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Merge branch 'sched/cputime' of git://git.kernel.org/pub/scm/linux/ke…
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…rnel/git/frederic/linux-dynticks into sched/core

Pull cputime changes from Frederic Weisbecker:

  * Generalize exception handling

  * Fix race in context tracking state restore on return from exception
    and irq exit kernel preemption

  * Fix cputime scaling in full dynticks accounting dynamic off-case

  * Fix default Kconfig value

Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Ingo Molnar committed Mar 8, 2013
2 parents 27b4b93 + 8b43876 commit 4e3da46
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Showing 10 changed files with 163 additions and 133 deletions.
21 changes: 0 additions & 21 deletions arch/x86/include/asm/context_tracking.h
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Original file line number Diff line number Diff line change
@@ -1,31 +1,10 @@
#ifndef _ASM_X86_CONTEXT_TRACKING_H
#define _ASM_X86_CONTEXT_TRACKING_H

#ifndef __ASSEMBLY__
#include <linux/context_tracking.h>
#include <asm/ptrace.h>

static inline void exception_enter(struct pt_regs *regs)
{
user_exit();
}

static inline void exception_exit(struct pt_regs *regs)
{
#ifdef CONFIG_CONTEXT_TRACKING
if (user_mode(regs))
user_enter();
#endif
}

#else /* __ASSEMBLY__ */

#ifdef CONFIG_CONTEXT_TRACKING
# define SCHEDULE_USER call schedule_user
#else
# define SCHEDULE_USER call schedule
#endif

#endif /* !__ASSEMBLY__ */

#endif
8 changes: 5 additions & 3 deletions arch/x86/kernel/kvm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
* Authors: Anthony Liguori <aliguori@us.ibm.com>
*/

#include <linux/context_tracking.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/kvm_para.h>
Expand All @@ -43,7 +44,6 @@
#include <asm/apicdef.h>
#include <asm/hypervisor.h>
#include <asm/kvm_guest.h>
#include <asm/context_tracking.h>

static int kvmapf = 1;

Expand Down Expand Up @@ -254,16 +254,18 @@ EXPORT_SYMBOL_GPL(kvm_read_and_reset_pf_reason);
dotraplinkage void __kprobes
do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
{
enum ctx_state prev_state;

switch (kvm_read_and_reset_pf_reason()) {
default:
do_page_fault(regs, error_code);
break;
case KVM_PV_REASON_PAGE_NOT_PRESENT:
/* page is swapped out by the host. */
exception_enter(regs);
prev_state = exception_enter();
exit_idle();
kvm_async_pf_task_wait((u32)read_cr2());
exception_exit(regs);
exception_exit(prev_state);
break;
case KVM_PV_REASON_PAGE_READY:
rcu_irq_enter();
Expand Down
68 changes: 42 additions & 26 deletions arch/x86/kernel/traps.c
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/context_tracking.h>
#include <linux/interrupt.h>
#include <linux/kallsyms.h>
#include <linux/spinlock.h>
Expand Down Expand Up @@ -55,8 +56,6 @@
#include <asm/i387.h>
#include <asm/fpu-internal.h>
#include <asm/mce.h>
#include <asm/context_tracking.h>

#include <asm/mach_traps.h>

#ifdef CONFIG_X86_64
Expand Down Expand Up @@ -176,34 +175,38 @@ do_trap(int trapnr, int signr, char *str, struct pt_regs *regs,
#define DO_ERROR(trapnr, signr, str, name) \
dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
{ \
exception_enter(regs); \
enum ctx_state prev_state; \
\
prev_state = exception_enter(); \
if (notify_die(DIE_TRAP, str, regs, error_code, \
trapnr, signr) == NOTIFY_STOP) { \
exception_exit(regs); \
exception_exit(prev_state); \
return; \
} \
conditional_sti(regs); \
do_trap(trapnr, signr, str, regs, error_code, NULL); \
exception_exit(regs); \
exception_exit(prev_state); \
}

#define DO_ERROR_INFO(trapnr, signr, str, name, sicode, siaddr) \
dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \
{ \
siginfo_t info; \
enum ctx_state prev_state; \
\
info.si_signo = signr; \
info.si_errno = 0; \
info.si_code = sicode; \
info.si_addr = (void __user *)siaddr; \
exception_enter(regs); \
prev_state = exception_enter(); \
if (notify_die(DIE_TRAP, str, regs, error_code, \
trapnr, signr) == NOTIFY_STOP) { \
exception_exit(regs); \
exception_exit(prev_state); \
return; \
} \
conditional_sti(regs); \
do_trap(trapnr, signr, str, regs, error_code, &info); \
exception_exit(regs); \
exception_exit(prev_state); \
}

DO_ERROR_INFO(X86_TRAP_DE, SIGFPE, "divide error", divide_error, FPE_INTDIV,
Expand All @@ -226,22 +229,24 @@ DO_ERROR_INFO(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check,
/* Runs on IST stack */
dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code)
{
exception_enter(regs);
enum ctx_state prev_state;

prev_state = exception_enter();
if (notify_die(DIE_TRAP, "stack segment", regs, error_code,
X86_TRAP_SS, SIGBUS) != NOTIFY_STOP) {
preempt_conditional_sti(regs);
do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL);
preempt_conditional_cli(regs);
}
exception_exit(regs);
exception_exit(prev_state);
}

dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
{
static const char str[] = "double fault";
struct task_struct *tsk = current;

exception_enter(regs);
exception_enter();
/* Return not checked because double check cannot be ignored */
notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);

Expand All @@ -261,8 +266,9 @@ dotraplinkage void __kprobes
do_general_protection(struct pt_regs *regs, long error_code)
{
struct task_struct *tsk;
enum ctx_state prev_state;

exception_enter(regs);
prev_state = exception_enter();
conditional_sti(regs);

#ifdef CONFIG_X86_32
Expand Down Expand Up @@ -300,12 +306,14 @@ do_general_protection(struct pt_regs *regs, long error_code)

force_sig(SIGSEGV, tsk);
exit:
exception_exit(regs);
exception_exit(prev_state);
}

/* May run on IST stack. */
dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_code)
{
enum ctx_state prev_state;

#ifdef CONFIG_DYNAMIC_FTRACE
/*
* ftrace must be first, everything else may cause a recursive crash.
Expand All @@ -315,7 +323,7 @@ dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_co
ftrace_int3_handler(regs))
return;
#endif
exception_enter(regs);
prev_state = exception_enter();
#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
SIGTRAP) == NOTIFY_STOP)
Expand All @@ -336,7 +344,7 @@ dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_co
preempt_conditional_cli(regs);
debug_stack_usage_dec();
exit:
exception_exit(regs);
exception_exit(prev_state);
}

#ifdef CONFIG_X86_64
Expand Down Expand Up @@ -393,11 +401,12 @@ asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
{
struct task_struct *tsk = current;
enum ctx_state prev_state;
int user_icebp = 0;
unsigned long dr6;
int si_code;

exception_enter(regs);
prev_state = exception_enter();

get_debugreg(dr6, 6);

Expand Down Expand Up @@ -467,7 +476,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
debug_stack_usage_dec();

exit:
exception_exit(regs);
exception_exit(prev_state);
}

/*
Expand Down Expand Up @@ -561,17 +570,21 @@ void math_error(struct pt_regs *regs, int error_code, int trapnr)

dotraplinkage void do_coprocessor_error(struct pt_regs *regs, long error_code)
{
exception_enter(regs);
enum ctx_state prev_state;

prev_state = exception_enter();
math_error(regs, error_code, X86_TRAP_MF);
exception_exit(regs);
exception_exit(prev_state);
}

dotraplinkage void
do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
{
exception_enter(regs);
enum ctx_state prev_state;

prev_state = exception_enter();
math_error(regs, error_code, X86_TRAP_XF);
exception_exit(regs);
exception_exit(prev_state);
}

dotraplinkage void
Expand Down Expand Up @@ -639,7 +652,9 @@ EXPORT_SYMBOL_GPL(math_state_restore);
dotraplinkage void __kprobes
do_device_not_available(struct pt_regs *regs, long error_code)
{
exception_enter(regs);
enum ctx_state prev_state;

prev_state = exception_enter();
BUG_ON(use_eager_fpu());

#ifdef CONFIG_MATH_EMULATION
Expand All @@ -650,23 +665,24 @@ do_device_not_available(struct pt_regs *regs, long error_code)

info.regs = regs;
math_emulate(&info);
exception_exit(regs);
exception_exit(prev_state);
return;
}
#endif
math_state_restore(); /* interrupts still off */
#ifdef CONFIG_X86_32
conditional_sti(regs);
#endif
exception_exit(regs);
exception_exit(prev_state);
}

#ifdef CONFIG_X86_32
dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
{
siginfo_t info;
enum ctx_state prev_state;

exception_enter(regs);
prev_state = exception_enter();
local_irq_enable();

info.si_signo = SIGILL;
Expand All @@ -678,7 +694,7 @@ dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,
&info);
}
exception_exit(regs);
exception_exit(prev_state);
}
#endif

Expand Down
8 changes: 5 additions & 3 deletions arch/x86/mm/fault.c
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Original file line number Diff line number Diff line change
Expand Up @@ -13,12 +13,12 @@
#include <linux/perf_event.h> /* perf_sw_event */
#include <linux/hugetlb.h> /* hstate_index_to_shift */
#include <linux/prefetch.h> /* prefetchw */
#include <linux/context_tracking.h> /* exception_enter(), ... */

#include <asm/traps.h> /* dotraplinkage, ... */
#include <asm/pgalloc.h> /* pgd_*(), ... */
#include <asm/kmemcheck.h> /* kmemcheck_*(), ... */
#include <asm/fixmap.h> /* VSYSCALL_START */
#include <asm/context_tracking.h> /* exception_enter(), ... */

/*
* Page fault error code bits:
Expand Down Expand Up @@ -1222,7 +1222,9 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code)
dotraplinkage void __kprobes
do_page_fault(struct pt_regs *regs, unsigned long error_code)
{
exception_enter(regs);
enum ctx_state prev_state;

prev_state = exception_enter();
__do_page_fault(regs, error_code);
exception_exit(regs);
exception_exit(prev_state);
}
24 changes: 22 additions & 2 deletions include/linux/context_tracking.h
View file
Original file line number Diff line number Diff line change
@@ -1,9 +1,9 @@
#ifndef _LINUX_CONTEXT_TRACKING_H
#define _LINUX_CONTEXT_TRACKING_H

#ifdef CONFIG_CONTEXT_TRACKING
#include <linux/sched.h>
#include <linux/percpu.h>
#include <asm/ptrace.h>

struct context_tracking {
/*
Expand All @@ -13,12 +13,13 @@ struct context_tracking {
* may be further optimized using static keys.
*/
bool active;
enum {
enum ctx_state {
IN_KERNEL = 0,
IN_USER,
} state;
};

#ifdef CONFIG_CONTEXT_TRACKING
DECLARE_PER_CPU(struct context_tracking, context_tracking);

static inline bool context_tracking_in_user(void)
Expand All @@ -33,12 +34,31 @@ static inline bool context_tracking_active(void)

extern void user_enter(void);
extern void user_exit(void);

static inline enum ctx_state exception_enter(void)
{
enum ctx_state prev_ctx;

prev_ctx = this_cpu_read(context_tracking.state);
user_exit();

return prev_ctx;
}

static inline void exception_exit(enum ctx_state prev_ctx)
{
if (prev_ctx == IN_USER)
user_enter();
}

extern void context_tracking_task_switch(struct task_struct *prev,
struct task_struct *next);
#else
static inline bool context_tracking_in_user(void) { return false; }
static inline void user_enter(void) { }
static inline void user_exit(void) { }
static inline enum ctx_state exception_enter(void) { return 0; }
static inline void exception_exit(enum ctx_state prev_ctx) { }
static inline void context_tracking_task_switch(struct task_struct *prev,
struct task_struct *next) { }
#endif /* !CONFIG_CONTEXT_TRACKING */
Expand Down
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