* [PATCH] sparc/smp: Remove on-stack cpumask var
@ 2025-11-03 15:15 Dawei Li
0 siblings, 0 replies; only message in thread
From: Dawei Li @ 2025-11-03 15:15 UTC (permalink / raw)
To: davem, andreas; +Cc: sparclinux, linux-kernel, dawei.li, set_pte_at, Dawei Li
From: Dawei Li <dawei.li@shingroup.cn>
In general it's preferable to avoid placing cpumasks on the stack, as
for large values of NR_CPUS these can consume significant amounts of
stack space and make stack overflows more likely.
- Change prototype of sparc32_ipi_ops::cross_call() so that it takes
const cpumask * arg and all its callers accordingly.
- As for all cross_call() implementations, divide cpumask_test_cpu() call
into several sub calls to avoid on-stack cpumask var.
Signed-off-by: Dawei Li <dawei.li@shingroup.cn>
Signed-off-by: Dawei Li <dawei.li@linux.dev>
---
arch/sparc/include/asm/smp_32.h | 12 ++++++------
arch/sparc/kernel/kernel.h | 11 +++++++++++
arch/sparc/kernel/leon_smp.c | 11 ++++-------
arch/sparc/kernel/sun4d_smp.c | 10 ++++------
arch/sparc/kernel/sun4m_smp.c | 10 ++++------
5 files changed, 29 insertions(+), 25 deletions(-)
diff --git a/arch/sparc/include/asm/smp_32.h b/arch/sparc/include/asm/smp_32.h
index 9c6ed98fbaf1..cba3dd83e45d 100644
--- a/arch/sparc/include/asm/smp_32.h
+++ b/arch/sparc/include/asm/smp_32.h
@@ -54,7 +54,7 @@ void smp_bogo(struct seq_file *);
void smp_info(struct seq_file *);
struct sparc32_ipi_ops {
- void (*cross_call)(void *func, cpumask_t mask, unsigned long arg1,
+ void (*cross_call)(void *func, const cpumask_t *mask, unsigned long arg1,
unsigned long arg2, unsigned long arg3,
unsigned long arg4);
void (*resched)(int cpu);
@@ -65,29 +65,29 @@ extern const struct sparc32_ipi_ops *sparc32_ipi_ops;
static inline void xc0(void *func)
{
- sparc32_ipi_ops->cross_call(func, *cpu_online_mask, 0, 0, 0, 0);
+ sparc32_ipi_ops->cross_call(func, cpu_online_mask, 0, 0, 0, 0);
}
static inline void xc1(void *func, unsigned long arg1)
{
- sparc32_ipi_ops->cross_call(func, *cpu_online_mask, arg1, 0, 0, 0);
+ sparc32_ipi_ops->cross_call(func, cpu_online_mask, arg1, 0, 0, 0);
}
static inline void xc2(void *func, unsigned long arg1, unsigned long arg2)
{
- sparc32_ipi_ops->cross_call(func, *cpu_online_mask, arg1, arg2, 0, 0);
+ sparc32_ipi_ops->cross_call(func, cpu_online_mask, arg1, arg2, 0, 0);
}
static inline void xc3(void *func, unsigned long arg1, unsigned long arg2,
unsigned long arg3)
{
- sparc32_ipi_ops->cross_call(func, *cpu_online_mask,
+ sparc32_ipi_ops->cross_call(func, cpu_online_mask,
arg1, arg2, arg3, 0);
}
static inline void xc4(void *func, unsigned long arg1, unsigned long arg2,
unsigned long arg3, unsigned long arg4)
{
- sparc32_ipi_ops->cross_call(func, *cpu_online_mask,
+ sparc32_ipi_ops->cross_call(func, cpu_online_mask,
arg1, arg2, arg3, arg4);
}
diff --git a/arch/sparc/kernel/kernel.h b/arch/sparc/kernel/kernel.h
index 8328a3b78a44..7010a691b0e1 100644
--- a/arch/sparc/kernel/kernel.h
+++ b/arch/sparc/kernel/kernel.h
@@ -4,6 +4,7 @@
#include <linux/interrupt.h>
#include <linux/ftrace.h>
+#include <linux/smp.h>
#include <asm/traps.h>
#include <asm/head.h>
@@ -79,6 +80,16 @@ int sparc32_classify_syscall(unsigned int syscall);
#endif
#ifdef CONFIG_SPARC32
+
+#ifdef CONFIG_SMP
+static inline bool cpu_for_ipi(const cpumask_t *mask, unsigned int cpu)
+{
+ return cpumask_test_cpu(cpu, mask) &&
+ cpumask_test_cpu(cpu, cpu_online_mask) &&
+ cpu != smp_processor_id();
+}
+#endif /* CONFIG_SMP */
+
/* setup_32.c */
struct linux_romvec;
void sparc32_start_kernel(struct linux_romvec *rp);
diff --git a/arch/sparc/kernel/leon_smp.c b/arch/sparc/kernel/leon_smp.c
index 1ee393abc463..291884c8d82a 100644
--- a/arch/sparc/kernel/leon_smp.c
+++ b/arch/sparc/kernel/leon_smp.c
@@ -372,7 +372,7 @@ static struct smp_funcall {
static DEFINE_SPINLOCK(cross_call_lock);
/* Cross calls must be serialized, at least currently. */
-static void leon_cross_call(void *func, cpumask_t mask, unsigned long arg1,
+static void leon_cross_call(void *func, const cpumask_t *mask, unsigned long arg1,
unsigned long arg2, unsigned long arg3,
unsigned long arg4)
{
@@ -403,14 +403,11 @@ static void leon_cross_call(void *func, cpumask_t mask, unsigned long arg1,
{
register int i;
- cpumask_clear_cpu(smp_processor_id(), &mask);
- cpumask_and(&mask, cpu_online_mask, &mask);
for (i = 0; i <= high; i++) {
- if (cpumask_test_cpu(i, &mask)) {
+ if (cpu_for_ipi(mask, i)) {
ccall_info.processors_in[i] = 0;
ccall_info.processors_out[i] = 0;
leon_send_ipi(i, LEON3_IRQ_CROSS_CALL);
-
}
}
}
@@ -420,7 +417,7 @@ static void leon_cross_call(void *func, cpumask_t mask, unsigned long arg1,
i = 0;
do {
- if (!cpumask_test_cpu(i, &mask))
+ if (!cpu_for_ipi(mask, i))
continue;
while (!ccall_info.processors_in[i])
@@ -429,7 +426,7 @@ static void leon_cross_call(void *func, cpumask_t mask, unsigned long arg1,
i = 0;
do {
- if (!cpumask_test_cpu(i, &mask))
+ if (!cpu_for_ipi(mask, i))
continue;
while (!ccall_info.processors_out[i])
diff --git a/arch/sparc/kernel/sun4d_smp.c b/arch/sparc/kernel/sun4d_smp.c
index 9a62a5cf3337..7dc57ca05728 100644
--- a/arch/sparc/kernel/sun4d_smp.c
+++ b/arch/sparc/kernel/sun4d_smp.c
@@ -281,7 +281,7 @@ static struct smp_funcall {
static DEFINE_SPINLOCK(cross_call_lock);
/* Cross calls must be serialized, at least currently. */
-static void sun4d_cross_call(void *func, cpumask_t mask, unsigned long arg1,
+static void sun4d_cross_call(void *func, const cpumask_t *mask, unsigned long arg1,
unsigned long arg2, unsigned long arg3,
unsigned long arg4)
{
@@ -315,10 +315,8 @@ static void sun4d_cross_call(void *func, cpumask_t mask, unsigned long arg1,
{
register int i;
- cpumask_clear_cpu(smp_processor_id(), &mask);
- cpumask_and(&mask, cpu_online_mask, &mask);
for (i = 0; i <= high; i++) {
- if (cpumask_test_cpu(i, &mask)) {
+ if (cpu_for_ipi(mask, i)) {
ccall_info.processors_in[i] = 0;
ccall_info.processors_out[i] = 0;
sun4d_send_ipi(i, IRQ_CROSS_CALL);
@@ -331,7 +329,7 @@ static void sun4d_cross_call(void *func, cpumask_t mask, unsigned long arg1,
i = 0;
do {
- if (!cpumask_test_cpu(i, &mask))
+ if (!cpu_for_ipi(mask, i))
continue;
while (!ccall_info.processors_in[i])
barrier();
@@ -339,7 +337,7 @@ static void sun4d_cross_call(void *func, cpumask_t mask, unsigned long arg1,
i = 0;
do {
- if (!cpumask_test_cpu(i, &mask))
+ if (!cpu_for_ipi(mask, i))
continue;
while (!ccall_info.processors_out[i])
barrier();
diff --git a/arch/sparc/kernel/sun4m_smp.c b/arch/sparc/kernel/sun4m_smp.c
index 056df034e79e..3f43f64e3489 100644
--- a/arch/sparc/kernel/sun4m_smp.c
+++ b/arch/sparc/kernel/sun4m_smp.c
@@ -170,7 +170,7 @@ static struct smp_funcall {
static DEFINE_SPINLOCK(cross_call_lock);
/* Cross calls must be serialized, at least currently. */
-static void sun4m_cross_call(void *func, cpumask_t mask, unsigned long arg1,
+static void sun4m_cross_call(void *func, const cpumask_t *mask, unsigned long arg1,
unsigned long arg2, unsigned long arg3,
unsigned long arg4)
{
@@ -191,10 +191,8 @@ static void sun4m_cross_call(void *func, cpumask_t mask, unsigned long arg1,
{
register int i;
- cpumask_clear_cpu(smp_processor_id(), &mask);
- cpumask_and(&mask, cpu_online_mask, &mask);
for (i = 0; i < ncpus; i++) {
- if (cpumask_test_cpu(i, &mask)) {
+ if (cpu_for_ipi(mask, i)) {
ccall_info.processors_in[i] = 0;
ccall_info.processors_out[i] = 0;
sun4m_send_ipi(i, IRQ_CROSS_CALL);
@@ -210,7 +208,7 @@ static void sun4m_cross_call(void *func, cpumask_t mask, unsigned long arg1,
i = 0;
do {
- if (!cpumask_test_cpu(i, &mask))
+ if (!cpu_for_ipi(mask, i))
continue;
while (!ccall_info.processors_in[i])
barrier();
@@ -218,7 +216,7 @@ static void sun4m_cross_call(void *func, cpumask_t mask, unsigned long arg1,
i = 0;
do {
- if (!cpumask_test_cpu(i, &mask))
+ if (!cpu_for_ipi(mask, i))
continue;
while (!ccall_info.processors_out[i])
barrier();
--
2.25.1
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