perfmon.c

linux-2.4.29操作系统的源码

#ifdef PFM_PMU_USES_DBR
/*
 * Only call this function when a process it trying to
 * write the debug registers (reading is always allowed)
 */
int
pfm_use_debug_registers(struct task_struct *task)
{
	pfm_context_t *ctx = task->thread.pfm_context;
	int ret = 0;

	DBprintk(("called for [%d]\n", task->pid));

	/*
	 * do it only once
	 */
	if (task->thread.flags & IA64_THREAD_DBG_VALID) return 0;

	/*
	 * Even on SMP, we do not need to use an atomic here because
	 * the only way in is via ptrace() and this is possible only when the
	 * process is stopped. Even in the case where the ctxsw out is not totally
	 * completed by the time we come here, there is no way the 'stopped' process
	 * could be in the middle of fiddling with the pfm_write_ibr_dbr() routine.
	 * So this is always safe.
	 */
	if (ctx && ctx->ctx_fl_using_dbreg == 1) return -1;

	LOCK_PFS();

	/*
	 * We cannot allow setting breakpoints when system wide monitoring
	 * sessions are using the debug registers.
	 */
	if (pfm_sessions.pfs_sys_use_dbregs> 0)
		ret = -1;
	else
		pfm_sessions.pfs_ptrace_use_dbregs++;

	DBprintk(("ptrace_use_dbregs=%u  sys_use_dbregs=%u by [%d] ret = %d\n", 
		  pfm_sessions.pfs_ptrace_use_dbregs, 
		  pfm_sessions.pfs_sys_use_dbregs, 
		  task->pid, ret));

	UNLOCK_PFS();

	return ret;
}

/*
 * This function is called for every task that exits with the
 * IA64_THREAD_DBG_VALID set. This indicates a task which was
 * able to use the debug registers for debugging purposes via
 * ptrace(). Therefore we know it was not using them for
 * perfmormance monitoring, so we only decrement the number
 * of "ptraced" debug register users to keep the count up to date
 */
int
pfm_release_debug_registers(struct task_struct *task)
{
	int ret;

	LOCK_PFS();
	if (pfm_sessions.pfs_ptrace_use_dbregs == 0) {
		printk(KERN_DEBUG "perfmon: invalid release for [%d] ptrace_use_dbregs=0\n",
		       task->pid);
		ret = -1;
	}  else {
		pfm_sessions.pfs_ptrace_use_dbregs--;
		ret = 0;
	}
	UNLOCK_PFS();

	return ret;
}
#else /* PFM_PMU_USES_DBR is true */
/*
 * in case, the PMU does not use the debug registers, these two functions are nops.
 * The first function is called from arch/ia64/kernel/ptrace.c.
 * The second function is called from arch/ia64/kernel/process.c.
 */
int
pfm_use_debug_registers(struct task_struct *task)
{
	return 0;
}

int
pfm_release_debug_registers(struct task_struct *task)
{
	return 0;
}
#endif /* PFM_PMU_USES_DBR */

static int
pfm_restart(struct task_struct *task, pfm_context_t *ctx, void *arg, int count, 
	 struct pt_regs *regs)
{
	void *sem = &ctx->ctx_restart_sem;

	/* 
	 * Cannot do anything before PMU is enabled 
	 */
	if (!CTX_IS_ENABLED(ctx)) return -EINVAL;

	if (task == current) {
		DBprintk(("restarting self %d frozen=%d ovfl_regs=0x%lx\n", 
			task->pid, 
			ctx->ctx_fl_frozen,
			ctx->ctx_ovfl_regs[0]));

		pfm_reset_regs(ctx, ctx->ctx_ovfl_regs, PFM_PMD_LONG_RESET);

		ctx->ctx_ovfl_regs[0] = 0UL;

		/*
		 * We ignore block/don't block because we never block
		 * for a self-monitoring process.
		 */
		ctx->ctx_fl_frozen = 0;

		if (CTX_HAS_SMPL(ctx)) {
			ctx->ctx_psb->psb_hdr->hdr_count = 0;
			ctx->ctx_psb->psb_index = 0;
		}

		/* simply unfreeze */
		pfm_unfreeze_pmu();

		return 0;
	} 
	/* restart on another task */

	/*
	 * if blocking, then post the semaphore.
	 * if non-blocking, then we ensure that the task will go into
	 * pfm_overflow_must_block() before returning to user mode. 
	 * We cannot explicitely reset another task, it MUST always
	 * be done by the task itself. This works for system wide because
	 * the tool that is controlling the session is doing "self-monitoring".
	 *
	 * XXX: what if the task never goes back to user?
	 *
	 */
	if (CTX_OVFL_NOBLOCK(ctx) == 0) {
		DBprintk(("unblocking %d \n", task->pid));
		up(sem);
	} else {
		task->thread.pfm_ovfl_block_reset = 1;
	}
#if 0
	/*
	 * in case of non blocking mode, then it's just a matter of
	 * of reseting the sampling buffer (if any) index. The PMU
	 * is already active.
	 */

	/*
	 * must reset the header count first
	 */
	if (CTX_HAS_SMPL(ctx)) {
		DBprintk(("resetting sampling indexes for %d \n", task->pid));
		ctx->ctx_psb->psb_hdr->hdr_count = 0;
		ctx->ctx_psb->psb_index = 0;
	}
#endif
	return 0;
}

static int
pfm_stop(struct task_struct *task, pfm_context_t *ctx, void *arg, int count, 
	 struct pt_regs *regs)
{
	/* we don't quite support this right now */
	if (task != current) return -EINVAL;

	/* 
	 * Cannot do anything before PMU is enabled 
	 */
	if (!CTX_IS_ENABLED(ctx)) return -EINVAL;

	DBprintk(("[%d] fl_system=%d owner=%p current=%p\n",
				current->pid,
				ctx->ctx_fl_system, PMU_OWNER(),
				current));

	/* simply stop monitoring but not the PMU */
	if (ctx->ctx_fl_system) {

		/* disable dcr pp */
		ia64_set_dcr(ia64_get_dcr() & ~IA64_DCR_PP);

		/* stop monitoring */
		pfm_clear_psr_pp();
		ia64_srlz_i();

		PFM_CPUINFO_CLEAR(PFM_CPUINFO_DCR_PP);

		ia64_psr(regs)->pp = 0;

	} else {

		/* stop monitoring */
		pfm_clear_psr_up();
		ia64_srlz_i();

		/*
		 * clear user level psr.up
		 */
		ia64_psr(regs)->up = 0;
	}
	return 0;
}

static int
pfm_disable(struct task_struct *task, pfm_context_t *ctx, void *arg, int count, 
	   struct pt_regs *regs)
{	
	/* we don't quite support this right now */
	if (task != current) return -EINVAL;

	if (!CTX_IS_ENABLED(ctx)) return -EINVAL;

	/*
	 * stop monitoring, freeze PMU, and save state in context
	 * this call will clear IA64_THREAD_PM_VALID for per-task sessions.
	 */
	pfm_flush_regs(task);

	if (ctx->ctx_fl_system) {	
		ia64_psr(regs)->pp = 0;
	} else {
		ia64_psr(regs)->up = 0;
	}
	/* 
	 * goes back to default behavior: no user level control
	 * no need to change live psr.sp because useless at the kernel level
	 */
	ia64_psr(regs)->sp = 1;

	DBprintk(("enabling psr.sp for [%d]\n", current->pid));

	ctx->ctx_flags.state = PFM_CTX_DISABLED;

	return 0;
}

static int
pfm_context_destroy(struct task_struct *task, pfm_context_t *ctx, void *arg, int count, 
	 struct pt_regs *regs)
{
	/* we don't quite support this right now */
	if (task != current) return -EINVAL;

	/*
	 * if context was never enabled, then there is not much
	 * to do
	 */
	if (!CTX_IS_ENABLED(ctx)) goto skipped_stop;

	/*
	 * Disable context: stop monitoring, flush regs to software state (useless here), 
	 * and freeze PMU
	 * 
	 * The IA64_THREAD_PM_VALID is cleared by pfm_flush_regs() called from pfm_disable()
	 */
	pfm_disable(task, ctx, arg, count, regs);

	if (ctx->ctx_fl_system) {	
		ia64_psr(regs)->pp = 0;
	} else {
		ia64_psr(regs)->up = 0;
	}

skipped_stop:
	/*
	 * remove sampling buffer mapping, if any
	 */
	if (ctx->ctx_smpl_vaddr) {
		pfm_remove_smpl_mapping(task);
		ctx->ctx_smpl_vaddr = 0UL;
	}
	/* now free context and related state */
	pfm_context_exit(task);

	return 0;
}

/*
 * does nothing at the moment
 */
static int
pfm_context_unprotect(struct task_struct *task, pfm_context_t *ctx, void *arg, int count, 
	 struct pt_regs *regs)
{
	return 0;
}

static int
pfm_protect_context(struct task_struct *task, pfm_context_t *ctx, void *arg, int count, 
	 struct pt_regs *regs)
{
	/*
	 * from now on, only the creator of the context has access to it
	 */
	ctx->ctx_fl_protected = 1;

	/*
	 * reinforce secure monitoring: cannot toggle psr.up
	 */
	if (ctx->ctx_fl_unsecure == 0) ia64_psr(regs)->sp = 1;

	DBprintk(("[%d] protected psr.sp=%d\n", task->pid, ia64_psr(regs)->sp));

	return 0;
}

static int
pfm_debug(struct task_struct *task, pfm_context_t *ctx, void *arg, int count, 
	 struct pt_regs *regs)
{
	unsigned int mode = *(unsigned int *)arg;

	pfm_sysctl.debug = mode == 0 ? 0 : 1;

	printk(KERN_INFO "perfmon debugging %s\n", pfm_sysctl.debug ? "on" : "off");

	return 0;
}

#ifdef PFM_PMU_USES_DBR

typedef struct {
	unsigned long ibr_mask:56;
	unsigned long ibr_plm:4;
	unsigned long ibr_ig:3;
	unsigned long ibr_x:1;
} ibr_mask_reg_t;

typedef struct {
	unsigned long dbr_mask:56;
	unsigned long dbr_plm:4;
	unsigned long dbr_ig:2;
	unsigned long dbr_w:1;
	unsigned long dbr_r:1;
} dbr_mask_reg_t;

typedef union {
	unsigned long  val;
	ibr_mask_reg_t ibr;
	dbr_mask_reg_t dbr;
} dbreg_t;


static int
pfm_write_ibr_dbr(int mode, struct task_struct *task, void *arg, int count, struct pt_regs *regs)
{
	struct thread_struct *thread = &task->thread;
	pfm_context_t *ctx = task->thread.pfm_context;
	pfarg_dbreg_t tmp, *req = (pfarg_dbreg_t *)arg;
	dbreg_t dbreg;
	unsigned int rnum;
	int first_time;
	int i, ret = 0;

	/*
	 * we do not need to check for ipsr.db because we do clear ibr.x, dbr.r, and dbr.w
	 * ensuring that no real breakpoint can be installed via this call.
	 */

	first_time = ctx->ctx_fl_using_dbreg == 0;

	/*
	 * check for debug registers in system wide mode
	 *
	 */
	LOCK_PFS();
	if (ctx->ctx_fl_system && first_time) {
		if (pfm_sessions.pfs_ptrace_use_dbregs) 
			ret = -EBUSY;
		else
			pfm_sessions.pfs_sys_use_dbregs++;
	}
	UNLOCK_PFS();

	if (ret != 0) return ret;

	if (ctx->ctx_fl_system) {
		/* we mark ourselves as owner  of the debug registers */
		ctx->ctx_fl_using_dbreg = 1;
		DBprintk(("system-wide setting fl_using_dbreg for [%d]\n", task->pid));
	} else if (first_time) {
			ret= -EBUSY;
			if ((thread->flags & IA64_THREAD_DBG_VALID) != 0) {
				DBprintk(("debug registers already in use for [%d]\n", task->pid));
				goto abort_mission;
			}
			/* we mark ourselves as owner  of the debug registers */
			ctx->ctx_fl_using_dbreg = 1;

			DBprintk(("setting fl_using_dbreg for [%d]\n", task->pid));
			/* 
			 * Given debug registers cannot be used for both debugging 
			 * and performance monitoring at the same time, we reuse
			 * the storage area to save and restore the registers on ctxsw.
			 */
			memset(task->thread.dbr, 0, sizeof(task->thread.dbr));
			memset(task->thread.ibr, 0, sizeof(task->thread.ibr));
	}

	if (first_time) {
		DBprintk(("[%d] clearing ibrs,dbrs\n", task->pid));
		/*
	 	 * clear hardware registers to make sure we don't
	 	 * pick up stale state. 
		 *
		 * for a system wide session, we do not use
		 * thread.dbr, thread.ibr because this process
		 * never leaves the current CPU and the state
		 * is shared by all processes running on it
	 	 */
		for (i=0; i < pmu_conf.num_ibrs; i++) {
			ia64_set_ibr(i, 0UL);
		}
		ia64_srlz_i();
		for (i=0; i < pmu_conf.num_dbrs; i++) {
			ia64_set_dbr(i, 0UL);
		}
		ia64_srlz_d();
	}

	ret = -EFAULT;

	/*
	 * Now install the values into the registers
	 */
	for (i = 0; i < count; i++, req++) {
		
		if (__copy_from_user(&tmp, req, sizeof(tmp))) goto abort_mission;
		
		rnum      = tmp.dbreg_num;
		dbreg.val = tmp.dbreg_value;
		
		ret = -EINVAL;

		if ((mode == 0 && !IBR_IS_IMPL(rnum)) || ((mode == 1) && !DBR_IS_IMPL(rnum))) {
			DBprintk(("invalid register %u val=0x%lx mode=%d i=%d count=%d\n", 
				  rnum, dbreg.val, mode, i, count));

			goto abort_mission;
		}

		/*
		 * make sure we do not install enabled breakpoint
		 */
		if (rnum & 0x1) {
			if (mode == 0) 
				dbreg.ibr.ibr_x = 0;
			else
				dbreg.dbr.dbr_r = dbreg.dbr.dbr_w = 0;
		}

		/*
		 * clear return flags and copy back to user
		 *
		 * XXX: fix once EAGAIN is implemented
		 */