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Message-ID: <20231102112850.3448745-4-ubizjak@gmail.com>
Date: Thu, 2 Nov 2023 12:25:48 +0100
From: Uros Bizjak <ubizjak@...il.com>
To: x86@...nel.org, linux-kernel@...r.kernel.org
Cc: Uros Bizjak <ubizjak@...il.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"H. Peter Anvin" <hpa@...or.com>,
Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH 3/3] x86/callthunks: Fix and unify call thunks assembly snippets
Currently thunk debug macros explicitly define %gs: segment register
prefix for their percpu variables. This is not compatible with
!CONFIG_SMP, which requires non-prefixed percpu variables.
Fix call thunks debug macros to use PER_CPU_VAR macro from percpu.h
to conditionally use %gs: segment register prefix, depending on
CONFIG_SMP.
Finally, unify ASM_ prefixed assembly macros with their non-prefixed
variants. With support of %rip-relative relocations in place, call
thunk templates allow %rip-relative addressing, so unified assembly
snippet can be used everywhere.
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Uros Bizjak <ubizjak@...il.com>
---
arch/x86/include/asm/nospec-branch.h | 23 +++++++----------------
1 file changed, 7 insertions(+), 16 deletions(-)
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index f93e9b96927a..6f677be6bdb9 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -59,13 +59,13 @@
#ifdef CONFIG_CALL_THUNKS_DEBUG
# define CALL_THUNKS_DEBUG_INC_CALLS \
- incq %gs:__x86_call_count;
+ incq PER_CPU_VAR(__x86_call_count);
# define CALL_THUNKS_DEBUG_INC_RETS \
- incq %gs:__x86_ret_count;
+ incq PER_CPU_VAR(__x86_ret_count);
# define CALL_THUNKS_DEBUG_INC_STUFFS \
- incq %gs:__x86_stuffs_count;
+ incq PER_CPU_VAR(__x86_stuffs_count);
# define CALL_THUNKS_DEBUG_INC_CTXSW \
- incq %gs:__x86_ctxsw_count;
+ incq PER_CPU_VAR(__x86_ctxsw_count);
#else
# define CALL_THUNKS_DEBUG_INC_CALLS
# define CALL_THUNKS_DEBUG_INC_RETS
@@ -80,9 +80,6 @@
#define CREDIT_CALL_DEPTH \
movq $-1, PER_CPU_VAR(pcpu_hot + X86_call_depth);
-#define ASM_CREDIT_CALL_DEPTH \
- movq $-1, PER_CPU_VAR(pcpu_hot + X86_call_depth);
-
#define RESET_CALL_DEPTH \
xor %eax, %eax; \
bts $63, %rax; \
@@ -95,20 +92,14 @@
CALL_THUNKS_DEBUG_INC_CALLS
#define INCREMENT_CALL_DEPTH \
- sarq $5, %gs:pcpu_hot + X86_call_depth; \
- CALL_THUNKS_DEBUG_INC_CALLS
-
-#define ASM_INCREMENT_CALL_DEPTH \
sarq $5, PER_CPU_VAR(pcpu_hot + X86_call_depth); \
CALL_THUNKS_DEBUG_INC_CALLS
#else
#define CREDIT_CALL_DEPTH
-#define ASM_CREDIT_CALL_DEPTH
#define RESET_CALL_DEPTH
-#define INCREMENT_CALL_DEPTH
-#define ASM_INCREMENT_CALL_DEPTH
#define RESET_CALL_DEPTH_FROM_CALL
+#define INCREMENT_CALL_DEPTH
#endif
/*
@@ -158,7 +149,7 @@
jnz 771b; \
/* barrier for jnz misprediction */ \
lfence; \
- ASM_CREDIT_CALL_DEPTH \
+ CREDIT_CALL_DEPTH \
CALL_THUNKS_DEBUG_INC_CTXSW
#else
/*
@@ -311,7 +302,7 @@
.macro CALL_DEPTH_ACCOUNT
#ifdef CONFIG_CALL_DEPTH_TRACKING
ALTERNATIVE "", \
- __stringify(ASM_INCREMENT_CALL_DEPTH), X86_FEATURE_CALL_DEPTH
+ __stringify(INCREMENT_CALL_DEPTH), X86_FEATURE_CALL_DEPTH
#endif
.endm
--
2.41.0
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