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[ARM] Add thread_notify infrastructure

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Some machine classes need to allow VFP support to be built into the
kernel, but still allow the kernel to run even though VFP isn't
present.  Unfortunately, the kernel hard-codes VFP instructions
into the thread switch, which prevents this being run-time selectable.

Solve this by introducing a notifier which things such as VFP can
hook into to be informed of events which affect the VFP subsystem
(eg, creation and destruction of threads, switches between threads.)

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King
2006-06-21 13:31:52 +01:00
committed by Russell King
parent 52ab3f3dc7
commit d6551e884c
6 changed files with 135 additions and 59 deletions
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24
arch/arm/kernel/process.c
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@@ -33,6 +33,7 @@
#include <asm/leds.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/thread_notify.h>
#include <asm/uaccess.h>
#include <asm/mach/time.h>
@@ -338,13 +339,9 @@ void exit_thread(void)
{
}
static void default_fp_init(union fp_state *fp)
{
memset(fp, 0, sizeof(union fp_state));
}
ATOMIC_NOTIFIER_HEAD(thread_notify_head);
void (*fp_init)(union fp_state *) = default_fp_init;
EXPORT_SYMBOL(fp_init);
EXPORT_SYMBOL_GPL(thread_notify_head);
void flush_thread(void)
{
@@ -353,22 +350,21 @@ void flush_thread(void)
memset(thread->used_cp, 0, sizeof(thread->used_cp));
memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
memset(&thread->fpstate, 0, sizeof(union fp_state));
thread_notify(THREAD_NOTIFY_FLUSH, thread);
#if defined(CONFIG_IWMMXT)
iwmmxt_task_release(thread);
#endif
fp_init(&thread->fpstate);
#if defined(CONFIG_VFP)
vfp_flush_thread(&thread->vfpstate);
#endif
}
void release_thread(struct task_struct *dead_task)
{
#if defined(CONFIG_VFP)
vfp_release_thread(&task_thread_info(dead_task)->vfpstate);
#endif
struct thread_info *thread = task_thread_info(dead_task);
thread_notify(THREAD_NOTIFY_RELEASE, thread);
#if defined(CONFIG_IWMMXT)
iwmmxt_task_release(task_thread_info(dead_task));
iwmmxt_task_release(thread);
#endif
}