[BUG REPORT] kexec and makedumpfile can't detect PAGE_OFFSET on arm (Wang Nan)

[Dave Anderson]

----- Original Message -----
> 
> On 2014/5/20 3:41, Dave Anderson wrote:
> > 
> > 
> > ----- Original Message -----
> >>
> >> Hi Atsushi and Simon,
> >>
> >> I find a problem about VMSPLIT on arm plarform, related to kexec and
> >> makedumpfile.
> >>
> >> When CONFIG_VMSPLIT_1G/2G is selected by kernel, PAGE_OFFSET is actually
> >> 0x40000000 or 0x80000000. However, kexec hard codes PAGE_OFFSET to
> >> 0xc0000000 (in kexec/arch/arm/crashdump-arm.h), which is incorrect in
> >> these situations. For example, on realview-pbx board with 1G/3G VMSPLIT,
> >> PHDRs in generated /proc/vmcore is as follow:
> >>
> >>   Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
> >>   NOTE           0x001000 0x00000000 0x00000000 0x00690 0x00690     0
> >>   LOAD           0x002000 0xc0000000 0x00000000 0x10000000 0x10000000 RWE
> >>   0
> >>   LOAD           0x10002000 0xe0000000 0x20000000 0x8000000 0x8000000 RWE
> >>   0
> >>   LOAD           0x18002000 0xf0000000 0x30000000 0x10000000 0x10000000
> >>   RWE 0
> >>   LOAD           0x28002000 0x40000000 0x80000000 0x10000000 0x10000000
> >>   RWE 0
> >>
> >> Which should be:
> >>
> >>   Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
> >>   ...
> >>   LOAD            ...     0x40000000 0x00000000 0x10000000 0x10000000 RWE
> >>   0
> >>   LOAD            ...     0x60000000 0x20000000 0x8000000 0x8000000 RWE 0
> >>   LOAD            ...     0x70000000 0x30000000 0x10000000 0x10000000 RWE
> >>   0
> >>   LOAD            ...     0xc0000000 0x80000000 0x10000000 0x10000000 RWE
> >>   0
> >>
> >> I don't know why crash utility can deal with it without problem,
> > 
> > For ARM the crash utility masks the symbol value of "_stext" with 0x1fffffff
> > to determine the PAGE_OFFSET value, which was basically copied from the way
> > it was done for i386.
> > 
> 
> kexec-tools can do the same thing by reading /proc/kallsyms (crashdump-x86.c has already done this).
> However, KALLSYMS and KALLSYMS_ALL are turned off on some embedded systems with memory limitation,
> which is common on ARM.

But you could use VMCOREINFO_SYMBOL(_stext), right?

Dave