https://sourceware.org/bugzilla/show_bug.cgi?id=18010
--- Comment #1 from Alan Modra <amodra at gmail dot com> ---
We have a bunch of strings in a string merge section
.section .rodata.str1.8,"aMS",@progbits,1
all nicely aligned to 8 byte boundaries (as you'd expect from the .8 in the
name). Somehow the alignment isn't respected and we end up with misaligned
strings. Since a powerpc64 ld reg+offset form address must be a multiple of 4,
we lose low bits of the address.
This is the code reading the " break;\n" string. .LC84 happens to be
defined at .rodata.str1.8+0x570.
1d50: 3d 02 00 00 addis r8,r2,0
1d52: R_PPC64_TOC16_HA .LC84+0x8
1d54: 80 e8 00 00 lwz r7,0(r8)
1d56: R_PPC64_TOC16_LO .LC84+0x8
1d58: 3d 02 00 00 addis r8,r2,0
1d5a: R_PPC64_TOC16_HA .LC84+0xc
1d5c: 89 28 00 00 lbz r9,0(r8)
1d5e: R_PPC64_TOC16_LO .LC84+0xc
1d60: 3d 02 00 00 addis r8,r2,0
1d62: R_PPC64_TOC16_HA .rodata.str1.8+0x570
1d64: 90 ea 00 08 stw r7,8(r10)
1d68: 99 2a 00 0c stb r9,12(r10)
1d6c: e9 28 00 00 ld r9,0(r8)
1d6e: R_PPC64_TOC16_LO_DS .rodata.str1.8+0x570
This is linked to
100fdad0: 3d 02 ff fb addis r8,r2,-5
100fdad4: 80 e8 7b 22 lwz r7,31522(r8)
100fdad8: 3d 02 ff fb addis r8,r2,-5
100fdadc: 89 28 7b 26 lbz r9,31526(r8)
100fdae0: 3d 02 ff fb addis r8,r2,-5
100fdae4: 90 ea 00 08 stw r7,8(r10)
100fdae8: 99 2a 00 0c stb r9,12(r10)
100fdaec: e9 28 7b 18 ld r9,31512(r8)
For starters, I'll be committing a patch that makes gold complain if LO_DS
relocs attempt to apply a misaligned value.
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