On Wed, Feb 14, 2018 at 1:21 PM, Dominik Brodowski <li...@dominikbrodowski.net> wrote: > We can also move the SWAPGS and the switch_to_thread_stack to the > interrupt helper function. As we do not want call depths of two, > convert switch_to_thread_stack to a macro. However, as entry_64_compat.S > expects switch_to_thread_stack to be a function, provide a wrapper for > that, which leads to some code duplication if CONFIG_IA32_EMULATION is > enabled. Therefore, the size reduction differs slightly: > > With CONFIG_IA32_EMULATION enabled (-0.13k): > text data bss dec hex filename > 16897 0 0 16897 4201 entry_64.o-orig > 16767 0 0 16767 417f entry_64.o > > With CONFIG_IA32_EMULATION disabled (-0.27k): > text data bss dec hex filename > 16897 0 0 16897 4201 entry_64.o-orig > 16622 0 0 16622 40ee entry_64.o > > Signed-off-by: Dominik Brodowski <li...@dominikbrodowski.net> > --- > arch/x86/entry/entry_64.S | 65 > ++++++++++++++++++++++++++--------------------- > 1 file changed, 36 insertions(+), 29 deletions(-) > > diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S > index 3046b12a1acb..b60a3b692ca9 100644 > --- a/arch/x86/entry/entry_64.S > +++ b/arch/x86/entry/entry_64.S > @@ -536,6 +536,31 @@ END(irq_entries_start) > decl PER_CPU_VAR(irq_count) > .endm > > +/* > + * Switch to the thread stack. This is called with the IRET frame and > + * orig_ax on the stack. (That is, RDI..R12 are not on the stack and > + * space has not been allocated for them.) > + */ > +.macro DO_SWITCH_TO_THREAD_STACK > + pushq %rdi > + /* Need to switch before accessing the thread stack. */ > + SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi > + movq %rsp, %rdi > + movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp > + UNWIND_HINT sp_offset=16 sp_reg=ORC_REG_DI > + > + pushq 7*8(%rdi) /* regs->ss */ > + pushq 6*8(%rdi) /* regs->rsp */ > + pushq 5*8(%rdi) /* regs->eflags */ > + pushq 4*8(%rdi) /* regs->cs */ > + pushq 3*8(%rdi) /* regs->ip */ > + pushq 2*8(%rdi) /* regs->orig_ax */ > + pushq 8(%rdi) /* return address */ > + UNWIND_HINT_FUNC > + > + movq (%rdi), %rdi > +.endm > + > /* > * Interrupt entry/exit. > * > @@ -543,10 +568,17 @@ END(irq_entries_start) > * > * Entry runs with interrupts off. > */ > +/* 8(%rsp): ~(interrupt number) */ > ENTRY(interrupt_helper) > UNWIND_HINT_FUNC > cld > > + testb $3, CS-ORIG_RAX+8(%rsp) > + jz 1f > + SWAPGS > + DO_SWITCH_TO_THREAD_STACK > +1: > + > PUSH_AND_CLEAR_REGS save_ret=1 > ENCODE_FRAME_POINTER 8 > > @@ -579,12 +611,6 @@ END(interrupt_helper) > .macro interrupt func > cld > > - testb $3, CS-ORIG_RAX(%rsp) > - jz 1f > - SWAPGS > - call switch_to_thread_stack > -1: > - > call interrupt_helper > > call \func /* rdi points to pt_regs */ > @@ -853,33 +879,14 @@ apicinterrupt IRQ_WORK_VECTOR > irq_work_interrupt smp_irq_work_interrupt > */ > #define CPU_TSS_IST(x) PER_CPU_VAR(cpu_tss_rw) + (TSS_ist + ((x) - 1) * 8) > > -/* > - * Switch to the thread stack. This is called with the IRET frame and > - * orig_ax on the stack. (That is, RDI..R12 are not on the stack and > - * space has not been allocated for them.) > - */ > +#if defined(CONFIG_IA32_EMULATION) > +/* entry_64_compat.S::entry_INT80_compat expects this to be an ASM function > */ > ENTRY(switch_to_thread_stack) > UNWIND_HINT_FUNC > - > - pushq %rdi > - /* Need to switch before accessing the thread stack. */ > - SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi > - movq %rsp, %rdi > - movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp > - UNWIND_HINT sp_offset=16 sp_reg=ORC_REG_DI > - > - pushq 7*8(%rdi) /* regs->ss */ > - pushq 6*8(%rdi) /* regs->rsp */ > - pushq 5*8(%rdi) /* regs->eflags */ > - pushq 4*8(%rdi) /* regs->cs */ > - pushq 3*8(%rdi) /* regs->ip */ > - pushq 2*8(%rdi) /* regs->orig_ax */ > - pushq 8(%rdi) /* return address */ > - UNWIND_HINT_FUNC > - > - movq (%rdi), %rdi > + DO_SWITCH_TO_THREAD_STACK > ret > END(switch_to_thread_stack) > +#endif > > .macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1 > ENTRY(\sym) > -- > 2.16.1 >
Move the macro to calling.h, and inline it into the compat entry. -- Brian Gerst