When building the x86_64 gdbidt with newer gcc it fails recognizing the segment registers FS/GS being too short for pushq/popq. arch/x86_64/core/gdbidt.S:109: Error: operand type mismatch for `push' arch/x86_64/core/gdbidt.S:110: Error: operand type mismatch for `push' arch/x86_64/core/gdbidt.S:161: Error: operand type mismatch for `pop' arch/x86_64/core/gdbidt.S:162: Error: operand type mismatch for `pop'
It seems gcc considers the segment registers as 16 bit, so we'd have to use pushw/popw and fill the rest with zeros as gdb expects no change in size. I failed to find a trustworthy resource clearly stating the how the sizes of GS/FS are in .code64 as in src/arch/x86_64/core/gdbidt.S so I'm unsure. But I fixed the build assuming it would stay 16, so it might be enough to start the discussion with it. Yet OTOH we already have pushw $0; pushw %gs (safe with zeroes in between) in src/arch/i386/core/gdbidt.S restored by non 16bit popl. Why doesn't that break on the same size check at least for the popl? Might it be a false detection in gcc (actually as)? References: - full failing build log https://launchpadlibrarian.net/441262285/buildlog_ubuntu-eoan-amd64.ipxe_1.0.0+git-20190109.133f4c4-0ubuntu2_BUILDING.txt.gz - Ubuntu bug https://bugs.launchpad.net/ubuntu/+source/ipxe/+bug/1843394 Signed-off-by: Christian Ehrhardt <christian.ehrha...@canonical.com> --- src/arch/x86_64/core/gdbidt.S | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/src/arch/x86_64/core/gdbidt.S b/src/arch/x86_64/core/gdbidt.S index 89280bf8..ac5b9e86 100644 --- a/src/arch/x86_64/core/gdbidt.S +++ b/src/arch/x86_64/core/gdbidt.S @@ -106,8 +106,14 @@ gdbmach_sigill: gdbmach_interrupt: /* Create register dump */ - pushq %gs - pushq %fs + pushw $0 + pushw $0 + pushw $0 + pushw %gs + pushw $0 + pushw $0 + pushw $0 + pushw %fs pushq $0 /* %es unused in long mode */ pushq $0 /* %ds unused in long mode */ pushq ( frame_ss - regs_ss - SIZEOF_REG )(%rsp) @@ -158,8 +164,10 @@ gdbmach_interrupt: popq ( frame_cs - regs_cs - SIZEOF_REG )(%rsp) popq ( frame_ss - regs_ss - SIZEOF_REG )(%rsp) addq $( regs_fs - regs_ds ), %rsp /* skip %ds, %es */ - popq %fs - popq %gs + popw %fs + add %rsp,6 + popw %gs + add %rsp,6 /* Skip code */ addq $( gdb_end - gdb_code ), %rsp /* skip code */ -- 2.23.0 _______________________________________________ ipxe-devel mailing list ipxe-devel@lists.ipxe.org https://lists.ipxe.org/mailman/listinfo.cgi/ipxe-devel
