[PATCH 6/5] x86/asm/entry/64: tidy up some instructions

From: Denys Vlasenko
Date: Tue Mar 31 2015 - 06:37:30 EST


Tidy up TEST insns width to use shorter insn form,
Use logically correct JZ mnemonic instead of JE (this doesn't change code).
Replace several BT insns with equivalent, but shorter TEST insns.

Signed-off-by: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
CC: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
CC: Steven Rostedt <rostedt@xxxxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxxxxx>
CC: Borislav Petkov <bp@xxxxxxxxx>
CC: "H. Peter Anvin" <hpa@xxxxxxxxx>
CC: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
CC: Oleg Nesterov <oleg@xxxxxxxxxx>
CC: Frederic Weisbecker <fweisbec@xxxxxxxxx>
CC: Alexei Starovoitov <ast@xxxxxxxxxxxx>
CC: Will Drewry <wad@xxxxxxxxxxxx>
CC: Kees Cook <keescook@xxxxxxxxxxxx>
CC: x86@xxxxxxxxxx
CC: linux-kernel@xxxxxxxxxxxxxxx
---
arch/x86/kernel/entry_64.S | 34 +++++++++++++++++-----------------
1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 356266c..cc166ab 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -67,8 +67,8 @@ ENDPROC(native_usergs_sysret64)

.macro TRACE_IRQS_IRETQ
#ifdef CONFIG_TRACE_IRQFLAGS
- bt $9,EFLAGS(%rsp) /* interrupts off? */
- jnc 1f
+ testb $2, EFLAGS+1(%rsp) /* interrupts off? */
+ jz 1f
TRACE_IRQS_ON
1:
#endif
@@ -100,8 +100,8 @@ ENDPROC(native_usergs_sysret64)
.endm

.macro TRACE_IRQS_IRETQ_DEBUG
- bt $9,EFLAGS(%rsp) /* interrupts off? */
- jnc 1f
+ testb $2, EFLAGS+1(%rsp) /* interrupts off? */
+ jz 1f
TRACE_IRQS_ON_DEBUG
1:
.endm
@@ -513,8 +513,8 @@ ENTRY(ret_from_fork)

RESTORE_EXTRA_REGS

- testl $3,CS(%rsp) # from kernel_thread?
- jz 1f
+ testb $3, CS(%rsp) # from kernel_thread?
+ jz 1f

/*
* By the time we get here, we have no idea whether our pt_regs,
@@ -598,8 +598,8 @@ END(interrupt)

leaq -RBP(%rsp),%rdi /* arg1 for \func (pointer to pt_regs) */

- testl $3, CS-RBP(%rsp)
- je 1f
+ testb $3, CS-RBP(%rsp)
+ jz 1f
SWAPGS
1:
/*
@@ -653,8 +653,8 @@ ret_from_intr:
CFI_DEF_CFA_REGISTER rsp
CFI_ADJUST_CFA_OFFSET RBP

- testl $3,CS(%rsp)
- je retint_kernel
+ testb $3, CS(%rsp)
+ jz retint_kernel
/* Interrupt came from user space */

GET_THREAD_INFO(%rcx)
@@ -739,8 +739,8 @@ retint_kernel:
#ifdef CONFIG_PREEMPT
/* Interrupts are off */
/* Check if we need preemption */
- bt $9,EFLAGS(%rsp) /* interrupts were off? */
- jnc 1f
+ testb $2,EFLAGS+1(%rsp) /* interrupts were off? */
+ jz 1f
0: cmpl $0,PER_CPU_VAR(__preempt_count)
jnz 1f
call preempt_schedule_irq
@@ -950,8 +950,8 @@ ENTRY(\sym)
.if \paranoid
.if \paranoid == 1
CFI_REMEMBER_STATE
- testl $3, CS(%rsp) /* If coming from userspace, switch */
- jnz 1f /* stacks. */
+ testb $3, CS(%rsp) /* If coming from userspace, switch */
+ jnz 1f /* stacks. */
.endif
call paranoid_entry
.else
@@ -1291,8 +1291,8 @@ ENTRY(error_entry)
SAVE_C_REGS 8
SAVE_EXTRA_REGS 8
xorl %ebx,%ebx
- testl $3,CS+8(%rsp)
- je error_kernelspace
+ testb $3,CS+8(%rsp)
+ jz error_kernelspace
error_swapgs:
SWAPGS
error_sti:
@@ -1343,7 +1343,7 @@ ENTRY(error_exit)
TRACE_IRQS_OFF
GET_THREAD_INFO(%rcx)
testl %eax,%eax
- jne retint_kernel
+ jnz retint_kernel
LOCKDEP_SYS_EXIT_IRQ
movl TI_flags(%rcx),%edx
movl $_TIF_WORK_MASK,%edi
--
1.8.1.4

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/