From: Peter H. Froehlich <peter.hans.froehlich@gmail.com>
Date: Fri, 16 Oct 2015 21:41:17 +0000 (-0400)
Subject: Small changes related to memlayout.h primarily.
X-Git-Url: https://hydra-www.ietfng.org/gitweb/?a=commitdiff_plain;h=55543c55679695705f89bab7cd8ddea7924f1e7b;p=xv6-public

Small changes related to memlayout.h primarily.

Resolved v2p/p2v/V2P/P2V duplication, minimized memlayout.h use,
clarified entry.S "indirect jump" confusion, nits.
---

diff --git a/bootasm.S b/bootasm.S
index 91a595e..d84d4ab 100644
--- a/bootasm.S
+++ b/bootasm.S
@@ -1,5 +1,4 @@
 #include "asm.h"
-#include "memlayout.h"
 #include "mmu.h"
 
 # Start the first CPU: switch to 32-bit protected mode, jump into C.
@@ -18,7 +17,7 @@ start:
   movw    %ax,%es             # -> Extra Segment
   movw    %ax,%ss             # -> Stack Segment
 
-  # Physical address line A20 is tied to zero so that the first PCs 
+  # Physical address line A20 is tied to zero so that the first PCs
   # with 2 MB would run software that assumed 1 MB.  Undo that.
 seta20.1:
   inb     $0x64,%al               # Wait for not busy
diff --git a/bootmain.c b/bootmain.c
index 6c6f080..3d3603d 100644
--- a/bootmain.c
+++ b/bootmain.c
@@ -8,7 +8,6 @@
 #include "types.h"
 #include "elf.h"
 #include "x86.h"
-#include "memlayout.h"
 #include "ide.h"
 
 void readseg(uchar*, uint, uint);
diff --git a/entry.S b/entry.S
index 5f4e124..5017a49 100644
--- a/entry.S
+++ b/entry.S
@@ -52,13 +52,13 @@ entry:
   movl    %eax, %cr0
 
   # Set up the stack pointer.
-  movl $(stack + KSTACKSIZE), %esp
+  movl    $(stack + KSTACKSIZE), %esp
 
-  # Jump to main(), and switch to executing at
-  # high addresses. The indirect call is needed because
-  # the assembler produces a PC-relative instruction
-  # for a direct jump.
-  mov $main, %eax
-  jmp *%eax
+  # Jump to main() and switch to executing at high addresses.
+  # Need an explicit long jump (indirect jump would work as
+  # well, as would a push/ret trick to save 1 byte) because
+  # the assembler produces a PC-relative instruction for a
+  # direct jump.
+  ljmp    $(SEG_KCODE<<3), $main
 
 .comm stack, KSTACKSIZE
diff --git a/entryother.S b/entryother.S
index 9f94cd3..a745a41 100644
--- a/entryother.S
+++ b/entryother.S
@@ -1,7 +1,6 @@
 #include "asm.h"
-#include "memlayout.h"
 #include "mmu.h"
-	
+
 # Each non-boot CPU ("AP") is started up in response to a STARTUP
 # IPI from the boot CPU.  Section B.4.2 of the Multi-Processor
 # Specification says that the AP will start in real mode with CS:IP
@@ -21,10 +20,10 @@
 #   - it does not need to enable A20
 #   - it uses the address at start-4, start-8, and start-12
 
-.code16           
+.code16
 .globl start
 start:
-  cli            
+  cli
 
   xorw    %ax,%ax
   movw    %ax,%ds
@@ -37,7 +36,7 @@ start:
   movl    %eax, %cr0
 
 //PAGEBREAK!
-  ljmpl    $(SEG_KCODE<<3), $(start32)
+  ljmp    $(SEG_KCODE<<3), $start32
 
 .code32
 start32:
@@ -58,13 +57,13 @@ start32:
   movl    %eax, %cr3
   # Turn on paging.
   movl    %cr0, %eax
-  orl     $(CR0_PE|CR0_PG|CR0_WP), %eax
+  orl     $(CR0_PG|CR0_WP), %eax
   movl    %eax, %cr0
 
   # Switch to the stack allocated by startothers()
   movl    (start-4), %esp
   # Call mpenter()
-  call	 *(start-8)
+  call	  *(start-8)
 
   movw    $0x8a00, %ax
   movw    %ax, %dx
@@ -80,7 +79,6 @@ gdt:
   SEG_ASM(STA_X|STA_R, 0, 0xffffffff)
   SEG_ASM(STA_W, 0, 0xffffffff)
 
-
 gdtdesc:
   .word   (gdtdesc - gdt - 1)
   .long   gdt
diff --git a/exec.c b/exec.c
index 8dbbdb6..0d4ac4f 100644
--- a/exec.c
+++ b/exec.c
@@ -1,6 +1,5 @@
 #include "types.h"
 #include "param.h"
-#include "memlayout.h"
 #include "mmu.h"
 #include "proc.h"
 #include "defs.h"
diff --git a/ide.c b/ide.c
index b713433..e904e61 100644
--- a/ide.c
+++ b/ide.c
@@ -3,7 +3,6 @@
 #include "types.h"
 #include "defs.h"
 #include "param.h"
-#include "memlayout.h"
 #include "mmu.h"
 #include "proc.h"
 #include "x86.h"
diff --git a/kalloc.c b/kalloc.c
index 417c20f..ca30d55 100644
--- a/kalloc.c
+++ b/kalloc.c
@@ -61,7 +61,7 @@ kfree(char *v)
 {
   struct run *r;
 
-  if((uint)v % PGSIZE || v < end || v2p(v) >= PHYSTOP)
+  if((uint)v % PGSIZE || v < end || V2P(v) >= PHYSTOP)
     panic("kfree");
 
   // Fill with junk to catch dangling refs.
diff --git a/main.c b/main.c
index 40facc4..c958e51 100644
--- a/main.c
+++ b/main.c
@@ -8,7 +8,6 @@
 
 static void startothers(void);
 static void mpmain(void)  __attribute__((noreturn));
-extern pde_t *kpgdir;
 extern char end[]; // first address after kernel loaded from ELF file
 
 // Bootstrap processor starts running C code here.
@@ -45,7 +44,7 @@ main(void)
 static void
 mpenter(void)
 {
-  switchkvm(); 
+  switchkvm();
   seginit();
   lapicinit();
   mpmain();
@@ -75,22 +74,22 @@ startothers(void)
   // Write entry code to unused memory at 0x7000.
   // The linker has placed the image of entryother.S in
   // _binary_entryother_start.
-  code = p2v(0x7000);
+  code = P2V(0x7000);
   memmove(code, _binary_entryother_start, (uint)_binary_entryother_size);
 
   for(c = cpus; c < cpus+ncpu; c++){
     if(c == cpus+cpunum())  // We've started already.
       continue;
 
-    // Tell entryother.S what stack to use, where to enter, and what 
+    // Tell entryother.S what stack to use, where to enter, and what
     // pgdir to use. We cannot use kpgdir yet, because the AP processor
     // is running in low  memory, so we use entrypgdir for the APs too.
     stack = kalloc();
     *(void**)(code-4) = stack + KSTACKSIZE;
     *(void**)(code-8) = mpenter;
-    *(int**)(code-12) = (void *) v2p(entrypgdir);
+    *(int**)(code-12) = (void *) V2P(entrypgdir);
 
-    lapicstartap(c->id, v2p(code));
+    lapicstartap(c->id, V2P(code));
 
     // wait for cpu to finish mpmain()
     while(c->started == 0)
@@ -100,7 +99,7 @@ startothers(void)
 
 // Boot page table used in entry.S and entryother.S.
 // Page directories (and page tables), must start on a page boundary,
-// hence the "__aligned__" attribute.  
+// hence the "__aligned__" attribute.
 // Use PTE_PS in page directory entry to enable 4Mbyte pages.
 __attribute__((__aligned__(PGSIZE)))
 pde_t entrypgdir[NPDENTRIES] = {
diff --git a/memlayout.h b/memlayout.h
index 6a62cd7..e5093fb 100644
--- a/memlayout.h
+++ b/memlayout.h
@@ -1,7 +1,7 @@
 // Memory layout
 
-#define EXTMEM  0x100000            // Start of extended memory
-#define PHYSTOP 0xE000000           // Top physical memory
+#define EXTMEM  0x100000            // Start of extended memory, 1 MB
+#define PHYSTOP 0xE000000           // Top physical memory, 224 MB
 #define DEVSPACE 0xFE000000         // Other devices are at high addresses
 
 // Key addresses for address space layout (see kmap in vm.c for layout)
@@ -10,13 +10,14 @@
 
 #ifndef __ASSEMBLER__
 
-static inline uint v2p(void *a) { return ((uint) (a))  - KERNBASE; }
-static inline void *p2v(uint a) { return (void *) ((a) + KERNBASE); }
-
-#endif
-
+// Convert virtual and physical addresses (from kernel's perspective)
 #define V2P(a) (((uint) (a)) - KERNBASE)
 #define P2V(a) (((void *) (a)) + KERNBASE)
 
-#define V2P_WO(x) ((x) - KERNBASE)    // same as V2P, but without casts
-#define P2V_WO(x) ((x) + KERNBASE)    // same as V2P, but without casts
+#else
+
+// The same without casts (for use in assembly)
+#define V2P_WO(x) ((x) - KERNBASE)
+#define P2V_WO(x) ((x) + KERNBASE)
+
+#endif
diff --git a/mp.c b/mp.c
index a257749..90fa48a 100644
--- a/mp.c
+++ b/mp.c
@@ -33,7 +33,7 @@ mpsearch1(uint a, int len)
 {
   uchar *e, *p, *addr;
 
-  addr = p2v(a);
+  addr = P2V(a);
   e = addr+len;
   for(p = addr; p < e; p += sizeof(struct mp))
     if(memcmp(p, "_MP_", 4) == 0 && sum(p, sizeof(struct mp)) == 0)
@@ -78,7 +78,7 @@ mpconfig(struct mp **pmp)
 
   if((mp = mpsearch()) == 0 || mp->physaddr == 0)
     return 0;
-  conf = (struct mpconf*) p2v((uint) mp->physaddr);
+  conf = (struct mpconf*) P2V((uint) mp->physaddr);
   if(memcmp(conf, "PCMP", 4) != 0)
     return 0;
   if(conf->version != 1 && conf->version != 4)
diff --git a/proc.c b/proc.c
index 3ac41f6..d983233 100644
--- a/proc.c
+++ b/proc.c
@@ -1,7 +1,6 @@
 #include "types.h"
 #include "defs.h"
 #include "param.h"
-#include "memlayout.h"
 #include "mmu.h"
 #include "x86.h"
 #include "proc.h"
@@ -55,11 +54,11 @@ found:
     return 0;
   }
   sp = p->kstack + KSTACKSIZE;
-  
+
   // Leave room for trap frame.
   sp -= sizeof *p->tf;
   p->tf = (struct trapframe*)sp;
-  
+
   // Set up new context to start executing at forkret,
   // which returns to trapret.
   sp -= 4;
@@ -80,7 +79,7 @@ userinit(void)
 {
   struct proc *p;
   extern char _binary_initcode_start[], _binary_initcode_size[];
-  
+
   p = allocproc();
   initproc = p;
   if((p->pgdir = setupkvm()) == 0)
@@ -108,7 +107,7 @@ int
 growproc(int n)
 {
   uint sz;
-  
+
   sz = proc->sz;
   if(n > 0){
     if((sz = allocuvm(proc->pgdir, sz, sz + n)) == 0)
@@ -155,14 +154,14 @@ fork(void)
   np->cwd = idup(proc->cwd);
 
   safestrcpy(np->name, proc->name, sizeof(proc->name));
- 
+
   pid = np->pid;
 
   // lock to force the compiler to emit the np->state write last.
   acquire(&ptable.lock);
   np->state = RUNNABLE;
   release(&ptable.lock);
-  
+
   return pid;
 }
 
@@ -336,13 +335,13 @@ forkret(void)
 
   if (first) {
     // Some initialization functions must be run in the context
-    // of a regular process (e.g., they call sleep), and thus cannot 
+    // of a regular process (e.g., they call sleep), and thus cannot
     // be run from main().
     first = 0;
     iinit(ROOTDEV);
     initlog(ROOTDEV);
   }
-  
+
   // Return to "caller", actually trapret (see allocproc).
 }
 
@@ -447,7 +446,7 @@ procdump(void)
   struct proc *p;
   char *state;
   uint pc[10];
-  
+
   for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
     if(p->state == UNUSED)
       continue;
diff --git a/syscall.c b/syscall.c
index 799ebc2..9ef66a1 100644
--- a/syscall.c
+++ b/syscall.c
@@ -1,7 +1,6 @@
 #include "types.h"
 #include "defs.h"
 #include "param.h"
-#include "memlayout.h"
 #include "mmu.h"
 #include "proc.h"
 #include "x86.h"
@@ -55,7 +54,7 @@ int
 argptr(int n, char **pp, int size)
 {
   int i;
-  
+
   if(argint(n, &i) < 0)
     return -1;
   if((uint)i >= proc->sz || (uint)i+size > proc->sz)
diff --git a/sysproc.c b/sysproc.c
index 027a5e5..26c232c 100644
--- a/sysproc.c
+++ b/sysproc.c
@@ -3,7 +3,6 @@
 #include "defs.h"
 #include "date.h"
 #include "param.h"
-#include "memlayout.h"
 #include "mmu.h"
 #include "proc.h"
 
@@ -61,7 +60,7 @@ sys_sleep(void)
 {
   int n;
   uint ticks0;
-  
+
   if(argint(0, &n) < 0)
     return -1;
   acquire(&tickslock);
@@ -83,7 +82,7 @@ int
 sys_uptime(void)
 {
   uint xticks;
-  
+
   acquire(&tickslock);
   xticks = ticks;
   release(&tickslock);
diff --git a/trap.c b/trap.c
index 3f80145..6118f81 100644
--- a/trap.c
+++ b/trap.c
@@ -1,7 +1,6 @@
 #include "types.h"
 #include "defs.h"
 #include "param.h"
-#include "memlayout.h"
 #include "mmu.h"
 #include "proc.h"
 #include "x86.h"
@@ -9,7 +8,7 @@
 #include "spinlock.h"
 
 // Interrupt descriptor table (shared by all CPUs).
-struct gatedesc idt[256];
+static struct gatedesc idt[256];
 extern uint vectors[];  // in vectors.S: array of 256 entry pointers
 struct spinlock tickslock;
 uint ticks;
@@ -22,7 +21,7 @@ tvinit(void)
   for(i = 0; i < 256; i++)
     SETGATE(idt[i], 0, SEG_KCODE<<3, vectors[i], 0);
   SETGATE(idt[T_SYSCALL], 1, SEG_KCODE<<3, vectors[T_SYSCALL], DPL_USER);
-  
+
   initlock(&tickslock, "time");
 }
 
@@ -77,7 +76,7 @@ trap(struct trapframe *tf)
             cpu->id, tf->cs, tf->eip);
     lapiceoi();
     break;
-   
+
   //PAGEBREAK: 13
   default:
     if(proc == 0 || (tf->cs&3) == 0){
@@ -89,13 +88,13 @@ trap(struct trapframe *tf)
     // In user space, assume process misbehaved.
     cprintf("pid %d %s: trap %d err %d on cpu %d "
             "eip 0x%x addr 0x%x--kill proc\n",
-            proc->pid, proc->name, tf->trapno, tf->err, cpu->id, tf->eip, 
+            proc->pid, proc->name, tf->trapno, tf->err, cpu->id, tf->eip,
             rcr2());
     proc->killed = 1;
   }
 
   // Force process exit if it has been killed and is in user space.
-  // (If it is still executing in the kernel, let it keep running 
+  // (If it is still executing in the kernel, let it keep running
   // until it gets to the regular system call return.)
   if(proc && proc->killed && (tf->cs&3) == DPL_USER)
     exit();
diff --git a/vm.c b/vm.c
index fc61781..8f34f58 100644
--- a/vm.c
+++ b/vm.c
@@ -49,7 +49,7 @@ walkpgdir(pde_t *pgdir, const void *va, int alloc)
 
   pde = &pgdir[PDX(va)];
   if(*pde & PTE_P){
-    pgtab = (pte_t*)p2v(PTE_ADDR(*pde));
+    pgtab = (pte_t*)P2V(PTE_ADDR(*pde));
   } else {
     if(!alloc || (pgtab = (pte_t*)kalloc()) == 0)
       return 0;
@@ -58,7 +58,7 @@ walkpgdir(pde_t *pgdir, const void *va, int alloc)
     // The permissions here are overly generous, but they can
     // be further restricted by the permissions in the page table
     // entries, if necessary.
-    *pde = v2p(pgtab) | PTE_P | PTE_W | PTE_U;
+    *pde = V2P(pgtab) | PTE_P | PTE_W | PTE_U;
   }
   return &pgtab[PTX(va)];
 }
@@ -133,7 +133,7 @@ setupkvm(void)
   if((pgdir = (pde_t*)kalloc()) == 0)
     return 0;
   memset(pgdir, 0, PGSIZE);
-  if (p2v(PHYSTOP) > (void*)DEVSPACE)
+  if (P2V(PHYSTOP) > (void*)DEVSPACE)
     panic("PHYSTOP too high");
   for(k = kmap; k < &kmap[NELEM(kmap)]; k++)
     if(mappages(pgdir, k->virt, k->phys_end - k->phys_start,
@@ -156,7 +156,7 @@ kvmalloc(void)
 void
 switchkvm(void)
 {
-  lcr3(v2p(kpgdir));   // switch to the kernel page table
+  lcr3(V2P(kpgdir));   // switch to the kernel page table
 }
 
 // Switch TSS and h/w page table to correspond to process p.
@@ -171,7 +171,7 @@ switchuvm(struct proc *p)
   ltr(SEG_TSS << 3);
   if(p->pgdir == 0)
     panic("switchuvm: no pgdir");
-  lcr3(v2p(p->pgdir));  // switch to new address space
+  lcr3(V2P(p->pgdir));  // switch to new address space
   popcli();
 }
 
@@ -187,7 +187,7 @@ inituvm(pde_t *pgdir, char *init, uint sz)
   if ((mem = kalloc()) == 0)
     panic("inituvm: cannot allocate memory");
   memset(mem, 0, PGSIZE);
-  if (mappages(pgdir, 0, PGSIZE, v2p(mem), PTE_W|PTE_U) < 0)
+  if (mappages(pgdir, 0, PGSIZE, V2P(mem), PTE_W|PTE_U) < 0)
     panic("inituvm: cannot create pagetable");
   memmove(mem, init, sz);
 }
@@ -210,7 +210,7 @@ loaduvm(pde_t *pgdir, char *addr, struct inode *ip, uint offset, uint sz)
       n = sz - i;
     else
       n = PGSIZE;
-    if(readi(ip, p2v(pa), offset+i, n) != n)
+    if(readi(ip, P2V(pa), offset+i, n) != n)
       return -1;
   }
   return 0;
@@ -238,7 +238,7 @@ allocuvm(pde_t *pgdir, uint oldsz, uint newsz)
       return 0;
     }
     memset(mem, 0, PGSIZE);
-    if (mappages(pgdir, (char*)a, PGSIZE, v2p(mem), PTE_W|PTE_U) < 0)
+    if (mappages(pgdir, (char*)a, PGSIZE, V2P(mem), PTE_W|PTE_U) < 0)
       panic("allocuvm: cannot create pagetable");
   }
   return newsz;
@@ -266,7 +266,7 @@ deallocuvm(pde_t *pgdir, uint oldsz, uint newsz)
       pa = PTE_ADDR(*pte);
       if(pa == 0)
         panic("kfree");
-      char *v = p2v(pa);
+      char *v = P2V(pa);
       kfree(v);
       *pte = 0;
     }
@@ -286,7 +286,7 @@ freevm(pde_t *pgdir)
   deallocuvm(pgdir, KERNBASE, 0);
   for(i = 0; i < NPDENTRIES; i++){
     if(pgdir[i] & PTE_P){
-      char * v = p2v(PTE_ADDR(pgdir[i]));
+      char * v = P2V(PTE_ADDR(pgdir[i]));
       kfree(v);
     }
   }
@@ -327,8 +327,8 @@ copyuvm(pde_t *pgdir, uint sz)
     flags = PTE_FLAGS(*pte);
     if((mem = kalloc()) == 0)
       goto bad;
-    memmove(mem, (char*)p2v(pa), PGSIZE);
-    if(mappages(d, (void*)i, PGSIZE, v2p(mem), flags) < 0)
+    memmove(mem, (char*)P2V(pa), PGSIZE);
+    if(mappages(d, (void*)i, PGSIZE, V2P(mem), flags) < 0)
       goto bad;
   }
   return d;
@@ -350,7 +350,7 @@ uva2ka(pde_t *pgdir, char *uva)
     return 0;
   if((*pte & PTE_U) == 0)
     return 0;
-  return (char*)p2v(PTE_ADDR(*pte));
+  return (char*)P2V(PTE_ADDR(*pte));
 }
 
 // Copy len bytes from p to user address va in page table pgdir.