kernel hexdump分析
驱动调试中,很多时候是二进制的，这个时候hexdump就是个非常有用的工具了。
不要再自己去实现类似的功能，kernel代码里面就有：
参考： kernel/lib/hexdump.c
// 0Xxx转换成 ASCII ,实现简单巧妙
const char hex_asc[] = "0123456789abcdef"; #define hex_asc_lo(x) hex_asc[((x) & 0x0f)] #define hex_asc_hi(x) hex_asc[((x) & 0xf0) >> 4]
void hex_dump_to_buffer(const void *buf, size_t len, int rowsize,
int groupsize, char *linebuf, size_t linebuflen,
bool ascii)
{
const u8 *ptr = buf;
u8 ch;
int j, lx = 0;
int ascii_column;
// 每行固定16或者32个字节，符合国际审美观
if (rowsize != 16 && rowsize != 32)
rowsize = 16;
if (!len)
goto nil;
if (len > rowsize) /* limit to one line at a time */
len = rowsize;
if ((len % groupsize) != 0) /* no mixed size output */
groupsize = 1;
switch (groupsize) {
......
default:
// 转换成ASCii 形式
for (j = 0; (j < len) && (lx + 3) <= linebuflen; j++) {
ch = ptr[j];
linebuf[lx++] = hex_asc_hi(ch);
linebuf[lx++] = hex_asc_lo(ch);
linebuf[lx++] = ' ';
}
if (j)
lx--;
ascii_column = 3 * rowsize + 2;
break;
}
if (!ascii)
goto nil;
// 加上对应的ASCII字符串，区别如下：
// 0009ab42: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO
// 0009ab42: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f
while (lx < (linebuflen - 1) && lx < (ascii_column - 1))
linebuf[lx++] = ' ';
for (j = 0; (j < len) && (lx + 2) < linebuflen; j++) {
ch = ptr[j];
linebuf[lx++] = (isascii(ch) && isprint(ch)) ? ch : '.';
}
nil:
// 记得加上结束符号，有可能导致printk --> kernel panic
linebuf[lx++] = '\0';
}
void print_hex_dump(const char *level, const char *prefix_str, int prefix_type,
int rowsize, int groupsize,
const void *buf, size_t len, bool ascii)
{
const u8 *ptr = buf;
int i, linelen, remaining = len;
/* 每行数据类似下面
40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO
| | | |
-----------------------------------------------
16*3 or 32*3 2 32+1
*/
unsigned char linebuf[32 * 3 + 2 + 32 + 1];
if (rowsize != 16 && rowsize != 32)
rowsize = 16;
for (i = 0; i < len; i += rowsize) {
linelen = min(remaining, rowsize);
remaining -= rowsize;
// linebuf 返回需要打印的字符串
hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
linebuf, sizeof(linebuf), ascii);
// 是否使用前缀
switch (prefix_type) {
// 加上绝对地址
case DUMP_PREFIX_ADDRESS:
printk("%s%s%p: %s\n",
level, prefix_str, ptr + i, linebuf);
break;
// 只是简单地加上偏移量而已
case DUMP_PREFIX_OFFSET:
printk("%s%s%.8x: %s\n", level, prefix_str, i, linebuf);
break;
default:
printk("%s%s%s\n", level, prefix_str, linebuf);
break;
}
}
}
// 一般在kernel代码中，调用此接口，许多参数用默认的，不需要了解太多细节
void print_hex_dump_bytes(const char *prefix_str, int prefix_type,
const void *buf, size_t len)
{
print_hex_dump(KERN_DEBUG, prefix_str, prefix_type, 16, 1,
buf, len, true);
}