Messages in this thread Patch in this message |  | | From | Dominik Brodowski <> | Subject | [RFC PATCH v2 3/5] x86/entry/64: move switch_to_thread_stack to interrupt helper function | Date | Sun, 18 Feb 2018 13:31:14 +0100 |
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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, switch_to_thread_stack has another user in entry_64_compat.S, which currently expects it to be a function. To keep the code changes in this patch minimal, create a wrapper function.
The switch to a macro means that there is some binary code duplication if CONFIG_IA32_EMULATION is enabled. Therefore, the size reduction differs whether CONFIG_IA32_EMULATION is enabled or not:
CONFIG_IA32_EMULATION=y (-0.13k): text data bss dec hex filename 17158 0 0 17158 4306 entry_64.o-orig 17028 0 0 17028 4284 entry_64.o
CONFIG_IA32_EMULATION=n (-0.27k): text data bss dec hex filename 17158 0 0 17158 4306 entry_64.o-orig 16883 0 0 16883 41f3 entry_64.o
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net> --- arch/x86/entry/entry_64.S | 64 +++++++++++++++++++++++++++-------------------- 1 file changed, 37 insertions(+), 27 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 93a9bea6b969..266bfcba3bb5 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -538,6 +538,31 @@ 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. * @@ -545,10 +570,17 @@ 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 @@ -581,12 +613,6 @@ 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 UNWIND_HINT_REGS indirect=1 @@ -860,33 +886,17 @@ 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 + cld - 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 + DO_SWITCH_TO_THREAD_STACK - movq (%rdi), %rdi 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
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