hardirq/nmi: Allow nested nmi_enter()

Since there are already a number of sites (ARM64, PowerPC) that effectively
nest nmi_enter(), make the primitive support this before adding even more.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Marc Zyngier <maz@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lkml.kernel.org/r/20200505134100.864179229@linutronix.de
This commit is contained in:
Peter Zijlstra 2020-02-19 09:46:47 +01:00 коммит произвёл Thomas Gleixner
Родитель 28f6bf9e24
Коммит 69ea03b56e
5 изменённых файлов: 16 добавлений и 37 удалений

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@ -251,22 +251,12 @@ asmlinkage __kprobes notrace unsigned long
__sdei_handler(struct pt_regs *regs, struct sdei_registered_event *arg)
{
unsigned long ret;
bool do_nmi_exit = false;
/*
* nmi_enter() deals with printk() re-entrance and use of RCU when
* RCU believed this CPU was idle. Because critical events can
* interrupt normal events, we may already be in_nmi().
*/
if (!in_nmi()) {
nmi_enter();
do_nmi_exit = true;
}
nmi_enter();
ret = _sdei_handler(regs, arg);
if (do_nmi_exit)
nmi_exit();
nmi_exit();
return ret;
}

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@ -906,17 +906,13 @@ bool arm64_is_fatal_ras_serror(struct pt_regs *regs, unsigned int esr)
asmlinkage void do_serror(struct pt_regs *regs, unsigned int esr)
{
const bool was_in_nmi = in_nmi();
if (!was_in_nmi)
nmi_enter();
nmi_enter();
/* non-RAS errors are not containable */
if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(regs, esr))
arm64_serror_panic(regs, esr);
if (!was_in_nmi)
nmi_exit();
nmi_exit();
}
asmlinkage void enter_from_user_mode(void)

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@ -441,15 +441,9 @@ nonrecoverable:
void system_reset_exception(struct pt_regs *regs)
{
unsigned long hsrr0, hsrr1;
bool nested = in_nmi();
bool saved_hsrrs = false;
/*
* Avoid crashes in case of nested NMI exceptions. Recoverability
* is determined by RI and in_nmi
*/
if (!nested)
nmi_enter();
nmi_enter();
/*
* System reset can interrupt code where HSRRs are live and MSR[RI]=1.
@ -521,8 +515,7 @@ out:
mtspr(SPRN_HSRR1, hsrr1);
}
if (!nested)
nmi_exit();
nmi_exit();
/* What should we do here? We could issue a shutdown or hard reset. */
}
@ -823,9 +816,8 @@ int machine_check_generic(struct pt_regs *regs)
void machine_check_exception(struct pt_regs *regs)
{
int recover = 0;
bool nested = in_nmi();
if (!nested)
nmi_enter();
nmi_enter();
__this_cpu_inc(irq_stat.mce_exceptions);
@ -851,8 +843,7 @@ void machine_check_exception(struct pt_regs *regs)
if (check_io_access(regs))
goto bail;
if (!nested)
nmi_exit();
nmi_exit();
die("Machine check", regs, SIGBUS);
@ -863,8 +854,7 @@ void machine_check_exception(struct pt_regs *regs)
return;
bail:
if (!nested)
nmi_exit();
nmi_exit();
}
void SMIException(struct pt_regs *regs)

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@ -65,13 +65,16 @@ extern void irq_exit(void);
#define arch_nmi_exit() do { } while (0)
#endif
/*
* nmi_enter() can nest up to 15 times; see NMI_BITS.
*/
#define nmi_enter() \
do { \
arch_nmi_enter(); \
printk_nmi_enter(); \
lockdep_off(); \
ftrace_nmi_enter(); \
BUG_ON(in_nmi()); \
BUG_ON(in_nmi() == NMI_MASK); \
preempt_count_add(NMI_OFFSET + HARDIRQ_OFFSET); \
rcu_nmi_enter(); \
lockdep_hardirq_enter(); \

Просмотреть файл

@ -26,13 +26,13 @@
* PREEMPT_MASK: 0x000000ff
* SOFTIRQ_MASK: 0x0000ff00
* HARDIRQ_MASK: 0x000f0000
* NMI_MASK: 0x00100000
* NMI_MASK: 0x00f00000
* PREEMPT_NEED_RESCHED: 0x80000000
*/
#define PREEMPT_BITS 8
#define SOFTIRQ_BITS 8
#define HARDIRQ_BITS 4
#define NMI_BITS 1
#define NMI_BITS 4
#define PREEMPT_SHIFT 0
#define SOFTIRQ_SHIFT (PREEMPT_SHIFT + PREEMPT_BITS)