From bd71a45046eb13797284216c43353b9b6c92f18c Mon Sep 17 00:00:00 2001 From: Frans Kaashoek Date: Thu, 11 Aug 2011 12:25:10 -0400 Subject: [PATCH] Make AP processors boot using bootpgdir Remove device mapping from bootpgdir Remove unnecessary vmenable Set CPUS back to 2 in Makefile Passes all usertests --- Makefile | 10 +++++----- bootother.S | 29 +++++++++++++++++++---------- lapic.c | 1 - main.c | 37 ++++++++++++++----------------------- vm.c | 30 ++++-------------------------- 5 files changed, 42 insertions(+), 65 deletions(-) diff --git a/Makefile b/Makefile index e71e6b6..bd4fb4c 100644 --- a/Makefile +++ b/Makefile @@ -98,10 +98,10 @@ bootblock: bootasm.S bootmain.c ./sign.pl bootblock bootother: bootother.S - $(CC) $(CFLAGS) -nostdinc -I. -c bootother.S - $(LD) $(LDFLAGS) -N -e start -Ttext 0x7000 -o bootother.out bootother.o - $(OBJCOPY) -S -O binary bootother.out bootother - $(OBJDUMP) -S bootother.o > bootother.asm + $(CC) $(CFLAGS) -fno-pic -nostdinc -I. -c bootother.S + $(LD) $(LDFLAGS) -N -e start -Ttext 0x7000 -o bootblockother.o bootother.o + $(OBJCOPY) -S -O binary -j .text bootblockother.o bootother + $(OBJDUMP) -S bootblockother.o > bootother.asm initcode: initcode.S $(CC) $(CFLAGS) -nostdinc -I. -c initcode.S @@ -199,7 +199,7 @@ QEMUGDB = $(shell if $(QEMU) -help | grep -q '^-gdb'; \ then echo "-gdb tcp::$(GDBPORT)"; \ else echo "-s -p $(GDBPORT)"; fi) ifndef CPUS -CPUS := 1 +CPUS := 2 endif QEMUOPTS = -hdb fs.img xv6.img -smp $(CPUS) -m 512 diff --git a/bootother.S b/bootother.S index 7b0b815..56edac2 100644 --- a/bootother.S +++ b/bootother.S @@ -14,12 +14,13 @@ # Bootothers (in main.c) sends the STARTUPs one at a time. # It copies this code (start) at 0x7000. # It puts the address of a newly allocated per-core stack in start-4, -# and the address of the place to jump to (mpmain) in start-8. +# the address of the place to jump to (mpboot) in start-8, and the physical +# address of bootpgdir in start-12. +# # # This code is identical to bootasm.S except: # - it does not need to enable A20 -# - it uses the address at start-4 for the %esp -# - it jumps to the address at start-8 instead of calling bootmain +# - it uses the address at start-4, start-8, and start-12 .code16 .globl start @@ -37,7 +38,7 @@ start: movl %eax, %cr0 //PAGEBREAK! - ljmpl $(SEG_KCODE<<3), $(start32+KERNBASE) + ljmpl $(SEG_KCODE<<3), $(start32) .code32 start32: @@ -49,11 +50,18 @@ start32: movw %ax, %fs movw %ax, %gs - # switch to the stack allocated by bootothers() - movl P2V_WO(start-4), %esp + # Use bootpgdir as our initial page table + movl (start-12), %eax + movl %eax, %cr3 + # Turn on paging. + movl %cr0, %eax + orl $(CR0_PE|CR0_PG|CR0_WP), %eax + movl %eax, %cr0 - # call mpmain() - call *(P2V_WO(start)-8) + # Switch to the stack allocated by bootothers() + movl (start-4), %esp + # Call mpboot() + call *(start-8) movw $0x8a00, %ax movw %ax, %dx @@ -66,10 +74,11 @@ spin: .p2align 2 gdt: SEG_NULLASM - SEG_ASM(STA_X|STA_R, -KERNBASE, 0xffffffff) - SEG_ASM(STA_W, -KERNBASE, 0xffffffff) + SEG_ASM(STA_X|STA_R, 0, 0xffffffff) + SEG_ASM(STA_W, 0, 0xffffffff) gdtdesc: .word (gdtdesc - gdt - 1) .long gdt + diff --git a/lapic.c b/lapic.c index 5a758be..7554f73 100644 --- a/lapic.c +++ b/lapic.c @@ -52,7 +52,6 @@ lapicw(int index, int value) void lapicinit(int c) { - cprintf("lapicinit: %d 0x%x\n", c, lapic); if(!lapic) return; diff --git a/main.c b/main.c index 416723e..dabca19 100644 --- a/main.c +++ b/main.c @@ -8,7 +8,7 @@ static void bootothers(void); static void mpmain(void) __attribute__((noreturn)); -static volatile int newpgdir; +extern pde_t *kpgdir; // Bootstrap processor starts running C code here. // Allocate a real stack and switch to it, first @@ -21,7 +21,6 @@ main(void) lapicinit(mpbcpu()); seginit(); // set up segments cprintf("\ncpu%d: starting xv6\n\n", cpu->id); - kinit(); // initialize memory allocator picinit(); // interrupt controller ioapicinit(); // another interrupt controller consoleinit(); // I/O devices & their interrupts @@ -34,39 +33,35 @@ main(void) ideinit(); // disk if(!ismp) timerinit(); // uniprocessor timer - userinit(); // first user process - bootothers(); // start other processors - newpgdir = 1; + bootothers(); // start other processors (must come before kinit; must use boot_alloc) + kinit(); // initialize memory allocator + userinit(); // first user process (must come after kinit) // Finish setting up this processor in mpmain. mpmain(); } -// Common CPU setup code. -// Bootstrap CPU comes here from mainc(). // Other CPUs jump here from bootother.S. static void mpboot(void) { - vmenable(); // turn on paging + switchkvm(); seginit(); lapicinit(cpunum()); mpmain(); } // Common CPU setup code. -// Bootstrap CPU comes here from mainc(). -// Other CPUs jump here from bootother.S. static void mpmain(void) { cprintf("cpu%d: starting\n", cpu->id); idtinit(); // load idt register xchg(&cpu->booted, 1); // tell bootothers() we're up - while (!newpgdir) ; // wait until we have new page dir - switchkvm(); // switch to new page dir scheduler(); // start running processes } +pde_t bootpgdir[]; + // Start the non-boot processors. static void bootothers(void) @@ -86,41 +81,37 @@ bootothers(void) if(c == cpus+cpunum()) // We've started already. continue; - // Tell bootother.S what stack to use and the address of mpmain; - // it expects to find these two addresses stored just before - // its first instruction. - stack = kalloc(); + // Tell bootother.S what stack to use, the address of mpboot and pgdir; + stack = boot_alloc(); // We need a stack below 4Mbyte with bootpgdir *(void**)(code-4) = stack + KSTACKSIZE; *(void**)(code-8) = mpboot; + *(int**)(code-12) = (void *) v2p(bootpgdir); lapicstartap(c->id, v2p(code)); - // Wait for cpu to finish mpmain() + // wait for cpu to finish mpmain() while(c->booted == 0) ; } } -// Boot page table used in multiboot.S. +// Boot page table used in multiboot.S and bootother.S. // Page directories (and page tables), must start on a page boundary, // hence the "__aligned__" attribute. Also, because of restrictions // related to linking and static initializers, we use "x + PTE_P" // here, rather than the more standard "x | PTE_P". Everywhere else // you should use "|" to combine flags. -pte_t entry_pgtable[NPTENTRIES]; pte_t dev_pgtable[NPTENTRIES]; +pte_t entry_pgtable[NPTENTRIES]; __attribute__((__aligned__(PGSIZE))) pde_t bootpgdir[NPDENTRIES] = { // Map VA's [0, 4MB) to PA's [0, 4MB) [0] - = ((uint)entry_pgtable - KERNBASE) + PTE_P, + = ((uint)entry_pgtable - KERNBASE) + PTE_P + PTE_W, // Map VA's [KERNBASE, KERNBASE+4MB) to PA's [0, 4MB) [KERNBASE>>PDXSHIFT] = ((uint)entry_pgtable - KERNBASE) + PTE_P + PTE_W, - // Map VA's [DEVSPACE, DEVSPACE+4MB) to PA's [DEVSPACE, 4MB) - [0xFEE00000>>PDXSHIFT] - = ((uint)dev_pgtable - KERNBASE) + PTE_P + PTE_W, }; // XXX switch to super pages diff --git a/vm.c b/vm.c index fe6bb08..049a25e 100644 --- a/vm.c +++ b/vm.c @@ -8,7 +8,7 @@ #include "elf.h" extern char data[]; // defined in data.S -static pde_t *kpgdir; // for use in scheduler() +pde_t *kpgdir; // for use in scheduler() struct segdesc gdt[NSEGS]; // Set up CPU's kernel segment descriptors. @@ -40,7 +40,7 @@ seginit(void) } // Return the address of the PTE in page table pgdir -// that corresponds to linear address va. If create!=0, +// that corresponds to linear address va. If alloc!=0, // create any required page table pages. static pte_t * walkpgdir(pde_t *pgdir, const void *va, char* (*alloc)(void)) @@ -102,8 +102,8 @@ mappages(pde_t *pgdir, void *la, uint size, uint pa, int perm, char* (*alloc)(vo // setupkvm() and exec() set up every page table like this: // 0..USERTOP : user memory (text, data, stack, heap), mapped to some unused phys mem // KERNBASE..KERNBASE+1M: mapped to 0..1M -// KERNBASE+1M..KERNBASE+end : mapped to 1M..end -// KERNBASE+end..KERBASE+PHYSTOP : mapped to end..PHYSTOP (free memory) +// KERNBASE+1M..KERNBASE+end : mapped to 1M..end (mapped without write permission) +// KERNBASE+end..KERBASE+PHYSTOP : mapped to end..PHYSTOP (rw data + free memory) // 0xfe000000..0 : mapped direct (devices such as ioapic) // // The kernel allocates memory for its heap and for user memory @@ -150,28 +150,6 @@ kvmalloc(void) switchkvm(); } -// Turn on paging. -void -vmenable(void) -{ - uint cr0; - - switchkvm(); // load kpgdir into cr3 - cr0 = rcr0(); - cr0 |= CR0_PG; - lcr0(cr0); - - struct cpu *c = &cpus[0]; - lgdt((void *)v2p((void *)(c->gdt)), sizeof(c->gdt)); - loadgs(SEG_KCPU << 3); - loadfs(SEG_KDATA << 3); - loades(SEG_KDATA << 3); - loadds(SEG_KDATA << 3); - loadss(SEG_KDATA << 3); - - __asm volatile("ljmp %0,$1f\n 1:\n" :: "i" (SEG_KCODE << 3)); // reload cs -} - // Switch h/w page table register to the kernel-only page table, // for when no process is running. void