Module Name: src
Committed By: maxv
Date: Sat Mar 25 15:05:16 UTC 2017
Modified Files:
src/sys/arch/amd64/amd64: gdt.c
Log Message:
Use a bitmap-based allocator, will be easier to share with i386.
To generate a diff of this commit:
cvs rdiff -u -r1.37 -r1.38 src/sys/arch/amd64/amd64/gdt.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/amd64/amd64/gdt.c
diff -u src/sys/arch/amd64/amd64/gdt.c:1.37 src/sys/arch/amd64/amd64/gdt.c:1.38
--- src/sys/arch/amd64/amd64/gdt.c:1.37 Wed Feb 8 18:50:51 2017
+++ src/sys/arch/amd64/amd64/gdt.c Sat Mar 25 15:05:16 2017
@@ -1,4 +1,4 @@
-/* $NetBSD: gdt.c,v 1.37 2017/02/08 18:50:51 kre Exp $ */
+/* $NetBSD: gdt.c,v 1.38 2017/03/25 15:05:16 maxv Exp $ */
/*-
* Copyright (c) 1996, 1997, 2009 The NetBSD Foundation, Inc.
@@ -37,7 +37,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: gdt.c,v 1.37 2017/02/08 18:50:51 kre Exp $");
+__KERNEL_RCSID(0, "$NetBSD: gdt.c,v 1.38 2017/03/25 15:05:16 maxv Exp $");
#include "opt_multiprocessor.h"
#include "opt_xen.h"
@@ -57,16 +57,20 @@ __KERNEL_RCSID(0, "$NetBSD: gdt.c,v 1.37
#include <xen/hypervisor.h>
#endif
-int gdt_size; /* size of GDT in bytes */
-int gdt_dyncount; /* number of dyn. allocated GDT entries in use */
-int gdt_dynavail;
-int gdt_next; /* next available slot for sweeping */
-int gdt_free; /* next free slot; terminated with GNULL_SEL */
+#define NDYNSLOTS \
+ ((MAXGDTSIZ - DYNSEL_START) / sizeof(struct sys_segment_descriptor))
+
+typedef struct {
+ bool busy[NDYNSLOTS];
+ size_t nslots;
+} gdt_bitmap_t;
+
+size_t gdt_size; /* size of GDT in bytes */
+static gdt_bitmap_t gdt_bitmap; /* bitmap of busy slots */
#if defined(USER_LDT) || !defined(XEN)
static void set_sys_gdt(int, void *, size_t, int, int, int);
#endif
-void gdt_init(void);
void
update_descriptor(void *tp, void *ep)
@@ -83,7 +87,7 @@ update_descriptor(void *tp, void *ep)
if (!pmap_extract_ma(pmap_kernel(), (vaddr_t)table, &pa) ||
HYPERVISOR_update_descriptor(pa, *entry))
- panic("HYPERVISOR_update_descriptor failed\n");
+ panic("HYPERVISOR_update_descriptor failed");
#endif
}
@@ -124,11 +128,10 @@ gdt_init(void)
vaddr_t va;
struct cpu_info *ci = &cpu_info_primary;
+ /* Initialize the global values */
gdt_size = MINGDTSIZ;
- gdt_dyncount = 0;
- gdt_next = 0;
- gdt_free = GNULL_SEL;
- gdt_dynavail =
+ memset(&gdt_bitmap.busy, 0, sizeof(gdt_bitmap.busy));
+ gdt_bitmap.nslots =
(gdt_size - DYNSEL_START) / sizeof(struct sys_segment_descriptor);
old_gdt = gdtstore;
@@ -228,10 +231,10 @@ gdt_grow(void)
vaddr_t va;
old_size = gdt_size;
- gdt_size <<= 1;
+ gdt_size *= 2;
if (gdt_size > MAXGDTSIZ)
gdt_size = MAXGDTSIZ;
- gdt_dynavail =
+ gdt_bitmap.nslots =
(gdt_size - DYNSEL_START) / sizeof(struct sys_segment_descriptor);
for (CPU_INFO_FOREACH(cii, ci)) {
@@ -250,57 +253,34 @@ gdt_grow(void)
pmap_update(pmap_kernel());
}
-/*
- * Allocate a GDT slot as follows:
- * 1) If there are entries on the free list, use those.
- * 2) If there are fewer than gdt_dynavail entries in use, there are free slots
- * near the end that we can sweep through.
- * 3) As a last resort, we increase the size of the GDT, and sweep through
- * the new slots.
- */
static int
gdt_get_slot(void)
{
- int slot;
- struct sys_segment_descriptor *gdt;
-
- gdt = (struct sys_segment_descriptor *)&gdtstore[DYNSEL_START];
+ size_t i;
KASSERT(mutex_owned(&cpu_lock));
- if (gdt_free != GNULL_SEL) {
- slot = gdt_free;
- gdt_free = gdt[slot].sd_xx3; /* XXXfvdl res. field abuse */
- } else {
- KASSERT(gdt_next == gdt_dyncount);
- if (gdt_next >= gdt_dynavail) {
- if (gdt_size >= MAXGDTSIZ)
- panic("gdt_get_slot: out of memory");
- gdt_grow();
+ while (1) {
+ for (i = 0; i < gdt_bitmap.nslots; i++) {
+ if (!gdt_bitmap.busy[i]) {
+ gdt_bitmap.busy[i] = true;
+ return (int)i;
+ }
}
- slot = gdt_next++;
+ if (gdt_size >= MAXGDTSIZ)
+ panic("gdt_get_slot: out of memory");
+ gdt_grow();
}
-
- gdt_dyncount++;
- return slot;
+ /* NOTREACHED */
+ return 0;
}
-/*
- * Deallocate a GDT slot, putting it on the free list.
- */
static void
gdt_put_slot(int slot)
{
- struct sys_segment_descriptor *gdt;
-
KASSERT(mutex_owned(&cpu_lock));
-
- gdt = (struct sys_segment_descriptor *)&gdtstore[DYNSEL_START];
-
- gdt_dyncount--;
- gdt[slot].sd_type = SDT_SYSNULL;
- gdt[slot].sd_xx3 = gdt_free;
- gdt_free = slot;
+ KASSERT(slot < gdt_bitmap.nslots);
+ gdt_bitmap.busy[slot] = false;
}
#endif
@@ -319,7 +299,7 @@ tss_alloc(struct x86_64_tss *tss)
mutex_exit(&cpu_lock);
return GDYNSEL(slot, SEL_KPL);
-#else /* XEN */
+#else
/* TSS, what for? */
return GSEL(GNULL_SEL, SEL_KPL);
#endif
@@ -338,9 +318,6 @@ tss_free(int sel)
}
#ifdef USER_LDT
-/*
- * XXX: USER_LDT is not implemented on amd64.
- */
int
ldt_alloc(void *ldtp, size_t len)
{
@@ -380,25 +357,19 @@ lgdt(struct region_descriptor *desc)
* Zero out last frame after limit if needed.
*/
va = desc->rd_base + desc->rd_limit + 1;
- __PRINTK(("memset 0x%lx -> 0x%lx\n", va, roundup(va, PAGE_SIZE)));
- memset((void *) va, 0, roundup(va, PAGE_SIZE) - va);
+ memset((void *)va, 0, roundup(va, PAGE_SIZE) - va);
for (i = 0; i < roundup(desc->rd_limit, PAGE_SIZE) >> PAGE_SHIFT; i++) {
-
/*
* The lgdt instruction uses virtual addresses,
* do some translation for Xen.
* Mark pages R/O too, else Xen will refuse to use them.
*/
-
frames[i] = ((paddr_t) xpmap_ptetomach(
- (pt_entry_t *) (desc->rd_base + (i << PAGE_SHIFT))))
- >> PAGE_SHIFT;
- __PRINTK(("frames[%d] = 0x%lx (pa 0x%lx)\n", i, frames[i],
- xpmap_mtop(frames[i] << PAGE_SHIFT)));
+ (pt_entry_t *)(desc->rd_base + (i << PAGE_SHIFT)))) >>
+ PAGE_SHIFT;
pmap_pte_clearbits(kvtopte(desc->rd_base + (i << PAGE_SHIFT)),
PG_RW);
}
- __PRINTK(("HYPERVISOR_set_gdt(%d)\n", (desc->rd_limit + 1) >> 3));
if (HYPERVISOR_set_gdt(frames, (desc->rd_limit + 1) >> 3))
panic("lgdt(): HYPERVISOR_set_gdt() failed");
