GitHub-Mirror/Star64_linux
2
0
Fork 0
mirror of https://github.com/Fishwaldo/Star64_linux.git synced 2025-06-07 15:18:15 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

x86/entry: Use generic interrupt entry/exit code

Browse source 
Replace the x86 code with the generic variant. Use temporary defines for
idtentry_* which will be cleaned up in the next step.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200722220520.711492752@linutronix.de
This commit is contained in:
Thomas Gleixner 2020-07-23 00:00:07 +02:00
parent 517e499227
commit bdcd178ada
2 changed files with 5 additions and 172 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

167
arch/x86/entry/common.c
View file

@ -198,171 +198,6 @@ SYSCALL_DEFINE0(ni_syscall)
return -ENOSYS; return -ENOSYS;
} }
/**
* idtentry_enter - Handle state tracking on ordinary idtentries
* @regs: Pointer to pt_regs of interrupted context
*
* Invokes:
* - lockdep irqflag state tracking as low level ASM entry disabled
* interrupts.
*
* - Context tracking if the exception hit user mode.
*
* - The hardirq tracer to keep the state consistent as low level ASM
* entry disabled interrupts.
*
* As a precondition, this requires that the entry came from user mode,
* idle, or a kernel context in which RCU is watching.
*
* For kernel mode entries RCU handling is done conditional. If RCU is
* watching then the only RCU requirement is to check whether the tick has
* to be restarted. If RCU is not watching then rcu_irq_enter() has to be
* invoked on entry and rcu_irq_exit() on exit.
*
* Avoiding the rcu_irq_enter/exit() calls is an optimization but also
* solves the problem of kernel mode pagefaults which can schedule, which
* is not possible after invoking rcu_irq_enter() without undoing it.
*
* For user mode entries irqentry_enter_from_user_mode() must be invoked to
* establish the proper context for NOHZ_FULL. Otherwise scheduling on exit
* would not be possible.
*
* Returns: An opaque object that must be passed to idtentry_exit()
*
* The return value must be fed into the state argument of
* idtentry_exit().
*/
idtentry_state_t noinstr idtentry_enter(struct pt_regs *regs)
{
idtentry_state_t ret = {
.exit_rcu = false,
};
if (user_mode(regs)) {
irqentry_enter_from_user_mode(regs);
return ret;
}
/*
* If this entry hit the idle task invoke rcu_irq_enter() whether
* RCU is watching or not.
*
* Interupts can nest when the first interrupt invokes softirq
* processing on return which enables interrupts.
*
* Scheduler ticks in the idle task can mark quiescent state and
* terminate a grace period, if and only if the timer interrupt is
* not nested into another interrupt.
*
* Checking for __rcu_is_watching() here would prevent the nesting
* interrupt to invoke rcu_irq_enter(). If that nested interrupt is
* the tick then rcu_flavor_sched_clock_irq() would wrongfully
* assume that it is the first interupt and eventually claim
* quiescient state and end grace periods prematurely.
*
* Unconditionally invoke rcu_irq_enter() so RCU state stays
* consistent.
*
* TINY_RCU does not support EQS, so let the compiler eliminate
* this part when enabled.
*/
if (!IS_ENABLED(CONFIG_TINY_RCU) && is_idle_task(current)) {
/*
* If RCU is not watching then the same careful
* sequence vs. lockdep and tracing is required
* as in irqentry_enter_from_user_mode().
*/
lockdep_hardirqs_off(CALLER_ADDR0);
rcu_irq_enter();
instrumentation_begin();
trace_hardirqs_off_finish();
instrumentation_end();
ret.exit_rcu = true;
return ret;
}
/*
* If RCU is watching then RCU only wants to check whether it needs
* to restart the tick in NOHZ mode. rcu_irq_enter_check_tick()
* already contains a warning when RCU is not watching, so no point
* in having another one here.
*/
instrumentation_begin();
rcu_irq_enter_check_tick();
/* Use the combo lockdep/tracing function */
trace_hardirqs_off();
instrumentation_end();
return ret;
}
static void idtentry_exit_cond_resched(struct pt_regs *regs, bool may_sched)
{
if (may_sched && !preempt_count()) {
/* Sanity check RCU and thread stack */
rcu_irq_exit_check_preempt();
if (IS_ENABLED(CONFIG_DEBUG_ENTRY))
WARN_ON_ONCE(!on_thread_stack());
if (need_resched())
preempt_schedule_irq();
}
/* Covers both tracing and lockdep */
trace_hardirqs_on();
}
/**
* idtentry_exit - Handle return from exception that used idtentry_enter()
* @regs: Pointer to pt_regs (exception entry regs)
* @state: Return value from matching call to idtentry_enter()
*
* Depending on the return target (kernel/user) this runs the necessary
* preemption and work checks if possible and reguired and returns to
* the caller with interrupts disabled and no further work pending.
*
* This is the last action before returning to the low level ASM code which
* just needs to return to the appropriate context.
*
* Counterpart to idtentry_enter(). The return value of the entry
* function must be fed into the @state argument.
*/
void noinstr idtentry_exit(struct pt_regs *regs, idtentry_state_t state)
{
lockdep_assert_irqs_disabled();
/* Check whether this returns to user mode */
if (user_mode(regs)) {
irqentry_exit_to_user_mode(regs);
} else if (regs->flags & X86_EFLAGS_IF) {
/*
* If RCU was not watching on entry this needs to be done
* carefully and needs the same ordering of lockdep/tracing
* and RCU as the return to user mode path.
*/
if (state.exit_rcu) {
instrumentation_begin();
/* Tell the tracer that IRET will enable interrupts */
trace_hardirqs_on_prepare();
lockdep_hardirqs_on_prepare(CALLER_ADDR0);
instrumentation_end();
rcu_irq_exit();
lockdep_hardirqs_on(CALLER_ADDR0);
return;
}
instrumentation_begin();
idtentry_exit_cond_resched(regs, IS_ENABLED(CONFIG_PREEMPTION));
instrumentation_end();
} else {
/*
* IRQ flags state is correct already. Just tell RCU if it
* was not watching on entry.
*/
if (state.exit_rcu)
rcu_irq_exit();
}
}
#ifdef CONFIG_XEN_PV #ifdef CONFIG_XEN_PV
#ifndef CONFIG_PREEMPTION #ifndef CONFIG_PREEMPTION
/* /*
@ -427,7 +262,7 @@ __visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs)
inhcall = get_and_clear_inhcall(); inhcall = get_and_clear_inhcall();
if (inhcall && !WARN_ON_ONCE(state.exit_rcu)) { if (inhcall && !WARN_ON_ONCE(state.exit_rcu)) {
instrumentation_begin(); instrumentation_begin();
idtentry_exit_cond_resched(regs, true); irqentry_exit_cond_resched();
instrumentation_end(); instrumentation_end();
restore_inhcall(inhcall); restore_inhcall(inhcall);
} else { } else {

10
arch/x86/include/asm/idtentry.h
View file

@ -11,12 +11,10 @@
#include <asm/irq_stack.h> #include <asm/irq_stack.h>
typedef struct idtentry_state { /* Temporary defines */
bool exit_rcu; typedef irqentry_state_t idtentry_state_t;
} idtentry_state_t; #define idtentry_enter irqentry_enter
#define idtentry_exit irqentry_exit
idtentry_state_t idtentry_enter(struct pt_regs *regs);
void idtentry_exit(struct pt_regs *regs, idtentry_state_t state);
/** /**
* DECLARE_IDTENTRY - Declare functions for simple IDT entry points * DECLARE_IDTENTRY - Declare functions for simple IDT entry points