[Crash-utility] Question about ARM module address range
Hi guys,
While looking at the ARM per-cpu address range issue, I ran into
something re: the ARM module address range values that has me
confused.
In arm_init(), POST_VM, you've got:
machdep->machspec->modules_end = machdep->kvbase - 1;
But it never gets used, because here in arm_is_module_addr() the
local variable "module_end" is used instead -- although it is set
to the same value:
static int
arm_is_module_addr(ulong vaddr)
{
ulong modules_start;
ulong modules_end = machdep->kvbase - 1;
if (!MODULES_VADDR) {
/*
* In case we are still initializing, and vm_init() has not been
* called, we use defaults here which is 16MB below kernel start
* address.
*/
modules_start = machdep->kvbase - 16 * 1024 * 1024;
} else {
modules_start = MODULES_VADDR;
}
return (vaddr >= modules_start && vaddr <= modules_end);
}
and where MODULES_VADDR is #define'd as:
#define MODULES_VADDR (machdep->machspec->modules_vaddr)
So given that "modules_end" is set to "machdep->kvbase - 1", and
given the
output from "help -m" on the 3 sample ARM dumps I have:
2.6.35:
crash> help -m
...
kvbase: c0000000
...
vmalloc_start_addr: d0000000
modules_vaddr: d0807000
modules_end: bfffffff
kernel_text_start: c0008000
...
2.6.36:
crash> help -m
...
kvbase: c0000000
...
vmalloc_start_addr: c5800000
modules_vaddr: c6024000
modules_end: bfffffff
kernel_text_start: c0008000
2.6.38:
crash> help -m
...
kvbase: c0000000
...
vmalloc_start_addr: d0000000
modules_vaddr: d0807000
modules_end: bfffffff
kernel_text_start: c0008000
...
So given that "modules_end" is always below the kvbase (bfffffff),
then arm_is_module_addr() will always return FALSE -- except maybe
during pre-vm_init() time when the range is temporarily set to
be the "default range" between bf000000 and bfffffff. (and would
there *ever* be a module in that range?)
Anyway, although I don't think it's a problem, given that the
only caller of arm_is_module_addr() is arm_is_vmalloc_addr(),
and that function will fall through and still return TRUE if
it is a module address.
But it just looks strange, and at least it would seem that:
(1) the machdep->machspec->modules_end version should be used, and
(2) it should be updated post-vm_init() so that the arm_is_module_addr()
function actually works?
Or am I missing something?
Dave