Changes in Makefile

1105ab42 - x86/sev: Disable jump tables in SEV startup code

Mon, 27 Jan 2025 11:43:37 +0000

x86/sev: Disable jump tables in SEV startup codeWhen retpolines and IBT are both disabled, the compiler is free to usejump tables to optimize switch instructions. However, these are emittedby Clang as absolute references into .rodata: jmp *-0x7dfffe90(,%r9,8) R_X86_64_32S .rodata+0x170Given that this code will execute before that address in .rodata has evenbeen mapped, it is guaranteed to crash a SEV-SNP guest in a way that isdifficult to diagnose.So disable jump tables when building this code. It would be better if wecould attach this annotation to the __head macro but this appears to beimpossible.Reported-by: Linus Torvalds Tested-by: Linus Torvalds Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20250127114334.1045857-6-ardb+git@google.com List of files: /linux-6.15/arch/x86/coco/sev/Makefile

99b863d2 - x86/sev: Disable UBSAN on SEV code that may execute very early

Wed, 01 Jan 2025 11:51:20 +0000

x86/sev: Disable UBSAN on SEV code that may execute very earlyClang 14 and older may emit UBSAN instrumentation into code that isinlined into functions marked with __no_sanitize_undefined¹. This mayresult in faults when the code is executed very early, which may be thecase for functions annotated as __head. Now that this requirement isstrictly enforced, the build will fail in this case with the followingmessage Absolute reference to symbol '.data' not permitted in .head.textWork around this by disabling UBSAN instrumentation on all SEV corecode.¹ https://lore.kernel.org/r/20250101024348.GA1828419@ax162 [ bp: Add a footnote with Nathan's detailed explanation and a Fixes tag ]Fixes: 3b6f99a94b04 ("x86/boot: Disable UBSAN in early boot code")Signed-off-by: Ard Biesheuvel Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Nathan Chancellor Link: https://lore.kernel.org/r/20250101115119.114584-2-ardb@kernel.org List of files: /linux-6.15/arch/x86/coco/sev/Makefile

38918e0b - x86/sev: Move SEV compilation units

Wed, 19 Jun 2024 09:03:16 +0000

x86/sev: Move SEV compilation unitsA long time ago it was agreed upon that the coco stuff needs to go whereit belongs: https://lore.kernel.org/all/Yg5nh1RknPRwIrb8@zn.tnicand not keep it in arch/x86/kernel. TDX did that and SEV can't find timeto do so. So lemme do it. If people have trouble converting theirongoing featuritis patches, ask me for a sed script.No functional changes.Move the instrumentation exclusion bits too, as helpfully caught andreported by the 0day folks.Closes: https://lore.kernel.org/oe-kbuild-all/202406220748.hG3qlmDx-lkp@intel.comReported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202407091342.46d7dbb-oliver.sang@intel.comReported-by: kernel test robot Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Nikunj A Dadhania Reviewed-by: Ashish Kalra Tested-by: kernel test robot Link: https://lore.kernel.org/r/20240619093014.17962-1-bp@kernel.org List of files: /linux-6.15/arch/x86/coco/sev/Makefile