amd64 kernel modules: mapping sections to addresses
avg at freebsd.org
Mon Jun 21 14:39:12 UTC 2010
I've noticed that on amd64 addresses (sh_addr) of all sections in a kernel module
This is unlike kernel itself and i386 modules.
Kernel linker maps SHT_PROGBITS and SHT_NOBITS sections sequentially starting at a
certain base address and taking into account their sizes and alignment requirements.
On the other hand, kgdb calculates section address as module base address plus
sh_addr of the section. Which puts all sections, e.g. .text, .data, .bss, at the
same address. This is correct only for .text which is normally the first section
described in a header.
DTrace situation is even worse, because don't even take into account module base
address, not speaking of section relative addresses.
Perhaps we should put some sh_addr values into amd64 kernel modules that would
match calculations done in link_elf_load_file.
Or should we replicate logic from link_elf_load_file in all places that need to
map loaded module's sections to load addresses?
What do you think?
As I understand CTF data includes a symbol table.
What kind of symbol addresses is used there? Are they relative within a
corresponding section? Or something else?
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