The following commit has been merged into the x86/entry branch of tip: Commit-ID: 3728dd935c76646515e91e109067659200eb3a1b Gitweb: https://git.kernel.org/tip/3728dd935c76646515e91e109067659200eb3a1b Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> AuthorDate: Thu, 21 May 2020 22:05:49 +02:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Tue, 26 May 2020 19:06:29 +02:00 x86/entry/32: Remove redundant irq disable code All exceptions/interrupts return with interrupts disabled now. No point in doing this in ASM again. Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Acked-by: Andy Lutomirski <luto@xxxxxxxxxx> Link: https://lore.kernel.org/r/20200521202120.221223450@xxxxxxxxxxxxx --- arch/x86/entry/entry_32.S | 76 +-------------------------------------- 1 file changed, 76 deletions(-) diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 4a4f34b..96fa462 100644 --- 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 @@ restore_all_switch_stack: */ 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_iret_error) pushl $0 # no error code
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