The following commit has been merged into the x86/core branch of tip: Commit-ID: 73e8079be9e7ae5ed197d074e0ba6c43674c52f7 Gitweb: https://git.kernel.org/tip/73e8079be9e7ae5ed197d074e0ba6c43674c52f7 Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Mon, 03 Mar 2025 10:21:47 +01:00 Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx> CommitterDate: Mon, 03 Mar 2025 10:54:11 +01:00 x86/ibt: Make cfi_bhi a constant for FINEIBT_BHI=n Robot yielded a .config that tripped: vmlinux.o: warning: objtool: do_jit+0x276: relocation to !ENDBR: .noinstr.text+0x6a60 This is the result of using __bhi_args[1] in unreachable code; make sure the compiler is able to determine this is unreachable and trigger DCE. Closes: https://lore.kernel.org/oe-kbuild-all/202503030704.H9KFysNS-lkp@xxxxxxxxx/ Reported-by: kernel test robot <lkp@xxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Link: https://lkml.kernel.org/r/20250303094911.GL5880@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx --- arch/x86/include/asm/cfi.h | 5 +++++ arch/x86/kernel/alternative.c | 7 +++++++ 2 files changed, 12 insertions(+) diff --git a/arch/x86/include/asm/cfi.h b/arch/x86/include/asm/cfi.h index 2f6a01f..3e51ba4 100644 --- a/arch/x86/include/asm/cfi.h +++ b/arch/x86/include/asm/cfi.h @@ -100,7 +100,12 @@ enum cfi_mode { }; extern enum cfi_mode cfi_mode; + +#ifdef CONFIG_FINEIBT_BHI extern bool cfi_bhi; +#else +#define cfi_bhi (0) +#endif typedef u8 bhi_thunk[32]; extern bhi_thunk __bhi_args[]; diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 32e4b80..bf82c6f 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -936,7 +936,10 @@ void __init_or_module apply_seal_endbr(s32 *start, s32 *end) { } #endif enum cfi_mode cfi_mode __ro_after_init = __CFI_DEFAULT; + +#ifdef CONFIG_FINEIBT_BHI bool cfi_bhi __ro_after_init = false; +#endif #ifdef CONFIG_CFI_CLANG struct bpf_insn; @@ -1070,11 +1073,15 @@ static __init int cfi_parse_cmdline(char *str) pr_err("Ignoring paranoid; depends on fineibt.\n"); } } else if (!strcmp(str, "bhi")) { +#ifdef CONFIG_FINEIBT_BHI if (cfi_mode == CFI_FINEIBT) { cfi_bhi = true; } else { pr_err("Ignoring bhi; depends on fineibt.\n"); } +#else + pr_err("Ignoring bhi; depends on FINEIBT_BHI=y.\n"); +#endif } else { pr_err("Ignoring unknown cfi option (%s).", str); }
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