On Wed, 2024-12-18 at 01:03 -0800, Josh Poimboeuf wrote: > On Tue, Dec 17, 2024 at 01:03:07PM +0100, David Woodhouse wrote: > > I've dropped this for now and just posted the __nocfi thing as the > > regression fix. I think we *should* provide the CFI information in > > relocate_kernel_64.S though, so I've left these commits in my tree at > > https://git.infradead.org/?p=users/dwmw2/linux.git;a=shortlog;h=refs/heads/kexec-debug > > > > I'd really appreciate some help in getting objtool to stop whining > > about them, for *both* Clang and GCC builds at the same time :) > > Hm, I can't fetch for some reason: > > $ git fetch https://git.infradead.org/users/dwmw2/linux.git kexec-debug > fatal: https://git.infradead.org/users/dwmw2/linux.git/info/refs not valid: could not determine hash algorithm; is this a git repository? > The https URL is just gitweb. You can fetch from git://git.infradead.org/users/dwmw2/linux.git > At some point we had discussed placing the code in .rodata, was it the > alternative preventing that? No, the alternative seems to be fine, and it's all in the .data section now (since the kernel does write some variables there which are then accessed %rip-relative from the code itself). The problem is when I use SYM_TYPED_FUNC_START for relocate_kernel itself, objtool starts to whine that the first instruction of relocate_kernel is unreachable (presumably) because it is never jumped to directly, but copied into the control page and then called via a calculated function pointer). There's also an objtool warning about loading the stack pointer. I seem to get different warnings from objtool for Clang and GCC builds, and can't find a set of hints which will make them both shut up at the same time.
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