi: prev task we switched from

 */

ENTRY(ret_from_fork)

	DEFAULT_FRAME



	LOCK ; btr $TIF_FORK,TI_flags(%r8)



	pushq_cfi $0x0002

	popfq_cfi				# reset kernel eflags



	call schedule_tail			# rdi: 'prev' task parameter



	GET_THREAD_INFO(%rcx)



	RESTORE_EXTRA_REGS



	testl $3,CS(%rsp)			# from kernel_thread?

	jz   1f



	testl $_TIF_IA32, TI_flags(%rcx)	# 32-bit compat task needs IRET

	jnz  int_ret_from_sys_call



	RESTORE_TOP_OF_STACK %rdi

	jmp ret_from_sys_call			# go to the SYSRET fastpath



1:

	movq %rbp, %rdi

	call *%rbx

	movl $0, RAX(%rsp)

	RESTORE_EXTRA_REGS

	jmp int_ret_from_sys_call

	CFI_ENDPROC

END(ret_from_fork)



/*

 * 64bit SYSCALL instruction entry. Up to 6 arguments in registers.

 *
@@ -581,6 +528,43 @@ END(stub_x32_execveat) 


#endif



/*

 * A newly forked process directly context switches into this address.

 *

 * rdi: prev task we switched from

 */

ENTRY(ret_from_fork)

	DEFAULT_FRAME



	LOCK ; btr $TIF_FORK,TI_flags(%r8)



	pushq_cfi $0x0002

	popfq_cfi				# reset kernel eflags



	call schedule_tail			# rdi: 'prev' task parameter



	GET_THREAD_INFO(%rcx)



	RESTORE_EXTRA_REGS



	testl $3,CS(%rsp)			# from kernel_thread?

	jz   1f



	testl $_TIF_IA32, TI_flags(%rcx)	# 32-bit compat task needs IRET

	jnz  int_ret_from_sys_call



	RESTORE_TOP_OF_STACK %rdi

	jmp ret_from_sys_call			# go to the SYSRET fastpath



1:

	movq %rbp, %rdi

	call *%rbx

	movl $0, RAX(%rsp)

	RESTORE_EXTRA_REGS

	jmp int_ret_from_sys_call

	CFI_ENDPROC

END(ret_from_fork)



/*

 * Build the entry stubs and pointer table with some assembler magic.

 * We pack 7 stubs into a single 32-byte chunk, which will fit in a
@@ -1273,6 +1257,22 @@ idtentry async_page_fault do_async_page_fault has_error_code=1 
idtentry machine_check has_error_code=0 paranoid=1 do_sym=*machine_check_vector(%rip)

#endif



ENTRY(save_paranoid)

	XCPT_FRAME 1 RDI+8

	cld

	SAVE_C_REGS 8

	SAVE_EXTRA_REGS 8

	movl $1,%ebx

	movl $MSR_GS_BASE,%ecx

	rdmsr

	testl %edx,%edx

	js 1f	/* negative -> in kernel */

	SWAPGS

	xorl %ebx,%ebx

1:	ret

	CFI_ENDPROC

END(save_paranoid)



	/*

	 * "Paranoid" exit path from exception stack.  This is invoked

	 * only on return from non-NMI IST interrupts that came