From 38755018f8f8d577b0ff15efddbf71181dab162b Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 1 Nov 2012 11:03:47 +0100 Subject: x86: Support for lazy preemption Implement the x86 pieces for lazy preempt. Signed-off-by: Thomas Gleixner --- arch/x86/Kconfig | 1 + arch/x86/include/asm/thread_info.h | 6 ++++++ arch/x86/kernel/asm-offsets.c | 2 ++ arch/x86/kernel/entry_32.S | 20 ++++++++++++++++++-- arch/x86/kernel/entry_64.S | 24 ++++++++++++++++++++---- 5 files changed, 47 insertions(+), 6 deletions(-) (limited to 'arch') diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 2c79a68d4c78..aac357a4cd5c 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -22,6 +22,7 @@ config X86_64 ### Arch settings config X86 def_bool y + select HAVE_PREEMPT_LAZY select ACPI_SYSTEM_POWER_STATES_SUPPORT if ACPI select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI select ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index b4bdec3e9523..606144afb990 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -55,6 +55,8 @@ struct thread_info { __u32 status; /* thread synchronous flags */ __u32 cpu; /* current CPU */ int saved_preempt_count; + int preempt_lazy_count; /* 0 => lazy preemptable + <0 => BUG */ mm_segment_t addr_limit; void __user *sysenter_return; unsigned int sig_on_uaccess_error:1; @@ -95,6 +97,7 @@ struct thread_info { #define TIF_SYSCALL_EMU 6 /* syscall emulation active */ #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ #define TIF_SECCOMP 8 /* secure computing */ +#define TIF_NEED_RESCHED_LAZY 9 /* lazy rescheduling necessary */ #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ #define TIF_UPROBE 12 /* breakpointed or singlestepping */ #define TIF_NOTSC 16 /* TSC is not accessible in userland */ @@ -119,6 +122,7 @@ struct thread_info { #define _TIF_SYSCALL_EMU (1 << TIF_SYSCALL_EMU) #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT) #define _TIF_SECCOMP (1 << TIF_SECCOMP) +#define _TIF_NEED_RESCHED_LAZY (1 << TIF_NEED_RESCHED_LAZY) #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) #define _TIF_UPROBE (1 << TIF_UPROBE) #define _TIF_NOTSC (1 << TIF_NOTSC) @@ -168,6 +172,8 @@ struct thread_info { #define _TIF_WORK_CTXSW_PREV (_TIF_WORK_CTXSW|_TIF_USER_RETURN_NOTIFY) #define _TIF_WORK_CTXSW_NEXT (_TIF_WORK_CTXSW) +#define _TIF_NEED_RESCHED_MASK (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY) + #define STACK_WARN (THREAD_SIZE/8) /* diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c index 9f6b9341950f..5701b507510b 100644 --- a/arch/x86/kernel/asm-offsets.c +++ b/arch/x86/kernel/asm-offsets.c @@ -32,6 +32,7 @@ void common(void) { OFFSET(TI_flags, thread_info, flags); OFFSET(TI_status, thread_info, status); OFFSET(TI_addr_limit, thread_info, addr_limit); + OFFSET(TI_preempt_lazy_count, thread_info, preempt_lazy_count); BLANK(); OFFSET(crypto_tfm_ctx_offset, crypto_tfm, __crt_ctx); @@ -71,4 +72,5 @@ void common(void) { BLANK(); DEFINE(PTREGS_SIZE, sizeof(struct pt_regs)); + DEFINE(_PREEMPT_ENABLED, PREEMPT_ENABLED); } diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index 1c309763e321..8612b314af92 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -359,8 +359,24 @@ END(ret_from_exception) ENTRY(resume_kernel) DISABLE_INTERRUPTS(CLBR_ANY) need_resched: + # preempt count == 0 + NEED_RS set? cmpl $0,PER_CPU_VAR(__preempt_count) +#ifndef CONFIG_PREEMPT_LAZY jnz restore_all +#else + jz test_int_off + + # atleast preempt count == 0 ? + cmpl $_PREEMPT_ENABLED,PER_CPU_VAR(__preempt_count) + jne restore_all + + cmpl $0,TI_preempt_lazy_count(%ebp) # non-zero preempt_lazy_count ? + jnz restore_all + + testl $_TIF_NEED_RESCHED_LAZY, TI_flags(%ebp) + jz restore_all +test_int_off: +#endif testl $X86_EFLAGS_IF,PT_EFLAGS(%esp) # interrupts off (exception path) ? jz restore_all call preempt_schedule_irq @@ -594,7 +610,7 @@ ENDPROC(system_call) ALIGN RING0_PTREGS_FRAME # can't unwind into user space anyway work_pending: - testb $_TIF_NEED_RESCHED, %cl + testl $_TIF_NEED_RESCHED_MASK, %ecx jz work_notifysig work_resched: call schedule @@ -607,7 +623,7 @@ work_resched: andl $_TIF_WORK_MASK, %ecx # is there any work to be done other # than syscall tracing? jz restore_all - testb $_TIF_NEED_RESCHED, %cl + testl $_TIF_NEED_RESCHED_MASK, %ecx jnz work_resched work_notifysig: # deal with pending signals and diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index 486de7d220fd..9bf90702036a 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -370,8 +370,8 @@ GLOBAL(int_with_check) /* First do a reschedule test. */ /* edx: work, edi: workmask */ int_careful: - bt $TIF_NEED_RESCHED,%edx - jnc int_very_careful + testl $_TIF_NEED_RESCHED_MASK,%edx + jz int_very_careful TRACE_IRQS_ON ENABLE_INTERRUPTS(CLBR_NONE) pushq_cfi %rdi @@ -776,7 +776,23 @@ retint_kernel: bt $9,EFLAGS(%rsp) /* interrupts were off? */ jnc 1f 0: cmpl $0,PER_CPU_VAR(__preempt_count) +#ifndef CONFIG_PREEMPT_LAZY jnz 1f +#else + jz do_preempt_schedule_irq + + # atleast preempt count == 0 ? + cmpl $_PREEMPT_ENABLED,PER_CPU_VAR(__preempt_count) + jnz 1f + + GET_THREAD_INFO(%rcx) + cmpl $0, TI_preempt_lazy_count(%rcx) + jnz 1f + + bt $TIF_NEED_RESCHED_LAZY,TI_flags(%rcx) + jnc 1f +do_preempt_schedule_irq: +#endif call preempt_schedule_irq jmp 0b 1: @@ -846,8 +862,8 @@ native_irq_return_ldt: /* edi: workmask, edx: work */ retint_careful: CFI_RESTORE_STATE - bt $TIF_NEED_RESCHED,%edx - jnc retint_signal + testl $_TIF_NEED_RESCHED_MASK,%edx + jz retint_signal TRACE_IRQS_ON ENABLE_INTERRUPTS(CLBR_NONE) pushq_cfi %rdi -- cgit v1.2.3