[tip: x86/bugs] x86/nospec: Refactor UNTRAIN_RET[_*]

From: tip-bot2 for Josh Poimboeuf
Date: Sat Sep 23 2023 - 08:20:15 EST


The following commit has been merged into the x86/bugs branch of tip:

Commit-ID: e653cf101de2ac99d92049c38735cebc537fa2fb
Gitweb: https://git.kernel.org/tip/e653cf101de2ac99d92049c38735cebc537fa2fb
Author: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
AuthorDate: Mon, 04 Sep 2023 22:05:03 -07:00
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitterDate: Sat, 23 Sep 2023 14:13:03 +02:00

x86/nospec: Refactor UNTRAIN_RET[_*]

Factor out the UNTRAIN_RET[_*] common bits into a helper macro.

Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Acked-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Link: https://lore.kernel.org/r/f06d45489778bd49623297af2a983eea09067a74.1693889988.git.jpoimboe@xxxxxxxxxx
---
arch/x86/include/asm/nospec-branch.h | 31 ++++++++-------------------
1 file changed, 10 insertions(+), 21 deletions(-)

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 51e3f1a..dcc7847 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -288,35 +288,24 @@
* 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.
*/
-.macro UNTRAIN_RET
+.macro __UNTRAIN_RET ibpb_feature, call_depth_insns
#if defined(CONFIG_RETHUNK) || defined(CONFIG_CPU_IBPB_ENTRY)
VALIDATE_UNRET_END
ALTERNATIVE_3 "", \
CALL_UNTRAIN_RET, X86_FEATURE_UNRET, \
- "call entry_ibpb", X86_FEATURE_ENTRY_IBPB, \
- __stringify(RESET_CALL_DEPTH), X86_FEATURE_CALL_DEPTH
+ "call entry_ibpb", \ibpb_feature, \
+ __stringify(\call_depth_insns), X86_FEATURE_CALL_DEPTH
#endif
.endm

-.macro UNTRAIN_RET_VM
-#if defined(CONFIG_RETHUNK) || defined(CONFIG_CPU_IBPB_ENTRY)
- VALIDATE_UNRET_END
- ALTERNATIVE_3 "", \
- CALL_UNTRAIN_RET, X86_FEATURE_UNRET, \
- "call entry_ibpb", X86_FEATURE_IBPB_ON_VMEXIT, \
- __stringify(RESET_CALL_DEPTH), X86_FEATURE_CALL_DEPTH
-#endif
-.endm
+#define UNTRAIN_RET \
+ __UNTRAIN_RET X86_FEATURE_ENTRY_IBPB, __stringify(RESET_CALL_DEPTH)

-.macro UNTRAIN_RET_FROM_CALL
-#if defined(CONFIG_RETHUNK) || defined(CONFIG_CPU_IBPB_ENTRY)
- VALIDATE_UNRET_END
- ALTERNATIVE_3 "", \
- CALL_UNTRAIN_RET, X86_FEATURE_UNRET, \
- "call entry_ibpb", X86_FEATURE_ENTRY_IBPB, \
- __stringify(RESET_CALL_DEPTH_FROM_CALL), X86_FEATURE_CALL_DEPTH
-#endif
-.endm
+#define UNTRAIN_RET_VM \
+ __UNTRAIN_RET X86_FEATURE_IBPB_ON_VMEXIT, __stringify(RESET_CALL_DEPTH)
+
+#define UNTRAIN_RET_FROM_CALL \
+ __UNTRAIN_RET X86_FEATURE_ENTRY_IBPB, __stringify(RESET_CALL_DEPTH_FROM_CALL)


.macro CALL_DEPTH_ACCOUNT