Better support memory mapped console devices, such as VGA and EFI

frame buffers and memory mapped UARTs.

1.  Delay calling cninit() until after pmap_bootstrap(). This makes
    sure we have PMAP initialized enough to add translations. Keep
    kdb_init() after cninit() so that we have console when we need
    to break into the debugger on boot.
2.  Unfortunately, the ATPIC code had be moved as well so as to
    avoid a spurious trap #30. The reason for which is not known
    at this time.
3.  In pmap_mapdev_attr(), when we need to map a device prior to the
    VM system being initialized, use virtual_avail as the KVA to map
    the device at. In particular, avoid using the direct map on amd64
    because we can't demote by virtue of not being able to allocate
    yet. Keep track of the translation.
    Re-use the translation after the VM has been initialized to not
    waste KVA and to satisfy the assumption in uart(4) that the handle
    returned for the low-level console is the same as later returned
    when the device is probed and attached.
4.  In pmap_unmapdev() remove the mapping from the table when called
    pre-init. Otherwise keep the mapping. During bus probe and attach
    device resources are mapped and unmapped multiple times, which
    would have us destroy the mapping used by the low-level console.
5.  In pmap_init(), set pmap_initialized to signal that we're not
    pre-init anymore. On amd64, bring the direct map in sync with the
    translations created at that time.
6.  Implement bus_space_map() and bus_space_unmap() for real: when
    the tag corresponds to memory space, call the corresponding
    pmap_mapdev() and pmap_unmapdev() functions to construct and
    actual handle.
7.  In efifb.c and vt_vga.c, remove the crutches and hacks and simply
    call pmap_mapdev_attr() or bus_space_map() as desired.

Notes:
1.  uart(4) already used bus_space_map() during low-level console
    setup but since serial ports have traditionally been I/O port
    based, the lack of a proper implementation for said function
    was not a problem. It has always supported memory mapped UARTs
    for low-level consoles by setting hw.uart.console accordingly.
2.  The use of the direct map on amd64 without setting caching
    attributes has been a bigger problem than previously thought.
    This change has the fortunate (and unexpected) side-effect of
    fixing various EFI frame buffer problems (though not all).

PR: 191564, 194952

Special thanks to:
1.  XipLink, Inc -- generously donated an Intel Bay Trail E3800
    based eval board (ADLE3800PC).
2.  The FreeBSD Foundation, in particular emaste@ -- for UEFI
    support in general and testing.
3.  Everyone who tested the proposed for PR 191564.
4.  jhb@ and kib@ for being a soundboard and applying a clue bat
    if so needed.

2 files changed, 109 insertions, 41 deletions

diff --git a/sys/i386/i386/machdep.c b/sys/i386/i386/machdep.c
index 76790f0..1818264 100644
--- a/sys/i386/i386/machdep.c
+++ b/sys/i386/i386/machdep.c
@@ -2612,6 +2612,40 @@ init386(first)
 	 */
 	clock_init();
 
+	finishidentcpu();	/* Final stage of CPU initialization */
+	setidt(IDT_UD, &IDTVEC(ill),  SDT_SYS386TGT, SEL_KPL,
+	    GSEL(GCODE_SEL, SEL_KPL));
+	setidt(IDT_GP, &IDTVEC(prot),  SDT_SYS386TGT, SEL_KPL,
+	    GSEL(GCODE_SEL, SEL_KPL));
+	initializecpu();	/* Initialize CPU registers */
+	initializecpucache();
+
+	/* pointer to selector slot for %fs/%gs */
+	PCPU_SET(fsgs_gdt, &gdt[GUFS_SEL].sd);
+
+	dblfault_tss.tss_esp = dblfault_tss.tss_esp0 = dblfault_tss.tss_esp1 =
+	    dblfault_tss.tss_esp2 = (int)&dblfault_stack[sizeof(dblfault_stack)];
+	dblfault_tss.tss_ss = dblfault_tss.tss_ss0 = dblfault_tss.tss_ss1 =
+	    dblfault_tss.tss_ss2 = GSEL(GDATA_SEL, SEL_KPL);
+#if defined(PAE) || defined(PAE_TABLES)
+	dblfault_tss.tss_cr3 = (int)IdlePDPT;
+#else
+	dblfault_tss.tss_cr3 = (int)IdlePTD;
+#endif
+	dblfault_tss.tss_eip = (int)dblfault_handler;
+	dblfault_tss.tss_eflags = PSL_KERNEL;
+	dblfault_tss.tss_ds = dblfault_tss.tss_es =
+	    dblfault_tss.tss_gs = GSEL(GDATA_SEL, SEL_KPL);
+	dblfault_tss.tss_fs = GSEL(GPRIV_SEL, SEL_KPL);
+	dblfault_tss.tss_cs = GSEL(GCODE_SEL, SEL_KPL);
+	dblfault_tss.tss_ldt = GSEL(GLDT_SEL, SEL_KPL);
+
+	vm86_initialize();
+	getmemsize(first);
+	init_param2(physmem);
+
+	/* now running on new page tables, configured,and u/iom is accessible */
+
 	/*
 	 * Initialize the console before we print anything out.
 	 */
@@ -2652,40 +2686,6 @@ init386(first)
 		kdb_enter(KDB_WHY_BOOTFLAGS, "Boot flags requested debugger");
 #endif
 
-	finishidentcpu();	/* Final stage of CPU initialization */
-	setidt(IDT_UD, &IDTVEC(ill),  SDT_SYS386TGT, SEL_KPL,
-	    GSEL(GCODE_SEL, SEL_KPL));
-	setidt(IDT_GP, &IDTVEC(prot),  SDT_SYS386TGT, SEL_KPL,
-	    GSEL(GCODE_SEL, SEL_KPL));
-	initializecpu();	/* Initialize CPU registers */
-	initializecpucache();
-
-	/* pointer to selector slot for %fs/%gs */
-	PCPU_SET(fsgs_gdt, &gdt[GUFS_SEL].sd);
-
-	dblfault_tss.tss_esp = dblfault_tss.tss_esp0 = dblfault_tss.tss_esp1 =
-	    dblfault_tss.tss_esp2 = (int)&dblfault_stack[sizeof(dblfault_stack)];
-	dblfault_tss.tss_ss = dblfault_tss.tss_ss0 = dblfault_tss.tss_ss1 =
-	    dblfault_tss.tss_ss2 = GSEL(GDATA_SEL, SEL_KPL);
-#if defined(PAE) || defined(PAE_TABLES)
-	dblfault_tss.tss_cr3 = (int)IdlePDPT;
-#else
-	dblfault_tss.tss_cr3 = (int)IdlePTD;
-#endif
-	dblfault_tss.tss_eip = (int)dblfault_handler;
-	dblfault_tss.tss_eflags = PSL_KERNEL;
-	dblfault_tss.tss_ds = dblfault_tss.tss_es =
-	    dblfault_tss.tss_gs = GSEL(GDATA_SEL, SEL_KPL);
-	dblfault_tss.tss_fs = GSEL(GPRIV_SEL, SEL_KPL);
-	dblfault_tss.tss_cs = GSEL(GCODE_SEL, SEL_KPL);
-	dblfault_tss.tss_ldt = GSEL(GLDT_SEL, SEL_KPL);
-
-	vm86_initialize();
-	getmemsize(first);
-	init_param2(physmem);
-
-	/* now running on new page tables, configured,and u/iom is accessible */
-
 	msgbufinit(msgbufp, msgbufsize);
 #ifdef DEV_NPX
 	npxinit(true);
diff --git a/sys/i386/i386/pmap.c b/sys/i386/i386/pmap.c
index f8ae6d9..9b8b2ff 100644
--- a/sys/i386/i386/pmap.c
+++ b/sys/i386/i386/pmap.c
@@ -228,6 +228,18 @@ SYSCTL_INT(_vm_pmap, OID_AUTO, pg_ps_enabled, CTLFLAG_RDTUN | CTLFLAG_NOFETCH,
 #define	PAT_INDEX_SIZE	8
 static int pat_index[PAT_INDEX_SIZE];	/* cache mode to PAT index conversion */
 
+/*
+ * pmap_mapdev support pre initialization (i.e. console)
+ */
+#define	PMAP_PREINIT_MAPPING_COUNT	8
+static struct pmap_preinit_mapping {
+	vm_paddr_t	pa;
+	vm_offset_t	va;
+	vm_size_t	sz;
+	int		mode;
+} pmap_preinit_mapping[PMAP_PREINIT_MAPPING_COUNT];
+static int pmap_initialized;
+
 static struct rwlock_padalign pvh_global_lock;
 
 /*
@@ -744,6 +756,7 @@ pmap_ptelist_init(vm_offset_t *head, void *base, int npages)
 void
 pmap_init(void)
 {
+	struct pmap_preinit_mapping *ppim;
 	vm_page_t mpte;
 	vm_size_t s;
 	int i, pv_npg;
@@ -827,6 +840,17 @@ pmap_init(void)
 	    UMA_ZONE_VM | UMA_ZONE_NOFREE);
 	uma_zone_set_allocf(pdptzone, pmap_pdpt_allocf);
 #endif
+
+	pmap_initialized = 1;
+	if (!bootverbose)
+		return;
+	for (i = 0; i < PMAP_PREINIT_MAPPING_COUNT; i++) {
+		ppim = pmap_preinit_mapping + i;
+		if (ppim->va == 0)
+			continue;
+		printf("PPIM %u: PA=%#jx, VA=%#x, size=%#x, mode=%#x\n", i,
+		    (uintmax_t)ppim->pa, ppim->va, ppim->sz, ppim->mode);
+	}
 }
 
 
@@ -5071,8 +5095,10 @@ pmap_pde_attr(pd_entry_t *pde, int cache_bits)
 void *
 pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, int mode)
 {
+	struct pmap_preinit_mapping *ppim;
 	vm_offset_t va, offset;
 	vm_size_t tmpsize;
+	int i;
 
 	offset = pa & PAGE_MASK;
 	size = round_page(offset + size);
@@ -5080,11 +5106,36 @@ pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, int mode)
 
 	if (pa < KERNLOAD && pa + size <= KERNLOAD)
 		va = KERNBASE + pa;
-	else
+	else if (!pmap_initialized) {
+		va = 0;
+		for (i = 0; i < PMAP_PREINIT_MAPPING_COUNT; i++) {
+			ppim = pmap_preinit_mapping + i;
+			if (ppim->va == 0) {
+				ppim->pa = pa;
+				ppim->sz = size;
+				ppim->mode = mode;
+				ppim->va = virtual_avail;
+				virtual_avail += size;
+				va = ppim->va;
+				break;
+			}
+		}
+		if (va == 0)
+			panic("%s: too many preinit mappings", __func__);
+	} else {
+		/*
+		 * If we have a preinit mapping, re-use it.
+		 */
+		for (i = 0; i < PMAP_PREINIT_MAPPING_COUNT; i++) {
+			ppim = pmap_preinit_mapping + i;
+			if (ppim->pa == pa && ppim->sz == size &&
+			    ppim->mode == mode)
+				return ((void *)(ppim->va + offset));
+		}
 		va = kva_alloc(size);
-	if (!va)
-		panic("pmap_mapdev: Couldn't alloc kernel virtual memory");
-
+		if (va == 0)
+			panic("%s: Couldn't allocate KVA", __func__);
+	}
 	for (tmpsize = 0; tmpsize < size; tmpsize += PAGE_SIZE)
 		pmap_kenter_attr(va + tmpsize, pa + tmpsize, mode);
 	pmap_invalidate_range(kernel_pmap, va, va + tmpsize);
@@ -5109,14 +5160,31 @@ pmap_mapbios(vm_paddr_t pa, vm_size_t size)
 void
 pmap_unmapdev(vm_offset_t va, vm_size_t size)
 {
-	vm_offset_t base, offset;
+	struct pmap_preinit_mapping *ppim;
+	vm_offset_t offset;
+	int i;
 
 	if (va >= KERNBASE && va + size <= KERNBASE + KERNLOAD)
 		return;
-	base = trunc_page(va);
 	offset = va & PAGE_MASK;
 	size = round_page(offset + size);
-	kva_free(base, size);
+	va = trunc_page(va);
+	for (i = 0; i < PMAP_PREINIT_MAPPING_COUNT; i++) {
+		ppim = pmap_preinit_mapping + i;
+		if (ppim->va == va && ppim->sz == size) {
+			if (pmap_initialized)
+				return;
+			ppim->pa = 0;
+			ppim->va = 0;
+			ppim->sz = 0;
+			ppim->mode = 0;
+			if (va + size == virtual_avail)
+				virtual_avail = va;
+			return;
+		}
+	}
+	if (pmap_initialized)
+		kva_free(va, size);
 }
 
 /*