From: Dominik Brodowski <linux@dominikbrodowski.net>
To: linux-kernel@vger.kernel.org, mingo@kernel.org, x86@kernel.org
Cc: torvalds@linux-foundation.org, luto@kernel.org,
ak@linux.intel.com, tglx@linutronix.de, dan.j.williams@intel.com
Subject: [RFC PATCH 3/4] x86/entry/64: move switch_to_thread_stack to interrupt helper function
Date: Wed, 14 Feb 2018 19:21:12 +0100 [thread overview]
Message-ID: <20180214182113.27247-4-linux@dominikbrodowski.net> (raw)
In-Reply-To: <20180214182113.27247-1-linux@dominikbrodowski.net>
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 <linux@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
next prev parent reply other threads:[~2018-02-14 18:22 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-14 18:21 [RFC PATCH 0/4] x86/entry/64: interrupt entry size reduction Dominik Brodowski
2018-02-14 18:21 ` [RFC PATCH 1/4] x86/entry/64: move PUSH_AND_CLEAR_REGS from interrupt macro to helper function Dominik Brodowski
2018-02-14 18:21 ` [RFC PATCH 2/4] x86/entry/64: move ENTER_IRQ_STACK " Dominik Brodowski
2018-02-14 18:36 ` Brian Gerst
2018-02-15 0:17 ` Andy Lutomirski
2018-02-15 0:48 ` Brian Gerst
2018-02-15 3:11 ` Andy Lutomirski
2018-02-15 13:45 ` Brian Gerst
2018-02-14 18:21 ` Dominik Brodowski [this message]
2018-02-14 18:57 ` [RFC PATCH 3/4] x86/entry/64: move switch_to_thread_stack to interrupt " Brian Gerst
2018-02-14 19:06 ` Dominik Brodowski
2018-02-14 19:27 ` Brian Gerst
2018-02-14 18:21 ` [RFC PATCH 4/4] x86/entry/64: remove interrupt macro Dominik Brodowski
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