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);
}
|