[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v4 2/2] livepatch: set -f{function,data}-sections compiler option
On 09.03.2022 13:28, Roger Pau Monne wrote: > If livepatching support is enabled build the hypervisor with > -f{function,data}-sections compiler options, which is required by the > livepatching tools to detect changes and create livepatches. > > This shouldn't result in any functional change on the hypervisor > binary image, but does however require some changes in the linker > script in order to handle that each function and data item will now be > placed into its own section in object files. As a result add catch-all > for .text, .data and .bss in order to merge each individual item > section into the final image. > > The main difference will be that .text.startup will end up being part > of .text rather than .init, and thus won't be freed. .text.exit will > also be part of .text rather than dropped. Overall this could make the > image bigger, and package some .text code in a sub-optimal way. > > On Arm the .data.read_mostly needs to be moved ahead of the .data > section like it's already done on x86, so the .data.* catch-all > doesn't also include .data.read_mostly. The alignment of > .data.read_mostly also needs to be set to PAGE_SIZE so it doesn't end > up being placed at the tail of a read-only page from the previous > section. While there move the alignment of the .data section ahead of > the section declaration, like it's done for other sections. > > The benefit of having CONFIG_LIVEPATCH enable those compiler option > is that the livepatch build tools no longer need to fiddle with the > build system in order to enable them. Note the current livepatch tools > are broken after the recent build changes due to the way they > attempt to set -f{function,data}-sections. > > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> > Acked-by: Julien Grall <jgrall@xxxxxxxxxx> # xen/arm Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
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