When a module has relocation sections with tens of thousands of
entries, counting the distinct/unique entries only (i.e. no
duplicates) at load time can take tens of seconds and up to minutes.
The sore point is the count_relocs() function which is called as part
of the architecture specific module loading processing path:
-> load_module() generic
-> module_frob_arch_sections() arch specific
-> get_plt_size() 32-bit
-> get_stubs_size() 64-bit
-> count_relocs()
Here count_relocs is being called to find out how many distinct
targets of R_PPC_REL24 relocations there are, since each distinct
target needs a PLT entry or a stub created for it.
The previous counting algorithm has O(n^2) complexity. Basically two
solutions were proposed on the e-mail list: a hash based approach and
a sort based approach.
The hash based approach is the fastest (O(n)) but the has it needs
additional memory and for certain corner cases it could take lots of
memory due to the degeneration of the hash. One such proposal was
submitted here:
http://ozlabs.org/pipermail/linuxppc-dev/2007-June/037641.html
The sort based approach is slower (O(n * log n + n)) but if the
sorting is done "in place" it doesn't need additional memory.
This has O(n + n * log n) complexity with no additional memory
requirements.
This commit implements the in-place sort option.
Signed-off-by: Emil Medve <Emilian.Medve@Freescale.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This makes powerpc use the generic BUG machinery. The biggest reports the
function name, since it is redundant with kallsyms, and not needed in general.
There is an overall reduction of code, since module_32/64 duplicated several
functions.
Unfortunately there's no way to tell gcc that BUG won't return, so the BUG
macro includes a goto loop. This will generate a real jmp instruction, which
is never used.
[akpm@osdl.org: build fix]
[paulus@samba.org: remove infinite loop in BUG_ON]
Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Andi Kleen <ak@muc.de>
Cc: Hugh Dickens <hugh@veritas.com>
Cc: Michael Ellerman <michael@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This patch adds support for feature fixups in modules. This involves
adding support for R_PPC64_REL64 relocs to the 64 bits module loader.
It also modifies modpost.c to ignore the powerpc fixup sections (or it
would warn when used in .init.text).
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Normally, ppc64 module .ko files contain a table-of-contents (.toc)
section, but if the module doesn't reference any static or external
data or external procedures, it is possible for gcc/binutils to
generate a .ko that doesn't have a .toc. Currently the module
loader refuses to load such a module, since it needs the address
of the .toc section to use in relocations.
This patch fixes the problem by using the address of the .stubs
section instead, which is an acceptable substitute in this situation.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Also deletes files in arch/ppc64 that are no longer used now that
we don't compile with ARCH=ppc64 any more.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Emil Medve