From: Denys Vlasenko <dvlasenk@xxxxxxxxxx> 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@xxxxxxxxxx> Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Will Drewry <wad@xxxxxxxxxxxx> Link: http://lkml.kernel.org/r/1429889495-27850-1-git-send-email-dvlasenk@xxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> (cherry picked from commit 63332a8455d8310b77d38779c6c21a660a8d9feb) Signed-off-by: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> --- 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) -- 2.16.2