----- "Wei Jiang" <talk90091e@xxxxxxxxx> wrote:
> Hi,
>
> I found nr_cpus is not calculated properly in 32 bits(x86) at
> crash-4.0-8.9.
>
> Around line 140 in file lkcd_v8.c.
> 137 * to find out how many CPUs are configured.
> 138 */
> 139 offset = offsetof(dump_header_asm_t, dha_smp_regs[0]);
> 140 nr_cpus = (hdr_size - offset) / sizeof(dump_CPU_info_t);
> 141
> 142 fprintf(stderr, "CPU number NR_CPUS %d \n", NR_CPUS);
> 143 fprintf(stderr, "header_asm_t size %d \n",
> sizeof(dump_header_asm_t));
>
> And in the corresponding head file.
> # cat -n lkcd_dump_v8.h|grep -A 20 434
> 434 /* smp specific */
> 435 uint32_t dha_smp_num_cpus;
> 436 uint32_t dha_dumping_cpu;
> 437 struct pt_regs dha_smp_regs[NR_CPUS];
> 438 uint32_t dha_smp_current_task[NR_CPUS];
> 439 uint32_t dha_stack[NR_CPUS];
> 440 uint32_t dha_stack_ptr[NR_CPUS];
> 441 } __attribute__((packed)) dump_header_asm_t;
> 442
> 443 /*
> 444 * CPU specific part of dump_header_asm_t
> 445 */
> 446 typedef struct dump_CPU_info_s {
> 447 struct pt_regs dha_smp_regs;
> 448 uint64_t dha_smp_current_task;
> 449 uint64_t dha_stack;
> 450 uint64_t dha_stack_ptr;
> 451 } __attribute__ ((packed)) dump_CPU_info_t;
> 452
> 453
> 454 /*
>
> As we know, on x86(32 bits), uint32_t is 4 bytes and uint64_t is 8
> bytes.
>
> So this line
> 140 nr_cpus = (hdr_size - offset) / sizeof(dump_CPU_info_t);
>
> would not get a correct nr_cpus due to the sizeof().
>
> A patch to fix this problem as below.
BTW, what exactly are the ramifications without the patch -- does the
crash session die during initialization? How come nobody ran into
this issue given that the code has been in place for almost 2 years?
4.0-4.8 - ...
- Change for support of LKCD dumpfile version 8 and later to determine
the backtrace starting registers from the dumpfile header. Increase
(maximum) NR_CPUS for ia64 to 4096.
(bwalle@xxxxxxx)
...
(10/30/07)
Anyway, the patch looks reasonable to me, but I don't touch the LKCD
code without a sign-off from the LKCD maintainers on this mailing
list.
LKCD maintainers -- do you have any objection to this patch?
Thanks,
Dave
>
> Thanks.
> -Wj
>
> --- lkcd_dump_v8.h.orig 2009-04-16 13:14:22.000000000 -0400
> +++ lkcd_dump_v8.h 2009-06-10 03:31:37.815122032 -0400
> @@ -445,9 +445,9 @@ typedef struct _dump_header_asm_s {
> */
> typedef struct dump_CPU_info_s {
> struct pt_regs dha_smp_regs;
> - uint64_t dha_smp_current_task;
> - uint64_t dha_stack;
> - uint64_t dha_stack_ptr;
> + uint32_t dha_smp_current_task;
> + uint32_t dha_stack;
> + uint32_t dha_stack_ptr;
> } __attribute__ ((packed)) dump_CPU_info_t;
--
Crash-utility mailing list
Crash-utility@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/crash-utility
