From b47005e42e52da061d3279a038e350140b299ee1 Mon Sep 17 00:00:00 2001
From: AceVest <zhaoyanbai@126.com>
Date: Sun, 27 Jul 2014 17:08:24 +0800
Subject: [PATCH] fix bug in syscall.S

---
 Makefile          |   1 +
 bin/shell.c       |  39 ++++++++------
 drivers/vga.c     |   1 +
 fs/ext2.c         |  28 ++++++++--
 fs/write.c        |   1 +
 include/ext2.h    |   6 ++-
 include/mm.h      |   2 +-
 include/page.h    |   2 +-
 include/syscall.h |   2 -
 include/system.h  |  59 ++++++++++++++------
 kernel/exec.c     | 135 ++++++++++++++++++++++------------------------
 kernel/fork.c     |  29 ++++++++--
 kernel/innerint.c |   6 ++-
 kernel/setup.c    |   1 +
 kernel/syscall.S  |   6 ++-
 kernel/syscall.c  |  13 +++--
 lib/syscall.c     |  19 ++-----
 lib/write.c       |   2 +-
 mm/buddy.c        |  11 ++--
 mm/mm.c           |   5 +-
 mm/page.c         |   6 ++-
 21 files changed, 223 insertions(+), 151 deletions(-)

diff --git a/Makefile b/Makefile
index 0cfd1a5..45a147e 100644
--- a/Makefile
+++ b/Makefile
@@ -40,4 +40,5 @@ install:
 	cp bin/hello /kernel/bin/
 	cp bin/shell /kernel/bin/
 cp:
+	cd bin && make
 	./scripts/copy.sh
diff --git a/bin/shell.c b/bin/shell.c
index bca1539..65eeaac 100644
--- a/bin/shell.c
+++ b/bin/shell.c
@@ -16,25 +16,32 @@
 int systest();
 int main()
 {
+    char x[10];
+    x[0] = 'a';
+    x[1] = 'b';
+    x[2] = 'c';
+    x[3] = '\n';
+#if 1
+    //while(1) write(0, x, 4);
+    //while(1) systest();
+    int pid = fork();
 
-
-    while(1)
+    if(pid > 0)
     {
-    char buf[256];
-    read(0, buf, 256);
-    write(0, buf, 256);
-#if 0
-    asm("movl $11, %eax;"   \
-        "pushl $1f;"        \
-        "pushl %ecx;"       \
-        "pushl %edx;"       \
-        "pushl %ebp;"       \
-        "movl  %esp,%ebp;"  \
-        "sysenter;"         \
-        "1:");
+        //write(0, "parent\n", 7);
+        //write(0, x, 4);
+        while(1)
+        ;    systest();
+    }
+    else if(pid == 0)
 #endif
-        systest();
-        asm("nop;nop;nop;");
+    {
+        //write(0, "child\n", 6);
+        //write(0, x, 4);
+        while(1)
+        {
+            systest();
+        }
     }
 
     return 0;
diff --git a/drivers/vga.c b/drivers/vga.c
index c6fc7b6..a7724e7 100644
--- a/drivers/vga.c
+++ b/drivers/vga.c
@@ -174,6 +174,7 @@ void vga_putc(unsigned int nr, unsigned char c, const unsigned char color)
 
 void vga_puts(unsigned int nr, const char *buf, unsigned char color)
 {
+    assert(buf != 0);
     if(nr >= VGA_MAX_SCREEN_CNT)
         return ;
 
diff --git a/fs/ext2.c b/fs/ext2.c
index cd8731e..f29e731 100644
--- a/fs/ext2.c
+++ b/fs/ext2.c
@@ -28,6 +28,11 @@ ext2_inode_t ext2_root_inode;
 static ext2_inode_t boot_inode;
 static ext2_inode_t krnl_inode;
 
+unsigned long ext2_block_size()
+{
+    return (EXT2_MIN_BLOCK_SIZE << (EXT2_SB)->s_log_block_size);
+}
+
 void *ext2_alloc_block()
 {
     return (void *) kmem_cache_alloc(ext2_block_cache, 0);
@@ -86,13 +91,13 @@ void ext2_read_file(const ext2_inode_t *inode, char *buf)
     for(i=0; i<blkcnt; ++i)
     {
         BLKRW(inode->i_block[i], 1, buf+i*EXT2_BLOCK_SIZE);
-        printk("read block\n");
+        printd("read block\n");
     }
 
     unsigned int left = inode->i_size % EXT2_BLOCK_SIZE;
     if(left)
     {
-        printk("read left %u bytes\n", left);
+        printd("read left %u bytes\n", left);
 
         void *blk = ext2_alloc_block();
 
@@ -100,9 +105,26 @@ void ext2_read_file(const ext2_inode_t *inode, char *buf)
 
         ext2_free_block(blk);
     }
-    printk("read file done\n");
+    printd("read file done\n");
+}
+
+void ext2_read_data(const ext2_inode_t *inode, unsigned int offset, size_t size, char *buf)
+{
+    assert(inode != 0);
+    assert(buf != 0);
+    assert(inode->i_size > 0 && inode->i_size<=MAX_SUPT_FILE_SIZE);
+    assert(offset+size <= inode->i_size);
+    assert(offset % EXT2_BLOCK_SIZE == 0);  // for easy
+    printk("offset %x size %x  %x\n", offset, size, offset+size);
+    assert((offset+size) % EXT2_BLOCK_SIZE == 0);
+
+    unsigned int blkid  = offset / EXT2_BLOCK_SIZE;
+    unsigned int blkcnt = size   / EXT2_BLOCK_SIZE;
+    printk("id %u cnt %u\n", blkid, blkcnt);
+    BLKRW(inode->i_block[blkid], blkcnt, buf);
 }
 
+
 unsigned int ext2_search_indir(const char *name, const ext2_inode_t *inode)
 {
     unsigned int ino = 0;
diff --git a/fs/write.c b/fs/write.c
index efb85e7..b80d133 100644
--- a/fs/write.c
+++ b/fs/write.c
@@ -14,6 +14,7 @@
  *--------------------------------------------------------------------------
  */
 
+#include<assert.h>
 
 extern void vga_puts(unsigned int nr, const char *buf, unsigned char color);
 int sysc_write(int fd, const char *buf, unsigned long size)
diff --git a/include/ext2.h b/include/ext2.h
index fa487fb..bc20046 100644
--- a/include/ext2.h
+++ b/include/ext2.h
@@ -34,7 +34,10 @@
 
 #define EXT2_SB                 (&ext2_fs.ext2_sb)
 #define EXT2_GD                 (ext2_fs.ext2_gd)
-#define EXT2_BLOCK_SIZE        (EXT2_MIN_BLOCK_SIZE << (EXT2_SB)->s_log_block_size)
+
+unsigned long ext2_block_size();
+#define EXT2_BLOCK_SIZE ext2_block_size()
+//#define EXT2_BLOCK_SIZE        (EXT2_MIN_BLOCK_SIZE << (EXT2_SB)->s_log_block_size)
 
 #define EXT2_SECT_PER_BLOCK    (EXT2_BLOCK_SIZE/512)
 
@@ -209,5 +212,6 @@ enum
 
 void ext2_read_inode(unsigned int ino, ext2_inode_t *inode);
 void ext2_read_file(const ext2_inode_t *inode, char *buf);
+void ext2_read_data(const ext2_inode_t *inode, unsigned int offset, size_t size, char *buf);
 
 #endif //_EXT2_H
diff --git a/include/mm.h b/include/mm.h
index ec39222..07620fb 100644
--- a/include/mm.h
+++ b/include/mm.h
@@ -15,7 +15,7 @@
 #define BOOTMEM_PAGE_USED 1
 
 void *alloc_bootmem(unsigned long size, unsigned long align);
-unsigned long bootmem_total_pages();
+unsigned long bootmem_max_pfn();
 unsigned long bootmem_page_state(unsigned long pfn);
 
 #define bootmem_alloc_pages(n) alloc_bootmem((n)*PAGE_SIZE, PAGE_SIZE)
diff --git a/include/page.h b/include/page.h
index ee926d4..8624991 100644
--- a/include/page.h
+++ b/include/page.h
@@ -44,7 +44,7 @@ typedef unsigned long pte_t;
 #define PTECNT_PER_PAGE (PAGE_SIZE/sizeof(pte_t))
 
 #define PAGE_ITEMS (PAGE_SIZE/sizeof(unsigned long))
-#define PAGE_ALIGN(page)    (page & PAGE_MASK)
+#define PAGE_ALIGN(page)    (((unsigned long)(page)) & PAGE_MASK)
 #define PAGE_UP(page)     (((unsigned long)page + PAGE_SIZE -1) & PAGE_MASK)
 #define PAGE_DOWN    PAGE_ALIGN
 
diff --git a/include/syscall.h b/include/syscall.h
index 3ea6fcf..7530188 100644
--- a/include/syscall.h
+++ b/include/syscall.h
@@ -29,14 +29,12 @@ int _syscall1(int nr, unsigned long a);
 int _syscall2(int nr, unsigned long a, unsigned long b);
 int _syscall3(int nr, unsigned long a, unsigned long b, unsigned long c);
 int _syscall4(int nr, unsigned long a, unsigned long b, unsigned long c, unsigned long d);
-int _syscall5(int nr, unsigned long a, unsigned long b, unsigned long c, unsigned long d, unsigned long e);
 
 #define syscall0(nr)                _syscall0(nr)
 #define syscall1(nr, a)             _syscall1(nr, (unsigned long)a)
 #define syscall2(nr, a, b)          _syscall2(nr, (unsigned long)a, (unsigned long)b)
 #define syscall3(nr, a, b, c)       _syscall3(nr, (unsigned long)a, (unsigned long)b, (unsigned long)c)
 #define syscall4(nr, a, b, c, d)    _syscall4(nr, (unsigned long)a, (unsigned long)b, (unsigned long)c, (unsigned long)d)
-#define syscall5(nr, a, b, c, d, e) _syscall5(nr, (unsigned long)a, (unsigned long)b, (unsigned long)c, (unsigned long)d, (unsigned long)e)
 
 enum
 {
diff --git a/include/system.h b/include/system.h
index 7adc73e..ac2b5ff 100644
--- a/include/system.h
+++ b/include/system.h
@@ -21,12 +21,12 @@
 #include <assert.h>
 #define KRNLADDR    PAGE_OFFSET
 
-#define PT_REGS_EDI     0
-#define PT_REGS_ESI     4
-#define PT_REGS_EBP     8
-#define PT_REGS_EBX     12
-#define PT_REGS_EDX     16
-#define PT_REGS_ECX     20
+#define PT_REGS_EBX     0
+#define PT_REGS_ECX     4
+#define PT_REGS_EDX     8
+#define PT_REGS_ESI     12
+#define PT_REGS_EDI     16
+#define PT_REGS_EBP     20
 #define PT_REGS_EAX     24
 #define PT_REGS_DS      28
 #define PT_REGS_ES      32
@@ -131,6 +131,7 @@ enum GDTSelectorIndex
     INDEX_EMP8,
     INDEX_TSS,
 };
+#if 0
 // pushal push eax, ecx, edx, ebx, esp, ebp, esi, edi
 typedef struct pt_regs
 {
@@ -156,16 +157,42 @@ typedef struct pt_regs
     u32    esp;
     u16    ss, _ss;
 } __attribute__((packed)) pt_regs_t;
+#else
+typedef struct pt_regs
+{
+    u32    ebx;
+    u32    ecx;
+    u32    edx;
+    u32    esi;
+    u32    edi;
+    u32    ebp;
+    u32    eax;
+    u16    ds, _ds;
+    u16    es, _es;
+    u16    fs, _fs;
+    u16    gs, _gs;
+    union
+    {
+        u32    irq;
+        u32    errcode;
+    };
+    u32    eip;
+    u16    cs, _cs;
+    u32    eflags;
+    u32    esp;
+    u16    ss, _ss;
+} __attribute__((packed)) pt_regs_t;
+#endif
 
 typedef unsigned long dev_t;
 
 typedef struct system
 {
     u32 mmap_addr;
-    u32 mmap_size;    // Byte
+    u32 mmap_size;  // Byte
 
-    u32 mm_lower;    // KB
-    u32 mm_upper;    // KB
+    u32 mm_lower;   // KB
+    u32 mm_upper;   // KB
     u64 mm_size;    // Byte
 
     u32 page_count;
@@ -206,20 +233,20 @@ extern    System system;
     pushl   %es;        \
     pushl   %ds;        \
     pushl   %eax;       \
-    pushl   %ecx;       \
-    pushl   %edx;       \
-    pushl   %ebx;       \
     pushl   %ebp;       \
     pushl   %esi;       \
-    pushl   %edi;
+    pushl   %edi;       \
+    pushl   %edx;       \
+    pushl   %ecx;       \
+    pushl   %ebx;
 
 #define RESTORE_REGS    \
+    popl    %ebx;       \
+    popl    %ecx;       \
+    popl    %edx;       \
     popl    %edi;       \
     popl    %esi;       \
     popl    %ebp;       \
-    popl    %ebx;       \
-    popl    %edx;       \
-    popl    %ecx;       \
     popl    %eax;       \
     popl    %ds;        \
     popl    %es;        \
diff --git a/kernel/exec.c b/kernel/exec.c
index 3c69cb5..393e29e 100644
--- a/kernel/exec.c
+++ b/kernel/exec.c
@@ -20,9 +20,33 @@
 #include <elf.h>
 #include <fs.h>
 #include <ext2.h>
+#include <page.h>
 
 extern void *syscall_exit;
 
+void put_paging(unsigned long vaddr, unsigned long paddr, unsigned long flags)
+{
+    assert(PAGE_ALIGN(vaddr) == vaddr);
+    assert(PAGE_ALIGN(paddr) == paddr);
+
+    unsigned int npde = get_npd(vaddr);
+    unsigned int npte = get_npt(vaddr);
+
+    pde_t *page_dir = (pde_t *) current->cr3;
+    pte_t *page_table = (pte_t *) PAGE_ALIGN(page_dir[npde]);
+
+    if(page_table == 0)
+    {
+        page_table = (pte_t *) va2pa(alloc_one_page(0));
+        assert(page_table != 0);
+    }
+
+
+    page_dir[npde] = (unsigned long) page_table | flags;
+    page_table = pa2va(page_table);
+    page_table[npte] = paddr | flags;
+}
+
 int sysc_exec(const char *path, char *const argv[])
 {
     assert(argv == NULL);    // unsupport now
@@ -35,93 +59,58 @@ int sysc_exec(const char *path, char *const argv[])
 
     ext2_read_inode(ino, &inode);
 
-    //void *buf = (void*)kmalloc(inode.i_size, 0);
-    void *buf = (void *) alloc_pages(0, 5);
-    assert(buf != 0);
+    Elf32_Ehdr *ehdr= (Elf32_Ehdr *)alloc_one_page(0);
+    assert(ehdr != 0);
+    ext2_read_data(&inode, 0, PAGE_SIZE, (char *)ehdr);
+    printk("%08x\n", *((unsigned long *)ehdr->e_ident));
+    assert(strncmp(ELFMAG, ehdr->e_ident, sizeof(ELFMAG)-1) == 0);
+    printk("Elf Entry: %08x\n", ehdr->e_entry);
 
-    printk("exec buf %08x \n", buf);
-    printd("begin read elf\n");
-    ext2_read_file(&inode, buf);
-    printd("end read elf\n");
 
 
-    pElf32_Ehdr ehdr = (pElf32_Ehdr) buf;
-    //assert(strncmp(ELFMAG, ehdr->e_ident, sizeof(ELFMAG)-1) == 0);
-    if(strncmp(ELFMAG, ehdr->e_ident, sizeof(ELFMAG)-1) != 0)
+    int i, j;
+    for(i=0; i<ehdr->e_phnum; ++i)
     {
-        printk("file %s can not execute\n", path);
-        kfree(buf);
-        return -ENOEXEC;
-    }
-    //printk("Entry: %08x phnum:%d\n", ehdr->e_entry, ehdr->e_phnum);
-    
-    int size = 0;
-    int i;
-    for(i=0; i<ehdr->e_phnum; i++)
-    {
-        pElf32_Phdr phdr;
-        phdr = (pElf32_Phdr)(buf+ehdr->e_phoff+(i*ehdr->e_phentsize));
+        Elf32_Phdr *phdr;
+        phdr = (Elf32_Phdr*)(((unsigned long)ehdr) + ehdr->e_phoff + (i*ehdr->e_phentsize));
 
         printk("Type %08x Off %08x Va %08x Pa %08x Fsz %08x Mmsz %08x\n",
-            phdr->p_type, phdr->p_offset, phdr->p_vaddr, phdr->p_paddr,
-            phdr->p_filesz, phdr->p_memsz);
+                phdr->p_type, phdr->p_offset, phdr->p_vaddr, phdr->p_paddr,
+                phdr->p_filesz, phdr->p_memsz);
 
-        if(phdr->p_type == PT_LOAD)
-        {
-            if(phdr->p_offset > 0 && phdr->p_memsz > 0)
-            {
-                size = ALIGN(phdr->p_offset + phdr->p_memsz, 0x1000);
-            }
-        }
-    }
 
-    printk("ELF MEM SIZE %u\n", size);
+        unsigned long vaddr = phdr->p_vaddr;
+        unsigned long offset= phdr->p_offset;
+        unsigned long mmsz  = phdr->p_memsz;
+        unsigned long filesz= phdr->p_filesz;
 
-    char *exe = (char *) kmalloc(size, 0);
-    assert(exe != 0);
-    printk("EXE ADDR %08x\n", exe);
-    for(i=0; i<ehdr->e_phnum; i++)
-    {
-        pElf32_Phdr phdr;
-        phdr = (pElf32_Phdr)(buf+ehdr->e_phoff+(i*ehdr->e_phentsize));
         if(phdr->p_type != PT_LOAD)
             continue;
-        if(phdr->p_filesz != 0)
+
+        assert(mmsz >= filesz);
+
+        unsigned int pgcnt = (mmsz + PAGE_SIZE - 1) / PAGE_SIZE;
+        unsigned int blkcnt= (filesz + EXT2_BLOCK_SIZE - 1) / EXT2_BLOCK_SIZE;
+
+        void *buf = kmalloc(pgcnt*PAGE_SIZE, PAGE_SIZE);
+        assert(PAGE_ALIGN(buf) == (unsigned long)buf);
+        assert(buf != 0);
+
+
+        printk("vvvbufsz %08x datasz %08x\n", pgcnt*PAGE_SIZE, blkcnt*EXT2_BLOCK_SIZE);
+
+        if(filesz > 0)
+            ext2_read_data(&inode, offset, blkcnt*EXT2_BLOCK_SIZE, buf);
+
+        for(j=0; j<pgcnt; ++j)
         {
-            memcpy((void*)(exe+phdr->p_offset), (void*)(buf+phdr->p_offset), phdr->p_filesz);
+            put_paging(vaddr + j*PAGE_SIZE, (unsigned long) (va2pa(buf)) + j*PAGE_SIZE, 7);
         }
     }
 
-
-    /*
-     *  因为目前文件支持最大为12*EXT2_BLOCK_SIZE
-     *  即12K~48K之间
-     *  所以就以一个页目录项来简化处理
-     */
-    u32    *pd = (u32*) current->cr3;
-    u32    *pt;
-    u32    pa_exe;
-    u32    npd, npt;
-    int    c;
-    pa_exe  = va2pa(exe);
-    npd     = get_npd(ehdr->e_entry);
-    npt     = get_npt(ehdr->e_entry);
-    pt      = (u32*)va2pa(alloc_one_page(0));
-    if(pt == NULL)
-        panic("out of memory");
-
-    //printk("npd: %d pt:%08x\n", npd, pt);
-    memset(pa2va(pt), 0, PAGE_SIZE);
-    pd[npd]    = (u32) pt | 7;
-    pt = pa2va(pt);
-    for(i=npt, c=0; i<1024; i++, c++)
-    {
-        pt[i] = va2pa(PAGE_ALIGN((unsigned long)exe)) + c * PAGE_SIZE;
-        pt[i] |= 7;
-    }
-    
     load_cr3(current);
-    printk("exe : %08x cr3:%08x\n", exe, pd);
+
+    disable_irq();
 
     pt_regs_t *regs = ((pt_regs_t *)(TASK_SIZE+(unsigned long)current)) - 1;
     memset((void*)regs, 0, sizeof(pt_regs_t));
@@ -137,7 +126,9 @@ int sysc_exec(const char *path, char *const argv[])
     regs->edx   = regs->eip;
     regs->ecx   = (0xC0000000 - 16);
 
-    kfree(buf);
+    //kfree(buf);
+
+    free_pages((unsigned long)ehdr);
 
     asm("movl $0, %%eax; movl %%ebx,%%ebp; movl %%ebp,%%esp;jmp syscall_exit;"::"b"((unsigned long)(regs)));
 
diff --git a/kernel/fork.c b/kernel/fork.c
index 257eb6e..0d5f08f 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -11,6 +11,7 @@
  */
 
 #include <sched.h>
+#include <page.h>
 
 int sysc_fork(pt_regs_t regs)
 {
@@ -23,6 +24,7 @@ extern pid_t get_next_pid();
 
 int do_fork(pt_regs_t *regs, unsigned long flags)
 {
+    static int forkcnt = 7;
     task_union *tsk;
     tsk = alloc_task_union();
     printk("fork task %08x flags %08x\n", tsk, flags);
@@ -31,7 +33,7 @@ int do_fork(pt_regs_t *regs, unsigned long flags)
 
     memcpy(tsk, current, sizeof(task_union));
 
-    {
+    //{
         tsk->cr3 = (unsigned long) alloc_one_page(0);
         if(tsk->cr3 == 0)
             panic("failed init tsk cr3");
@@ -55,22 +57,38 @@ int do_fork(pt_regs_t *regs, unsigned long flags)
                 continue;
             }
 
-            if(spde != 0)
-                dpde = PAGE_FLAGS(spde) | (unsigned long) va2pa(alloc_one_page(0));
+            if(pde_src[i] == 0)
+                continue;
+
+            if(PAGE_ALIGN(spde) != 0)
+            {
+                dpde = alloc_one_page(0);
+                assert(dpde != 0);
+                memset((void*)dpde, 0, PAGE_SIZE);
+                dpde = PAGE_FLAGS(spde) | (unsigned long) va2pa(dpde);
+            }
+            else
+            {
+                pde_dst[i] = 0;
+                continue;
+            }
             pde_dst[i] = dpde;
 
             pte_t *pte_src = pa2va(PAGE_ALIGN(spde));
             pte_t *pte_dst = pa2va(PAGE_ALIGN(dpde));
             for(j=0; j< PAGE_PTE_CNT; ++j)
             {
+
+                //printl(20, "[%d %d]", i, j);
                 pte_src[j] &= ~PAGE_WR;
                 pte_dst[j] = pte_src[j];
 
                 page_t *page = pa2page(pte_src[j]);
                 page->count ++;
             }
+
         }
-    }
+    //}
 
     tsk->pid    = get_next_pid();
     tsk->ppid   = current->pid;
@@ -82,7 +100,6 @@ int do_fork(pt_regs_t *regs, unsigned long flags)
     child_regs->eax = 0;
     child_regs->eflags |= 0x200; //enable IF
 
-
     tsk->esp0   = TASK_SIZE + (unsigned long) tsk;
     tsk->esp    = (unsigned long) child_regs;
     tsk->eip    = (unsigned long) ret_from_fork_user;
@@ -104,5 +121,7 @@ int do_fork(pt_regs_t *regs, unsigned long flags)
     list_add(&tsk->list, &root_task.list);
     irq_restore(iflags);
 
+
+    printk("%s:%d\n", __func__, __LINE__);
     return (int)tsk->pid;
 }
diff --git a/kernel/innerint.c b/kernel/innerint.c
index 6705301..da05f74 100644
--- a/kernel/innerint.c
+++ b/kernel/innerint.c
@@ -96,9 +96,11 @@ void doPageFault(pt_regs_t regs)
 
     //printd("do page fault errcode %x addr %08x\n", errcode, addr);
 
-    if(errcode & PAGE_US)
+    if(errcode == 0 || errcode == 2)
     {
-        //panic("user program try to access a page and cause a protection fault. addr %08x", addr);
+        unsigned long *pde_src = (unsigned long *) current->cr3;
+        printk("p=%x\n", pde_src[796]);
+        //panic("errcode %08x addr %08x", errcode, addr);
     }
 
     if((errcode & PAGE_P) == 0)
diff --git a/kernel/setup.c b/kernel/setup.c
index 90d81db..f3e623f 100644
--- a/kernel/setup.c
+++ b/kernel/setup.c
@@ -94,5 +94,6 @@ void setup_kernel()
     setup_fs();
 
     printk("%s\n", version);
+    //vga_dbg_toggle();
 }
 
diff --git a/kernel/syscall.S b/kernel/syscall.S
index c9fb5d6..7a44a44 100644
--- a/kernel/syscall.S
+++ b/kernel/syscall.S
@@ -54,9 +54,11 @@ syscall_entry:
 
     call    *sysc_handler_table(,%eax,4)
 
+normal_syscall_exit:
     leal    sysexit, %edx
     movl    %edx, PT_REGS_EDX(%esp)
-    movl    %ebp, PT_REGS_ECX(%esp)
+    movl    PT_REGS_EBP(%esp), %edx
+    movl    %edx, PT_REGS_ECX(%esp)
 
 syscall_exit:
     movl    %eax, PT_REGS_EAX(%esp)
@@ -72,7 +74,7 @@ bad_sysc_nr:
 
 ret_from_fork_user:
     xorl    %eax, %eax
-    jmp     syscall_exit
+    jmp     normal_syscall_exit
 
 ret_from_fork_krnl:
     movl    PT_REGS_EDX(%esp), %edx
diff --git a/kernel/syscall.c b/kernel/syscall.c
index 91084b4..3c7292d 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -52,6 +52,9 @@ int sysc_test()
 {
     static unsigned int cnt=0;
     printl(MPL_TEST, "sysc_test %u", cnt++);
+
+    //unsigned long *pde = (unsigned long *)current->cr3;
+    //printk("sysctest %08x\n", pde[797]);
 }
 
 void    init_sysc_handler_table()
@@ -60,11 +63,11 @@ void    init_sysc_handler_table()
     for(i=0; i<SYSC_NUM; i++)
         sysc_handler_table[i] = (unsigned long) sysc_none;
 
-#define _sysc_(nr, sym)                                    \
-    do                                                    \
-    {                                                    \
-        extern int sym ();                                \
-        sysc_handler_table[nr] = (unsigned long) sym;    \
+#define _sysc_(nr, sym)                                 \
+    do                                                  \
+    {                                                   \
+        extern int sym ();                              \
+        sysc_handler_table[nr] = (unsigned long) sym;   \
     }while(0);
 
     _sysc_(SYSC_WRITE,       sysc_write);
diff --git a/lib/syscall.c b/lib/syscall.c
index d781aa9..0cfa8d1 100644
--- a/lib/syscall.c
+++ b/lib/syscall.c
@@ -7,9 +7,10 @@
  * ------------------------------------------------------------------------
  */
 
-
+// "movl     $1f, %%edi;"
+//
 #define SYSENTER_ASM            \
-        "pushl  $1f;"           \
+        "pushl  $1f;"   \
         "pushl    %%ecx;"       \
         "pushl    %%edx;"       \
         "pushl    %%ebp;"       \
@@ -52,15 +53,6 @@ static int __syscall4(int nr, unsigned long a, unsigned long b, unsigned long c,
     return __sysc_ret__;
 }
 
-static int __syscall5(int nr, unsigned long a, unsigned long b, unsigned long c, unsigned long d, unsigned long e)
-{
-    int __sysc_ret__ = 0;
-    asm(SYSENTER_ASM:"=a"(__sysc_ret__):"a"(nr), "b"(a), "c"(b), "d"(c), "S"(d), "D"(e));
-    return __sysc_ret__;
-}
-
-
-
 int _syscall0(int nr)
 {
     return __syscall0(nr);
@@ -85,8 +77,3 @@ int _syscall4(int nr, unsigned long a, unsigned long b, unsigned long c, unsigne
 {
     return __syscall4(nr, a, b, c, d);
 }
-
-int _syscall5(int nr, unsigned long a, unsigned long b, unsigned long c, unsigned long d, unsigned long e)
-{
-    return __syscall5(nr, a, b, c, d, e);
-}
diff --git a/lib/write.c b/lib/write.c
index 09d2b27..9ab3b1d 100644
--- a/lib/write.c
+++ b/lib/write.c
@@ -22,7 +22,7 @@ int write(int fd, const char *buf, unsigned long size)
     //sysenter(0);
     //syscall3(0, fd, buf, size);
     //asm("nop;nop;nop;");
-
+    
     syscall3(SYSC_WRITE, fd, buf, size);
 
     return size;
diff --git a/mm/buddy.c b/mm/buddy.c
index 53b1b1c..ca9f512 100644
--- a/mm/buddy.c
+++ b/mm/buddy.c
@@ -28,7 +28,8 @@ int buddy_is_free(page_t *page, unsigned int order)
 
 page_t *va2page(unsigned long addr)
 {
-    return buddy_system.page_map + va2pfn(addr);
+    page_t *page = buddy_system.page_map + va2pfn(addr);
+    return page;
 }
 
 void *page2va(page_t *page)
@@ -99,7 +100,8 @@ unsigned long alloc_pages(unsigned int gfp_mask, unsigned int order)
     page_t *page = __alloc_pages(order);
     irq_restore(flags);
 
-    return (unsigned long) page2va(page);
+    unsigned long addr = (unsigned long) page2va(page);
+    return addr;
 }
 
 void __free_pages(page_t *page, unsigned int order)
@@ -196,7 +198,7 @@ void init_buddy_system()
 {
     page_t *page;
     unsigned long i;
-    unsigned long pfn_cnt = bootmem_total_pages();
+    unsigned long pfn_cnt = bootmem_max_pfn();
 
     // init free area
     memset(&buddy_system, 0, sizeof(buddy_system));
@@ -215,8 +217,7 @@ void init_buddy_system()
         while(1);
     }
 
-    printk("page_map begin %08x end %08x\n", buddy_system.page_map, buddy_system.page_map + pfn_cnt);
-
+    printk("page_map begin %08x end %08x pfncnt %u page_t size %u\n", buddy_system.page_map, buddy_system.page_map + pfn_cnt + 1, pfn_cnt, sizeof(page_t));
     for(i=0; i<pfn_cnt; ++i)
     {
         page = buddy_system.page_map + i;
diff --git a/mm/mm.c b/mm/mm.c
index 537d854..8c50ba1 100644
--- a/mm/mm.c
+++ b/mm/mm.c
@@ -83,7 +83,7 @@ typedef struct bootmem_data {
 
 bootmem_data_t bootmem_data;
 
-unsigned long bootmem_total_pages()
+unsigned long bootmem_max_pfn()
 {
     return bootmem_data.max_pfn;
 }
@@ -308,6 +308,8 @@ extern void sysexit();
 
 void init_paging()
 {
+    printk("max_pfn %u", bootmem_data.max_pfn);
+    //while(1);
     unsigned int i;
     unsigned long pfn = 0;
     pte_t *pte = 0;
@@ -331,7 +333,6 @@ void init_paging()
         *pte = (pte_t) (page_addr | PAGE_P | PAGE_WR);
     }
 
-
     // paging for kernel space
     unsigned long delta = get_npd(PAGE_OFFSET);
     for(i=delta; i<PDECNT_PER_PAGE; ++i)
diff --git a/mm/page.c b/mm/page.c
index 8037c17..5b64628 100644
--- a/mm/page.c
+++ b/mm/page.c
@@ -19,6 +19,7 @@
 
 void do_no_page(void *addr)
 {
+    printk("%s   addr %08x\n", __func__, (unsigned long)addr);
     pde_t *pde = (pde_t *)current->cr3;
     pte_t *pte;
     unsigned long page = alloc_one_page(0);
@@ -52,6 +53,7 @@ void do_no_page(void *addr)
 
 void do_wp_page(void *addr)
 {
+    //printk("%s   addr %08x\n", __func__, (unsigned long)addr);
     int npde = get_npd(addr);
     int npte = get_npt(addr);
 
@@ -84,6 +86,8 @@ void do_wp_page(void *addr)
         dst = va2pa(dst);
 
         pt[npte] = dst | flags;
+        pt[npte] |= PAGE_WR;
+        pd[npde] |= PAGE_WR;
 
         dst = (unsigned long)pa2va(PAGE_ALIGN(dst));
 
@@ -91,7 +95,7 @@ void do_wp_page(void *addr)
     }
     else
     {
-        //pd[npde] |= PAGE_WR;
+        pd[npde] |= PAGE_WR;
         pt[npte] |= PAGE_WR;
         //pd[npde] |= PAGE_US;
         //pt[npte] |= PAGE_US;
-- 
2.44.0