Re: [FYI] objtool: .export_symbol…: data relocation to !ENDBR: stpcpy

[Peter Zijlstra]

On Thu, Aug 01, 2024 at 05:28:36PM +0200, Sebastian Andrzej Siewior wrote:
> Hi,
> 
> defconfig on x86-64 with gcc-14 I get this:
> | vmlinux.o: warning: objtool: .export_symbol+0x26980: data relocation to !ENDBR: stpcpy+0x0
> 
> objdump ->
> 
> | 0000000000000110 <stpcpy>:
> |  110:   66 66 2e 0f 1f 84 00    data16 cs nopw 0x0(%rax,%rax,1)
> |  117:   00 00 00 00 
> |  11b:   0f 1f 44 00 00          nopl   0x0(%rax,%rax,1)
> |  120:   f3 0f 1e fa             endbr64
> 
> okay, no endbr64 on entry label.
> 
> | $ make lib/string.s
> ->
> |         .type   stpcpy, @function
> | stpcpy:
> |         .p2align 5
> |         endbr64
> | .L30:
> | # lib/string.c:193:  while ((*dest++ = *src++) != '\0')
> |         movzbl  (%rsi), %eax    # MEM[(const char *)src_8 + -1B], _1
> 
> an alignment request after the function label before endbr64 which gets
> expanded into NOP_11+NOP_5.
> I don't see this with gcc-13.
> Reported as https://gcc.gnu.org/PR116174

Fun, thanks for tracking that down!