----- "Chandru" <chandru@xxxxxxxxxx> wrote:
> Hi Dave,
>
> Thanks a lot for catching the segfault issue and finding the root cause for it. Here
> follows the updated patch taking in the suggestions from the review comments.
>
> kdump installs NT_PRSTATUS notes into vmcore file only to the cpus that were
> online at the time of crash. In such cases, while reading in the notes from the
> dump file, we are unsure of the cpu to NT_PRSTATUS mapping. The cpu
> possible, present and online map is not available until cpu_maps_init() initializes
> them. Hence we remap the prstatus pointer array to online cpus just after
> a call to this function.
>
> Signed-off-by: Chandru Siddalingappa <chandru@xxxxxxxxxxxxxxxxxx>
> Reviewed-by: Dave Anderson <anderson@xxxxxxxxxx>
> Cc: Haren Myneni <haren@xxxxxxxxxx>
> ---
This looks one good. The only change that I will make is
in the map_cpu_prstatus() function -- which should just return
immediately if get_cpus_online() is equal to nd->num_prstatus_notes.
Thanks,
Dave
>
> --- crash-4.0-8.10/ppc64.c.orig 2009-06-08 16:08:09.000000000 +0530
> +++ crash-4.0-8.10/ppc64.c 2009-06-09 15:45:39.000000000 +0530
> @@ -2407,13 +2407,16 @@ ppc64_paca_init(void)
> if (!symbol_exists("paca"))
> error(FATAL, "PPC64: Could not find 'paca' symbol\n");
>
> - if (cpu_map_addr("present"))
> + if (cpu_map_addr("possible"))
> + map = POSSIBLE;
> + else if (cpu_map_addr("present"))
> map = PRESENT;
> else if (cpu_map_addr("online"))
> map = ONLINE;
> else
> - error(FATAL,
> - "PPC64: cannot find 'cpu_present_map' or 'cpu_online_map'
> symbols\n");
> + error(FATAL,
> + "PPC64: cannot find 'cpu_possible_map' or\
> + 'cpu_present_map' or 'cpu_online_map' symbols\n");
>
> if (!MEMBER_EXISTS("paca_struct", "data_offset"))
> return;
> @@ -2423,8 +2426,8 @@ ppc64_paca_init(void)
>
> cpu_paca_buf = GETBUF(SIZE(ppc64_paca));
>
> - if (!(nr_paca = get_array_length("paca", NULL, 0)))
> - nr_paca = NR_CPUS;
> + if (!(nr_paca = get_array_length("paca", NULL, 0)))
> + nr_paca = (kt->kernel_NR_CPUS ? kt->kernel_NR_CPUS : NR_CPUS);
>
> if (nr_paca > NR_CPUS) {
> error(WARNING,
> @@ -2435,7 +2438,7 @@ ppc64_paca_init(void)
>
> for (i = cpus = 0; i < nr_paca; i++) {
> /*
> - * CPU present (or online)?
> + * CPU present or online or can exist in the system(possible)?
> */
> if (!in_cpu_map(map, i))
> continue;
> --- crash-4.0-8.10/kernel.c.orig 2009-06-08 16:07:53.000000000 +0530
> +++ crash-4.0-8.10/kernel.c 2009-06-09 15:01:51.000000000 +0530
> @@ -74,6 +74,9 @@ kernel_init()
>
> cpu_maps_init();
>
> + if (KDUMP_DUMPFILE())
> + map_cpu_prstatus();
> +
> kt->stext = symbol_value("_stext");
> kt->etext = symbol_value("_etext");
> get_text_init_space();
> --- crash-4.0-8.10/netdump.c.orig 2009-06-08 16:07:58.000000000 +0530
> +++ crash-4.0-8.10/netdump.c 2009-06-09 16:24:52.000000000 +0530
> @@ -45,6 +45,38 @@ static void check_dumpfile_size(char *);
> (machine_type("IA64") || machine_type("PPC64"))
>
> /*
> + * kdump installs NT_PRSTATUS elf notes only to the cpus
> + * that were online during dumping. Hence we call into
> + * this function after reading the cpu map from the kernel,
> + * to remap the NT_PRSTATUS notes only to the online cpus
> + */
> +void map_cpu_prstatus(void)
> +{
> + void *nt_ptr;
> + int i, j, nrcpus;
> +
> + /* temporary buffer to hold the prstatus_percpu array */
> + if ((nt_ptr = (void *)calloc(nd->num_prstatus_notes,
> + sizeof(void *))) == NULL)
> + error(FATAL,
> + "cannot allocate a buffer to hold prstatus_percpu array\n");
> +
> + memcpy((void *)nt_ptr, nd->nt_prstatus_percpu,
> + (nd->num_prstatus_notes * sizeof(void *)));
> + memset(nd->nt_prstatus_percpu, 0,
> + (nd->num_prstatus_notes * sizeof(void *)));
> +
> + nrcpus = (kt->kernel_NR_CPUS ? kt->kernel_NR_CPUS : NR_CPUS);
> +
> + /* re-populate the array with the notes mapping to online cpus */
> + for (i = 0, j = 0; i < nrcpus; i++)
> + if (in_cpu_map(ONLINE, i))
> + ((unsigned long *)nd->nt_prstatus_percpu)[i] =
> + ((unsigned long *)nt_ptr)[j++];
> + free(nt_ptr);
> +}
> +
> +/*
> * Determine whether a file is a netdump/diskdump/kdump creation,
> * and if TRUE, initialize the vmcore_data structure.
> */
> @@ -618,7 +650,7 @@ get_netdump_panic_task(void)
> crashing_cpu = -1;
> if (kernel_symbol_exists("crashing_cpu")) {
> get_symbol_data("crashing_cpu", sizeof(int), &i);
> - if ((i >= 0) && (i < nd->num_prstatus_notes)) {
> + if ((i >= 0) && in_cpu_map(ONLINE, i)) {
> crashing_cpu = i;
> if (CRASHDEBUG(1))
> error(INFO,
> @@ -2236,7 +2268,7 @@ get_netdump_regs_ppc64(struct bt_info *b
> * CPUs if they responded to an IPI.
> */
> if (nd->num_prstatus_notes > 1) {
> - if (bt->tc->processor >= nd->num_prstatus_notes)
> + if (!nd->nt_prstatus_percpu[bt->tc->processor])
> error(FATAL,
> "cannot determine NT_PRSTATUS ELF note "
> "for %s task: %lx\n",
--
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