diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index ce6af4460e9c575ec24fa1a7bbb975dc8c86a456..7e82e553183aeb79f2e3e0d12c6fca4b1a763ec2 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -215,18 +215,20 @@ ENTRY(entry_SYSCALL_64) /* * This path is only taken when PAGE_TABLE_ISOLATION is disabled so it * is not required to switch CR3. + * + * tss.sp2 is scratch space. */ - movq %rsp, PER_CPU_VAR(rsp_scratch) + movq %rsp, PER_CPU_VAR(cpu_tss_rw + TSS_sp2) movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp /* Construct struct pt_regs on stack */ - pushq $__USER_DS /* pt_regs->ss */ - pushq PER_CPU_VAR(rsp_scratch) /* pt_regs->sp */ - pushq %r11 /* pt_regs->flags */ - pushq $__USER_CS /* pt_regs->cs */ - pushq %rcx /* pt_regs->ip */ + pushq $__USER_DS /* pt_regs->ss */ + pushq PER_CPU_VAR(cpu_tss_rw + TSS_sp2) /* pt_regs->sp */ + pushq %r11 /* pt_regs->flags */ + pushq $__USER_CS /* pt_regs->cs */ + pushq %rcx /* pt_regs->ip */ GLOBAL(entry_SYSCALL_64_after_hwframe) - pushq %rax /* pt_regs->orig_ax */ + pushq %rax /* pt_regs->orig_ax */ PUSH_AND_CLEAR_REGS rax=$-ENOSYS diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index d53c54b842daca1c847d8076aadd89564b23cf00..b2bb1d691efc54139d9635b42a11df53de4b035d 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -315,7 +315,13 @@ struct x86_hw_tss { */ u64 sp1; + /* + * Since Linux does not use ring 2, the 'sp2' slot is unused by + * hardware. entry_SYSCALL_64 uses it as scratch space to stash + * the user RSP value. + */ u64 sp2; + u64 reserved2; u64 ist[7]; u32 reserved3; diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c index 01de31db300d3cbf17de120b3a89011f170f65d3..fc2e90d3429a6eb8605453a52c951651f96b4c14 100644 --- a/arch/x86/kernel/asm-offsets.c +++ b/arch/x86/kernel/asm-offsets.c @@ -105,7 +105,8 @@ void common(void) { DEFINE(SIZEOF_entry_stack, sizeof(struct entry_stack)); DEFINE(MASK_entry_stack, (~(sizeof(struct entry_stack) - 1))); - /* Offset for sp0 and sp1 into the tss_struct */ + /* Offset for fields in tss_struct */ OFFSET(TSS_sp0, tss_struct, x86_tss.sp0); OFFSET(TSS_sp1, tss_struct, x86_tss.sp1); + OFFSET(TSS_sp2, tss_struct, x86_tss.sp2); } diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index a451bc374b9b3e5001be9978995848946867759b..0fa7aa19f09e00696f38d19e156107760c2bb2cb 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -59,8 +59,6 @@ #include #endif -__visible DEFINE_PER_CPU(unsigned long, rsp_scratch); - /* Prints also some state that isn't saved in the pt_regs */ void __show_regs(struct pt_regs *regs, int all) { diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S index 417b339e5c8e1aadedd20231c9be82ac93dbe728..bb1c2da0381decd365b62008b441a870a048fcfd 100644 --- a/arch/x86/xen/xen-asm_64.S +++ b/arch/x86/xen/xen-asm_64.S @@ -91,13 +91,15 @@ ENTRY(xen_iret) ENTRY(xen_sysret64) /* * We're already on the usermode stack at this point, but - * still with the kernel gs, so we can easily switch back + * still with the kernel gs, so we can easily switch back. + * + * tss.sp2 is scratch space. */ - movq %rsp, PER_CPU_VAR(rsp_scratch) + movq %rsp, PER_CPU_VAR(cpu_tss_rw + TSS_sp2) movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp pushq $__USER_DS - pushq PER_CPU_VAR(rsp_scratch) + pushq PER_CPU_VAR(cpu_tss_rw + TSS_sp2) pushq %r11 pushq $__USER_CS pushq %rcx