On Fri, 2025-03-14 at 09:07 -0700, Josh Poimboeuf wrote: > On Wed, Mar 12, 2025 at 02:34:20PM +0000, David Woodhouse wrote: > > From: David Woodhouse <d...@amazon.co.uk> > > > > A previous commit added __nocfi to machine_kexec() because it makes an > > indirect call to relocate_kernel() which lacked CFI type information, > > and caused the system to crash. > > > > Use SYM_TYPED_FUNC_START() to ensure that the type information is > > present, and remove the __nocfi tag. > > > > I still can't make objtool happy with this in both GCC and Clang builds > > at the same time, so not yet for merging; only included in this series > > to nerd-snipe the objtool maintainers. > > Again, I'd recommend just compiling the code in .data..relocate_kernel. > Then objtool doesn't need to care. > > Otherwise it would help to know what warnings you're getting with this > patch, and the corresponding .config.
ISTR this version is OK with Clang and CONFIG_CFI_CLANG but with GCC I
get this:
vmlinux.o: warning: objtool: relocate_kernel+0x69: unsupported stack register
modification
/* setup a new stack at the end of the physical control page */
lea PAGE_SIZE(%rsi), %rsp
79: 48 8d a6 00 10 00 00 lea 0x1000(%rsi),%rsp
Maybe the answer is to put the UNWIND_HINT_FUNC into #ifdef
CONFIG_CFI_CLANG but that seems wrong.
I'll have another look at putting it in the data section, and see if I
can remember why I didn't want to do that before (and if that's still
relevant now).
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