[patch V5 35/38] x86/entry/32: Remove redundant irq disable code

Thomas Gleixner
2020-05-12T22:23:49Z

From: Thomas Gleixner <tglx@linutronix.de>

All exceptions/interrupts return with interrupts disabled now. No point in
doing this in ASM again.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
arch/x86/entry/entry_32.S | 76 ----------------------------------------------
1 file changed, 76 deletions(-)

--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -51,34 +51,6 @@

.section .entry.text, "ax"

-/*
- * We use macros for low-level operations which need to be overridden
- * for paravirtualization. The following will never clobber any registers:
- * INTERRUPT_RETURN (aka. "iret")
- * GET_CR0_INTO_EAX (aka. "movl %cr0, %eax")
- * ENABLE_INTERRUPTS_SYSEXIT (aka "sti; sysexit").
- *
- * For DISABLE_INTERRUPTS/ENABLE_INTERRUPTS (aka "cli"/"sti"), you must
- * specify what registers can be overwritten (CLBR_NONE, CLBR_EAX/EDX/ECX/ANY).
- * Allowing a register to be clobbered can shrink the paravirt replacement
- * enough to patch inline, increasing performance.
- */
-
-#ifdef CONFIG_PREEMPTION
-# define preempt_stop(clobbers) DISABLE_INTERRUPTS(clobbers); TRACE_IRQS_OFF
-#else
-# define preempt_stop(clobbers)
-#endif
-
-.macro TRACE_IRQS_IRET
-#ifdef CONFIG_TRACE_IRQFLAGS
- testl $X86_EFLAGS_IF, PT_EFLAGS(%esp) # interrupts off?
- jz 1f
- TRACE_IRQS_ON
-1:
-#endif
-.endm
-
#define PTI_SWITCH_MASK (1 << PAGE_SHIFT)

/*
@@ -881,38 +853,6 @@ SYM_CODE_START(ret_from_fork)
SYM_CODE_END(ret_from_fork)
.popsection

-/*
- * Return to user mode is not as complex as all this looks,
- * but we want the default path for a system call return to
- * go as quickly as possible which is why some of this is
- * less clear than it otherwise should be.
- */
-
- # userspace resumption stub bypassing syscall exit tracing
-SYM_CODE_START_LOCAL(ret_from_exception)
- preempt_stop(CLBR_ANY)
-ret_from_intr:
-#ifdef CONFIG_VM86
- movl PT_EFLAGS(%esp), %eax # mix EFLAGS and CS
- movb PT_CS(%esp), %al
- andl $(X86_EFLAGS_VM | SEGMENT_RPL_MASK), %eax
-#else
- /*
- * We can be coming here from child spawned by kernel_thread().
- */
- movl PT_CS(%esp), %eax
- andl $SEGMENT_RPL_MASK, %eax
-#endif
- cmpl $USER_RPL, %eax
- jb restore_all_kernel # not returning to v8086 or userspace
-
- DISABLE_INTERRUPTS(CLBR_ANY)
- TRACE_IRQS_OFF
- movl %esp, %eax
- call prepare_exit_to_usermode
- jmp restore_all_switch_stack
-SYM_CODE_END(ret_from_exception)
-
SYM_ENTRY(__begin_SYSENTER_singlestep_region, SYM_L_GLOBAL, SYM_A_NONE)
/*
* All code from here through __end_SYSENTER_singlestep_region is subject
@@ -1147,22 +1087,6 @@ SYM_FUNC_START(entry_INT80_32)
*/
INTERRUPT_RETURN

-restore_all_kernel:
-#ifdef CONFIG_PREEMPTION
- DISABLE_INTERRUPTS(CLBR_ANY)
- cmpl $0, PER_CPU_VAR(__preempt_count)
- jnz .Lno_preempt
- testl $X86_EFLAGS_IF, PT_EFLAGS(%esp) # interrupts off (exception path) ?
- jz .Lno_preempt
- call preempt_schedule_irq
-.Lno_preempt:
-#endif
- TRACE_IRQS_IRET
- PARANOID_EXIT_TO_KERNEL_MODE
- BUG_IF_WRONG_CR3
- RESTORE_REGS 4
- jmp .Lirq_return
-
.section .fixup, "ax"
SYM_CODE_START(asm_exc_iret_error)
pushl $0 # no error code