On Thu, 21 Jan 2016 14:55:00 -0800 Kees Cook <keescook@xxxxxxxxxxxx> wrote: > IIUC, this means that the relocation work done after decompression now > doesn't have to do relocation updates for all these values, which > means a smaller relocation table as well. Makes sense, thanks. I altered the changelog : Similar to how relative extables are implemented, it is possible to : emit the kallsyms table in such a way that it contains offsets relative : to some anchor point in the kernel image rather than absolute : addresses. : : The benefit is that such table entries are no longer subject to dynamic : relocation when the build time so the relocation work done after : decompression now doesn't have to do relocation updates for all these : values, which means a smaller relocation table as well. : : Also, the runtime offsets of the kernel image are different. Also, on : 64-bit architectures, it essentially cuts the size of the address table : in half since offsets can typically be expressed in 32 bits. : : Since it is useful for some architectures (like x86) to retain the ability : to emit absolute values as well, this patch adds support for both, by : emitting absolute addresses as positive 32-bit values, and addresses : relative to the lowest encountered relative symbol as negative values, : which are subtracted from the runtime address of this base symbol to : produce the actual address. : : Support for the above is enabled by default for all architectures except : IA-64, whose symbols are too far apart to capture in this manner. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
