On Wed, May 18, 2022 at 05:24:45AM -0500, Dullfire wrote: > > > It appears that binutils as for sparc(64) is emitting incorrect relocations > for some case of 'setx' > for example > ``` > > > % echo 'setx _data, %g7, %g4' | sparc64-misc-linux-gnu-as -KPIC -o > /tmp/test-sparc64.o > > % sparc64-misc-linux-gnu-objdump -rD /tmp/test-sparc64.o > > > > /tmp/test-sparc64.o: file format elf64-sparc > > > > > > Disassembly of section .text: > > > > 0000000000000000 <.text>: > > 0: 0f 00 00 00 sethi %hi(0), %g7 > > 0: R_SPARC_HH22 _data > > 4: 09 00 00 00 sethi %hi(0), %g4 > > 4: R_SPARC_LM22 _data > > 8: 8e 11 e0 00 mov %g7, %g7 > > 8: R_SPARC_HM10 _data > > c: 88 11 20 00 mov %g4, %g4 > > c: R_SPARC_GOT10 _data > > 10: 8f 29 f0 20 sllx %g7, 0x20, %g7 > > 14: 88 11 00 07 or %g4, %g7, %g4 > > > ``` > This relocation set will give bits [63:10] of the symbol address, and > bits[9:0] of the got entry. Which is probably never the desired result. > I have observed this on both 2.37 and > master(85aaf32e610e01ccde008e5bbfd6df95558dbeae).
Yes, the GOT10 reloc is due to the BFD_RELOC_LO10 emitted by gas/config/tc-sparc.c:synthetize_setx being converted in tc_gen_reloc. That's not the only problem. The relocs emitted in synthetize_setx will cause text relocations in a dynamic library or PIE. So it looks to me that setx with a non-constant value when PIC is simply unsupported. I'd encourage you to post a patch to binut...@sourceware.org fixing the problem, or at least emitting an error rather than bad code. -- Alan Modra Australia Development Lab, IBM
