From: Ira Weiny ira.weiny@intel.com
Currently struct irqentry_state_t only contains a single bool value which makes passing it by value is reasonable. However, future patches propose to add information to this struct, for example the PKRS register/thread state.
Adding information to irqentry_state_t makes passing by value less efficient. Therefore, change the entry/exit calls to pass irq_state by reference.
While at it, make the code easier to follow by changing all the usage sites to consistently use the variable name 'irq_state'.
Signed-off-by: Ira Weiny ira.weiny@intel.com
--- Changes from V1 From Thomas: Update commit message Further clean up Kernel doc and comments Missed some 'return' comments which are no longer valid
Changes from RFC V3 Clean up @irq_state comments Standardize on 'irq_state' for the state variable name Refactor based on new patch from Thomas Gleixner Also addresses Peter Zijlstra's comment --- arch/x86/entry/common.c | 8 ++++---- arch/x86/include/asm/idtentry.h | 25 ++++++++++++++---------- arch/x86/kernel/cpu/mce/core.c | 4 ++-- arch/x86/kernel/kvm.c | 6 +++--- arch/x86/kernel/nmi.c | 4 ++-- arch/x86/kernel/traps.c | 21 ++++++++++++-------- arch/x86/mm/fault.c | 6 +++--- include/linux/entry-common.h | 18 +++++++++-------- kernel/entry/common.c | 34 +++++++++++++-------------------- 9 files changed, 65 insertions(+), 61 deletions(-)
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index 18d8f17f755c..87dea56a15d2 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -259,9 +259,9 @@ __visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs) { struct pt_regs *old_regs; bool inhcall; - irqentry_state_t state; + irqentry_state_t irq_state;
- state = irqentry_enter(regs); + irqentry_enter(regs, &irq_state); old_regs = set_irq_regs(regs);
instrumentation_begin(); @@ -271,13 +271,13 @@ __visible noinstr void xen_pv_evtchn_do_upcall(struct pt_regs *regs) set_irq_regs(old_regs);
inhcall = get_and_clear_inhcall(); - if (inhcall && !WARN_ON_ONCE(state.exit_rcu)) { + if (inhcall && !WARN_ON_ONCE(irq_state.exit_rcu)) { instrumentation_begin(); irqentry_exit_cond_resched(); instrumentation_end(); restore_inhcall(inhcall); } else { - irqentry_exit(regs, state); + irqentry_exit(regs, &irq_state); } } #endif /* CONFIG_XEN_PV */ diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index 247a60a47331..282d2413b6a1 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -49,12 +49,13 @@ static __always_inline void __##func(struct pt_regs *regs); \ \ __visible noinstr void func(struct pt_regs *regs) \ { \ - irqentry_state_t state = irqentry_enter(regs); \ + irqentry_state_t irq_state; \ \ + irqentry_enter(regs, &irq_state); \ instrumentation_begin(); \ __##func (regs); \ instrumentation_end(); \ - irqentry_exit(regs, state); \ + irqentry_exit(regs, &irq_state); \ } \ \ static __always_inline void __##func(struct pt_regs *regs) @@ -96,12 +97,13 @@ static __always_inline void __##func(struct pt_regs *regs, \ __visible noinstr void func(struct pt_regs *regs, \ unsigned long error_code) \ { \ - irqentry_state_t state = irqentry_enter(regs); \ + irqentry_state_t irq_state; \ \ + irqentry_enter(regs, &irq_state); \ instrumentation_begin(); \ __##func (regs, error_code); \ instrumentation_end(); \ - irqentry_exit(regs, state); \ + irqentry_exit(regs, &irq_state); \ } \ \ static __always_inline void __##func(struct pt_regs *regs, \ @@ -192,15 +194,16 @@ static __always_inline void __##func(struct pt_regs *regs, u8 vector); \ __visible noinstr void func(struct pt_regs *regs, \ unsigned long error_code) \ { \ - irqentry_state_t state = irqentry_enter(regs); \ + irqentry_state_t irq_state; \ \ + irqentry_enter(regs, &irq_state); \ instrumentation_begin(); \ irq_enter_rcu(); \ kvm_set_cpu_l1tf_flush_l1d(); \ __##func (regs, (u8)error_code); \ irq_exit_rcu(); \ instrumentation_end(); \ - irqentry_exit(regs, state); \ + irqentry_exit(regs, &irq_state); \ } \ \ static __always_inline void __##func(struct pt_regs *regs, u8 vector) @@ -234,15 +237,16 @@ static void __##func(struct pt_regs *regs); \ \ __visible noinstr void func(struct pt_regs *regs) \ { \ - irqentry_state_t state = irqentry_enter(regs); \ + irqentry_state_t irq_state; \ \ + irqentry_enter(regs, &irq_state); \ instrumentation_begin(); \ irq_enter_rcu(); \ kvm_set_cpu_l1tf_flush_l1d(); \ run_sysvec_on_irqstack_cond(__##func, regs); \ irq_exit_rcu(); \ instrumentation_end(); \ - irqentry_exit(regs, state); \ + irqentry_exit(regs, &irq_state); \ } \ \ static noinline void __##func(struct pt_regs *regs) @@ -263,15 +267,16 @@ static __always_inline void __##func(struct pt_regs *regs); \ \ __visible noinstr void func(struct pt_regs *regs) \ { \ - irqentry_state_t state = irqentry_enter(regs); \ + irqentry_state_t irq_state; \ \ + irqentry_enter(regs, &irq_state); \ instrumentation_begin(); \ __irq_enter_raw(); \ kvm_set_cpu_l1tf_flush_l1d(); \ __##func (regs); \ __irq_exit_raw(); \ instrumentation_end(); \ - irqentry_exit(regs, state); \ + irqentry_exit(regs, &irq_state); \ } \ \ static __always_inline void __##func(struct pt_regs *regs) diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index 403561a89c28..169168e535f2 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -1993,7 +1993,7 @@ static __always_inline void exc_machine_check_kernel(struct pt_regs *regs) mce_check_crashing_cpu()) return;
- irq_state = irqentry_nmi_enter(regs); + irqentry_nmi_enter(regs, &irq_state); /* * The call targets are marked noinstr, but objtool can't figure * that out because it's an indirect call. Annotate it. @@ -2004,7 +2004,7 @@ static __always_inline void exc_machine_check_kernel(struct pt_regs *regs) if (regs->flags & X86_EFLAGS_IF) trace_hardirqs_on_prepare(); instrumentation_end(); - irqentry_nmi_exit(regs, irq_state); + irqentry_nmi_exit(regs, &irq_state); }
static __always_inline void exc_machine_check_user(struct pt_regs *regs) diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 7f57ede3cb8e..ed7427c6e74d 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -238,12 +238,12 @@ EXPORT_SYMBOL_GPL(kvm_read_and_reset_apf_flags); noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token) { u32 flags = kvm_read_and_reset_apf_flags(); - irqentry_state_t state; + irqentry_state_t irq_state;
if (!flags) return false;
- state = irqentry_enter(regs); + irqentry_enter(regs, &irq_state); instrumentation_begin();
/* @@ -264,7 +264,7 @@ noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token) }
instrumentation_end(); - irqentry_exit(regs, state); + irqentry_exit(regs, &irq_state); return true; }
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index bf250a339655..1fd7780e99dd 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -502,14 +502,14 @@ DEFINE_IDTENTRY_RAW(exc_nmi)
this_cpu_write(nmi_dr7, local_db_save());
- irq_state = irqentry_nmi_enter(regs); + irqentry_nmi_enter(regs, &irq_state);
inc_irq_stat(__nmi_count);
if (!ignore_nmis) default_do_nmi(regs);
- irqentry_nmi_exit(regs, irq_state); + irqentry_nmi_exit(regs, &irq_state);
local_db_restore(this_cpu_read(nmi_dr7));
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index e1b78829d909..8481cc373794 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -245,7 +245,7 @@ static noinstr bool handle_bug(struct pt_regs *regs)
DEFINE_IDTENTRY_RAW(exc_invalid_op) { - irqentry_state_t state; + irqentry_state_t irq_state;
/* * We use UD2 as a short encoding for 'CALL __WARN', as such @@ -255,11 +255,11 @@ DEFINE_IDTENTRY_RAW(exc_invalid_op) if (!user_mode(regs) && handle_bug(regs)) return;
- state = irqentry_enter(regs); + irqentry_enter(regs, &irq_state); instrumentation_begin(); handle_invalid_op(regs); instrumentation_end(); - irqentry_exit(regs, state); + irqentry_exit(regs, &irq_state); }
DEFINE_IDTENTRY(exc_coproc_segment_overrun) @@ -343,6 +343,7 @@ __visible void __noreturn handle_stack_overflow(const char *message, */ DEFINE_IDTENTRY_DF(exc_double_fault) { + irqentry_state_t irq_state; static const char str[] = "double fault"; struct task_struct *tsk = current;
@@ -405,7 +406,7 @@ DEFINE_IDTENTRY_DF(exc_double_fault) } #endif
- irqentry_nmi_enter(regs); + irqentry_nmi_enter(regs, &irq_state); instrumentation_begin(); notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV);
@@ -651,13 +652,15 @@ DEFINE_IDTENTRY_RAW(exc_int3) instrumentation_end(); irqentry_exit_to_user_mode(regs); } else { - irqentry_state_t irq_state = irqentry_nmi_enter(regs); + irqentry_state_t irq_state; + + irqentry_nmi_enter(regs, &irq_state);
instrumentation_begin(); if (!do_int3(regs)) die("int3", regs, 0); instrumentation_end(); - irqentry_nmi_exit(regs, irq_state); + irqentry_nmi_exit(regs, &irq_state); } }
@@ -852,7 +855,9 @@ 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(); - irqentry_state_t irq_state = irqentry_nmi_enter(regs); + irqentry_state_t irq_state; + + irqentry_nmi_enter(regs, &irq_state); instrumentation_begin();
/* @@ -909,7 +914,7 @@ static __always_inline void exc_debug_kernel(struct pt_regs *regs, regs->flags &= ~X86_EFLAGS_TF; out: instrumentation_end(); - irqentry_nmi_exit(regs, irq_state); + irqentry_nmi_exit(regs, &irq_state);
local_db_restore(dr7); } diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 82bf37a5c9ec..8d20c4c13abf 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1441,7 +1441,7 @@ handle_page_fault(struct pt_regs *regs, unsigned long error_code, DEFINE_IDTENTRY_RAW_ERRORCODE(exc_page_fault) { unsigned long address = read_cr2(); - irqentry_state_t state; + irqentry_state_t irq_state;
prefetchw(¤t->mm->mmap_lock);
@@ -1479,11 +1479,11 @@ DEFINE_IDTENTRY_RAW_ERRORCODE(exc_page_fault) * code reenabled RCU to avoid subsequent wreckage which helps * debugability. */ - state = irqentry_enter(regs); + irqentry_enter(regs, &irq_state);
instrumentation_begin(); handle_page_fault(regs, error_code, address); instrumentation_end();
- irqentry_exit(regs, state); + irqentry_exit(regs, &irq_state); } diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index 7dff07713a07..0e10d0b85817 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -367,6 +367,8 @@ typedef struct irqentry_state { /** * irqentry_enter - Handle state tracking on ordinary interrupt entries * @regs: Pointer to pt_regs of interrupted context + * @irq_state: Pointer to an opaque object to store state information; to be + * passed back to irqentry_exit() * * Invokes: * - lockdep irqflag state tracking as low level ASM entry disabled @@ -392,10 +394,8 @@ typedef struct irqentry_state { * For user mode entries irqentry_enter_from_user_mode() is 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() */ -irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs); +void noinstr irqentry_enter(struct pt_regs *regs, irqentry_state_t *irq_state);
/** * irqentry_exit_cond_resched - Conditionally reschedule on return from interrupt @@ -407,7 +407,7 @@ void irqentry_exit_cond_resched(void); /** * irqentry_exit - Handle return from exception that used irqentry_enter() * @regs: Pointer to pt_regs (exception entry regs) - * @state: Return value from matching call to irqentry_enter() + * @irq_state: Pointer to state information passed to irqentry_enter() * * Depending on the return target (kernel/user) this runs the necessary * preemption and work checks if possible and reguired and returns to @@ -418,25 +418,27 @@ void irqentry_exit_cond_resched(void); * * Counterpart to irqentry_enter(). */ -void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state); +void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t *irq_state);
/** * irqentry_nmi_enter - Handle NMI entry * @regs: Pointer to currents pt_regs + * @irq_state: Pointer to an opaque object to store state information; to be + * passed back to irqentry_nmi_exit() * * Similar to irqentry_enter() but taking care of the NMI constraints. */ -irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs); +void noinstr irqentry_nmi_enter(struct pt_regs *regs, irqentry_state_t *irq_state);
/** * 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() + * @irq_state: Pointer to state information passed 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); +void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t *irq_state);
#endif diff --git a/kernel/entry/common.c b/kernel/entry/common.c index 372f14cc347f..359688400c6b 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -281,15 +281,13 @@ noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs) exit_to_user_mode(); }
-noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs) +noinstr void irqentry_enter(struct pt_regs *regs, irqentry_state_t *irq_state) { - irqentry_state_t ret = { - .exit_rcu = false, - }; + irq_state->exit_rcu = false;
if (user_mode(regs)) { irqentry_enter_from_user_mode(regs); - return ret; + return; }
/* @@ -327,8 +325,8 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs) trace_hardirqs_off_finish(); instrumentation_end();
- ret.exit_rcu = true; - return ret; + irq_state->exit_rcu = true; + return; }
/* @@ -342,8 +340,6 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs) /* Use the combo lockdep/tracing function */ trace_hardirqs_off(); instrumentation_end(); - - return ret; }
void irqentry_exit_cond_resched(void) @@ -358,7 +354,7 @@ void irqentry_exit_cond_resched(void) } }
-noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state) +noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t *irq_state) { lockdep_assert_irqs_disabled();
@@ -371,7 +367,7 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state) * carefully and needs the same ordering of lockdep/tracing * and RCU as the return to user mode path. */ - if (state.exit_rcu) { + if (irq_state->exit_rcu) { instrumentation_begin(); /* Tell the tracer that IRET will enable interrupts */ trace_hardirqs_on_prepare(); @@ -393,16 +389,14 @@ noinstr void irqentry_exit(struct pt_regs *regs, irqentry_state_t state) * IRQ flags state is correct already. Just tell RCU if it * was not watching on entry. */ - if (state.exit_rcu) + if (irq_state->exit_rcu) rcu_irq_exit(); } }
-irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs) +void noinstr irqentry_nmi_enter(struct pt_regs *regs, irqentry_state_t *irq_state) { - irqentry_state_t irq_state; - - irq_state.lockdep = lockdep_hardirqs_enabled(); + irq_state->lockdep = lockdep_hardirqs_enabled();
__nmi_enter(); lockdep_hardirqs_off(CALLER_ADDR0); @@ -413,15 +407,13 @@ irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs) 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) +void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t *irq_state) { instrumentation_begin(); ftrace_nmi_exit(); - if (irq_state.lockdep) { + if (irq_state->lockdep) { trace_hardirqs_on_prepare(); lockdep_hardirqs_on_prepare(CALLER_ADDR0); } @@ -429,7 +421,7 @@ void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state)
rcu_nmi_exit(); lockdep_hardirq_exit(); - if (irq_state.lockdep) + if (irq_state->lockdep) lockdep_hardirqs_on(CALLER_ADDR0); __nmi_exit(); }