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x86/entry: Move nmi entry/exit into common code

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Lockdep state handling on NMI enter and exit is nothing specific to X86. It's
not any different on other architectures. Also the extra state type is not
necessary, irqentry_state_t can carry the necessary information as well.

Move it to common code and extend irqentry_state_t to carry lockdep state.

[ Ira: Make exit_rcu and lockdep a union as they are mutually exclusive
  between the IRQ and NMI exceptions, and add kernel documentation for
  struct irqentry_state_t ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201102205320.1458656-7-ira.weiny@intel.com
This commit is contained in:
Thomas Gleixner 2020-11-02 12:53:16 -08:00
parent 01be83eea0
commit b6be002bcd
7 changed files with 87 additions and 50 deletions
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34
arch/x86/entry/common.c
View File

@ -209,40 +209,6 @@ SYSCALL_DEFINE0(ni_syscall)
return -ENOSYS;
}
noinstr bool idtentry_enter_nmi(struct pt_regs *regs)
{
bool irq_state = lockdep_hardirqs_enabled();
__nmi_enter();
lockdep_hardirqs_off(CALLER_ADDR0);
lockdep_hardirq_enter();
rcu_nmi_enter();
instrumentation_begin();
trace_hardirqs_off_finish();
ftrace_nmi_enter();
instrumentation_end();
return irq_state;
}
noinstr void idtentry_exit_nmi(struct pt_regs *regs, bool restore)
{
instrumentation_begin();
ftrace_nmi_exit();
if (restore) {
trace_hardirqs_on_prepare();
lockdep_hardirqs_on_prepare(CALLER_ADDR0);
}
instrumentation_end();
rcu_nmi_exit();
lockdep_hardirq_exit();
if (restore)
lockdep_hardirqs_on(CALLER_ADDR0);
__nmi_exit();
}
#ifdef CONFIG_XEN_PV
#ifndef CONFIG_PREEMPTION
/*

3
arch/x86/include/asm/idtentry.h
View File

@ -11,9 +11,6 @@
#include <asm/irq_stack.h>
bool idtentry_enter_nmi(struct pt_regs *regs);
void idtentry_exit_nmi(struct pt_regs *regs, bool irq_state);
/**
* DECLARE_IDTENTRY - Declare functions for simple IDT entry points
* No error code pushed by hardware

6
arch/x86/kernel/cpu/mce/core.c
View File

@ -1983,7 +1983,7 @@ void (*machine_check_vector)(struct pt_regs *) = unexpected_machine_check;
static __always_inline void exc_machine_check_kernel(struct pt_regs *regs)
{
bool irq_state;
irqentry_state_t irq_state;
WARN_ON_ONCE(user_mode(regs));
@ -1995,7 +1995,7 @@ static __always_inline void exc_machine_check_kernel(struct pt_regs *regs)
mce_check_crashing_cpu())
return;
irq_state = idtentry_enter_nmi(regs);
irq_state = irqentry_nmi_enter(regs);
/*
* The call targets are marked noinstr, but objtool can't figure
* that out because it's an indirect call. Annotate it.
@ -2006,7 +2006,7 @@ static __always_inline void exc_machine_check_kernel(struct pt_regs *regs)
if (regs->flags & X86_EFLAGS_IF)
trace_hardirqs_on_prepare();
instrumentation_end();
idtentry_exit_nmi(regs, irq_state);
irqentry_nmi_exit(regs, irq_state);
}
static __always_inline void exc_machine_check_user(struct pt_regs *regs)

6
arch/x86/kernel/nmi.c
View File

@ -475,7 +475,7 @@ static DEFINE_PER_CPU(unsigned long, nmi_dr7);
DEFINE_IDTENTRY_RAW(exc_nmi)
{
bool irq_state;
irqentry_state_t irq_state;
/*
* Re-enable NMIs right here when running as an SEV-ES guest. This might
@ -502,14 +502,14 @@ nmi_restart:
this_cpu_write(nmi_dr7, local_db_save());
irq_state = idtentry_enter_nmi(regs);
irq_state = irqentry_nmi_enter(regs);
inc_irq_stat(__nmi_count);
if (!ignore_nmis)
default_do_nmi(regs);
idtentry_exit_nmi(regs, irq_state);
irqentry_nmi_exit(regs, irq_state);
local_db_restore(this_cpu_read(nmi_dr7));

13
arch/x86/kernel/traps.c
View File

@ -405,7 +405,7 @@ DEFINE_IDTENTRY_DF(exc_double_fault)
}
#endif
idtentry_enter_nmi(regs);
irqentry_nmi_enter(regs);
instrumentation_begin();
notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
@ -651,12 +651,13 @@ DEFINE_IDTENTRY_RAW(exc_int3)
instrumentation_end();
irqentry_exit_to_user_mode(regs);
} else {
bool irq_state = idtentry_enter_nmi(regs);
irqentry_state_t irq_state = irqentry_nmi_enter(regs);
instrumentation_begin();
if (!do_int3(regs))
die("int3", regs, 0);
instrumentation_end();
idtentry_exit_nmi(regs, irq_state);
irqentry_nmi_exit(regs, irq_state);
}
}
@ -851,7 +852,7 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs,
* includes the entry stack is excluded for everything.
*/
unsigned long dr7 = local_db_save();
bool irq_state = idtentry_enter_nmi(regs);
irqentry_state_t irq_state = irqentry_nmi_enter(regs);
instrumentation_begin();
/*
@ -908,7 +909,7 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs,
regs->flags &= ~X86_EFLAGS_TF;
out:
instrumentation_end();
idtentry_exit_nmi(regs, irq_state);
irqentry_nmi_exit(regs, irq_state);
local_db_restore(dr7);
}
@ -926,7 +927,7 @@ static __always_inline void exc_debug_user(struct pt_regs *regs,
/*
* NB: We can't easily clear DR7 here because
* idtentry_exit_to_usermode() can invoke ptrace, schedule, access
* irqentry_exit_to_usermode() can invoke ptrace, schedule, access
* user memory, etc. This means that a recursive #DB is possible. If
* this happens, that #DB will hit exc_debug_kernel() and clear DR7.
* Since we're not on the IST stack right now, everything will be

39
include/linux/entry-common.h
View File

@ -346,8 +346,26 @@ void irqentry_enter_from_user_mode(struct pt_regs *regs);
void irqentry_exit_to_user_mode(struct pt_regs *regs);
#ifndef irqentry_state
/**
* struct irqentry_state - Opaque object for exception state storage
* @exit_rcu: Used exclusively in the irqentry_*() calls; signals whether the
* exit path has to invoke rcu_irq_exit().
* @lockdep: Used exclusively in the irqentry_nmi_*() calls; ensures that
* lockdep state is restored correctly on exit from nmi.
*
* This opaque object is filled in by the irqentry_*_enter() functions and
* must be passed back into the corresponding irqentry_*_exit() functions
* when the exception is complete.
*
* Callers of irqentry_*_[enter|exit]() must consider this structure opaque
* and all members private. Descriptions of the members are provided to aid in
* the maintenance of the irqentry_*() functions.
*/
typedef struct irqentry_state {
bool exit_rcu;
union {
bool exit_rcu;
bool lockdep;
};
} irqentry_state_t;
#endif
@ -407,4 +425,23 @@ void irqentry_exit_cond_resched(void);
*/
void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state);
/**
* irqentry_nmi_enter - Handle NMI entry
* @regs: Pointer to currents pt_regs
*
* Similar to irqentry_enter() but taking care of the NMI constraints.
*/
irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs);
/**
* irqentry_nmi_exit - Handle return from NMI handling
* @regs: Pointer to pt_regs (NMI entry regs)
* @irq_state: Return value from matching call to irqentry_nmi_enter()
*
* Last action before returning to the low level assmenbly code.
*
* Counterpart to irqentry_nmi_enter().
*/
void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state);
#endif

36
kernel/entry/common.c
View File

@ -405,3 +405,39 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state)
rcu_irq_exit();
}
}
irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs)
{
irqentry_state_t irq_state;
irq_state.lockdep = lockdep_hardirqs_enabled();
__nmi_enter();
lockdep_hardirqs_off(CALLER_ADDR0);
lockdep_hardirq_enter();
rcu_nmi_enter();
instrumentation_begin();
trace_hardirqs_off_finish();
ftrace_nmi_enter();
instrumentation_end();
return irq_state;
}
void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state)
{
instrumentation_begin();
ftrace_nmi_exit();
if (irq_state.lockdep) {
trace_hardirqs_on_prepare();
lockdep_hardirqs_on_prepare(CALLER_ADDR0);
}
instrumentation_end();
rcu_nmi_exit();
lockdep_hardirq_exit();
if (irq_state.lockdep)
lockdep_hardirqs_on(CALLER_ADDR0);
__nmi_exit();
}