vmcore-dmesg: Determine correct machine pointer size

A 32bit arch can prepare ELF64 headers. For example for PAE case to
preresent file offsets 64bit but data size at the offset still remains
32bit. If we just base our decision based on EI_CLASS, then we will try
to read 64bit data from file and can run into various issues.

We ran into following issue when we tried to run vmcore-dmesg on a 32bit
PAE system vmcore which had 64bit elf headers.

No program header covering vaddr 0xc0a6a688c0b89100found kexec bug?

Basically we try to read value of log_buf variable from address
log_buf_vaddr. We read in 64bit value and then pass that value again
to vaddr_to_offset() in an attempt to get to actual log_buf start
and get error message.

So determine the machine pointer size based on ELF class and arch and read
the bytes from file accordingly.

v2: Fixed the code as per suggestion from Eric.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Simon Horman <horms@verge.net.au>

0 files changed, 0 insertions, 0 deletions