Imbus/xv6-riscv-kernel
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Merge branch 'nogs'

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This commit is contained in:
Frans Kaashoek 2017-08-07 14:35:05 -04:00
commit 61cb32aa9b
19 changed files with 181 additions and 165 deletions
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21
vm.c
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@ -21,21 +21,12 @@ seginit(void)
// Cannot share a CODE descriptor for both kernel and user
// because it would have to have DPL_USR, but the CPU forbids
// an interrupt from CPL=0 to DPL=3.
c = &cpus[cpunum()];
c = &cpus[cpuid()];
c->gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, 0);
c->gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0);
c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, 0, 0xffffffff, DPL_USER);
c->gdt[SEG_UDATA] = SEG(STA_W, 0, 0xffffffff, DPL_USER);
// Map cpu and proc -- these are private per cpu.
c->gdt[SEG_KCPU] = SEG(STA_W, &c->cpu, 8, 0);
lgdt(c->gdt, sizeof(c->gdt));
loadgs(SEG_KCPU << 3);
// Initialize cpu-local storage.
cpu = c;
proc = 0;
}
// Return the address of the PTE in page table pgdir
@ -173,13 +164,13 @@ switchuvm(struct proc *p)
panic("switchuvm: no pgdir");
pushcli();
cpu->gdt[SEG_TSS] = SEG16(STS_T32A, &cpu->ts, sizeof(cpu->ts)-1, 0);
cpu->gdt[SEG_TSS].s = 0;
cpu->ts.ss0 = SEG_KDATA << 3;
cpu->ts.esp0 = (uint)p->kstack + KSTACKSIZE;
mycpu()->gdt[SEG_TSS] = SEG16(STS_T32A, &mycpu()->ts, sizeof(mycpu()->ts)-1, 0);
mycpu()->gdt[SEG_TSS].s = 0;
mycpu()->ts.ss0 = SEG_KDATA << 3;
mycpu()->ts.esp0 = (uint)p->kstack + KSTACKSIZE;
// setting IOPL=0 in eflags *and* iomb beyond the tss segment limit
// forbids I/O instructions (e.g., inb and outb) from user space
cpu->ts.iomb = (ushort) 0xFFFF;
mycpu()->ts.iomb = (ushort) 0xFFFF;
ltr(SEG_TSS << 3);
lcr3(V2P(p->pgdir)); // switch to process's address space
popcli();