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Explain a little what we are doing. Also, make sure gdt_init_cpu is called

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on the currently running CPU. Theoretically, we could put the same KASSERT
in gdt_reload_cpu, but the associated IPI is never sent, which is another
issue.
This commit is contained in:
maxv 2016-08-21 10:07:15 +00:00
parent 39cfab9701
commit e7b13942e7
1 changed files with 31 additions and 11 deletions
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42
sys/arch/amd64/amd64/gdt.c
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@ -1,4 +1,4 @@
/* $NetBSD: gdt.c,v 1.31 2016/08/21 08:30:22 christos Exp $ */
/* $NetBSD: gdt.c,v 1.32 2016/08/21 10:07:15 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 1.31 2016/08/21 08:30:22 christos Exp $");
__KERNEL_RCSID(0, "$NetBSD: gdt.c,v 1.32 2016/08/21 10:07:15 maxv Exp $");
#include "opt_multiprocessor.h"
#include "opt_xen.h"
@ -105,7 +105,8 @@ set_sys_gdt(int slot, void *base, size_t limit, int type, int dpl, int gran)
}
/*
* Initialize the GDT.
* Initialize the GDT. We already have a gdtstore, which was temporarily used
* by the bootstrap code. Now, we allocate a new gdtstore, and put it in cpu0.
*/
void
gdt_init(void)
@ -120,11 +121,18 @@ gdt_init(void)
gdt_next = 0;
gdt_free = GNULL_SEL;
gdt_dynavail =
(gdt_size - DYNSEL_START) / sizeof (struct sys_segment_descriptor);
(gdt_size - DYNSEL_START) / sizeof(struct sys_segment_descriptor);
old_gdt = gdtstore;
/* Allocate MAXGDTSIZ bytes of virtual memory. */
gdtstore = (char *)uvm_km_alloc(kernel_map, MAXGDTSIZ, 0,
UVM_KMF_VAONLY);
/*
* Allocate only MINGDTSIZ bytes of physical memory. We will grow this
* area in gdt_grow at run-time if needed.
*/
for (va = (vaddr_t)gdtstore; va < (vaddr_t)gdtstore + MINGDTSIZ;
va += PAGE_SIZE) {
pg = uvm_pagealloc(NULL, 0, NULL, UVM_PGA_ZERO);
@ -135,17 +143,21 @@ gdt_init(void)
VM_PROT_READ | VM_PROT_WRITE, 0);
}
pmap_update(pmap_kernel());
/* Copy the initial bootstrap GDT into the new area. */
memcpy(gdtstore, old_gdt, DYNSEL_START);
ci->ci_gdt = (void *)gdtstore;
#ifndef XEN
set_sys_segment(GDT_ADDR_SYS(gdtstore, GLDT_SEL), ldtstore,
LDT_SIZE - 1, SDT_SYSLDT, SEL_KPL, 0);
#endif
gdt_init_cpu(ci);
}
/*
* Allocate shadow GDT for a slave CPU.
* Allocate shadow GDT for a secondary CPU. It contains the same values as the
* GDT present in cpu0 (gdtstore).
*/
void
gdt_alloc_cpu(struct cpu_info *ci)
@ -157,6 +169,7 @@ gdt_alloc_cpu(struct cpu_info *ci)
ci->ci_gdt = (union descriptor *)uvm_km_alloc(kernel_map, max_len,
0, UVM_KMF_VAONLY);
for (va = (vaddr_t)ci->ci_gdt; va < (vaddr_t)ci->ci_gdt + min_len;
va += PAGE_SIZE) {
while ((pg = uvm_pagealloc(NULL, 0, NULL, UVM_PGA_ZERO))
@ -167,20 +180,22 @@ gdt_alloc_cpu(struct cpu_info *ci)
VM_PROT_READ | VM_PROT_WRITE, 0);
}
pmap_update(pmap_kernel());
memset(ci->ci_gdt, 0, min_len);
memcpy(ci->ci_gdt, gdtstore, gdt_size);
}
/*
* Load appropriate gdt descriptor; we better be running on *ci
* (for the most part, this is how a CPU knows who it is).
* Load appropriate GDT descriptor into the currently running CPU, which must
* be ci.
*/
void
gdt_init_cpu(struct cpu_info *ci)
{
struct region_descriptor region;
KASSERT(curcpu() == ci);
#ifndef XEN
setregion(&region, ci->ci_gdt, (uint16_t)(MAXGDTSIZ - 1));
#else
@ -206,7 +221,9 @@ gdt_reload_cpu(struct cpu_info *ci)
#if !defined(XEN) || defined(USER_LDT)
/*
* Grow the GDT.
* Grow the GDT. The GDT is present on each CPU, so we need to iterate over all
* of them. We already have the virtual memory, we only need to grow the
* physical memory.
*/
static void
gdt_grow(void)
@ -305,10 +322,13 @@ tss_alloc(struct x86_64_tss *tss)
int slot;
mutex_enter(&cpu_lock);
slot = gdt_get_slot();
set_sys_gdt(slot, tss, sizeof (struct x86_64_tss) - 1,
SDT_SYS386TSS, SEL_KPL, 0);
set_sys_gdt(slot, tss, sizeof(struct x86_64_tss) - 1, SDT_SYS386TSS,
SEL_KPL, 0);
mutex_exit(&cpu_lock);
return GDYNSEL(slot, SEL_KPL);
#else /* XEN */
/* TSS, what for? */