linux-toradex.git/arch/powerpc/relocs_check.pl, branch v3.2.26 Linux kernel for Apalis and Colibri modules powerpc: Check for unsupported relocs when using CONFIG_RELOCATABLE 2009-09-24T05:31:40+00:00 Tony Breeds tony@bakeyournoodle.com 2009-09-14T19:57:02+00:00 144ef909c09b60c97b3c20b69ea30abd1e60e54d When using CONFIG_RELOCATABLE, we build the kernel as a position independent executable. The kernel then uses a little bit of relocation code to relocate itself. That code only deals with R_PPC64_RELATIVE relocations though. If for some reason you use assembly constructs such as LOAD_REG_IMMEDIATE() to load the address of a symbol, you'll generate different kinds of relocations that won't be processed properly and bad things will happen. (We have 2 such bugs today). The perl script tries to filter out "known" bad ones. It's possible that we are missing some in the case of a weak function that nobody implements, we'll see if we get false positive and fix it. Signed-off-by: Tony Breeds <tony@bakeyournoodle.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
When using CONFIG_RELOCATABLE, we build the kernel as a position
independent executable. The kernel then uses a little bit of relocation
code to relocate itself. That code only deals with R_PPC64_RELATIVE
relocations though. If for some reason you use assembly constructs
such as LOAD_REG_IMMEDIATE() to load the address of a symbol, you'll
generate different kinds of relocations that won't be processed properly
and bad things will happen. (We have 2 such bugs today).

The perl script tries to filter out "known" bad ones. It's possible
that we are missing some in the case of a weak function that nobody
implements, we'll see if we get false positive and fix it.

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>