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Commit bcddc015 authored by Jan Beulich's avatar Jan Beulich Committed by Andi Kleen
Browse files

[PATCH] x86-64: miscellaneous entry.S adjustments 



This patch:
- makes ret_from_sys_call no longer global (all external users were
  previously switched to use int_ret_from_sys_call)
- adjusts placement of a CFI_{REMEMBER,RESTORE}_STATE pair to better
  fit logic flow
- eliminates an unnecessary pair of CFI_{REMEMBER,RESTORE}_STATE
- glues together function- and unwinder-wise the previously separate
  system_call and int_ret_from_sys_call function fragments

Signed-off-by: default avatarJan Beulich <jbeulich@novell.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent da68933e

arch/x86_64/kernel/entry.S

+6 −30
Original line number Diff line number Diff line
@@ -230,7 +230,6 @@ ENTRY(system_call) 
	CFI_REL_OFFSET rip,RIP-ARGOFFSET

	GET_THREAD_INFO(%rcx)

	testl $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP),threadinfo_flags(%rcx)

	CFI_REMEMBER_STATE

	jnz tracesys

	cmpq $__NR_syscall_max,%rax

	ja badsys
@@ -241,7 +240,6 @@ ENTRY(system_call) 
 * Syscall return path ending with SYSRET (fast path)

 * Has incomplete stack frame and undefined top of stack. 

 */		

	.globl ret_from_sys_call

ret_from_sys_call:

	movl $_TIF_ALLWORK_MASK,%edi

	/* edi:	flagmask */
@@ -251,8 +249,8 @@ sysret_check: 
	TRACE_IRQS_OFF

	movl threadinfo_flags(%rcx),%edx

	andl %edi,%edx

	CFI_REMEMBER_STATE

	jnz  sysret_careful 

	CFI_REMEMBER_STATE

	/*

	 * sysretq will re-enable interrupts:

	 */
@@ -265,10 +263,10 @@ sysret_check: 
	swapgs

	sysretq



	CFI_RESTORE_STATE

	/* Handle reschedules */

	/* edx:	work, edi: workmask */	

sysret_careful:

	CFI_RESTORE_STATE

	bt $TIF_NEED_RESCHED,%edx

	jnc sysret_signal

	TRACE_IRQS_ON
@@ -306,7 +304,6 @@ badsys: 


	/* Do syscall tracing */

tracesys:			 

	CFI_RESTORE_STATE

	SAVE_REST

	movq $-ENOSYS,RAX(%rsp)

	FIXUP_TOP_OF_STACK %rdi
@@ -322,32 +319,13 @@ tracesys: 
	call *sys_call_table(,%rax,8)

1:	movq %rax,RAX-ARGOFFSET(%rsp)

	/* Use IRET because user could have changed frame */

	jmp int_ret_from_sys_call

	CFI_ENDPROC

END(system_call)

		

/* 

 * Syscall return path ending with IRET.

 * Has correct top of stack, but partial stack frame.

 */

ENTRY(int_ret_from_sys_call)

	CFI_STARTPROC	simple

	CFI_SIGNAL_FRAME

	CFI_DEF_CFA	rsp,SS+8-ARGOFFSET

	/*CFI_REL_OFFSET	ss,SS-ARGOFFSET*/

	CFI_REL_OFFSET	rsp,RSP-ARGOFFSET

	/*CFI_REL_OFFSET	rflags,EFLAGS-ARGOFFSET*/

	/*CFI_REL_OFFSET	cs,CS-ARGOFFSET*/

	CFI_REL_OFFSET	rip,RIP-ARGOFFSET

	CFI_REL_OFFSET	rdx,RDX-ARGOFFSET

	CFI_REL_OFFSET	rcx,RCX-ARGOFFSET

	CFI_REL_OFFSET	rax,RAX-ARGOFFSET

	CFI_REL_OFFSET	rdi,RDI-ARGOFFSET

	CFI_REL_OFFSET	rsi,RSI-ARGOFFSET

	CFI_REL_OFFSET	r8,R8-ARGOFFSET

	CFI_REL_OFFSET	r9,R9-ARGOFFSET

	CFI_REL_OFFSET	r10,R10-ARGOFFSET

	CFI_REL_OFFSET	r11,R11-ARGOFFSET

	.globl int_ret_from_sys_call

int_ret_from_sys_call:

	cli

	TRACE_IRQS_OFF

	testl $3,CS-ARGOFFSET(%rsp)
@@ -394,8 +372,6 @@ int_very_careful: 
	popq %rdi

	CFI_ADJUST_CFA_OFFSET -8

	andl $~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP),%edi

	cli

	TRACE_IRQS_OFF

	jmp int_restore_rest

	

int_signal:
@@ -411,7 +387,7 @@ int_restore_rest: 
	TRACE_IRQS_OFF

	jmp int_with_check

	CFI_ENDPROC

END(int_ret_from_sys_call)

END(system_call)

		

/* 

 * Certain special system calls that need to save a complete full stack frame.