sh: Add support for 4K stacks.
This enables support for 4K stacks on SH.
Currently this depends on DEBUG_KERNEL, but likely all boards
will switch to this as the default in the future.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/kernel/irq.c b/arch/sh/kernel/irq.c
index 7066611..c7ebd6a 100644
--- a/arch/sh/kernel/irq.c
+++ b/arch/sh/kernel/irq.c
@@ -1,5 +1,4 @@
-/* $Id: irq.c,v 1.20 2004/01/13 05:52:11 kkojima Exp $
- *
+/*
* linux/arch/sh/kernel/irq.c
*
* Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
@@ -7,13 +6,15 @@
*
* SuperH version: Copyright (C) 1999 Niibe Yutaka
*/
-
#include <linux/irq.h>
#include <linux/interrupt.h>
+#include <linux/module.h>
#include <linux/kernel_stat.h>
#include <linux/seq_file.h>
#include <asm/irq.h>
#include <asm/processor.h>
+#include <asm/uaccess.h>
+#include <asm/thread_info.h>
#include <asm/cpu/mmu_context.h>
/*
@@ -60,11 +61,27 @@
}
#endif
+#ifdef CONFIG_4KSTACKS
+/*
+ * per-CPU IRQ handling contexts (thread information and stack)
+ */
+union irq_ctx {
+ struct thread_info tinfo;
+ u32 stack[THREAD_SIZE/sizeof(u32)];
+};
+
+static union irq_ctx *hardirq_ctx[NR_CPUS];
+static union irq_ctx *softirq_ctx[NR_CPUS];
+#endif
+
asmlinkage int do_IRQ(unsigned long r4, unsigned long r5,
unsigned long r6, unsigned long r7,
struct pt_regs regs)
{
int irq = r4;
+#ifdef CONFIG_4KSTACKS
+ union irq_ctx *curctx, *irqctx;
+#endif
irq_enter();
@@ -102,7 +119,135 @@
#endif
irq = irq_demux(irq);
- __do_IRQ(irq, ®s);
+
+#ifdef CONFIG_4KSTACKS
+ curctx = (union irq_ctx *)current_thread_info();
+ irqctx = hardirq_ctx[smp_processor_id()];
+
+ /*
+ * this is where we switch to the IRQ stack. However, if we are
+ * already using the IRQ stack (because we interrupted a hardirq
+ * handler) we can't do that and just have to keep using the
+ * current stack (which is the irq stack already after all)
+ */
+ if (curctx != irqctx) {
+ u32 *isp;
+
+ isp = (u32 *)((char *)irqctx + sizeof(*irqctx));
+ irqctx->tinfo.task = curctx->tinfo.task;
+ irqctx->tinfo.previous_sp = current_stack_pointer;
+
+ __asm__ __volatile__ (
+ "mov %0, r4 \n"
+ "mov %1, r5 \n"
+ "mov r15, r9 \n"
+ "jsr @%2 \n"
+ /* swith to the irq stack */
+ " mov %3, r15 \n"
+ /* restore the stack (ring zero) */
+ "mov r9, r15 \n"
+ : /* no outputs */
+ : "r" (irq), "r" (®s), "r" (__do_IRQ), "r" (isp)
+ /* XXX: A somewhat excessive clobber list? -PFM */
+ : "memory", "r0", "r1", "r2", "r3", "r4",
+ "r5", "r6", "r7", "r8", "t", "pr"
+ );
+ } else
+#endif
+ __do_IRQ(irq, ®s);
+
irq_exit();
+
return 1;
}
+
+#ifdef CONFIG_4KSTACKS
+/*
+ * These should really be __section__(".bss.page_aligned") as well, but
+ * gcc's 3.0 and earlier don't handle that correctly.
+ */
+static char softirq_stack[NR_CPUS * THREAD_SIZE]
+ __attribute__((__aligned__(THREAD_SIZE)));
+
+static char hardirq_stack[NR_CPUS * THREAD_SIZE]
+ __attribute__((__aligned__(THREAD_SIZE)));
+
+/*
+ * allocate per-cpu stacks for hardirq and for softirq processing
+ */
+void irq_ctx_init(int cpu)
+{
+ union irq_ctx *irqctx;
+
+ if (hardirq_ctx[cpu])
+ return;
+
+ irqctx = (union irq_ctx *)&hardirq_stack[cpu * THREAD_SIZE];
+ irqctx->tinfo.task = NULL;
+ irqctx->tinfo.exec_domain = NULL;
+ irqctx->tinfo.cpu = cpu;
+ irqctx->tinfo.preempt_count = HARDIRQ_OFFSET;
+ irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
+
+ hardirq_ctx[cpu] = irqctx;
+
+ irqctx = (union irq_ctx *)&softirq_stack[cpu * THREAD_SIZE];
+ irqctx->tinfo.task = NULL;
+ irqctx->tinfo.exec_domain = NULL;
+ irqctx->tinfo.cpu = cpu;
+ irqctx->tinfo.preempt_count = SOFTIRQ_OFFSET;
+ irqctx->tinfo.addr_limit = MAKE_MM_SEG(0);
+
+ softirq_ctx[cpu] = irqctx;
+
+ printk("CPU %u irqstacks, hard=%p soft=%p\n",
+ cpu, hardirq_ctx[cpu], softirq_ctx[cpu]);
+}
+
+void irq_ctx_exit(int cpu)
+{
+ hardirq_ctx[cpu] = NULL;
+}
+
+extern asmlinkage void __do_softirq(void);
+
+asmlinkage void do_softirq(void)
+{
+ unsigned long flags;
+ struct thread_info *curctx;
+ union irq_ctx *irqctx;
+ u32 *isp;
+
+ if (in_interrupt())
+ return;
+
+ local_irq_save(flags);
+
+ if (local_softirq_pending()) {
+ curctx = current_thread_info();
+ irqctx = softirq_ctx[smp_processor_id()];
+ irqctx->tinfo.task = curctx->task;
+ irqctx->tinfo.previous_sp = current_stack_pointer;
+
+ /* build the stack frame on the softirq stack */
+ isp = (u32 *)((char *)irqctx + sizeof(*irqctx));
+
+ __asm__ __volatile__ (
+ "mov r15, r9 \n"
+ "jsr @%0 \n"
+ /* switch to the softirq stack */
+ " mov %1, r15 \n"
+ /* restore the thread stack */
+ "mov r9, r15 \n"
+ : /* no outputs */
+ : "r" (__do_softirq), "r" (isp)
+ /* XXX: A somewhat excessive clobber list? -PFM */
+ : "memory", "r0", "r1", "r2", "r3", "r4",
+ "r5", "r6", "r7", "r8", "r9", "r15", "t", "pr"
+ );
+ }
+
+ local_irq_restore(flags);
+}
+EXPORT_SYMBOL(do_softirq);
+#endif