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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
Download Patch File Download Diff File Expand all files Collapse all files

24
arch/arm/kernel/entry-armv.S
View File

@ -20,6 +20,7 @@
#include <asm/glue.h>
#include <asm/vfpmacros.h>
#include <asm/arch/entry-macro.S>
#include <asm/thread_notify.h>
#include "entry-header.S"
@ -560,10 +561,8 @@ ENTRY(__switch_to)
add ip, r1, #TI_CPU_SAVE
ldr r3, [r2, #TI_TP_VALUE]
stmia ip!, {r4 - sl, fp, sp, lr} @ Store most regs on stack
#ifndef CONFIG_MMU
add r2, r2, #TI_CPU_DOMAIN
#else
ldr r6, [r2, #TI_CPU_DOMAIN]!
#ifdef CONFIG_MMU
ldr r6, [r2, #TI_CPU_DOMAIN]
#endif
#if __LINUX_ARM_ARCH__ >= 6
#ifdef CONFIG_CPU_32v6K
@ -585,21 +584,20 @@ ENTRY(__switch_to)
#ifdef CONFIG_MMU
mcr p15, 0, r6, c3, c0, 0 @ Set domain register
#endif
#ifdef CONFIG_VFP
@ Always disable VFP so we can lazily save/restore the old
@ state. This occurs in the context of the previous thread.
VFPFMRX r4, FPEXC
bic r4, r4, #FPEXC_ENABLE
VFPFMXR FPEXC, r4
#endif
#if defined(CONFIG_IWMMXT)
bl iwmmxt_task_switch
#elif defined(CONFIG_CPU_XSCALE)
add r4, r2, #40 @ cpu_context_save->extra
add r4, r2, #TI_CPU_DOMAIN + 40 @ cpu_context_save->extra
ldmib r4, {r4, r5}
mar acc0, r4, r5
#endif
ldmib r2, {r4 - sl, fp, sp, pc} @ Load all regs saved previously
mov r5, r0
add r4, r2, #TI_CPU_SAVE
ldr r0, =thread_notify_head
mov r1, #THREAD_NOTIFY_SWITCH
bl atomic_notifier_call_chain
mov r0, r5
ldmia r4, {r4 - sl, fp, sp, pc} @ Load all regs saved previously
__INIT

2
arch/arm/kernel/iwmmxt.S
View File

@ -285,7 +285,7 @@ ENTRY(iwmmxt_task_switch)
bne 1f @ yes: block them for next task
ldr r5, =concan_owner
add r6, r2, #(TI_IWMMXT_STATE - TI_CPU_DOMAIN) @ get next task Concan save area
add r6, r2, #TI_IWMMXT_STATE @ get next task Concan save area
ldr r5, [r5] @ get current Concan owner
teq r5, r6 @ next task owns it?
movne pc, lr @ no: leave Concan disabled

24
arch/arm/kernel/process.c
View File

@ -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
}