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authorMilton Miller <miltonm@bga.com>2011-05-10 19:29:39 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2011-05-19 15:31:03 +1000
commit23d72bfd8f9f24aa9efafed3586a99f5669c23d7 (patch)
treef8fbd87c64de43c1d85a830f1f3342818414764a /arch/powerpc/sysdev
parent17f9c8a73bac2c7dfe28a520516ea6b8bbbe977e (diff)
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powerpc: Consolidate ipi message mux and demux
Consolidate the mux and demux of ipi messages into smp.c and call a new smp_ops callback to actually trigger the ipi. The powerpc architecture code is optimised for having 4 distinct ipi triggers, which are mapped to 4 distinct messages (ipi many, ipi single, scheduler ipi, and enter debugger). However, several interrupt controllers only provide a single software triggered interrupt that can be delivered to each cpu. To resolve this limitation, each smp_ops implementation created a per-cpu variable that is manipulated with atomic bitops. Since these lines will be contended they are optimialy marked as shared_aligned and take a full cache line for each cpu. Distro kernels may have 2 or 3 of these in their config, each taking per-cpu space even though at most one will be in use. This consolidation removes smp_message_recv and replaces the single call actions cases with direct calls from the common message recognition loop. The complicated debugger ipi case with its muxed crash handling code is moved to debug_ipi_action which is now called from the demux code (instead of the multi-message action calling smp_message_recv). I put a call to reschedule_action to increase the likelyhood of correctly merging the anticipated scheduler_ipi() hook coming from the scheduler tree; that single required call can be inlined later. The actual message decode is a copy of the old pseries xics code with its memory barriers and cache line spacing, augmented with a per-cpu unsigned long based on the book-e doorbell code. The optional data is set via a callback from the implementation and is passed to the new cause-ipi hook along with the logical cpu number. While currently only the doorbell implemntation uses this data it should be almost zero cost to retrieve and pass it -- it adds a single register load for the argument from the same cache line to which we just completed a store and the register is dead on return from the call. I extended the data element from unsigned int to unsigned long in case some other code wanted to associate a pointer. The doorbell check_self is replaced by a call to smp_muxed_ipi_resend, conditioned on the CPU_DBELL feature. The ifdef guard could be relaxed to CONFIG_SMP but I left it with BOOKE for now. Also, the doorbell interrupt vector for book-e was not calling irq_enter and irq_exit, which throws off cpu accounting and causes code to not realize it is running in interrupt context. Add the missing calls. Signed-off-by: Milton Miller <miltonm@bga.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/sysdev')
-rw-r--r--arch/powerpc/sysdev/xics/icp-hv.c10
-rw-r--r--arch/powerpc/sysdev/xics/icp-native.c10
-rw-r--r--arch/powerpc/sysdev/xics/xics-common.c30
3 files changed, 8 insertions, 42 deletions
diff --git a/arch/powerpc/sysdev/xics/icp-hv.c b/arch/powerpc/sysdev/xics/icp-hv.c
index 234764c..9518d36 100644
--- a/arch/powerpc/sysdev/xics/icp-hv.c
+++ b/arch/powerpc/sysdev/xics/icp-hv.c
@@ -118,12 +118,8 @@ static void icp_hv_set_cpu_priority(unsigned char cppr)
#ifdef CONFIG_SMP
-static void icp_hv_message_pass(int cpu, int msg)
+static void icp_hv_cause_ipi(int cpu, unsigned long data)
{
- unsigned long *tgt = &per_cpu(xics_ipi_message, cpu);
-
- set_bit(msg, tgt);
- mb();
icp_hv_set_qirr(cpu, IPI_PRIORITY);
}
@@ -133,7 +129,7 @@ static irqreturn_t icp_hv_ipi_action(int irq, void *dev_id)
icp_hv_set_qirr(cpu, 0xff);
- return xics_ipi_dispatch(cpu);
+ return smp_ipi_demux();
}
#endif /* CONFIG_SMP */
@@ -146,7 +142,7 @@ static const struct icp_ops icp_hv_ops = {
.flush_ipi = icp_hv_flush_ipi,
#ifdef CONFIG_SMP
.ipi_action = icp_hv_ipi_action,
- .message_pass = icp_hv_message_pass,
+ .cause_ipi = icp_hv_cause_ipi,
#endif
};
diff --git a/arch/powerpc/sysdev/xics/icp-native.c b/arch/powerpc/sysdev/xics/icp-native.c
index 246500e..1f15ad4 100644
--- a/arch/powerpc/sysdev/xics/icp-native.c
+++ b/arch/powerpc/sysdev/xics/icp-native.c
@@ -134,12 +134,8 @@ static unsigned int icp_native_get_irq(void)
#ifdef CONFIG_SMP
-static void icp_native_message_pass(int cpu, int msg)
+static void icp_native_cause_ipi(int cpu, unsigned long data)
{
- unsigned long *tgt = &per_cpu(xics_ipi_message, cpu);
-
- set_bit(msg, tgt);
- mb();
icp_native_set_qirr(cpu, IPI_PRIORITY);
}
@@ -149,7 +145,7 @@ static irqreturn_t icp_native_ipi_action(int irq, void *dev_id)
icp_native_set_qirr(cpu, 0xff);
- return xics_ipi_dispatch(cpu);
+ return smp_ipi_demux();
}
#endif /* CONFIG_SMP */
@@ -267,7 +263,7 @@ static const struct icp_ops icp_native_ops = {
.flush_ipi = icp_native_flush_ipi,
#ifdef CONFIG_SMP
.ipi_action = icp_native_ipi_action,
- .message_pass = icp_native_message_pass,
+ .cause_ipi = icp_native_cause_ipi,
#endif
};
diff --git a/arch/powerpc/sysdev/xics/xics-common.c b/arch/powerpc/sysdev/xics/xics-common.c
index a0576b7..a31a710 100644
--- a/arch/powerpc/sysdev/xics/xics-common.c
+++ b/arch/powerpc/sysdev/xics/xics-common.c
@@ -126,32 +126,6 @@ void xics_mask_unknown_vec(unsigned int vec)
#ifdef CONFIG_SMP
-DEFINE_PER_CPU_SHARED_ALIGNED(unsigned long, xics_ipi_message);
-
-irqreturn_t xics_ipi_dispatch(int cpu)
-{
- unsigned long *tgt = &per_cpu(xics_ipi_message, cpu);
-
- mb(); /* order mmio clearing qirr */
- while (*tgt) {
- if (test_and_clear_bit(PPC_MSG_CALL_FUNCTION, tgt)) {
- smp_message_recv(PPC_MSG_CALL_FUNCTION);
- }
- if (test_and_clear_bit(PPC_MSG_RESCHEDULE, tgt)) {
- smp_message_recv(PPC_MSG_RESCHEDULE);
- }
- if (test_and_clear_bit(PPC_MSG_CALL_FUNC_SINGLE, tgt)) {
- smp_message_recv(PPC_MSG_CALL_FUNC_SINGLE);
- }
-#if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
- if (test_and_clear_bit(PPC_MSG_DEBUGGER_BREAK, tgt)) {
- smp_message_recv(PPC_MSG_DEBUGGER_BREAK);
- }
-#endif
- }
- return IRQ_HANDLED;
-}
-
static void xics_request_ipi(void)
{
unsigned int ipi;
@@ -170,8 +144,8 @@ static void xics_request_ipi(void)
int __init xics_smp_probe(void)
{
- /* Setup message_pass callback based on which ICP is used */
- smp_ops->message_pass = icp_ops->message_pass;
+ /* Setup cause_ipi callback based on which ICP is used */
+ smp_ops->cause_ipi = icp_ops->cause_ipi;
/* Register all the IPIs */
xics_request_ipi();
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