From: Denys Vlasenko dvlasenk@redhat.com
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: Denys 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.c... Signed-off-by: Ingo Molnar mingo@kernel.org (cherry picked from commit 63332a8455d8310b77d38779c6c21a660a8d9feb) Signed-off-by: Pavel Tatashin pasha.tatashin@oracle.com --- arch/x86/ia32/ia32entry.S | 2 +- arch/x86/include/asm/thread_info.h | 8 +++++++- arch/x86/kernel/entry_64.S | 4 ++-- arch/x86/xen/xen-asm_64.S | 5 +++-- 4 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S index 27e54946ef35..2ae22c951fa0 100644 --- a/arch/x86/ia32/ia32entry.S +++ b/arch/x86/ia32/ia32entry.S @@ -356,7 +356,7 @@ 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 */ diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index b4bdec3e9523..d656a363e1eb 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -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 diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 6c9cb6073832..99f67a38f7f0 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -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 */ @@ -1464,7 +1464,7 @@ ENTRY(nmi) SWAPGS_UNSAFE_STACK cld movq %rsp, %rdx - movq PER_CPU_VAR(kernel_stack), %rsp + movq PER_CPU_VAR(cpu_tss + TSS_sp0), %rsp pushq 5*8(%rdx) /* pt_regs->ss */ pushq 4*8(%rdx) /* pt_regs->rsp */ pushq 3*8(%rdx) /* pt_regs->flags */ diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S index 985fc3ee0973..acc49e088ec5 100644 --- a/arch/x86/xen/xen-asm_64.S +++ b/arch/x86/xen/xen-asm_64.S @@ -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>
@@ -69,7 +70,7 @@ 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) @@ -88,7 +89,7 @@ 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)