[PATCH 3.17-rc4 v5 6/6] arm: smp: Handle ipi_cpu_backtrace() using FIQ (if available)

From: Daniel Thompson
Date: Thu Sep 11 2014 - 07:32:00 EST


Previous changes have introduced a replacement default FIQ handler and
an implementation of arch_trigger_all_cpu_backtrace for ARM but these
are currently independant.

This patch plumbs together these features making it possible, on platforms
that support it, to trigger backtrace using FIQ.

Signed-off-by: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
---
arch/arm/include/asm/smp.h | 3 +++
arch/arm/kernel/smp.c | 4 +++-
arch/arm/kernel/traps.c | 3 +++
3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/arm/include/asm/smp.h b/arch/arm/include/asm/smp.h
index 2ec765c..0580270 100644
--- a/arch/arm/include/asm/smp.h
+++ b/arch/arm/include/asm/smp.h
@@ -18,6 +18,8 @@
# error "<asm/smp.h> included in non-SMP build"
#endif

+#define SMP_IPI_FIQ_MASK 0x0100
+
#define raw_smp_processor_id() (current_thread_info()->cpu)

struct seq_file;
@@ -85,6 +87,7 @@ extern void arch_send_call_function_single_ipi(int cpu);
extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
extern void arch_send_wakeup_ipi_mask(const struct cpumask *mask);

+extern void ipi_cpu_backtrace(struct pt_regs *regs);
extern int register_ipi_completion(struct completion *completion, int cpu);

struct smp_operations {
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 94959f9..7a79d11 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -543,7 +543,7 @@ static void ipi_cpu_stop(unsigned int cpu)
cpu_relax();
}

-static void ipi_cpu_backtrace(struct pt_regs *regs)
+void ipi_cpu_backtrace(struct pt_regs *regs)
{
int cpu = smp_processor_id();

@@ -584,6 +584,8 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
unsigned int cpu = smp_processor_id();
struct pt_regs *old_regs = set_irq_regs(regs);

+ BUILD_BUG_ON(SMP_IPI_FIQ_MASK != BIT(IPI_CPU_BACKTRACE));
+
if ((unsigned)ipinr < NR_IPI) {
trace_ipi_entry(ipi_types[ipinr]);
__inc_irq_stat(cpu, ipi_irqs[ipinr]);
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 92c4ea1..40b1de7 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -483,6 +483,9 @@ asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
#ifdef CONFIG_ARM_GIC
gic_handle_fiq_ipi();
#endif
+#ifdef CONFIG_SMP
+ ipi_cpu_backtrace(regs);
+#endif

nmi_exit();

--
1.9.3

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