Use objdump to debug the driver

Recently, I was tuning a driver + test program to determine whether NAND is a good or a bad one. So I learned a little about the following debugging process, so I should record it.

This article mainly describes the mode-driven method.

Let's take a look at the test program.

#include <string.h>#include <errno.h>#include "dragonboard_inc.h"#include <sys/ioctl.h>#include <linux/ioctl.h>#include <sys/types.h>#include <sys/stat.h>#include <unistd.h>#include <fcntl.h>#include <stdio.h>/* just define an ioctl cmd for nand test*/#define DRAGON_BOARD_TEST    _IO(‘V‘,55)  int main(int argc, char *argv[]){    char filename[256];    int fd;    int retval = -1;    if (argc == 2) {        strncpy(filename, argv[1], 256);    }    else {        db_error("Usage: nandrw FILE\n");        retval = -1;    }    /* open file */    fd = open(filename, O_RDWR);printf("filename is %s\n",filename);printf("nand fd = %d\n",fd);    if (fd < 0) {        db_error("can‘t open %s(%s)\n", filename, strerror(errno));        retval = -1;    }/* if nand ok,return 0;otherwise,return -1 */retval = ioctl(fd, DRAGON_BOARD_TEST);printf("ioctl_retval = %d\n",retval);if (retval < 0) {        db_error("error in ioctl(%s)......\n", strerror(errno));return retval;    }    /* TEST OK */    return retval;}

The test case is very simple. First open the/dev/Nanda device node and use it to return FD to IOCTL. cmd = dragon_board_test in IOCTL is the underlying implementation.

After IOCTL is called, it is returned. If 0 is returned, it indicates that NAND is good; otherwise, it indicates that NAND is bad. I will not elaborate on how the underlying layer is implemented.

It should be mentioned that the test case does not actively call close (FD), but, however, you should never forget that the system will automatically recycle it, the system will help you call the close function.

So we have the log information of the following BUG:

[    7.947228] Unable to handle kernel paging request at virtual address ed9f4b00[    7.956339] pgd = d78a8000[    7.956876] [ed9f4b00] *pgd=00000000[    7.956876] Internal error: Oops: 80000005 [#1] PREEMPT SMP ARM[    7.956876] Modules linked in: sunxi_keyboard ft5x_ts nand(O) lcd disp[    7.956876] CPU: 0    Tainted: G           O  (3.4.39 #21)[    7.956876] PC is at 0xed9f4b00[    7.956876] LR is at nand_blk_release+0x24/0x28 [nand][    7.956876] pc : [<ed9f4b00>]    lr : [<bf116ed4>]    psr: a0000033[    7.956876] sp : d76abe08  ip : d76abe18  fp : d76abe14[    7.956876] r10: d7dc5998  r9 : d7740a90  r8 : d7c02650[    7.956876] r7 : d7854000  r6 : 0000001f  r5 : bf11719c  r4 : bf14b828[    7.956876] r3 : ed9f4b01  r2 : d76abe00  r1 : 0000ffff  r0 : d7854400[    7.956876] Flags: NzCv  IRQs on  FIQs on  Mode SVC_32  ISA Thumb  Segment user[    7.956876] Control: 10c5387d  Table: 578a806a  DAC: 00000015[    7.956876] [    7.956876] PC: 0xed9f4a80:[    7.956876] 4a80  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4aa0  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4ac0  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4ae0  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4b00  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4b20  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4b40  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4b60  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] [    7.956876] SP: 0xd76abd88:[    7.956876] bd88  c09a7b40 c0e769e4 d76abdb4 d76abda0 c0062dec c0085640 ed9f4b00 a0000033[    7.956876] bda8  ffffffff d76abdf4 d76abe14 d76abdc0 c0010438 c000a25c d7854400 0000ffff[    7.956876] bdc8  d76abe00 ed9f4b01 bf14b828 bf11719c 0000001f d7854000 d7c02650 d7740a90[    7.956876] bde8  d7dc5998 d76abe14 d76abe18 d76abe08 bf116ed4 ed9f4b00 a0000033 ffffffff[    7.956876] be08  d76abe2c d76abe18 bf1171c8 bf116ebc bf14b7f8 d7c02640 d76abe5c d76abe30[    7.956876] be28  c0134da0 bf1171a8 d7c027a0 d7c02640 0000001f d7c02650 d7776688 00000000[    7.956876] be48  d7740a90 d7dc5998 d76abe7c d76abe60 c0134f5c c0134ce0 d7776680 d780f070[    7.956876] be68  00000008 d7776688 d76abe8c d76abe80 c0134f94 c0134e44 d76abec4 d76abe90[    7.956876] [    7.956876] IP: 0xd76abd98:[    7.956876] bd98  c0062dec c0085640 ed9f4b00 a0000033 ffffffff d76abdf4 d76abe14 d76abdc0[    7.956876] bdb8  c0010438 c000a25c d7854400 0000ffff d76abe00 ed9f4b01 bf14b828 bf11719c[    7.956876] bdd8  0000001f d7854000 d7c02650 d7740a90 d7dc5998 d76abe14 d76abe18 d76abe08[    7.956876] bdf8  bf116ed4 ed9f4b00 a0000033 ffffffff d76abe2c d76abe18 bf1171c8 bf116ebc[    7.956876] be18  bf14b7f8 d7c02640 d76abe5c d76abe30 c0134da0 bf1171a8 d7c027a0 d7c02640[    7.956876] be38  0000001f d7c02650 d7776688 00000000 d7740a90 d7dc5998 d76abe7c d76abe60[    7.956876] be58  c0134f5c c0134ce0 d7776680 d780f070 00000008 d7776688 d76abe8c d76abe80[    7.956876] be78  c0134f94 c0134e44 d76abec4 d76abe90 c01045a8 c0134f78 00000000 00000000[    7.956876] [    7.956876] FP: 0xd76abd94:[    7.956876] bd94  d76abda0 c0062dec c0085640 ed9f4b00 a0000033 ffffffff d76abdf4 d76abe14[    7.956876] bdb4  d76abdc0 c0010438 c000a25c d7854400 0000ffff d76abe00 ed9f4b01 bf14b828[    7.956876] bdd4  bf11719c 0000001f d7854000 d7c02650 d7740a90 d7dc5998 d76abe14 d76abe18[    7.956876] bdf4  d76abe08 bf116ed4 ed9f4b00 a0000033 ffffffff d76abe2c d76abe18 bf1171c8[    7.956876] be14  bf116ebc bf14b7f8 d7c02640 d76abe5c d76abe30 c0134da0 bf1171a8 d7c027a0[    7.956876] be34  d7c02640 0000001f d7c02650 d7776688 00000000 d7740a90 d7dc5998 d76abe7c[    7.956876] be54  d76abe60 c0134f5c c0134ce0 d7776680 d780f070 00000008 d7776688 d76abe8c[    7.956876] be74  d76abe80 c0134f94 c0134e44 d76abec4 d76abe90 c01045a8 c0134f78 00000000[    7.956876] [    7.956876] R0: 0xd7854380:[    7.956876] 4380  00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[    7.956876] 43a0  00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[    7.956876] 43c0  00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[    7.956876] 43e0  00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[    7.956876] 4400  bf14b828 ee367b0e ee205b07 ee376b02 eeb5cb05 ee311bc0 eef18b06 ee0efa10[    7.956876] 4420  bf48cb0e 5b41eeb1 eeb0d401 eeb55b41 eef16bc0 bf48fa10 7b46eeb1 eeb0d401[    7.956876] 4440  eeb47b46 eef15bc7 f301fa10 ee36839e 4bda7b48 ed93447b ee316b00 ed9d7b07[    7.956876] 4460  ee371b02 ee317b06 ee399b07 ed9f4b08 4bd37bc0 ed93447b ee201b00 ee246b07[    7.956876] [    7.956876] R2: 0xd76abd80:[    7.956876] bd80  00000000 c00d09b4 c09a7b40 c0e769e4 d76abdb4 d76abda0 c0062dec c0085640[    7.956876] bda0  ed9f4b00 a0000033 ffffffff d76abdf4 d76abe14 d76abdc0 c0010438 c000a25c[    7.956876] bdc0  d7854400 0000ffff d76abe00 ed9f4b01 bf14b828 bf11719c 0000001f d7854000[    7.956876] bde0  d7c02650 d7740a90 d7dc5998 d76abe14 d76abe18 d76abe08 bf116ed4 ed9f4b00[    7.956876] be00  a0000033 ffffffff d76abe2c d76abe18 bf1171c8 bf116ebc bf14b7f8 d7c02640[    7.956876] be20  d76abe5c d76abe30 c0134da0 bf1171a8 d7c027a0 d7c02640 0000001f d7c02650[    7.956876] be40  d7776688 00000000 d7740a90 d7dc5998 d76abe7c d76abe60 c0134f5c c0134ce0[    7.956876] be60  d7776680 d780f070 00000008 d7776688 d76abe8c d76abe80 c0134f94 c0134e44[    7.956876] [    7.956876] R3: 0xed9f4a81:[    7.956876] 4a80  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4aa0  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4ac0  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4ae0  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4b00  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4b20  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4b40  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4b60  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] 4b80  ******** ******** ******** ******** ******** ******** ******** ********[    7.956876] [    7.956876] R7: 0xd7853f80:[    7.956876] 3f80  00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[    7.956876] 3fa0  00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[    7.956876] 3fc0  00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[    7.956876] 3fe0  00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[    7.956876] 4000  0000005d 00000000 00000001 646e616e 00000061 00000000 00000000 00000000[    7.956876] 4020  00000000 00000000 00000000 00000000 00000000 00000000 d777c880 00000000[    7.956876] 4040  00000000 00000000 00000200 00000000 00000000 00000000 00000000 00000000[    7.956876] 4060  00000000 d79e4f40 d777c640 d776a22c d79e5e0c d81b3b40 d80c3d00 c097e5c8[    7.956876] [    7.956876] R8: 0xd7c025d0:[    7.956876] 25d0  00000000 00000000 d7c025d8 d7c025d8 00000000 00000000 00000000 c06496fc[    7.956876] 25f0  000200d0 d7761b70 00000000 00000000 d7c02600 d7c02600 00000000 d7c0260c[    7.956876] 2610  d7c0260c d7c02440 00000000 00000000 00000000 00000000 00000000 00000000[    7.956876] 2630  00000000 00000000 00000000 00000000 05d00000 00000000 d7c026d0 00000000[    7.956876] 2650  00000000 00000000 00000000 d7c0265c d7c0265c d78e73c0 d780f1ac d780f1ac[    7.956876] 2670  00000000 00000000 00000000 00000000 d7c02680 d7c02680 d7c02640 00001000[    7.956876] 2690  d7854040 00000000 00000000 d7854000 d760c078 d7c02aa4 c096d70c 00000000[    7.956876] 26b0  00000000 00000001 00000000 00000000 d7c026c0 d7c026c0 00000000 00000000[    7.956876] [    7.956876] R9: 0xd7740a10:[    7.956876] 0a10  d7740a10 d7740a10 d7740a18 d7740a18 d7740a20 d7740a20 00000000 d800ba40[    7.956876] 0a30  00000000 00000000 00000017 00000000 00000000 00000000 00000000 00000000[    7.956876] 0a50  00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000[    7.956876] 0a70  00000000 00000000 00000000 00000000 d801fd00 d801fd00 d8021380 d7d26aa8[    7.956876] 0a90  d7c01f70 d810dc00 00000020 c0940774 00000001 d7740cec d7740cec d80212ec[    7.956876] 0ab0  d7740dac d810dc8c d7740f34 d781aec0 d7740d00 d7740dc0 d7740ac8 d7740ac8[    7.956876] 0ad0  d7740ad0 d7740ad0 d7740ad8 d7740ad8 d7740ae0 d7740ae0 00000000 d800ba40[    7.956876] 0af0  00000000 00000000 00000014 00000000 00000000 00000000 00000000 00000000[    7.956876] [    7.956876] R10: 0xd7dc5918:[    7.956876] 5918  d7cda1a8 c12872e0 d7dc52b0 bf51d0bd 0000000f d7dc5934 d7e0ce58 74736574[    7.956876] 5938  6e6f635f 2e676966 00786566 00000000 00000000 00000000 00000000 00000000[    7.956876] 5958  00000000 00000000 00000000 c0652fc0 d782fc00 00000002 00000000 d782fc94[    7.956876] 5978  d782fc94 d7dc5324 d7dc5324 d7dc5984 d7dc5984 d7e0cefc d7e0cefc 00000000[    7.956876] 5998  00000088 00000004 00000000 c128ba94 d7c01f70 12770052 00000005 d7dc59bc[    7.956876] 59b8  d780f070 646e616e 00000061 00000000 00000000 00000000 00000000 00000000[    7.956876] 59d8  00000000 00000000 00000002 00000000 00000000 c0648a40 d810dc00 00000000[    7.956876] 59f8  00000000 d7dc59fc d7dc59fc d7d2a20c d7d23d34 d7dc5a0c d7dc5a0c d780f114[    7.956876] Process nandrw (pid: 159, stack limit = 0xd76aa2f8)[    7.956876] Stack: (0xd76abe08 to 0xd76ac000)[    7.956876] be00:                   d76abe2c d76abe18 bf1171c8 bf116ebc bf14b7f8 d7c02640[    7.956876] be20: d76abe5c d76abe30 c0134da0 bf1171a8 d7c027a0 d7c02640 0000001f d7c02650[    7.956876] be40: d7776688 00000000 d7740a90 d7dc5998 d76abe7c d76abe60 c0134f5c c0134ce0[    7.956876] be60: d7776680 d780f070 00000008 d7776688 d76abe8c d76abe80 c0134f94 c0134e44[    7.956876] be80: d76abec4 d76abe90 c01045a8 c0134f78 00000000 00000000 d76abec4 d7776680[    7.956876] bea0: 00000000 d8038380 d8038388 00000028 d76aa000 00000000 d76abee4 d76abec8[    7.956876] bec0: c0100dc4 c0104494 d80383fc d8038380 00000000 00000001 d76abf0c d76abee8[    7.956876] bee0: c00397cc c0100d50 d78e73c0 d8038380 d78e7680 000000f8 c00109e8 00000000[    7.956876] bf00: d76abf2c d76abf10 c00398c0 c0039738 00800000 d78e73c0 00000000 d76aa000[    7.956876] bf20: d76abf74 d76abf30 c0039b80 c0039884 d76abf6c 00000001 c0102b08 c013ae84[    7.956876] bf40: 00000000 00000000 d76abf64 d793eb80 00000000 d76aa000 000000f8 c00109e8[    7.956876] bf60: d76aa000 00000000 d76abf94 d76abf78 c003a384 c00398d0 000a27f0 b6fc475c[    7.956876] bf80: 00000000 000000f8 d76abfa4 d76abf98 c003a3d0 c003a2f8 00000000 d76abfa8[    7.956876] bfa0: c0010780 c003a3bc 000a27f0 b6fc475c 00000000 000a27dc ffffffff 00000000[    7.956876] bfc0: 000a27f0 b6fc475c 00000000 000000f8 b6fc6000 00000000 b6fc6000 00000000[    7.956876] bfe0: b6fee000 bede1b48 b6eb6494 b6f23964 60000010 00000000 587c1821 587c1c21[    7.956876] [<bf116ed4>] (nand_blk_release+0x24/0x28 [nand]) from [<bf1171c8>] (nand_release+0x2c/0x44 [nand])[    7.956876] [<bf1171c8>] (nand_release+0x2c/0x44 [nand]) from [<c0134da0>] (__blkdev_put+0xcc/0x164)[    7.956876] [<c0134da0>] (__blkdev_put+0xcc/0x164) from [<c0134f5c>] (blkdev_put+0x124/0x134)[    7.956876] [<c0134f5c>] (blkdev_put+0x124/0x134) from [<c0134f94>] (blkdev_close+0x28/0x2c)[    7.956876] [<c0134f94>] (blkdev_close+0x28/0x2c) from [<c01045a8>] (fput+0x120/0x228)[    7.956876] [<c01045a8>] (fput+0x120/0x228) from [<c0100dc4>] (filp_close+0x80/0x8c)[    7.956876] [<c0100dc4>] (filp_close+0x80/0x8c) from [<c00397cc>] (put_files_struct+0xa0/0xfc)[    7.956876] [<c00397cc>] (put_files_struct+0xa0/0xfc) from [<c00398c0>] (exit_files+0x48/0x4c)[    7.956876] [<c00398c0>] (exit_files+0x48/0x4c) from [<c0039b80>] (do_exit+0x2bc/0x7d0)[    7.956876] [<c0039b80>] (do_exit+0x2bc/0x7d0) from [<c003a384>] (do_group_exit+0x98/0xc4)[    7.956876] [<c003a384>] (do_group_exit+0x98/0xc4) from [<c003a3d0>] (__wake_up_parent+0x0/0x30)[    7.956876] [<c003a3d0>] (__wake_up_parent+0x0/0x30) from [<c0010780>] (ret_fast_syscall+0x0/0x30)[    7.956876] Code: bad PC value[    9.177219] ---[ end trace b1efa7b6baf6b056 ]---[    9.182375] Fixing recursive fault but reboot is needed!

From the preceding log, we can see why an error occurred while calling the nand_blk_release function, or PC pointer operation error. This proves that, even if the close function is not called, the system will help you call the close function when resources are automatically reclaimed.

The key point is that the adjustment method:

1. First find the file in which nand_blk_release is compiled, for example, nand_blk.c.

2. Arm-None-Linux-gnueabi-objdump-s nand_blk.o> ~ /NAND. s

3. Analyze NAND. S. It is a C language + Assembly file, which is much more convenient than the analysis of the full Assembly file.

Here we will not analyze NAND. s in detail, because it seems to involve company secrets.

Use objdump to debug the driver