ab08960f64
Change pushcli / popcli so that they can never turn on interrupts unexpectedly. That is, if interrupts are on, then pushcli(); popcli(); turns them off and back on, but if they are off to begin with, then pushcli(); popcli(); is a no-op. I think our fundamental mistake was having a primitive (release and then popcli nee spllo) that could turn interrupts on at unexpected moments instead of being explicit about when we want to start allowing interrupts. With the new semantics, all the manual fiddling of ncli to force interrupts off in certain sections goes away. In return, we must explicitly mark the places where we want to enable interrupts unconditionally, by calling sti(). There is only one: inside the scheduler loop.
87 lines
2 KiB
C
87 lines
2 KiB
C
#include "types.h"
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#include "defs.h"
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#include "param.h"
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#include "mmu.h"
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#include "proc.h"
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#include "x86.h"
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static void bootothers(void);
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static void mpmain(void) __attribute__((noreturn));
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// Bootstrap processor starts running C code here.
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int
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main(void)
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{
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extern char edata[], end[];
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// clear BSS
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memset(edata, 0, end - edata);
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mp_init(); // collect info about this machine
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lapic_init(mp_bcpu());
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cprintf("\ncpu%d: starting xv6\n\n", cpu());
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pinit(); // process table
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binit(); // buffer cache
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pic_init(); // interrupt controller
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ioapic_init(); // another interrupt controller
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kinit(); // physical memory allocator
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tvinit(); // trap vectors
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fileinit(); // file table
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iinit(); // inode cache
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console_init(); // I/O devices & their interrupts
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ide_init(); // disk
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if(!ismp)
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timer_init(); // uniprocessor timer
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userinit(); // first user process
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bootothers(); // start other processors
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// Finish setting up this processor in mpmain.
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mpmain();
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}
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// Bootstrap processor gets here after setting up the hardware.
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// Additional processors start here.
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static void
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mpmain(void)
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{
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cprintf("cpu%d: mpmain\n", cpu());
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idtinit();
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if(cpu() != mp_bcpu())
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lapic_init(cpu());
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setupsegs(0);
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cpuid(0, 0, 0, 0, 0); // memory barrier
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cpus[cpu()].booted = 1;
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scheduler();
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}
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static void
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bootothers(void)
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{
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extern uchar _binary_bootother_start[], _binary_bootother_size[];
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uchar *code;
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struct cpu *c;
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char *stack;
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// Write bootstrap code to unused memory at 0x7000.
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code = (uchar*)0x7000;
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memmove(code, _binary_bootother_start, (uint)_binary_bootother_size);
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for(c = cpus; c < cpus+ncpu; c++){
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if(c == cpus+cpu()) // We've started already.
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continue;
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// Fill in %esp, %eip and start code on cpu.
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stack = kalloc(KSTACKSIZE);
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*(void**)(code-4) = stack + KSTACKSIZE;
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*(void**)(code-8) = mpmain;
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lapic_startap(c->apicid, (uint)code);
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// Wait for cpu to get through bootstrap.
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while(c->booted == 0)
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;
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}
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}
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