On Mon, Feb 15, 2021 at 04:44:46PM -0500, Steven Rostedt wrote:
> From: "Steven Rostedt (VMware)" <[email protected]>
>
> 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
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
--
Josh
