[PATCH v12 03/12] x86/bhi: Rename clear_bhb_loop() to clear_bhb_loop_nofence()
From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Date: 2026-06-23 17:33:24
Also in:
bpf, kvm, linux-doc, lkml
Subsystem:
bpf jit for x86 64-bit, bpf [general] (safe dynamic programs and tools), the rest, x86 architecture (32-bit and 64-bit), x86 entry code, x86 hardware vulnerabilities · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski, Peter Zijlstra, Josh Poimboeuf
To reflect the recent change that moved LFENCE to the caller side. Suggested-by: Borislav Petkov <bp@alien8.de> Reviewed-by: Nikolay Borisov <redacted> Tested-by: Jon Kohler <redacted> Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com> --- arch/x86/entry/entry_64.S | 8 ++++---- arch/x86/include/asm/nospec-branch.h | 6 +++--- arch/x86/net/bpf_jit_comp.c | 2 +- 3 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index bbd4b1c7ec04..1f56d086d312 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S@@ -1532,7 +1532,7 @@ SYM_CODE_END(rewind_stack_and_make_dead) * Note, callers should use a speculation barrier like LFENCE immediately after * a call to this function to ensure BHB is cleared before indirect branches. */ -SYM_FUNC_START(clear_bhb_loop) +SYM_FUNC_START(clear_bhb_loop_nofence) ANNOTATE_NOENDBR push %rbp mov %rsp, %rbp
@@ -1570,6 +1570,6 @@ SYM_FUNC_START(clear_bhb_loop) 5: pop %rbp RET -SYM_FUNC_END(clear_bhb_loop) -EXPORT_SYMBOL_FOR_KVM(clear_bhb_loop) -STACK_FRAME_NON_STANDARD(clear_bhb_loop) +SYM_FUNC_END(clear_bhb_loop_nofence) +EXPORT_SYMBOL_FOR_KVM(clear_bhb_loop_nofence) +STACK_FRAME_NON_STANDARD(clear_bhb_loop_nofence)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 87b83ae7c97f..157eb69c7f0f 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h@@ -331,11 +331,11 @@ #ifdef CONFIG_X86_64 .macro CLEAR_BRANCH_HISTORY - ALTERNATIVE "", "call clear_bhb_loop; lfence", X86_FEATURE_CLEAR_BHB_LOOP + ALTERNATIVE "", "call clear_bhb_loop_nofence; lfence", X86_FEATURE_CLEAR_BHB_LOOP .endm .macro CLEAR_BRANCH_HISTORY_VMEXIT - ALTERNATIVE "", "call clear_bhb_loop; lfence", X86_FEATURE_CLEAR_BHB_VMEXIT + ALTERNATIVE "", "call clear_bhb_loop_nofence; lfence", X86_FEATURE_CLEAR_BHB_VMEXIT .endm #else #define CLEAR_BRANCH_HISTORY
@@ -389,7 +389,7 @@ extern void entry_untrain_ret(void); extern void write_ibpb(void); #ifdef CONFIG_X86_64 -extern void clear_bhb_loop(void); +extern void clear_bhb_loop_nofence(void); #endif extern void (*x86_return_thunk)(void);
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index f58ff2891d7d..e6d17eb4d949 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c@@ -1619,7 +1619,7 @@ static int emit_spectre_bhb_barrier(u8 **pprog, u8 *ip, EMIT1(0x51); /* push rcx */ ip += 2; - func = (u8 *)clear_bhb_loop; + func = (u8 *)clear_bhb_loop_nofence; ip += x86_call_depth_emit_accounting(&prog, func, ip); if (emit_call(&prog, func, ip))
--
2.34.1