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Commit 63332a84 authored by Denys Vlasenko's avatar Denys Vlasenko Committed by Ingo Molnar
Browse files

x86/entry: Stop using PER_CPU_VAR(kernel_stack) 



PER_CPU_VAR(kernel_stack) is redundant:

  - On the 64-bit build, we can use PER_CPU_VAR(cpu_tss + TSS_sp0).
  - On the 32-bit build, we can use PER_CPU_VAR(cpu_current_top_of_stack).

PER_CPU_VAR(kernel_stack) will be deleted by a separate change.

Signed-off-by: default avatarDenys Vlasenko <dvlasenk@redhat.com>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
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: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1429889495-27850-1-git-send-email-dvlasenk@redhat.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent e22438f8

arch/x86/ia32/ia32entry.S

+1 −1
Original line number Diff line number Diff line
@@ -346,7 +346,7 @@ ENTRY(ia32_cstar_target) 
	SWAPGS_UNSAFE_STACK

	movl	%esp,%r8d

	CFI_REGISTER	rsp,r8

	movq	PER_CPU_VAR(kernel_stack),%rsp

	movq	PER_CPU_VAR(cpu_tss + TSS_sp0),%rsp

	ENABLE_INTERRUPTS(CLBR_NONE)



	/* Zero-extending 32-bit regs, do not remove */

arch/x86/include/asm/thread_info.h

+7 −1
Original line number Diff line number Diff line
@@ -198,9 +198,15 @@ static inline unsigned long current_stack_pointer(void) 
#else /* !__ASSEMBLY__ */



/* Load thread_info address into "reg" */

#ifdef CONFIG_X86_32

#define GET_THREAD_INFO(reg) \

	_ASM_MOV PER_CPU_VAR(kernel_stack),reg ; \

	_ASM_MOV PER_CPU_VAR(cpu_current_top_of_stack),reg ; \

	_ASM_SUB $(THREAD_SIZE),reg ;

#else

#define GET_THREAD_INFO(reg) \

	_ASM_MOV PER_CPU_VAR(cpu_tss + TSS_sp0),reg ; \

	_ASM_SUB $(THREAD_SIZE),reg ;

#endif



/*

 * ASM operand which evaluates to a 'thread_info' address of

arch/x86/kernel/entry_64.S

+1 −1
Original line number Diff line number Diff line
@@ -216,7 +216,7 @@ ENTRY(system_call) 
GLOBAL(system_call_after_swapgs)



	movq	%rsp,PER_CPU_VAR(rsp_scratch)

	movq	PER_CPU_VAR(kernel_stack),%rsp

	movq	PER_CPU_VAR(cpu_tss + TSS_sp0),%rsp



	/* Construct struct pt_regs on stack */

	pushq_cfi $__USER_DS			/* pt_regs->ss */

arch/x86/xen/xen-asm_64.S

+3 −2
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#include <asm/percpu.h>

#include <asm/processor-flags.h>

#include <asm/segment.h>

#include <asm/asm-offsets.h>



#include <xen/interface/xen.h>
@@ -53,7 +54,7 @@ ENTRY(xen_sysret64) 
	 * still with the kernel gs, so we can easily switch back

	 */

	movq %rsp, PER_CPU_VAR(rsp_scratch)

	movq PER_CPU_VAR(kernel_stack), %rsp

	movq PER_CPU_VAR(cpu_tss + TSS_sp0), %rsp



	pushq $__USER_DS

	pushq PER_CPU_VAR(rsp_scratch)
@@ -72,7 +73,7 @@ ENTRY(xen_sysret32) 
	 * still with the kernel gs, so we can easily switch back

	 */

	movq %rsp, PER_CPU_VAR(rsp_scratch)

	movq PER_CPU_VAR(kernel_stack), %rsp

	movq PER_CPU_VAR(cpu_tss + TSS_sp0), %rsp



	pushq $__USER32_DS

	pushq PER_CPU_VAR(rsp_scratch)