ThunderX Panic after r368370

[Mark Millard]

On 2020-Dec-6, at 00:17, Michal Meloun <meloun.michal at gmail.com> wrote:

> On 06.12.2020 3:21, Marcel Flores wrote:
>> Hi All,
>> Looks like the ThunderX started panicking at boot after r368370:
>> https://reviews.freebsd.org/rS368370
>> From a verbose boot, it looks like it bails in gic0 redistributor setup(?):
>> gic0: CPU29 Re-Distributor woke up
>> gic0: CPU24 enabled CPU interface via system registers
>> gic0: CPU17 enabled CPU interface via system registers
>> gic0: CPU29 enabled CPU interface via system registers
>> done
>> Full Verbose boot:
>> https://gist.github.com/mesflores/f026122495c8494d041bce04d30b15bb
>> I'm not really familiar with the details of the commit, but happy to test
>> anything if anyone has any ideas.
> 
> 
> Hi Marcel
> are you able to get crashdump and do backtrace?
> https://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug.html#kerneldebug-obtain
> and
> https://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug-gdb.html
> If not, I'll make some debug patch.
> 
> It's weird, even though GIC is potentially affected by my patch, in this case the cpuid numbering was not changed.

(I've no access to a ThunderX. I just looked for my own curiosity.
Sorry if this is obvious and so is noise.)

When I looked at the code it appeared to be the last "->" in
the following that was dereferencing the nullptr value (via [x8]
in assembler notation):

static uint64_t
its_cmd_prepare(struct its_cmd *cmd, struct its_cmd_desc *desc)
{
        uint64_t target;
        uint8_t cmd_type;
        u_int size;

        cmd_type = desc->cmd_type;
        target = ITS_TARGET_NONE;

        switch (cmd_type) {
        case ITS_CMD_MOVI:      /* Move interrupt ID to another collection */
                target = desc->cmd_desc_movi.col->col_target;
. . .

In other words: it appeared to me that the above desc->cmd_desc_movi.col
evaluated as 0 when used in what was reported.

===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)