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[AVR32] Enable debugging only when needed

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Keep track of processes being debugged (including the kernel itself)
and turn the OCD system on and off as appropriate. Since enabling
debugging turns off some optimizations in the CPU core, this fixes the
issue that enabling KProbes support or simply running a program under
gdbserver will reduce system performance significantly until the next
reboot.

The CPU performance will still be reduced for all processes while a
process is being debugged, but this is a lot better than reducing the
performance forever.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
This commit is contained in:
Haavard Skinnemoen
2007-11-27 13:50:45 +01:00
parent 6ea6dd93c9
commit 13b54a5052
8 changed files with 186 additions and 13 deletions
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5
arch/avr32/kernel/kprobes.c
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@@ -48,6 +48,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
void __kprobes arch_arm_kprobe(struct kprobe *p)
{
pr_debug("arming kprobe at %p\n", p->addr);
ocd_enable(NULL);
*p->addr = BREAKPOINT_INSTRUCTION;
flush_icache_range((unsigned long)p->addr,
(unsigned long)p->addr + sizeof(kprobe_opcode_t));
@@ -56,6 +57,7 @@ void __kprobes arch_arm_kprobe(struct kprobe *p)
void __kprobes arch_disarm_kprobe(struct kprobe *p)
{
pr_debug("disarming kprobe at %p\n", p->addr);
ocd_disable(NULL);
*p->addr = p->opcode;
flush_icache_range((unsigned long)p->addr,
(unsigned long)p->addr + sizeof(kprobe_opcode_t));
@@ -260,9 +262,6 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
int __init arch_init_kprobes(void)
{
printk("KPROBES: Enabling monitor mode (MM|DBE)...\n");
ocd_write(DC, (1 << OCD_DC_MM_BIT) | (1 << OCD_DC_DBE_BIT));
/* TODO: Register kretprobe trampoline */
return 0;
}