/* devobj.c COPYRIGHT FUJITSU LIMITED 2015-2017 */
/**
 * \file devobj.c
 *  License details are found in the file LICENSE.
 * \brief
 *  memory mapped device pager client
 * \author Gou Nakamura  <go.nakamura.yw@hitachi-solutions.com> \par
 * 	Copyright (C) 2014  RIKEN AICS
 */
/*
 * HISTORY:
 */

#include <ihk/lock.h>
#include <kmalloc.h>
#include <memobj.h>
#include <page.h>	/* for allocate_pages() */
#include <pager.h>
#include <string.h>
#include <syscall.h>
#include <process.h>
#include <rusage_private.h>
#include <ihk/debug.h>

//#define DEBUG_PRINT_DEVOBJ

#ifdef DEBUG_PRINT_DEVOBJ
#undef DDEBUG_DEFAULT
#define DDEBUG_DEFAULT DDEBUG_PRINT
#endif


struct devobj {
	struct memobj	memobj;		/* must be first */
	long		ref;
	uintptr_t	handle;
	off_t		pfn_pgoff;
	uintptr_t *	pfn_table;
	ihk_spinlock_t  pfn_table_lock;
	size_t		npages;
};

static memobj_free_func_t devobj_free;
static memobj_get_page_func_t devobj_get_page;

static struct memobj_ops devobj_ops = {
	.free =		&devobj_free,
	.get_page =	&devobj_get_page,
};

static struct devobj *to_devobj(struct memobj *memobj)
{
	return (struct devobj *)memobj;
}

static struct memobj *to_memobj(struct devobj *devobj)
{
	return &devobj->memobj;
}

/***********************************************************************
 * devobj
 */
int devobj_create(int fd, size_t len, off_t off, struct memobj **objp, int *maxprotp,
	int prot, int populate_flags)
{
	ihk_mc_user_context_t ctx;
	struct pager_map_result result;	// XXX: assumes contiguous physical
	int error;
	struct devobj *obj  = NULL;
	const size_t npages = (len + PAGE_SIZE - 1) / PAGE_SIZE;
	const size_t uintptr_per_page = (PAGE_SIZE / sizeof(uintptr_t));
	const size_t pfn_npages =
		(npages + uintptr_per_page - 1) / uintptr_per_page;

	dkprintf("%s: fd: %d, len: %lu, off: %lu \n", __FUNCTION__, fd, len, off);

	obj = kmalloc(sizeof(*obj), IHK_MC_AP_NOWAIT);
	if (!obj) {
		error = -ENOMEM;
		kprintf("%s: error: fd: %d, len: %lu, off: %lu kmalloc failed.\n", 
			__FUNCTION__, fd, len, off);
		goto out;
	}
	memset(obj, 0, sizeof(*obj));

	obj->pfn_table = ihk_mc_alloc_pages(pfn_npages, IHK_MC_AP_NOWAIT);
	if (!obj->pfn_table) {
		error = -ENOMEM;
		kprintf("%s: error: fd: %d, len: %lu, off: %lu allocating PFN failed.\n", 
			__FUNCTION__, fd, len, off);
		goto out;
	}
	memset(obj->pfn_table, 0, pfn_npages * PAGE_SIZE);

	ihk_mc_syscall_arg0(&ctx) = PAGER_REQ_MAP;
	ihk_mc_syscall_arg1(&ctx) = fd;
	ihk_mc_syscall_arg2(&ctx) = len;
	ihk_mc_syscall_arg3(&ctx) = off;
	ihk_mc_syscall_arg4(&ctx) = virt_to_phys(&result);
	ihk_mc_syscall_arg5(&ctx) = prot | populate_flags;

	memset(&result, 0, sizeof(result));

	error = syscall_generic_forwarding(__NR_mmap, &ctx);
	if (error) {
		kprintf("%s: error: fd: %d, len: %lu, off: %lu map failed.\n", 
			__FUNCTION__, fd, len, off);
		goto out;
	}

	dkprintf("%s: fd: %d, len: %lu, off: %lu, handle: %p, maxprot: %x\n", 
		__FUNCTION__, fd, len, off, result.handle, result.maxprot);

	obj->memobj.ops = &devobj_ops;
	obj->memobj.flags = MF_HAS_PAGER | MF_REMAP_FILE_PAGES | MF_DEV_FILE;
	obj->memobj.size = len;
	ihk_atomic_set(&obj->memobj.refcnt, 1);
	obj->handle = result.handle;

	dkprintf("%s: path=%s\n", __FUNCTION__, result.path);
	if (result.path[0]) {
		obj->memobj.path = kmalloc(PATH_MAX, IHK_MC_AP_NOWAIT);
		if (!obj->memobj.path) {
			error = -ENOMEM;
			kprintf("%s: ERROR: Out of memory\n", __FUNCTION__);
			goto out;
		}
		strncpy(obj->memobj.path, result.path, PATH_MAX);
	}

	obj->pfn_pgoff = off >> PAGE_SHIFT;
	obj->npages = npages;
	ihk_mc_spinlock_init(&obj->pfn_table_lock);

	error = 0;
	*objp = to_memobj(obj);
	*maxprotp = result.maxprot;

#ifdef ENABLE_FUGAKU_HACKS
	/* Pre-populate device file PFNs for PMIx shared mem */
	if (!strncmp(obj->memobj.path,
				"/var/opt/FJSVtcs/ple/daemonif", 29)) {
		off_t offset;
		uintptr_t phys;
		unsigned long flag;

		for (offset = 0; offset < obj->memobj.size; offset += PAGE_SIZE) {
			if (devobj_get_page(&obj->memobj, offset, PAGE_P2ALIGN,
						&phys, &flag, 0) < 0) {
				kprintf("%s: WARNING: failed to populate offset %lu in %s\n",
						__func__, offset, obj->memobj.path);
			}
		}
		dkprintf("%s: pre-populated PFNs for %s, len: %lu\n",
			__func__, obj->memobj.path, obj->memobj.size);
	}
#endif

	obj = NULL;

out:
	if (obj) {
		if (obj->pfn_table) {
			ihk_mc_free_pages(obj->pfn_table, pfn_npages);
		}
		kfree(obj);
	}
	dkprintf("%s: ret: %d, fd: %d, len: %lu, off: %lu, handle: %p, maxprot: %x \n", 
		__FUNCTION__, error, fd, len, off, result.handle, result.maxprot);
	return error;
}

static void devobj_free(struct memobj *memobj)
{
	struct devobj *obj = to_devobj(memobj);
	uintptr_t handle;
	const size_t uintptr_per_page = (PAGE_SIZE / sizeof(uintptr_t));
	const size_t pfn_npages =
		(obj->npages + uintptr_per_page - 1) / uintptr_per_page;
	int error;
	ihk_mc_user_context_t ctx;

	dkprintf("%s(%p %lx)\n", __func__, obj, obj->handle);

	handle = obj->handle;

	ihk_mc_syscall_arg0(&ctx) = PAGER_REQ_UNMAP;
	ihk_mc_syscall_arg1(&ctx) = handle;
	ihk_mc_syscall_arg2(&ctx) = 1;

	error = syscall_generic_forwarding(__NR_mmap, &ctx);
	if (error) {
		dkprintf("%s(%p %lx): release failed. %d\n",
			__func__, obj, handle, error);
		/* through */
	}

	if (obj->pfn_table) {
		// Don't call memory_stat_rss_sub() because devobj related
		// pages don't reside in main memory
		ihk_mc_free_pages(obj->pfn_table, pfn_npages);
	}

	if (to_memobj(obj)->path) {
		kfree(to_memobj(obj)->path);
	}

	kfree(obj);

	dkprintf("%s(%p %lx):free\n", __func__, obj, handle);
	return;
}

static int devobj_get_page(struct memobj *memobj, off_t off, int p2align, uintptr_t *physp, unsigned long *flag, uintptr_t virt_addr)
{
	const off_t pgoff = off >> PAGE_SHIFT;
	struct devobj *obj = to_devobj(memobj);
	int error;
	uintptr_t pfn;
	uintptr_t attr;
	ihk_mc_user_context_t ctx;
	int ix;
	unsigned long irqstate;
#ifdef ENABLE_FUGAKU_HACKS
	int page_fault_attempts = 5;
#endif

	dkprintf("devobj_get_page(%p %lx,%lx,%d)\n", memobj, obj->handle, off, p2align);

	if ((pgoff < obj->pfn_pgoff) || ((obj->pfn_pgoff + obj->npages) <= pgoff)) {
		error = -EFBIG;
		kprintf("%s: error: out of range: off: %lu, page off: %lu obj->npages: %d\n", __FUNCTION__, off, pgoff, obj->npages);
		goto out;
	}
	ix = pgoff - obj->pfn_pgoff;
	dkprintf("ix: %ld\n", ix);

#ifdef PROFILE_ENABLE
	profile_event_add(PROFILE_page_fault_dev_file, PAGE_SIZE);
#endif // PROFILE_ENABLE

	irqstate = ihk_mc_spinlock_lock(&obj->pfn_table_lock);
	pfn = obj->pfn_table[ix];
	ihk_mc_spinlock_unlock(&obj->pfn_table_lock, irqstate);

	if (!(pfn & PFN_VALID)) {
#ifdef ENABLE_FUGAKU_HACKS
pf_retry:
#endif
		ihk_mc_syscall_arg0(&ctx) = PAGER_REQ_PFN;
		ihk_mc_syscall_arg1(&ctx) = obj->handle;
		ihk_mc_syscall_arg2(&ctx) = off & ~(PAGE_SIZE - 1);
		ihk_mc_syscall_arg3(&ctx) = virt_to_phys(&pfn);

		error = syscall_generic_forwarding(__NR_mmap, &ctx);
		if (error) {
			kprintf("devobj_get_page(%p %lx,%lx,%d):PAGER_REQ_PFN failed. %d\n", memobj, obj->handle, off, p2align, error);
			goto out;
		}

		if (pfn & PFN_PRESENT) {
			/* convert remote physical into local physical */
			dkprintf("devobj_get_page(%p %lx,%lx,%d):PFN_PRESENT before %#lx\n", memobj, obj->handle, off, p2align, pfn);
			attr = pfn & ~PFN_PFN;

			if (pfn_is_write_combined(pfn)) {
				*flag |= VR_WRITE_COMBINED;
			}

			pfn = ihk_mc_map_memory(NULL, (pfn & PFN_PFN), PAGE_SIZE);
			pfn &= PFN_PFN;
			pfn |= attr;
			dkprintf("devobj_get_page(%p %lx,%lx,%d):PFN_PRESENT after %#lx\n", memobj, obj->handle, off, p2align, pfn);
		}
#ifdef ENABLE_FUGAKU_HACKS
		else if (page_fault_attempts > 0) {
			kprintf("%s(): va: 0x%lx !PFN_PRESENT for offset %lu in %s, "
					"page_fault_attempts: %d\n",
					__func__, virt_addr, off,
					memobj->path ? memobj->path : "<unknown>",
					page_fault_attempts);
			--page_fault_attempts;
			goto pf_retry;
		}
#endif

		/* Update atomically if unset */
		irqstate = ihk_mc_spinlock_lock(&obj->pfn_table_lock);
		if (obj->pfn_table[ix] == 0) {
			obj->pfn_table[ix] = pfn;
		}
		ihk_mc_spinlock_unlock(&obj->pfn_table_lock, irqstate);
		// Don't call memory_stat_rss_add() because devobj related pages don't reside in main memory
	}

	if (!(pfn & PFN_PRESENT)) {
		kprintf("devobj_get_page(%p %lx,%lx,%d):not present. %lx\n", memobj, obj->handle, off, p2align, pfn);
		error = -EFAULT;
		goto out;
	}

	error = 0;
	*physp = pfn & PFN_PFN;

out:
	dkprintf("devobj_get_page(%p %lx,%lx,%d): %d %lx\n", memobj, obj->handle, off, p2align, error, *physp);
	return error;
}