From: Josh Poimboeuf <jpoimboe@kernel.org>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org, amit@kernel.org,
kvm@vger.kernel.org, amit.shah@amd.com, thomas.lendacky@amd.com,
bp@alien8.de, tglx@linutronix.de, peterz@infradead.org,
pawan.kumar.gupta@linux.intel.com, corbet@lwn.net,
mingo@redhat.com, dave.hansen@linux.intel.com, hpa@zytor.com,
seanjc@google.com, pbonzini@redhat.com,
daniel.sneddon@linux.intel.com, kai.huang@intel.com,
sandipan.das@amd.com, boris.ostrovsky@oracle.com,
Babu.Moger@amd.com, david.kaplan@amd.com, dwmw@amazon.co.uk,
andrew.cooper3@citrix.com
Subject: [PATCH v3 1/6] x86/bugs: Rename entry_ibpb()
Date: Wed, 2 Apr 2025 11:19:18 -0700 [thread overview]
Message-ID: <a3ce1558b68a64f52ea56000f2bbdfd6e7799258.1743617897.git.jpoimboe@kernel.org> (raw)
In-Reply-To: <cover.1743617897.git.jpoimboe@kernel.org>
There's nothing entry-specific about entry_ibpb(). In preparation for
calling it from elsewhere, rename it to __write_ibpb().
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/x86/entry/entry.S | 7 ++++---
arch/x86/include/asm/nospec-branch.h | 6 +++---
arch/x86/kernel/cpu/bugs.c | 6 +++---
3 files changed, 10 insertions(+), 9 deletions(-)
diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S
index d3caa31240ed..3a53319988b9 100644
--- a/arch/x86/entry/entry.S
+++ b/arch/x86/entry/entry.S
@@ -17,7 +17,8 @@
.pushsection .noinstr.text, "ax"
-SYM_FUNC_START(entry_ibpb)
+// Clobbers AX, CX, DX
+SYM_FUNC_START(__write_ibpb)
ANNOTATE_NOENDBR
movl $MSR_IA32_PRED_CMD, %ecx
movl $PRED_CMD_IBPB, %eax
@@ -27,9 +28,9 @@ SYM_FUNC_START(entry_ibpb)
/* Make sure IBPB clears return stack preductions too. */
FILL_RETURN_BUFFER %rax, RSB_CLEAR_LOOPS, X86_BUG_IBPB_NO_RET
RET
-SYM_FUNC_END(entry_ibpb)
+SYM_FUNC_END(__write_ibpb)
/* For KVM */
-EXPORT_SYMBOL_GPL(entry_ibpb);
+EXPORT_SYMBOL_GPL(__write_ibpb);
.popsection
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 8a5cc8e70439..bbac79cad04c 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -269,7 +269,7 @@
* typically has NO_MELTDOWN).
*
* While retbleed_untrain_ret() doesn't clobber anything but requires stack,
- * entry_ibpb() will clobber AX, CX, DX.
+ * __write_ibpb() will clobber AX, CX, DX.
*
* As such, this must be placed after every *SWITCH_TO_KERNEL_CR3 at a point
* where we have a stack but before any RET instruction.
@@ -279,7 +279,7 @@
VALIDATE_UNRET_END
CALL_UNTRAIN_RET
ALTERNATIVE_2 "", \
- "call entry_ibpb", \ibpb_feature, \
+ "call __write_ibpb", \ibpb_feature, \
__stringify(\call_depth_insns), X86_FEATURE_CALL_DEPTH
#endif
.endm
@@ -368,7 +368,7 @@ extern void srso_return_thunk(void);
extern void srso_alias_return_thunk(void);
extern void entry_untrain_ret(void);
-extern void entry_ibpb(void);
+extern void __write_ibpb(void);
#ifdef CONFIG_X86_64
extern void clear_bhb_loop(void);
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 4386aa6c69e1..310cb3f7139c 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1142,7 +1142,7 @@ static void __init retbleed_select_mitigation(void)
setup_clear_cpu_cap(X86_FEATURE_RETHUNK);
/*
- * There is no need for RSB filling: entry_ibpb() ensures
+ * There is no need for RSB filling: __write_ibpb() ensures
* all predictions, including the RSB, are invalidated,
* regardless of IBPB implementation.
*/
@@ -2676,7 +2676,7 @@ static void __init srso_select_mitigation(void)
setup_clear_cpu_cap(X86_FEATURE_RETHUNK);
/*
- * There is no need for RSB filling: entry_ibpb() ensures
+ * There is no need for RSB filling: __write_ibpb() ensures
* all predictions, including the RSB, are invalidated,
* regardless of IBPB implementation.
*/
@@ -2701,7 +2701,7 @@ static void __init srso_select_mitigation(void)
srso_mitigation = SRSO_MITIGATION_IBPB_ON_VMEXIT;
/*
- * There is no need for RSB filling: entry_ibpb() ensures
+ * There is no need for RSB filling: __write_ibpb() ensures
* all predictions, including the RSB, are invalidated,
* regardless of IBPB implementation.
*/
--
2.48.1
next prev parent reply other threads:[~2025-04-02 18:19 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-02 18:19 [PATCH v3 0/6] x86/bugs: RSB mitigation fixes and documentation Josh Poimboeuf
2025-04-02 18:19 ` Josh Poimboeuf [this message]
2025-04-02 18:29 ` [PATCH v3 1/6] x86/bugs: Rename entry_ibpb() Borislav Petkov
2025-04-02 18:44 ` Josh Poimboeuf
2025-04-02 18:48 ` Borislav Petkov
2025-04-02 19:37 ` Ingo Molnar
2025-04-03 0:34 ` Josh Poimboeuf
2025-04-02 18:19 ` [PATCH v3 2/6] x86/bugs: Use SBPB in __write_ibpb() if applicable Josh Poimboeuf
2025-04-02 20:41 ` Tom Lendacky
2025-04-03 2:12 ` Josh Poimboeuf
2025-04-02 21:04 ` Jim Mattson
2025-04-03 2:17 ` Josh Poimboeuf
2025-04-09 18:07 ` Jim Mattson
2025-04-09 18:29 ` Kaplan, David
2025-04-09 18:46 ` Jim Mattson
2025-04-02 18:19 ` [PATCH v3 3/6] x86/bugs: Fix RSB clearing in indirect_branch_prediction_barrier() Josh Poimboeuf
2025-04-04 14:45 ` Nikolay Borisov
2025-04-04 15:17 ` Josh Poimboeuf
2025-04-04 22:56 ` Nikolay Borisov
2025-04-05 0:56 ` Josh Poimboeuf
2025-04-08 7:15 ` Nikolay Borisov
2025-04-02 18:19 ` [PATCH v3 4/6] x86/bugs: Don't fill RSB on VMEXIT with eIBRS+retpoline Josh Poimboeuf
2025-04-08 13:50 ` Nikolay Borisov
2025-04-02 18:19 ` [PATCH v3 5/6] x86/bugs: Don't fill RSB on context switch with eIBRS Josh Poimboeuf
2025-04-08 13:51 ` Nikolay Borisov
2025-04-02 18:19 ` [PATCH v3 6/6] x86/bugs: Add RSB mitigation document Josh Poimboeuf
2025-04-02 19:58 ` Ingo Molnar
2025-04-03 0:38 ` Josh Poimboeuf
2025-04-03 2:57 ` Bagas Sanjaya
2025-04-03 7:48 ` Josh Poimboeuf
2025-04-04 2:39 ` Andrew Cooper
2025-04-04 19:30 ` Josh Poimboeuf
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