On Tue, Apr 20, 2021 at 11:14 AM Josh Poimboeuf <jpoim...@redhat.com> wrote:
>
> On Fri, Apr 16, 2021 at 01:38:30PM -0700, Sami Tolvanen wrote:
> > With -ffunction-sections, Clang can generate a jump beyond the end of
> > a section when the section ends in an unreachable instruction.
>
> Why? Can you show an example?
Here's the warning I'm seeing when building allyesconfig + CFI:
vmlinux.o: warning: objtool:
rockchip_spi_transfer_one.f088382d97b74759d70e27e891fe8f1c()+0x149:
can't find jump dest instruction at
.text.rockchip_spi_transfer_one.f088382d97b74759d70e27e891fe8f1c+0x7dc
$ objdump -d -r -j
.text.rockchip_spi_transfer_one.f088382d97b74759d70e27e891fe8f1c
vmlinux.o
0000000000000000 <rockchip_spi_transfer_one.f088382d97b74759d70e27e891fe8f1c>:
...
149: 0f 85 8d 06 00 00 jne 7dc <.compoundliteral.4>
...
7d7: e8 00 00 00 00 callq 7dc <.compoundliteral.4>
7d8: R_X86_64_PLT32 __stack_chk_fail-0x4
Sami
