On 2023/05/10 10:44, HAGIO KAZUHITO(萩尾 一仁) wrote:
> On 2023/05/10 4:33, Luiz Capitulino wrote:
>> On 2023-05-09 03:32, HAGIO KAZUHITO(萩尾 一仁) wrote:
>>> On 2023/05/02 3:41, Luiz Capitulino wrote:
>>>> Hi all,
>>>>
>>>> I'm trying to run latest crash (HEAD 2505a65ff54) against kernel
>>>> 4.14.314 but I'm getting the error below on startup.
>>>>
>>>> Is this a known issue? If not, any suggestions on how to debug it?
>>>
>>> hmm, I tried the kernel version, but could not reproduce it.
>>>
>>> crash> sys
>>> KERNEL: /lib/modules/4.14.314/build/vmlinux
>>> DUMPFILE: /proc/kcore
>>> CPUS: 4
>>> DATE: Tue May 9 16:16:14 JST 2023
>>> UPTIME: 00:07:02
>>> LOAD AVERAGE: 0.07, 0.12, 0.07
>>> TASKS: 174
>>> NODENAME: rhel78b
>>> RELEASE: 4.14.314
>>> VERSION: #1 SMP Tue May 9 15:28:59 JST 2023
>>> MACHINE: x86_64 (3408 Mhz)
>>> MEMORY: 4 GB
>>>
>>> Could you upload a startup log with "crash -d 8" option?
>>
>> I'm attaching a file with this information, thanks a lot for looking
>> into this.
>
> Thanks.
>
> -----
> module: ffffffffa00f8f80
> <readmem: ffffffffa00f8f80, KVADDR, "module struct", 896, (ROE|Q), 122f800>
> <readmem: 200e000, PHYSADDR, "pud page", 4096, (FOE), 1c95e00>
> <read_proc_kcore: addr: 200e000 paddr: 200e000 cnt: 4096>
> crash: seek error: physical address: 200e000 type: "pud page"
> -----
>
> It seems that the virt to phys conversion for ffffffffa00f8f80 fails
> because the file offset of the pud page is not found in /proc/kcore.
>
> According to read_proc_kcore(), it does
> 1. p2v for 200e000 i.e. phys:200e000 --> virt:???
> 2. search /proc/kcore pt_loads for the corresponding file offset to the
> virtual address. (as pc->curcmd_flags does not have MEMTYPE_KVADDR.)
> 3. read the file offset.
>
> so, what is the converted virtual address? For example,
>
> --- a/netdump.c
> +++ b/netdump.c
> @@ -4362,6 +4362,8 @@ read_proc_kcore(int fd, void *bufptr, int cnt, ulong addr, physaddr_t paddr)
> else
> kvaddr = PTOV((ulong)paddr);
>
> + fprintf(fp, "kvaddr: %lx\n", kvaddr);
> +
> offset = UNINITIALIZED;
> readcnt = cnt;
>
Ah, probably got it.
The PTOV() above is defined like this:
#define PTOV(X) ((unsigned long)(X)+(machdep->kvbase))
>
> Your kernel has the following pt_load information, probably it's out of
> these vaddr ranges?
>
> offset vaddr end paddr end size
> 7fffff604000 ffffffffff600000-ffffffffff601000 ffffffffffffffff- 0 (1000)
> 7fff81004000 ffffffff81000000-ffffffff8377f000 1000000- 377f000 (277f000)
> 490000004000 ffffc90000000000-ffffe90000000000 ffffffffffffffff- 0 (1fffffffffff)
> 7fffa0004000 ffffffffa0000000-ffffffffff000000 ffffffffffffffff- 0 (5f000000)
> 88000005000 ffff888000001000-ffff88800009f000 1000- 9f000 (9e000)
> 6a0000004000 ffffea0000000000-ffffea0000003000 ffffffffffffffff- 0 (3000)
> 88000104000 ffff888000100000-ffff8880bffe8000 100000- bffe8000 (bfee8000)
> 6a0000008000 ffffea0000004000-ffffea0003000000 ffffffffffffffff- 0 (2ffc000)
> 88100004000 ffff888100000000-ffff888fff000000 100000000-fff000000 (eff000000)
> 6a0004004000 ffffea0004000000-ffffea003ffc0000 ffffffffffffffff- 0 (3bfc0000)
Your kernel looks configured without CONFIG_RANDOMIZE_BASE. For such
kernels, a hard-coded value is used for PAGE_OFFSET and kvbase. And
I found that Linux 4.14.84 and later has the recent PAGE_OFFSET.
case POST_GDB:
if (!(machdep->flags & RANDOMIZED) &&
((THIS_KERNEL_VERSION >= LINUX(4,19,5)) ||
((THIS_KERNEL_VERSION >= LINUX(4,14,84)) &&
(THIS_KERNEL_VERSION < LINUX(4,15,0))))) {
machdep->machspec->page_offset = machdep->flags & VM_5LEVEL ?
PAGE_OFFSET_5LEVEL_4_20 : PAGE_OFFSET_4LEVEL_4_20;
machdep->kvbase = machdep->machspec->page_offset;
#define PAGE_OFFSET_4LEVEL_4_20 0xffff888000000000
But, the THIS_KERNEL_VERSION and LINUX() macros are defined like this:
#define THIS_KERNEL_VERSION ((kt->kernel_version[0] << 16) + \
(kt->kernel_version[1] << 8) + \
(kt->kernel_version[2]))
#define LINUX(x,y,z) (((uint)(x) << 16) + ((uint)(y) << 8) + (uint)(z))
So (THIS_KERNEL_VERSION < LINUX(4,15,0)) is false on Linux 4.14.256 and
later, and the old PAGE_OFFSET will be used.
So does this patch work well?
--- a/defs.h
+++ b/defs.h
@@ -807,10 +807,10 @@ struct kernel_table { /* kernel data */
} \
}
-#define THIS_KERNEL_VERSION ((kt->kernel_version[0] << 16) + \
- (kt->kernel_version[1] << 8) + \
+#define THIS_KERNEL_VERSION ((kt->kernel_version[0] << 24) + \
+ (kt->kernel_version[1] << 16) + \
(kt->kernel_version[2]))
-#define LINUX(x,y,z) (((uint)(x) << 16) + ((uint)(y) << 8) + (uint)(z))
+#define LINUX(x,y,z) (((uint)(x) << 24) + ((uint)(y) << 16) + (uint)(z))
#define THIS_GCC_VERSION ((kt->gcc_version[0] << 16) + \
(kt->gcc_version[1] << 8) + \
Thanks,
Kazu
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