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    Subject[PATCH 4.1 25/65] x86/entry: Define 'cpu_current_top_of_stack' for 64-bit code
    Date
    From: Denys Vlasenko <dvlasenk@redhat.com>

    32-bit code has PER_CPU_VAR(cpu_current_top_of_stack).
    64-bit code uses somewhat more obscure: PER_CPU_VAR(cpu_tss + TSS_sp0).

    Define the 'cpu_current_top_of_stack' macro on CONFIG_X86_64
    as well so that the PER_CPU_VAR(cpu_current_top_of_stack)
    expression can be used in both 32-bit and 64-bit code.

    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/1429889495-27850-3-git-send-email-dvlasenk@redhat.com
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    (cherry picked from commit 3a23208e69679597e767cf3547b1a30dd845d9b5)
    Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
    ---
    arch/x86/ia32/ia32entry.S | 4 ++--
    arch/x86/include/asm/thread_info.h | 10 ++++------
    arch/x86/kernel/entry_64.S | 4 ++--
    arch/x86/xen/xen-asm_64.S | 5 +++--
    4 files changed, 11 insertions(+), 12 deletions(-)

    diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
    index 2ae22c951fa0..b2fafcb37d4e 100644
    --- a/arch/x86/ia32/ia32entry.S
    +++ b/arch/x86/ia32/ia32entry.S
    @@ -119,7 +119,7 @@ ENTRY(ia32_sysenter_target)
    * it is too small to ever cause noticeable irq latency.
    */
    SWAPGS_UNSAFE_STACK
    - movq PER_CPU_VAR(cpu_tss + TSS_sp0), %rsp
    + movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
    ENABLE_INTERRUPTS(CLBR_NONE)

    /* Zero-extending 32-bit regs, do not remove */
    @@ -356,7 +356,7 @@ ENTRY(ia32_cstar_target)
    SWAPGS_UNSAFE_STACK
    movl %esp,%r8d
    CFI_REGISTER rsp,r8
    - movq PER_CPU_VAR(cpu_tss + TSS_sp0),%rsp
    + movq PER_CPU_VAR(cpu_current_top_of_stack),%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 472288962c99..225ee545e1a0 100644
    --- a/arch/x86/include/asm/thread_info.h
    +++ b/arch/x86/include/asm/thread_info.h
    @@ -195,16 +195,14 @@ static inline unsigned long current_stack_pointer(void)

    #else /* !__ASSEMBLY__ */

    +#ifdef CONFIG_X86_64
    +# define cpu_current_top_of_stack (cpu_tss + TSS_sp0)
    +#endif
    +
    /* Load thread_info address into "reg" */
    -#ifdef CONFIG_X86_32
    #define GET_THREAD_INFO(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 99f67a38f7f0..eaf3d4df76d5 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(cpu_tss + TSS_sp0),%rsp
    + movq PER_CPU_VAR(cpu_current_top_of_stack),%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(cpu_tss + TSS_sp0), %rsp
    + movq PER_CPU_VAR(cpu_current_top_of_stack), %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 acc49e088ec5..5e15e92099de 100644
    --- a/arch/x86/xen/xen-asm_64.S
    +++ b/arch/x86/xen/xen-asm_64.S
    @@ -16,6 +16,7 @@
    #include <asm/processor-flags.h>
    #include <asm/segment.h>
    #include <asm/asm-offsets.h>
    +#include <asm/thread_info.h>

    #include <xen/interface/xen.h>

    @@ -70,7 +71,7 @@ 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(cpu_tss + TSS_sp0), %rsp
    + movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp

    pushq $__USER_DS
    pushq PER_CPU_VAR(rsp_scratch)
    @@ -89,7 +90,7 @@ 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(cpu_tss + TSS_sp0), %rsp
    + movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp

    pushq $__USER32_DS
    pushq PER_CPU_VAR(rsp_scratch)
    --
    2.16.2
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