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Commit b3fe8ba3 authored by Denys Vlasenko's avatar Denys Vlasenko Committed by Ingo Molnar
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x86/asm/entry/64: Change the THREAD_INFO() definition to not depend on KERNEL_STACK_OFFSET 



This changes the THREAD_INFO() definition and all its callsites
so that they do not count stack position from
(top of stack - KERNEL_STACK_OFFSET), but from top of stack.

Semi-mysterious expressions THREAD_INFO(%rsp,RIP) - "why RIP??"
are now replaced by more logical THREAD_INFO(%rsp,SIZEOF_PTREGS)
- "calculate thread_info's address using information that
rsp is SIZEOF_PTREGS bytes below top of stack".

While at it, replace "(off)-THREAD_SIZE(reg)" with equivalent
"((off)-THREAD_SIZE)(reg)". The form without parentheses
falsely looks like we invoke THREAD_SIZE() macro.

Improve comment atop THREAD_INFO macro definition.

This patch does not change generated code (verified by objdump).

Signed-off-by: default avatarDenys Vlasenko <dvlasenk@redhat.com>
Acked-by: default avatarBorislav Petkov <bp@suse.de>
Acked-by: default avatarAndy Lutomirski <luto@kernel.org>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1426785469-15125-1-git-send-email-dvlasenk@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent a76c7f46

arch/x86/ia32/ia32entry.S

+15 −15
Original line number Diff line number Diff line
@@ -127,7 +127,7 @@ ENTRY(ia32_sysenter_target) 
	CFI_REL_OFFSET rsp,0

	pushfq_cfi

	/*CFI_REL_OFFSET rflags,0*/

	movl	TI_sysenter_return+THREAD_INFO(%rsp,3*8-KERNEL_STACK_OFFSET),%r10d

	movl	TI_sysenter_return+THREAD_INFO(%rsp,3*8),%r10d

	CFI_REGISTER rip,r10

	pushq_cfi $__USER32_CS

	/*CFI_REL_OFFSET cs,0*/
@@ -159,8 +159,8 @@ ENTRY(ia32_sysenter_target) 
	jnz sysenter_fix_flags

sysenter_flags_fixed:



	orl     $TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP)

	testl   $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP)

	orl     $TS_COMPAT,TI_status+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	testl   $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	CFI_REMEMBER_STATE

	jnz  sysenter_tracesys

	cmpq	$(IA32_NR_syscalls-1),%rax
@@ -177,10 +177,10 @@ sysenter_dispatch: 
	movq	%rax,RAX(%rsp)

	DISABLE_INTERRUPTS(CLBR_NONE)

	TRACE_IRQS_OFF

	testl	$_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,RIP)

	testl	$_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	jnz	sysexit_audit

sysexit_from_sys_call:

	andl    $~TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP)

	andl    $~TS_COMPAT,TI_status+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	/* clear IF, that popfq doesn't enable interrupts early */

	andl	$~0x200,EFLAGS(%rsp)

	movl	RIP(%rsp),%edx		/* User %eip */
@@ -225,7 +225,7 @@ sysexit_from_sys_call: 
	.endm



	.macro auditsys_exit exit

	testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,RIP)

	testl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	jnz ia32_ret_from_sys_call

	TRACE_IRQS_ON

	ENABLE_INTERRUPTS(CLBR_NONE)
@@ -240,7 +240,7 @@ sysexit_from_sys_call: 
	movl $(_TIF_ALLWORK_MASK & ~_TIF_SYSCALL_AUDIT),%edi

	DISABLE_INTERRUPTS(CLBR_NONE)

	TRACE_IRQS_OFF

	testl %edi,TI_flags+THREAD_INFO(%rsp,RIP)

	testl %edi,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	jz \exit

	CLEAR_RREGS

	jmp int_with_check
@@ -262,7 +262,7 @@ sysenter_fix_flags: 


sysenter_tracesys:

#ifdef CONFIG_AUDITSYSCALL

	testl	$(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,RIP)

	testl	$(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	jz	sysenter_auditsys

#endif

	SAVE_EXTRA_REGS
@@ -346,8 +346,8 @@ ENTRY(ia32_cstar_target) 
1:	movl	(%r8),%r9d

	_ASM_EXTABLE(1b,ia32_badarg)

	ASM_CLAC

	orl     $TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP)

	testl   $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP)

	orl     $TS_COMPAT,TI_status+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	testl   $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	CFI_REMEMBER_STATE

	jnz   cstar_tracesys

	cmpq $IA32_NR_syscalls-1,%rax
@@ -364,10 +364,10 @@ cstar_dispatch: 
	movq %rax,RAX(%rsp)

	DISABLE_INTERRUPTS(CLBR_NONE)

	TRACE_IRQS_OFF

	testl $_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,RIP)

	testl $_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	jnz sysretl_audit

sysretl_from_sys_call:

	andl $~TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP)

	andl $~TS_COMPAT,TI_status+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	RESTORE_RSI_RDI_RDX

	movl RIP(%rsp),%ecx

	CFI_REGISTER rip,rcx
@@ -402,7 +402,7 @@ sysretl_audit: 


cstar_tracesys:

#ifdef CONFIG_AUDITSYSCALL

	testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,RIP)

	testl $(_TIF_WORK_SYSCALL_ENTRY & ~_TIF_SYSCALL_AUDIT),TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	jz cstar_auditsys

#endif

	xchgl %r9d,%ebp
@@ -469,8 +469,8 @@ ENTRY(ia32_syscall) 
	   this could be a problem. */

	ALLOC_PT_GPREGS_ON_STACK

	SAVE_C_REGS_EXCEPT_R891011

	orl $TS_COMPAT,TI_status+THREAD_INFO(%rsp,RIP)

	testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP)

	orl $TS_COMPAT,TI_status+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	jnz ia32_tracesys

	cmpq $(IA32_NR_syscalls-1),%rax

	ja ia32_badsys

arch/x86/include/asm/thread_info.h

+5 −3
Original line number Diff line number Diff line
@@ -207,10 +207,12 @@ static inline unsigned long current_stack_pointer(void) 
	_ASM_SUB $(THREAD_SIZE-KERNEL_STACK_OFFSET),reg ;



/*

 * Same if PER_CPU_VAR(kernel_stack) is, perhaps with some offset, already in

 * a certain register (to be used in assembler memory operands).

 * ASM operand which evaluates to thread_info address

 * if it is known that "reg" is exactly "off" bytes below stack top.

 * Example (fetch thread_info->fieldname):

 *  mov TI_fieldname+THREAD_INFO(reg, off),%eax

 */

#define THREAD_INFO(reg, off) KERNEL_STACK_OFFSET+(off)-THREAD_SIZE(reg)

#define THREAD_INFO(reg, off) ((off)-THREAD_SIZE)(reg)



#endif

arch/x86/kernel/entry_64.S

+2 −2
Original line number Diff line number Diff line
@@ -258,7 +258,7 @@ GLOBAL(system_call_after_swapgs) 
	SAVE_C_REGS_EXCEPT_RAX_RCX_R11

	movq	$-ENOSYS,RAX(%rsp)

	CFI_REL_OFFSET rip,RIP

	testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,RIP)

	testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	jnz tracesys

system_call_fastpath:

#if __SYSCALL_MASK == ~0
@@ -276,7 +276,7 @@ system_call_fastpath: 
 * Has incompletely filled pt_regs, iret frame is also incomplete.

 */

ret_from_sys_call:

	testl $_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,RIP)

	testl $_TIF_ALLWORK_MASK,TI_flags+THREAD_INFO(%rsp,SIZEOF_PTREGS)

	jnz int_ret_from_sys_call_fixup	/* Go the the slow path */



	LOCKDEP_SYS_EXIT