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authorPaul Mundt <lethal@linux-sh.org>2006-09-27 18:22:14 +0900
committerPaul Mundt <lethal@linux-sh.org>2006-09-27 18:22:14 +0900
commita6a31139897a5e539efe7ad3b7bd351fa9673ce8 (patch)
tree6e2ad11d93ab95214694038080c79284c6da30d6
parent2cb7ce3bb384f30a377f66336c78546b834604df (diff)
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>
-rw-r--r--arch/sh/Kconfig.debug10
-rw-r--r--arch/sh/kernel/cpu/irq/ipr.c2
-rw-r--r--arch/sh/kernel/entry.S4
-rw-r--r--arch/sh/kernel/head.S5
-rw-r--r--arch/sh/kernel/irq.c153
-rw-r--r--arch/sh/kernel/traps.c18
-rw-r--r--arch/sh/kernel/vmlinux.lds.S1
-rw-r--r--include/asm-sh/irq.h9
-rw-r--r--include/asm-sh/thread_info.h12
9 files changed, 190 insertions, 24 deletions
diff --git a/arch/sh/Kconfig.debug b/arch/sh/Kconfig.debug
index f0188e626be0..48479e014dac 100644
--- a/arch/sh/Kconfig.debug
+++ b/arch/sh/Kconfig.debug
@@ -46,6 +46,16 @@ config DEBUG_STACK_USAGE
This option will slow down process creation somewhat.
+config 4KSTACKS
+ bool "Use 4Kb for kernel stacks instead of 8Kb"
+ depends on DEBUG_KERNEL
+ help
+ If you say Y here the kernel will use a 4Kb stacksize for the
+ kernel stack attached to each process/thread. This facilitates
+ running more threads on a system and also reduces the pressure
+ on the VM subsystem for higher order allocations. This option
+ will also use IRQ stacks to compensate for the reduced stackspace.
+
config KGDB
bool "Include KGDB kernel debugger"
select FRAME_POINTER
diff --git a/arch/sh/kernel/cpu/irq/ipr.c b/arch/sh/kernel/cpu/irq/ipr.c
index 4c4fd4118d1a..f785822cd5de 100644
--- a/arch/sh/kernel/cpu/irq/ipr.c
+++ b/arch/sh/kernel/cpu/irq/ipr.c
@@ -190,6 +190,8 @@ void __init init_IRQ(void)
/* Perform the machine specific initialisation */
if (sh_mv.mv_init_irq != NULL)
sh_mv.mv_init_irq();
+
+ irq_ctx_init(smp_processor_id());
}
#if !defined(CONFIG_CPU_HAS_PINT_IRQ)
diff --git a/arch/sh/kernel/entry.S b/arch/sh/kernel/entry.S
index fd5fe2349f20..fe8221855b28 100644
--- a/arch/sh/kernel/entry.S
+++ b/arch/sh/kernel/entry.S
@@ -716,8 +716,8 @@ ENTRY(handle_exception)
bt/s 1f ! It's a kernel to kernel transition.
mov r15, k0 ! save original stack to k0
/* User space to kernel */
- mov #0x20, k1
- shll8 k1 ! k1 := 8192 (== THREAD_SIZE)
+ mov #(THREAD_SIZE >> 8), k1
+ shll8 k1 ! k1 := THREAD_SIZE
add current, k1
mov k1, r15 ! change to kernel stack
!
diff --git a/arch/sh/kernel/head.S b/arch/sh/kernel/head.S
index 3e7d00b7985a..f5f53d14f245 100644
--- a/arch/sh/kernel/head.S
+++ b/arch/sh/kernel/head.S
@@ -12,7 +12,6 @@
*/
#include <linux/linkage.h>
#include <asm/thread_info.h>
-#include <asm/page.h>
#ifdef CONFIG_CPU_SH4A
#define SYNCO() synco
@@ -69,8 +68,8 @@ ENTRY(_stext)
!
mov.l 2f, r0
mov r0, r15 ! Set initial r15 (stack pointer)
- mov #0x20, r1 !
- shll8 r1 ! r1 = 8192
+ mov #(THREAD_SIZE >> 8), r1
+ shll8 r1 ! r1 = THREAD_SIZE
sub r1, r0 !
ldc r0, r7_bank ! ... and initial thread_info
diff --git a/arch/sh/kernel/irq.c b/arch/sh/kernel/irq.c
index 7066611aeb72..c7ebd6aec951 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 @@ unlock:
}
#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 @@ asmlinkage int do_IRQ(unsigned long r4, unsigned long r5,
#endif
irq = irq_demux(irq);
- __do_IRQ(irq, &regs);
+
+#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" (&regs), "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, &regs);
+
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
diff --git a/arch/sh/kernel/traps.c b/arch/sh/kernel/traps.c
index 95c810b3c97e..c2c597e09482 100644
--- a/arch/sh/kernel/traps.c
+++ b/arch/sh/kernel/traps.c
@@ -741,20 +741,12 @@ void show_stack(struct task_struct *tsk, unsigned long *sp)
unsigned long module_end = VMALLOC_END;
int i = 1;
- if (tsk && !sp) {
+ if (!tsk)
+ tsk = current;
+ if (tsk == current)
+ sp = (unsigned long *)current_stack_pointer;
+ else
sp = (unsigned long *)tsk->thread.sp;
- }
-
- if (!sp) {
- __asm__ __volatile__ (
- "mov r15, %0\n\t"
- "stc r7_bank, %1\n\t"
- : "=r" (module_start),
- "=r" (module_end)
- );
-
- sp = (unsigned long *)module_start;
- }
stack = sp;
diff --git a/arch/sh/kernel/vmlinux.lds.S b/arch/sh/kernel/vmlinux.lds.S
index 0220d8a838a7..5eb930918186 100644
--- a/arch/sh/kernel/vmlinux.lds.S
+++ b/arch/sh/kernel/vmlinux.lds.S
@@ -3,7 +3,6 @@
* Written by Niibe Yutaka
*/
#include <asm/thread_info.h>
-#include <asm/page.h>
#include <asm-generic/vmlinux.lds.h>
#ifdef CONFIG_CPU_LITTLE_ENDIAN
diff --git a/include/asm-sh/irq.h b/include/asm-sh/irq.h
index dd05e102fc0e..0e5f365aff70 100644
--- a/include/asm-sh/irq.h
+++ b/include/asm-sh/irq.h
@@ -719,6 +719,15 @@ static inline int generic_irq_demux(int irq)
#define irq_canonicalize(irq) (irq)
#define irq_demux(irq) __irq_demux(sh_mv.mv_irq_demux(irq))
+#ifdef CONFIG_4KSTACKS
+extern void irq_ctx_init(int cpu);
+extern void irq_ctx_exit(int cpu);
+# define __ARCH_HAS_DO_SOFTIRQ
+#else
+# define irq_ctx_init(cpu) do { } while (0)
+# define irq_ctx_exit(cpu) do { } while (0)
+#endif
+
#if defined(CONFIG_CPU_SUBTYPE_SH73180)
#include <asm/irq-sh73180.h>
#endif
diff --git a/include/asm-sh/thread_info.h b/include/asm-sh/thread_info.h
index 605259f88113..3ebc3f9039eb 100644
--- a/include/asm-sh/thread_info.h
+++ b/include/asm-sh/thread_info.h
@@ -9,8 +9,8 @@
* Copyright (C) 2002 David Howells (dhowells@redhat.com)
* - Incorporating suggestions made by Linus Torvalds and Dave Miller
*/
-
#ifdef __KERNEL__
+#include <asm/page.h>
#ifndef __ASSEMBLY__
#include <asm/processor.h>
@@ -23,13 +23,20 @@ struct thread_info {
int preempt_count; /* 0 => preemptable, <0 => BUG */
mm_segment_t addr_limit; /* thread address space */
struct restart_block restart_block;
+ unsigned long previous_sp; /* sp of previous stack in case
+ of nested IRQ stacks */
__u8 supervisor_stack[0];
};
#endif
#define PREEMPT_ACTIVE 0x10000000
+
+#ifdef CONFIG_4KSTACKS
+#define THREAD_SIZE (PAGE_SIZE)
+#else
#define THREAD_SIZE (PAGE_SIZE * 2)
+#endif
#define STACK_WARN (THREAD_SIZE / 8)
/*
@@ -52,6 +59,9 @@ struct thread_info {
#define init_thread_info (init_thread_union.thread_info)
#define init_stack (init_thread_union.stack)
+/* how to get the current stack pointer from C */
+register unsigned long current_stack_pointer asm("r15") __attribute_used__;
+
/* how to get the thread information struct from C */
static inline struct thread_info *current_thread_info(void)
{