On Mon, 15 Feb 2021 18:05:04 -0600 Josh Poimboeuf <jpoim...@redhat.com> wrote:
> On Mon, Feb 15, 2021 at 04:44:46PM -0500, Steven Rostedt wrote: > > From: "Steven Rostedt (VMware)" <rost...@goodmis.org> > > > > Starting with binutils 2.36, sections were being removed if they had weak > > functions that were optimized out. Unfortunately, these weak functions would > > leave references to mcount/fentry calls, that would make recordmcount fail > > to find the symbol that matched the call to fentry. > > Binutils 2.36 isn't removing sections, just section *symbols*. > > > Before returning the symbol of the section to create the mcount location, > > check if that section size is greater than zero. If it has no size, skip > > referencing that mcount call location. > > How does this even work? The .text.unlikely section isn't empty: > > # readelf -SW kernel/kexec_file.o Bah, because I messed up, and realized I was using the first section (shdr0) and not the one it was being used for. Strange, that when I applied this to the latest kernel on a my build system (binutils 2.35), it still created all the necessary mcount locations?? I'll look more into this. Thanks for pointing this out. -- Steve > > Section Headers: > [Nr] Name Type Address Off Size ES > Flg Lk Inf Al > [ 0] NULL 0000000000000000 000000 000000 00 > 0 0 0 > [ 1] .text PROGBITS 0000000000000000 000040 001acf 00 > AX 0 0 1 > [ 2] .rela.text RELA 0000000000000000 0049e0 001b30 18 > I 27 1 8 > [ 3] .data PROGBITS 0000000000000000 001b20 000e80 00 > WA 0 0 32 > [ 4] .rela.data RELA 0000000000000000 006510 0010e0 18 > I 27 3 8 > [ 5] .bss NOBITS 0000000000000000 0029a0 000060 00 > WA 0 0 32 > [ 6] .rodata PROGBITS 0000000000000000 0029a0 000b80 00 > A 0 0 32 > [ 7] .rodata.str1.1 PROGBITS 0000000000000000 003520 0001c6 01 > AMS 0 0 1 > [ 8] .text.unlikely PROGBITS 0000000000000000 0036e6 000038 00 > AX 0 0 1 >
