m68k 54418 fails to execute user space
Jean-Michel Hautbois
jeanmichel.hautbois at yoseli.org
Fri Jun 28 00:24:22 PDT 2024
Hi Michael,
On 28/06/2024 01:58, Michael Schmitz wrote:
> Jean-Michel,
>
> Am 28.06.2024 um 00:36 schrieb Jean-Michel Hautbois:
>>>> ./scripts/decode_stacktrace.sh vmlinux < /tmp/trace.log
>>>> [ 3.857000] Run /bin/bash as init process
>>>> [ 3.858000] with arguments:
>>>> [ 3.861000] /bin/bash
>>>> [ 3.862000] with environment:
>>>> [ 3.863000] HOME=/
>>>> [ 3.864000] TERM=linux
>>>> [ 4.242000] do page fault:
>>>> [ 4.242000] regs->sr=0x2000, regs->pc=0x41366924,
>>>> address=0x700b3364, 2, 41fb0000
>>>> [ 4.242000] Kernel panic - not syncing: page fault error
>>>> [ 4.242000] CPU: 0 PID: 1 Comm: bash Not tainted
>>>> 6.10.0-rc5-g927da6cf01fe-dirty #25
>>>> [ 4.242000] Stack from 4186dda8:
>>>> [ 4.242000] 4186dda8 41423aa4 41423aa4 700b3300 00000001
>>>> 00000000 4136ee10 41423aa4
>>>> [ 4.242000] 41366d7a 700b3364 700b3364 00000000 0000000d
>>>> 4186de60 41fb0000 41d51a60
>>>> [ 4.242000] 41005696 41416a90 41416a4d 00002000 41366924
>>>> 700b3364 00000002 41fb0000
>>>> [ 4.242000] 0000000a 700b3364 00000000 0000000d 00000012
>>>> 41d51a00 4186de60 41d51a60
>>>> [ 4.242000] 41fb81c0 41d51a60 410052fe 4100529a 4186de60
>>>> 700b3364 00000002 00000000
>>>> [ 4.242000] 700bc414 00000003 00008000 700ac000 41003660
>>>> 4186de60 00000000 00000000
>>>> [ 4.242000] Call Trace: dump_stack (lib/dump_stack.c:124)
>>>> [ 4.242000] panic (kernel/panic.c:266 kernel/panic.c:368)
>>>> [ 4.242000] do_page_fault (arch/m68k/mm/fault.c:88 (discriminator
>>>> 1))
>>>> [ 4.242000] __clear_user (arch/m68k/lib/uaccess.c:108)
>>>> [ 4.242000] buserr_c (arch/m68k/kernel/traps.c:725
>>>> arch/m68k/kernel/traps.c:775)
>>>> [ 4.242000] buserr_c (arch/m68k/kernel/traps.c:748
>>>> arch/m68k/kernel/traps.c:775)
>>>> [ 4.242000] buserr (arch/m68k/kernel/entry.S:116)
>>>> [ 4.242000] ma_slots (lib/maple_tree.c:759)
>>>> [ 4.242000] __clear_user (arch/m68k/lib/uaccess.c:108)
>>>> [ 4.242000] elf_load (fs/binfmt_elf.c:125 (discriminator 1)
>>>> fs/binfmt_elf.c:421 (discriminator 1))
>>>> [ 4.242000] load_elf_binary (fs/binfmt_elf.c:1132)
>>>> [ 4.242000] memset (arch/m68k/lib/memset.c:11)
>>>> [ 4.242000] load_misc_binary (fs/binfmt_misc.c:97
>>>> fs/binfmt_misc.c:146 fs/binfmt_misc.c:213)
>>>> [ 4.242000] memset (arch/m68k/lib/memset.c:11)
>>>> [ 4.242000] bprm_execve (fs/exec.c:1797 fs/exec.c:1839
>>>> fs/exec.c:1891 fs/exec.c:1867)
>>>> [ 4.242000] copy_strings_kernel (fs/exec.c:669)
>>>> [ 4.242000] count_strings_kernel (fs/exec.c:473)
>>>> [ 4.242000] kernel_execve (fs/exec.c:2058)
>>>> [ 4.242000] __dynamic_pr_debug (lib/dynamic_debug.c:865)
>>>> [ 4.242000] run_init_process (init/main.c:1389)
>>>> [ 4.242000] _printk (kernel/printk/printk.c:2365)
>>>> [ 4.242000] kernel_init (init/main.c:1508)
>>>> [ 4.242000] kernel_init (init/main.c:1459)
>>>> [ 4.242000] ret_from_kernel_thread (arch/m68k/kernel/entry.S:142)
>>>> [ 4.242000]
>>>> [ 4.242000] ---[ end Kernel panic - not syncing: page fault error
>>>> ]---
>>>>
>>>> Looks like a memory mapping failure, but why ?
>>>> My JTAG at this point dumps a list of 0s at 0x41fb0000 and my SDRAM
>>>> starts at 0x40000000 and ends at 0x50000000 (256MB).
>>> 0x41fb0000 seems to be init's page directory. The fault address is in
>>> the range where I'd expect dynamic libraries to reside.
>>>>
>>>> It looks like a TLB write miss which is obscure to me :-).
>>>>
>>>> I tried to use the /proc but as expected it is not alive after
>>>> mounting it.
>>>
>>> The memory map ought to be accessible through sysrq - an alternative
>>> would be to modify the ELF binfmt handler and dump the map once ld.so
>>> has finished with relocations.
>>
>> I added a dump in the binfmt_elf file:
>> diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
>> index a43897b03ce9..395f556f3a90 100644
>> --- a/fs/binfmt_elf.c
>> +++ b/fs/binfmt_elf.c
>> @@ -816,6 +816,63 @@ static int parse_elf_properties(struct file *f,
>> const struct elf_phdr *phdr,
>> return ret == -ENOENT ? 0 : ret;
>> }
>>
>> +static int dump_memory_map(struct task_struct *task)
>> +{
>> + struct mm_struct *mm = task->mm;
>> + struct vm_area_struct *vma;
>> + MA_STATE(mas, &mm->mm_mt, 0, -1);
>> + struct file *file;
>> + struct path *path;
>> + char *buf;
>> + char *pathname;
>> +
>> + // Acquire the read lock for mmap_lock
>> + down_read(&mm->mmap_lock);
>> + mas_lock(&mas);
>> + for (vma = mas_find(&mas, ULONG_MAX); vma; vma = mas_find(&mas,
>> ULONG_MAX)) {
>> + if (vma->vm_file) {
>> + buf = (char *)__get_free_page(GFP_KERNEL);
>> + if (!buf) {
>> + continue; // Handle memory allocation failure
>> + }
>> +
>> + file = vma->vm_file;
>> + path = &file->f_path;
>> + pathname = d_path(path, buf, PAGE_SIZE);
>> + if (IS_ERR(pathname)) {
>> + pathname = NULL;
>> + }
>> +
>> + pr_info("%lx-%lx %c%c%c%c %08lx %02x:%02x %lu %s\n",
>> + vma->vm_start, vma->vm_end,
>> + vma->vm_flags & VM_READ ? 'r' : '-',
>> + vma->vm_flags & VM_WRITE ? 'w' : '-',
>> + vma->vm_flags & VM_EXEC ? 'x' : '-',
>> + vma->vm_flags & VM_MAYSHARE ? 's' : 'p',
>> + vma->vm_pgoff << PAGE_SHIFT,
>> + MAJOR(file->f_inode->i_rdev),
>> + MINOR(file->f_inode->i_rdev),
>> + file->f_inode->i_ino,
>> + pathname ? pathname : "");
>> +
>> + free_page((unsigned long)buf);
>> + } else {
>> + pr_info("%lx-%lx %c%c%c%c %08lx 00:00 0\n",
>> + vma->vm_start, vma->vm_end,
>> + vma->vm_flags & VM_READ ? 'r' : '-',
>> + vma->vm_flags & VM_WRITE ? 'w' : '-',
>> + vma->vm_flags & VM_EXEC ? 'x' : '-',
>> + vma->vm_flags & VM_MAYSHARE ? 's' : 'p',
>> + vma->vm_pgoff << PAGE_SHIFT);
>> + }
>> + }
>> + mas_unlock(&mas);
>> + // Release the read lock for mmap_lock
>> + up_read(&mm->mmap_lock);
>> +
>> + return 0;
>> +}
>> +
>> static int load_elf_binary(struct linux_binprm *bprm)
>> {
>> struct file *interpreter = NULL; /* to shut gcc up */
>> @@ -1299,6 +1356,9 @@ static int load_elf_binary(struct linux_binprm
>> *bprm)
>>
>> finalize_exec(bprm);
>> START_THREAD(elf_ex, regs, elf_entry, bprm->p);
>> + if (current->pid == 1) { // Check if this is the init process
>> + dump_memory_map(current);
>> + }
>> retval = 0;
>> out:
>> return retval;
>>
>> I think it is quick and dirty, but seems to do the trick.
>> I then get in my console:
>> [ 4.265000] 60000000-6001e000 r-xp 00000000 00:00 178 /lib/ld.so.1
>> [ 4.266000] 6001e000-60022000 rw-p 0001c000 00:00 178 /lib/ld.so.1
>> [ 4.267000] 70000000-700ac000 r-xp 00000000 00:00 27 /bin/bash
>> [ 4.268000] 700ac000-700b4000 rw-p 000ac000 00:00 27 /bin/bash
>> [ 4.269000] 700b4000-700be000 rwxp 700b4000 00:00 0
>> [ 4.270000] bfe7a000-bfe9c000 rw-p bffde000 00:00 0
>>
>> But nothing rings a bell at this level for me...
>
> You are again using bash as init process, so the process of interest
> (/bin/ls) is a child of init and does not get logged here.
>
> But we are getting some mapping information at last. No shared libraries
> mapped as yet, but that's the same in Greg's dump.
>
> Comparing with what I get from cat /proc/1/maps on a 030 system., the
> rwxp section at 0x700b4000 is the process heap, and the rwp section at
> 0xbfe7a000 is the process stack.
>
> I forgot to take into account that libraries are loaded only the binary
> starts executing. Can you print the same map dump in the exit syscall
> code path? That ought to show all loaded libraries at that point.
Thanks for your suggestion !
I changed it a bit, and I added a call in do_exit() as suggested. When
executing ls I get:
bash-5.2# ls -l
load_elf_binary: Dump memory for ls (31):
mmap: 60000000-6001e000 r-xp 00000000 00:00 178 /lib/ld.so.1
mmap: 6001e000-60022000 rw-p 0001c000 00:00 178 /lib/ld.so.1
mmap: 70000000-700c2000 r-xp 00000000 00:00 28 /bin/busybox
mmap: 700c2000-700ca000 rw-p 000c0000 00:00 28 /bin/busybox
mmap: bfc1e000-bfc40000 rw-p bffde000 00:00 0 [stack]
do_exit: Dump memory for ls (31):
mmap: 60000000-6001e000 r-xp 00000000 00:00 178 /lib/ld.so.1
mmap: 6001e000-60020000 r--p 0001c000 00:00 178 /lib/ld.so.1
mmap: 60020000-60022000 rw-p 0001e000 00:00 178 /lib/ld.so.1
mmap: 60022000-6002c000 r-xp 00000000 00:00 193 /lib/libresolv.so.2
mmap: 6002c000-6002e000 r--p 00008000 00:00 193 /lib/libresolv.so.2
mmap: 6002e000-60030000 rw-p 0000a000 00:00 193 /lib/libresolv.so.2
mmap: 60030000-60032000 rw-p 60030000 00:00 0
mmap: 60032000-6015a000 r-xp 00000000 00:00 185 /lib/libc.so.6
mmap: 6015a000-6015c000 r--p 00126000 00:00 185 /lib/libc.so.6
mmap: 6015c000-60160000 rw-p 00128000 00:00 185 /lib/libc.so.6
mmap: 60160000-6016e000 rw-p 60160000 00:00 0
mmap: 70000000-700c2000 r-xp 00000000 00:00 28 /bin/busybox
mmap: 700c2000-700c4000 r--p 000c0000 00:00 28 /bin/busybox
mmap: 700c4000-700ca000 rw-p 000c2000 00:00 28 /bin/busybox
mmap: 700ca000-700ec000 rwxp 700ca000 00:00 0 [heap]
mmap: bfc1e000-bfc40000 rw-p bffde000 00:00 0 [stack]
When I call it a second time, I get:
bash-5.2# ls -l
load_elf_binary: Dump memory for ls (33):
mmap: 60000000-6001e000 r-xp 00000000 00:00 178 /lib/ld.so.1
mmap: 6001e000-60022000 rw-p 0001c000 00:00 178 /lib/ld.so.1
mmap: 70000000-700c2000 r-xp 00000000 00:00 28 /bin/busybox
mmap: 700c2000-700ca000 rw-p 000c0000 00:00 28 /bin/busybox
mmap: bfb5a000-bfb7c000 rw-p bffde000 00:00 0 [stack]
do_exit: Dump memory for ls (33):
mmap: 60000000-6001e000 r-xp 00000000 00:00 178 /lib/ld.so.1
mmap: 6001e000-60020000 r--p 0001c000 00:00 178 /lib/ld.so.1
mmap: 60020000-60022000 rw-p 0001e000 00:00 178 /lib/ld.so.1
mmap: 60022000-6002c000 r-xp 00000000 00:00 193 /lib/libresolv.so.2
mmap: 6002c000-6002e000 r--p 00008000 00:00 193 /lib/libresolv.so.2
mmap: 6002e000-60030000 rw-p 0000a000 00:00 193 /lib/libresolv.so.2
mmap: 60030000-60032000 rw-p 60030000 00:00 0
mmap: 60032000-6015a000 r-xp 00000000 00:00 185 /lib/libc.so.6
mmap: 6015a000-6015c000 r--p 00126000 00:00 185 /lib/libc.so.6
mmap: 6015c000-60160000 rw-p 00128000 00:00 185 /lib/libc.so.6
mmap: 60160000-6016e000 rw-p 60160000 00:00 0
mmap: 70000000-700c2000 r-xp 00000000 00:00 28 /bin/busybox
mmap: 700c2000-700c4000 r--p 000c0000 00:00 28 /bin/busybox
mmap: 700c4000-700ca000 rw-p 000c2000 00:00 28 /bin/busybox
mmap: bfb5a000-bfb7c000 rw-p bffde000 00:00 0 [stack]
The first call generates the "ls" output, not the second one.
The helper looks like:
diff --git a/mm/mmap.c b/mm/mmap.c
index 83b4682ec85c..14d861e9cba2 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -76,6 +76,87 @@ int mmap_rnd_compat_bits __read_mostly =
CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
static bool ignore_rlimit_data;
core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
+int dump_memory_map(struct task_struct *task)
+{
+ struct mm_struct *mm = task->mm;
+ struct vm_area_struct *vma;
+ struct file *file;
+ struct path *path;
+ char *buf;
+ char *pathname;
+
+ if (!mm) {
+ return -ENOMEM;
+ }
+
+ MA_STATE(mas, &mm->mm_mt, 0, -1);
+ // Acquire the read lock for mmap_lock
+ down_read(&mm->mmap_lock);
+ mas_lock(&mas);
+ for (vma = mas_find(&mas, ULONG_MAX); vma; vma = mas_find(&mas,
ULONG_MAX)) {
+ char perms[5] = "---p"; // Default permissions
+ // Set permissions based on vm_flags
+ if (vma->vm_flags & VM_READ) perms[0] = 'r';
+ if (vma->vm_flags & VM_WRITE) perms[1] = 'w';
+ if (vma->vm_flags & VM_EXEC) perms[2] = 'x';
+ if (vma->vm_flags & VM_MAYSHARE) perms[3] = 's';
+
+ if (vma->vm_file) { // If there's an associated file
+ buf = (char *)__get_free_page(GFP_KERNEL);
+ if (!buf) {
+ continue; // Handle memory allocation
failure
+ }
+
+ file = vma->vm_file;
+ path = &file->f_path;
+ pathname = d_path(path, buf, PAGE_SIZE);
+ if (IS_ERR(pathname)) {
+ pathname = NULL;
+ }
+
+ // Print memory area information with file path
+ pr_info("%08lx-%08lx %s %08lx %02x:%02x %lu %s\n",
+ vma->vm_start, vma->vm_end,
+ perms,
+ vma->vm_pgoff << PAGE_SHIFT,
+ MAJOR(file_inode(file)->i_rdev),
+ MINOR(file_inode(file)->i_rdev),
+ file_inode(file)->i_ino,
+ pathname ? pathname : "");
+
+ free_page((unsigned long)buf);
+ } else {
+ char *special_area_name = NULL;
+
+ // Check for heap
+ if (vma->vm_end > mm->start_brk && vma->vm_start
< mm->brk) {
+ special_area_name = "[heap]";
+ }
+ // Check for stack
+ else if (vma->vm_start <= mm->start_stack &&
vma->vm_end >= mm->start_stack) {
+ special_area_name = "[stack]";
+ }
+ // Check for vdso
+ else if (vma->vm_flags & VM_EXEC &&
vma->vm_flags & VM_READ && !vma->vm_file) {
+ special_area_name = "[vdso]";
+ }
+
+ // Print memory area information without file path
+ pr_info("%08lx-%08lx %s %08lx 00:00 0 %s\n",
+ vma->vm_start, vma->vm_end,
+ perms,
+ vma->vm_pgoff << PAGE_SHIFT,
+ special_area_name ? special_area_name :
" ");
+ }
+ }
+ mas_unlock(&mas);
+ // Release the read lock for mmap_lock
+ up_read(&mm->mmap_lock);
+
+ return 0;
+}
+EXPORT_SYMBOL(dump_memory_map);
Thanks,
JM
More information about the linux-mtd
mailing list