[PATCH AUTOSEL 5.9 27/39] sched/idle: Fix arch_cpu_idle() vs tracing

Sasha Levin
2020-12-03T13:39:06Z

From: Peter Zijlstra <peterz@infradead.org>

[ Upstream commit 58c644ba512cfbc2e39b758dd979edd1d6d00e27 ]

We call arch_cpu_idle() with RCU disabled, but then use
local_irq_{en,dis}able(), which invokes tracing, which relies on RCU.

Switch all arch_cpu_idle() implementations to use
raw_local_irq_{en,dis}able() and carefully manage the
lockdep,rcu,tracing state like we do in entry.

(XXX: we really should change arch_cpu_idle() to not return with
interrupts enabled)

Reported-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lkml.kernel.org/r/20201120114925.594122626@infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/alpha/kernel/process.c | 2 +-
arch/arm/kernel/process.c | 2 +-
arch/arm64/kernel/process.c | 2 +-
arch/csky/kernel/process.c | 2 +-
arch/h8300/kernel/process.c | 2 +-
arch/hexagon/kernel/process.c | 2 +-
arch/ia64/kernel/process.c | 2 +-
arch/microblaze/kernel/process.c | 2 +-
arch/mips/kernel/idle.c | 12 ++++++------
arch/nios2/kernel/process.c | 2 +-
arch/openrisc/kernel/process.c | 2 +-
arch/parisc/kernel/process.c | 2 +-
arch/powerpc/kernel/idle.c | 4 ++--
arch/riscv/kernel/process.c | 2 +-
arch/s390/kernel/idle.c | 6 +++---
arch/sh/kernel/idle.c | 2 +-
arch/sparc/kernel/leon_pmc.c | 4 ++--
arch/sparc/kernel/process_32.c | 2 +-
arch/sparc/kernel/process_64.c | 4 ++--
arch/um/kernel/process.c | 2 +-
arch/x86/include/asm/mwait.h | 2 --
arch/x86/kernel/process.c | 12 +++++++-----
kernel/sched/idle.c | 28 +++++++++++++++++++++++++++-
23 files changed, 64 insertions(+), 38 deletions(-)

diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c
index 7462a79110024..4c7b0414a3ff3 100644
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -57,7 +57,7 @@ EXPORT_SYMBOL(pm_power_off);
void arch_cpu_idle(void)
{
wtint(0);
- local_irq_enable();
+ raw_local_irq_enable();
}

void arch_cpu_idle_dead(void)
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 8e6ace03e960b..9f199b1e83839 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -71,7 +71,7 @@ void arch_cpu_idle(void)
arm_pm_idle();
else
cpu_do_idle();
- local_irq_enable();
+ raw_local_irq_enable();
}

void arch_cpu_idle_prepare(void)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 2da5f3f9d345f..f7c42a7d09b66 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -124,7 +124,7 @@ void arch_cpu_idle(void)
* tricks
*/
cpu_do_idle();
- local_irq_enable();
+ raw_local_irq_enable();
}

#ifdef CONFIG_HOTPLUG_CPU
diff --git a/arch/csky/kernel/process.c b/arch/csky/kernel/process.c
index f730869e21eed..69af6bc87e647 100644
--- a/arch/csky/kernel/process.c
+++ b/arch/csky/kernel/process.c
@@ -102,6 +102,6 @@ void arch_cpu_idle(void)
#ifdef CONFIG_CPU_PM_STOP
asm volatile("stop\n");
#endif
- local_irq_enable();
+ raw_local_irq_enable();
}
#endif
diff --git a/arch/h8300/kernel/process.c b/arch/h8300/kernel/process.c
index 83ce3caf73139..a2961c7b2332c 100644
--- a/arch/h8300/kernel/process.c
+++ b/arch/h8300/kernel/process.c
@@ -57,7 +57,7 @@ asmlinkage void ret_from_kernel_thread(void);
*/
void arch_cpu_idle(void)
{
- local_irq_enable();
+ raw_local_irq_enable();
__asm__("sleep");
}

diff --git a/arch/hexagon/kernel/process.c b/arch/hexagon/kernel/process.c
index dfd322c5ce83a..20962601a1b47 100644
--- a/arch/hexagon/kernel/process.c
+++ b/arch/hexagon/kernel/process.c
@@ -44,7 +44,7 @@ void arch_cpu_idle(void)
{
__vmwait();
/* interrupts wake us up, but irqs are still disabled */
- local_irq_enable();
+ raw_local_irq_enable();
}

/*
diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
index f19cb97c00987..1b2769260688d 100644
--- a/arch/ia64/kernel/process.c
+++ b/arch/ia64/kernel/process.c
@@ -252,7 +252,7 @@ void arch_cpu_idle(void)
if (mark_idle)
(*mark_idle)(1);

- safe_halt();
+ raw_safe_halt();

if (mark_idle)
(*mark_idle)(0);
diff --git a/arch/microblaze/kernel/process.c b/arch/microblaze/kernel/process.c
index a9e46e525cd0a..f99860771ff48 100644
--- a/arch/microblaze/kernel/process.c
+++ b/arch/microblaze/kernel/process.c
@@ -149,5 +149,5 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t *fpregs)

void arch_cpu_idle(void)
{
- local_irq_enable();
+ raw_local_irq_enable();
}
diff --git a/arch/mips/kernel/idle.c b/arch/mips/kernel/idle.c
index 5bc3b04693c7d..18e69ebf5691d 100644
--- a/arch/mips/kernel/idle.c
+++ b/arch/mips/kernel/idle.c
@@ -33,19 +33,19 @@ static void __cpuidle r3081_wait(void)
{
unsigned long cfg = read_c0_conf();
write_c0_conf(cfg | R30XX_CONF_HALT);
- local_irq_enable();
+ raw_local_irq_enable();
}

static void __cpuidle r39xx_wait(void)
{
if (!need_resched())
write_c0_conf(read_c0_conf() | TX39_CONF_HALT);
- local_irq_enable();
+ raw_local_irq_enable();
}

void __cpuidle r4k_wait(void)
{
- local_irq_enable();
+ raw_local_irq_enable();
__r4k_wait();
}

@@ -64,7 +64,7 @@ void __cpuidle r4k_wait_irqoff(void)
" .set arch=r4000 \n"
" wait \n"
" .set pop \n");
- local_irq_enable();
+ raw_local_irq_enable();
}

/*
@@ -84,7 +84,7 @@ static void __cpuidle rm7k_wait_irqoff(void)
" wait \n"
" mtc0 $1, $12 # stalls until W stage \n"
" .set pop \n");
- local_irq_enable();
+ raw_local_irq_enable();
}

/*
@@ -257,7 +257,7 @@ void arch_cpu_idle(void)
if (cpu_wait)
cpu_wait();
else
- local_irq_enable();
+ raw_local_irq_enable();
}

#ifdef CONFIG_CPU_IDLE
diff --git a/arch/nios2/kernel/process.c b/arch/nios2/kernel/process.c
index 88a4ec03edab4..f5cc55a88d310 100644
--- a/arch/nios2/kernel/process.c
+++ b/arch/nios2/kernel/process.c
@@ -33,7 +33,7 @@ EXPORT_SYMBOL(pm_power_off);

void arch_cpu_idle(void)
{
- local_irq_enable();
+ raw_local_irq_enable();
}

/*
diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
index 0ff391f00334c..3c98728cce249 100644
--- a/arch/openrisc/kernel/process.c
+++ b/arch/openrisc/kernel/process.c
@@ -79,7 +79,7 @@ void machine_power_off(void)
*/
void arch_cpu_idle(void)
{
- local_irq_enable();
+ raw_local_irq_enable();
if (mfspr(SPR_UPR) & SPR_UPR_PMP)
mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME);
}
diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index f196d96e2f9f5..a92a23d6acd93 100644
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -169,7 +169,7 @@ void __cpuidle arch_cpu_idle_dead(void)

void __cpuidle arch_cpu_idle(void)
{
- local_irq_enable();
+ raw_local_irq_enable();

/* nop on real hardware, qemu will idle sleep. */
asm volatile("or %%r10,%%r10,%%r10\n":::);
diff --git a/arch/powerpc/kernel/idle.c b/arch/powerpc/kernel/idle.c
index 422e31d2f5a2b..8df35f1329a42 100644
--- a/arch/powerpc/kernel/idle.c
+++ b/arch/powerpc/kernel/idle.c
@@ -60,9 +60,9 @@ void arch_cpu_idle(void)
* interrupts enabled, some don't.
*/
if (irqs_disabled())
- local_irq_enable();
+ raw_local_irq_enable();
} else {
- local_irq_enable();
+ raw_local_irq_enable();
/*
* Go into low thread priority and possibly
* low power mode.
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 2b97c493427c9..308e1d95ecbf0 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -36,7 +36,7 @@ extern asmlinkage void ret_from_kernel_thread(void);
void arch_cpu_idle(void)
{
wait_for_interrupt();
- local_irq_enable();
+ raw_local_irq_enable();
}

void show_regs(struct pt_regs *regs)
diff --git a/arch/s390/kernel/idle.c b/arch/s390/kernel/idle.c
index f7f1e64e0d980..2b85096964f84 100644
--- a/arch/s390/kernel/idle.c
+++ b/arch/s390/kernel/idle.c
@@ -33,10 +33,10 @@ void enabled_wait(void)
PSW_MASK_IO | PSW_MASK_EXT | PSW_MASK_MCHECK;
clear_cpu_flag(CIF_NOHZ_DELAY);

- local_irq_save(flags);
+ raw_local_irq_save(flags);
/* Call the assembler magic in entry.S */
psw_idle(idle, psw_mask);
- local_irq_restore(flags);
+ raw_local_irq_restore(flags);

/* Account time spent with enabled wait psw loaded as idle time. */
raw_write_seqcount_begin(&idle->seqcount);
@@ -123,7 +123,7 @@ void arch_cpu_idle_enter(void)
void arch_cpu_idle(void)
{
enabled_wait();
- local_irq_enable();
+ raw_local_irq_enable();
}

void arch_cpu_idle_exit(void)
diff --git a/arch/sh/kernel/idle.c b/arch/sh/kernel/idle.c
index 0dc0f52f9bb8d..f59814983bd59 100644
--- a/arch/sh/kernel/idle.c
+++ b/arch/sh/kernel/idle.c
@@ -22,7 +22,7 @@ static void (*sh_idle)(void);
void default_idle(void)
{
set_bl_bit();
- local_irq_enable();
+ raw_local_irq_enable();
/* Isn't this racy ? */
cpu_sleep();
clear_bl_bit();
diff --git a/arch/sparc/kernel/leon_pmc.c b/arch/sparc/kernel/leon_pmc.c
index 065e2d4b72908..396f46bca52eb 100644
--- a/arch/sparc/kernel/leon_pmc.c
+++ b/arch/sparc/kernel/leon_pmc.c
@@ -50,7 +50,7 @@ static void pmc_leon_idle_fixup(void)
register unsigned int address = (unsigned int)leon3_irqctrl_regs;

/* Interrupts need to be enabled to not hang the CPU */
- local_irq_enable();
+ raw_local_irq_enable();

__asm__ __volatile__ (
"wr %%g0, %%asr19\n"
@@ -66,7 +66,7 @@ static void pmc_leon_idle_fixup(void)
static void pmc_leon_idle(void)
{
/* Interrupts need to be enabled to not hang the CPU */
- local_irq_enable();
+ raw_local_irq_enable();

/* For systems without power-down, this will be no-op */
__asm__ __volatile__ ("wr %g0, %asr19\n\t");
diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c
index adfcaeab3ddc5..a023637359154 100644
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -74,7 +74,7 @@ void arch_cpu_idle(void)
{
if (sparc_idle)
(*sparc_idle)();
- local_irq_enable();
+ raw_local_irq_enable();
}

/* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index a75093b993f9a..6f8c7822fc065 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -62,11 +62,11 @@ void arch_cpu_idle(void)
{
if (tlb_type != hypervisor) {
touch_nmi_watchdog();
- local_irq_enable();
+ raw_local_irq_enable();
} else {
unsigned long pstate;

- local_irq_enable();
+ raw_local_irq_enable();

/* The sun4v sleeping code requires that we have PSTATE.IE cleared over
* the cpu sleep hypervisor call.
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 26b5e243d3fc0..495f101792b3d 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -217,7 +217,7 @@ void arch_cpu_idle(void)
{
cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
um_idle_sleep();
- local_irq_enable();
+ raw_local_irq_enable();
}

int __cant_sleep(void) {
diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h
index e039a933aca3c..29dd27b5a339d 100644
--- a/arch/x86/include/asm/mwait.h
+++ b/arch/x86/include/asm/mwait.h
@@ -88,8 +88,6 @@ static inline void __mwaitx(unsigned long eax, unsigned long ebx,

static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
{
- trace_hardirqs_on();
-
mds_idle_clear_cpu_buffers();
/* "mwait %eax, %ecx;" */
asm volatile("sti; .byte 0x0f, 0x01, 0xc9;"
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index ba4593a913fab..145a7ac0c19aa 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -685,7 +685,7 @@ void arch_cpu_idle(void)
*/
void __cpuidle default_idle(void)
{
- safe_halt();
+ raw_safe_halt();
}
#if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE)
EXPORT_SYMBOL(default_idle);
@@ -736,6 +736,8 @@ void stop_this_cpu(void *dummy)
/*
* AMD Erratum 400 aware idle routine. We handle it the same way as C3 power
* states (local apic timer and TSC stop).
+ *
+ * XXX this function is completely buggered vs RCU and tracing.
*/
static void amd_e400_idle(void)
{
@@ -757,9 +759,9 @@ static void amd_e400_idle(void)
* The switch back from broadcast mode needs to be called with
* interrupts disabled.
*/
- local_irq_disable();
+ raw_local_irq_disable();
tick_broadcast_exit();
- local_irq_enable();
+ raw_local_irq_enable();
}

/*
@@ -801,9 +803,9 @@ static __cpuidle void mwait_idle(void)
if (!need_resched())
__sti_mwait(0, 0);
else
- local_irq_enable();
+ raw_local_irq_enable();
} else {
- local_irq_enable();
+ raw_local_irq_enable();
}
__current_clr_polling();
}
diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c
index f324dc36fc43d..dee807ffad11b 100644
--- a/kernel/sched/idle.c
+++ b/kernel/sched/idle.c
@@ -78,7 +78,7 @@ void __weak arch_cpu_idle_dead(void) { }
void __weak arch_cpu_idle(void)
{
cpu_idle_force_poll = 1;
- local_irq_enable();
+ raw_local_irq_enable();
}

/**
@@ -94,9 +94,35 @@ void __cpuidle default_idle_call(void)

trace_cpu_idle(1, smp_processor_id());
stop_critical_timings();
+
+ /*
+ * arch_cpu_idle() is supposed to enable IRQs, however
+ * we can't do that because of RCU and tracing.
+ *
+ * Trace IRQs enable here, then switch off RCU, and have
+ * arch_cpu_idle() use raw_local_irq_enable(). Note that
+ * rcu_idle_enter() relies on lockdep IRQ state, so switch that
+ * last -- this is very similar to the entry code.
+ */
+ trace_hardirqs_on_prepare();
+ lockdep_hardirqs_on_prepare(_THIS_IP_);
rcu_idle_enter();
+ lockdep_hardirqs_on(_THIS_IP_);
+
arch_cpu_idle();
+
+ /*
+ * OK, so IRQs are enabled here, but RCU needs them disabled to
+ * turn itself back on.. funny thing is that disabling IRQs
+ * will cause tracing, which needs RCU. Jump through hoops to
+ * make it 'work'.
+ */
+ raw_local_irq_disable();
+ lockdep_hardirqs_off(_THIS_IP_);
rcu_idle_exit();
+ lockdep_hardirqs_on(_THIS_IP_);
+ raw_local_irq_enable();
+
start_critical_timings();
trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
}
--
2.27.0