utils/task: find_vma_span_area(): Add MIN_ULP_START_VMA_ADDR

Finish: commit 8500222 ("utils/task: find_vma_span_area(): Add first var")
Signed-off-by: Rong Tao <[email protected]>

src/patch/patch.c

@@ -246,7 +246,8 @@ static int create_mmap_vma_file(struct task_struct *task, struct load_info *info
 	 * 0xFFFFFFFFUL, maybe i should use jmp_table, see arch_jmp_table_jmp()
 	 * or, maybe we could use jmp/bl to register.
 	 *
-	 * The base address on aarch64 is bigger than 4bytes length, such as:
+	 * Such ad base address on ASLR process address space(PIC ELF) is
+	 * bigger than 4 bytes, Such as:
 	 * $ cat /proc/$(pidof hello)/maps
 	 * 5583490000-5583491000 r-xp 00000000 b3:02 1061933 /hello
 	 */

src/utils/task.c

@@ -166,10 +166,18 @@ struct vm_area_struct *next_vma(struct task_struct *task, struct vm_area_struct
 
 unsigned long find_vma_span_area(struct task_struct *task, size_t size)
 {
-	struct vm_area_struct *ivma;
+	struct vm_area_struct *ivma, *first_vma;
 	struct rb_node *first, *rnode;
 
 	first = rb_first(&task->vmas_rb);
+	first_vma = rb_entry(first, struct vm_area_struct, node_rb);
+
+	/**
+	 * Return the minimal address if the space is enough to store 'size'.
+	 */
+	if (first_vma->vm_start > MIN_ULP_START_VMA_ADDR &&
+	    first_vma->vm_start - MIN_ULP_START_VMA_ADDR >= size)
+		return MIN_ULP_START_VMA_ADDR;
 
 	for (rnode = first; rnode; rnode = rb_next(rnode)) {
 		ivma = rb_entry(rnode, struct vm_area_struct, node_rb);

src/utils/task.h

@@ -75,6 +75,7 @@ struct vma_ulp {
 	/* This is ELF */
 	void *elf_mem;
 
+#define MIN_ULP_START_VMA_ADDR	0x400000U
 	/* Belongs to */
 	struct vm_area_struct *vma;