fix mapping a not-aligned page bug at kernel/sys_exec.c.

YChuan1115 · Jul 6, 2017 · 8570418 · 8570418
1 parent 3c7371a
commit 8570418
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Showing 4 changed files with 35 additions and 17 deletions.
diff --git a/floppy.img b/floppy.img
diff --git a/kernel/kernel/sys_exec.c b/kernel/kernel/sys_exec.c
@@ -40,6 +40,7 @@
 #define Elf32_Word u32 //size 4 无符号大整数
 #define Elf32_Uchar u8
 #define EI_NIDENT 16
+#define PT_LOAD 1
 typedef struct{ 
  Elf32_Uchar e_ident[EI_NIDENT];
  Elf32_Half e_type;
@@ -80,7 +81,7 @@ static void new_task_entry()
 {
  u32 fself = 0;
  u32 fsize;
- u32 i;
+ u32 i, vstart, vend, pages;
  Elf32_Ehdr selfhead;
  Elf32_Phdr selfphdr;
 
@@ -100,22 +101,30 @@ static void new_task_entry()
  sys_read(fself, (u8 *)&selfphdr, sizeof(Elf32_Phdr));
 
  /*
- * 如果需要的p_memsz正好页对齐，则按照需要申请即可
- * 否则需要给出p_memsz的向上对齐值
+ * 早期编译器不生成除了 PT_LOAD 段之外的其他类型
+ * 这里要跳过对非 Loadable 段的处理
  */
- if (selfphdr.p_memsz % PAGE_SIZE != 0)
+ if (selfphdr.p_type == PT_LOAD) 
  {
- u_get_pages(selfphdr.p_memsz/PAGE_SIZE+1, 
- selfphdr.p_vaddr, 
- selfphdr.p_type);
- } else {
- u_get_pages(selfphdr.p_memsz/PAGE_SIZE, 
- selfphdr.p_vaddr, 
- selfphdr.p_type);
+ if (selfphdr.p_align != PAGE_SIZE)
+ {
+ panic("Task_entry: unknow segment align %x.", selfphdr.p_align);
+ }
+
+ /*
+ * 这里 p_vaddr 可能不是页对齐值
+ * 起始地址应该是 p_vaddr 的下边界
+ * 结束地址永远是 p_vaddr + p_memsz 的上边界
+ */
+ vstart = selfphdr.p_vaddr & PAGE_MASK;
+ vend = PAGE_ALIGN(selfphdr.p_vaddr + selfphdr.p_memsz);
+ pages = (vend - vstart) / PAGE_SIZE;
+
+ u_get_pages(pages, vstart, selfphdr.p_type);
+
+ sys_seek(fself, selfphdr.p_offset, SEEK_SET);
+ sys_read(fself, (u8 *)selfphdr.p_vaddr, selfphdr.p_filesz);
  }
-
- sys_seek(fself, selfphdr.p_offset, SEEK_SET);
- sys_read(fself, (u8 *)selfphdr.p_vaddr, selfphdr.p_filesz);
  }
 
  /*

diff --git a/kernel/kernel/traps.c b/kernel/kernel/traps.c
@@ -63,8 +63,16 @@ static void do_exception_exit(char * str,long * esp,long error_code,
  warning("DS=%04X ES=%04X FS=%04X CS=%04X EFLAGS: %08X",
  ds&0xffff, es&0xffff, fs&0xffff, esp[1]&0xffff, esp[2]);
  warning("EIP=%08X ", esp[0]);
- warning("Task %d exit.", current);
- sys_exit();
+
+ if ((esp[1]&0xffff) == KERNEL_CS)
+ {
+ panic("Kernel mode exception, panic!");
+ }
+ else
+ {
+ warning("User mode exception, Task %d exit.", current);
+ sys_exit();
+ }
 }
 
 void do_double_fault(long * esp, long error_code,

diff --git a/kernel/mm/memory.h b/kernel/mm/memory.h
@@ -35,7 +35,8 @@
 #define PAGE_READONLY (PAGE_PRESENT | PAGE_USER | PAGE_ACCESSED)
 #define PAGE_TABLE (PAGE_PRESENT | PAGE_RW | PAGE_USER | PAGE_ACCESSED)
 
-#define PAGE_ALIGN(_x) ((_x)&0xFFFFF000)
+#define PAGE_MASK (~(PAGE_SIZE-1))
+#define PAGE_ALIGN(X) (((X)+PAGE_SIZE-1)&PAGE_MASK)
 
 
 /* 用刷新cr3的方法来刷新TLB */