linux-kernel - [PATCH v5 09/17] powerpc/32: Use vmapped stacks for interrupts

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Date:   Sat, 21 Dec 2019 08:32:30 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>, dja@...ens.net
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-mm@...ck.org
Subject: [PATCH v5 09/17] powerpc/32: Use vmapped stacks for interrupts

In order to also catch overflows on IRQ stacks, use vmapped stacks.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 arch/powerpc/kernel/irq.c      | 22 ++++++++++++++++++++++
 arch/powerpc/kernel/setup_32.c |  3 +++
 2 files changed, 25 insertions(+)

diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index add67498c126..5c9b11878555 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -50,6 +50,7 @@
 #include <linux/debugfs.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>
+#include <linux/vmalloc.h>
 
 #include <linux/uaccess.h>
 #include <asm/io.h>
@@ -664,8 +665,29 @@ void do_IRQ(struct pt_regs *regs)
 	set_irq_regs(old_regs);
 }
 
+static void *__init alloc_vm_stack(void)
+{
+	return __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN, VMALLOC_START,
+				    VMALLOC_END, THREADINFO_GFP, PAGE_KERNEL,
+				     0, NUMA_NO_NODE, (void*)_RET_IP_);
+}
+
+static void __init vmap_irqstack_init(void)
+{
+	int i;
+
+	for_each_possible_cpu(i) {
+		softirq_ctx[i] = alloc_vm_stack();
+		hardirq_ctx[i] = alloc_vm_stack();
+	}
+}
+
+
 void __init init_IRQ(void)
 {
+	if (IS_ENABLED(CONFIG_VMAP_STACK))
+		vmap_irqstack_init();
+
 	if (ppc_md.init_IRQ)
 		ppc_md.init_IRQ();
 }
diff --git a/arch/powerpc/kernel/setup_32.c b/arch/powerpc/kernel/setup_32.c
index a55b4d9ab824..5b49b26eb154 100644
--- a/arch/powerpc/kernel/setup_32.c
+++ b/arch/powerpc/kernel/setup_32.c
@@ -153,6 +153,9 @@ void __init irqstack_early_init(void)
 {
 	unsigned int i;
 
+	if (IS_ENABLED(CONFIG_VMAP_STACK))
+		return;
+
 	/* interrupt stacks must be in lowmem, we get that for free on ppc32
 	 * as the memblock is limited to lowmem by default */
 	for_each_possible_cpu(i) {
-- 
2.13.3