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 <li...@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
