Commit aa6083ed authored by Vineet Gupta's avatar Vineet Gupta

ARCv2: SMP: ARConnect debug/robustness

- Handle possible interrupt coalescing from MCIP
- chk if prev IPI ack before sending new
Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent 82fea5a1
......@@ -448,9 +448,10 @@ menuconfig ARC_DBG
bool "ARC debugging"
default y
if ARC_DBG
config ARC_DW2_UNWIND
bool "Enable DWARF specific kernel stack unwind"
depends on ARC_DBG
default y
select KALLSYMS
help
......@@ -464,18 +465,26 @@ config ARC_DW2_UNWIND
config ARC_DBG_TLB_PARANOIA
bool "Paranoia Checks in Low Level TLB Handlers"
depends on ARC_DBG
default n
config ARC_DBG_TLB_MISS_COUNT
bool "Profile TLB Misses"
default n
select DEBUG_FS
depends on ARC_DBG
help
Counts number of I and D TLB Misses and exports them via Debugfs
The counters can be cleared via Debugfs as well
if SMP
config ARC_IPI_DBG
bool "Debug Inter Core interrupts"
default n
endif
endif
config ARC_UBOOT_SUPPORT
bool "Support uboot arg Handling"
default n
......
......@@ -33,27 +33,67 @@ void mcip_init_smp(unsigned int cpu)
static void mcip_ipi_send(int cpu)
{
unsigned long flags;
int ipi_was_pending;
/*
* NOTE: We must spin here if the other cpu hasn't yet
* serviced a previous message. This can burn lots
* of time, but we MUST follows this protocol or
* ipi messages can be lost!!!
* Also, we must release the lock in this loop because
* the other side may get to this same loop and not
* be able to ack -- thus causing deadlock.
*/
do {
raw_spin_lock_irqsave(&mcip_lock, flags);
__mcip_cmd(CMD_INTRPT_READ_STATUS, cpu);
ipi_was_pending = read_aux_reg(ARC_REG_MCIP_READBACK);
if (ipi_was_pending == 0)
break; /* break out but keep lock */
raw_spin_unlock_irqrestore(&mcip_lock, flags);
} while (1);
raw_spin_lock_irqsave(&mcip_lock, flags);
__mcip_cmd(CMD_INTRPT_GENERATE_IRQ, cpu);
raw_spin_unlock_irqrestore(&mcip_lock, flags);
#ifdef CONFIG_ARC_IPI_DBG
if (ipi_was_pending)
pr_info("IPI ACK delayed from cpu %d\n", cpu);
#endif
}
static void mcip_ipi_clear(int irq)
{
unsigned int cpu;
unsigned int cpu, c;
unsigned long flags;
unsigned int __maybe_unused copy;
raw_spin_lock_irqsave(&mcip_lock, flags);
/* Who sent the IPI */
__mcip_cmd(CMD_INTRPT_CHECK_SOURCE, 0);
cpu = read_aux_reg(ARC_REG_MCIP_READBACK); /* 1,2,4,8... */
copy = cpu = read_aux_reg(ARC_REG_MCIP_READBACK); /* 1,2,4,8... */
__mcip_cmd(CMD_INTRPT_GENERATE_ACK, __ffs(cpu)); /* 0,1,2,3... */
/*
* In rare case, multiple concurrent IPIs sent to same target can
* possibly be coalesced by MCIP into 1 asserted IRQ, so @cpus can be
* "vectored" (multiple bits sets) as opposed to typical single bit
*/
do {
c = __ffs(cpu); /* 0,1,2,3 */
__mcip_cmd(CMD_INTRPT_GENERATE_ACK, c);
cpu &= ~(1U << c);
} while (cpu);
raw_spin_unlock_irqrestore(&mcip_lock, flags);
#ifdef CONFIG_ARC_IPI_DBG
if (c != __ffs(copy))
pr_info("IPIs from %x coalesced to %x\n",
copy, raw_smp_processor_id());
#endif
}
volatile int wake_flag;
......
......@@ -278,8 +278,10 @@ static void ipi_cpu_stop(void)
machine_halt();
}
static inline void __do_IPI(unsigned long msg)
static inline int __do_IPI(unsigned long msg)
{
int rc = 0;
switch (msg) {
case IPI_RESCHEDULE:
scheduler_ipi();
......@@ -294,8 +296,10 @@ static inline void __do_IPI(unsigned long msg)
break;
default:
pr_warn("IPI with unexpected msg %ld\n", msg);
rc = 1;
}
return rc;
}
/*
......@@ -305,6 +309,7 @@ static inline void __do_IPI(unsigned long msg)
irqreturn_t do_IPI(int irq, void *dev_id)
{
unsigned long pending;
unsigned long __maybe_unused copy;
pr_debug("IPI [%ld] received on cpu %d\n",
*this_cpu_ptr(&ipi_data), smp_processor_id());
......@@ -316,11 +321,18 @@ irqreturn_t do_IPI(int irq, void *dev_id)
* "dequeue" the msg corresponding to this IPI (and possibly other
* piggybacked msg from elided IPIs: see ipi_send_msg_one() above)
*/
pending = xchg(this_cpu_ptr(&ipi_data), 0);
copy = pending = xchg(this_cpu_ptr(&ipi_data), 0);
do {
unsigned long msg = __ffs(pending);
__do_IPI(msg);
int rc;
rc = __do_IPI(msg);
#ifdef CONFIG_ARC_IPI_DBG
/* IPI received but no valid @msg */
if (rc)
pr_info("IPI with bogus msg %ld in %ld\n", msg, copy);
#endif
pending &= ~(1U << msg);
} while (pending);
......
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