linux-kernel - [PATCH 3/4] x86/cpu: Refactor sync

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Date:   Sun, 26 Jul 2020 21:31:31 -0700
From:   Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...e.de>,
        Andy Lutomirski <luto@...nel.org>, x86@...nel.org
Cc:     Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Cathy Zhang <cathy.zhang@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Kyung Min Park <kyung.min.park@...el.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        linux-kernel@...r.kernel.org,
        Ricardo Neri <ricardo.neri@...el.com>,
        Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-edac@...r.kernel.org
Subject: [PATCH 3/4] x86/cpu: Refactor sync_core() for readability

Instead of having #ifdef/#endif blocks inside sync_core() for X86_64 and
X86_32, implement the new function iret_to_self() with two versions.

In this manner, avoid having to use even more more #ifdef/#endif blocks
when adding support for SERIALIZE in sync_core().

Cc: Andy Lutomirski <luto@...nel.org>
Cc: Cathy Zhang <cathy.zhang@...el.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Fenghua Yu <fenghua.yu@...el.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Kyung Min Park <kyung.min.park@...el.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: "Ravi V. Shankar" <ravi.v.shankar@...el.com>
Cc: Sean Christopherson <sean.j.christopherson@...el.com>
Cc: linux-edac@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Co-developed-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Tony Luck <tony.luck@...el.com>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
---
---
 arch/x86/include/asm/special_insns.h |  1 -
 arch/x86/include/asm/sync_core.h     | 56 ++++++++++++++++------------
 2 files changed, 32 insertions(+), 25 deletions(-)

diff --git a/arch/x86/include/asm/special_insns.h b/arch/x86/include/asm/special_insns.h
index eb8e781c4353..59a3e13204c3 100644
--- a/arch/x86/include/asm/special_insns.h
+++ b/arch/x86/include/asm/special_insns.h
@@ -234,7 +234,6 @@ static inline void clwb(volatile void *__p)
 
 #define nop() asm volatile ("nop")
 
-
 #endif /* __KERNEL__ */
 
 #endif /* _ASM_X86_SPECIAL_INSNS_H */
diff --git a/arch/x86/include/asm/sync_core.h b/arch/x86/include/asm/sync_core.h
index 9c5573f2c333..fdb5b356e59b 100644
--- a/arch/x86/include/asm/sync_core.h
+++ b/arch/x86/include/asm/sync_core.h
@@ -6,6 +6,37 @@
 #include <asm/processor.h>
 #include <asm/cpufeature.h>
 
+#ifdef CONFIG_X86_32
+static inline void iret_to_self(void)
+{
+	asm volatile (
+		"pushfl\n\t"
+		"pushl %%cs\n\t"
+		"pushl $1f\n\t"
+		"iret\n\t"
+		"1:"
+		: ASM_CALL_CONSTRAINT : : "memory");
+}
+#else
+static inline void iret_to_self(void)
+{
+	unsigned int tmp;
+
+	asm volatile (
+		"mov %%ss, %0\n\t"
+		"pushq %q0\n\t"
+		"pushq %%rsp\n\t"
+		"addq $8, (%%rsp)\n\t"
+		"pushfq\n\t"
+		"mov %%cs, %0\n\t"
+		"pushq %q0\n\t"
+		"pushq $1f\n\t"
+		"iretq\n\t"
+		"1:"
+		: "=&r" (tmp), ASM_CALL_CONSTRAINT : : "cc", "memory");
+}
+#endif /* CONFIG_X86_32 */
+
 /*
  * This function forces the icache and prefetched instruction stream to
  * catch up with reality in two very specific cases:
@@ -44,30 +75,7 @@ static inline void sync_core(void)
 	 * Like all of Linux's memory ordering operations, this is a
 	 * compiler barrier as well.
 	 */
-#ifdef CONFIG_X86_32
-	asm volatile (
-		"pushfl\n\t"
-		"pushl %%cs\n\t"
-		"pushl $1f\n\t"
-		"iret\n\t"
-		"1:"
-		: ASM_CALL_CONSTRAINT : : "memory");
-#else
-	unsigned int tmp;
-
-	asm volatile (
-		"mov %%ss, %0\n\t"
-		"pushq %q0\n\t"
-		"pushq %%rsp\n\t"
-		"addq $8, (%%rsp)\n\t"
-		"pushfq\n\t"
-		"mov %%cs, %0\n\t"
-		"pushq %q0\n\t"
-		"pushq $1f\n\t"
-		"iretq\n\t"
-		"1:"
-		: "=&r" (tmp), ASM_CALL_CONSTRAINT : : "cc", "memory");
-#endif
+	iret_to_self();
 }
 
 /*
-- 
2.17.1