linux-kernel - [tip: objtool/core] x86/xen: Make write

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Date:   Fri, 17 Sep 2021 12:58:08 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Juergen Gross <jgross@...e.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: objtool/core] x86/xen: Make write_cr2() noinstr

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     209cfd0cbb6722d3461e4f928dc150e4c3811948
Gitweb:        https://git.kernel.org/tip/209cfd0cbb6722d3461e4f928dc150e4c3811948
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Thu, 24 Jun 2021 11:41:14 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Fri, 17 Sep 2021 13:12:16 +02:00

x86/xen: Make write_cr2() noinstr

vmlinux.o: warning: objtool: pv_ops[42]: native_write_cr2
vmlinux.o: warning: objtool: pv_ops[42]: xen_write_cr2
vmlinux.o: warning: objtool: exc_nmi()+0x127: call to pv_ops[42]() leaves .noinstr.text section

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Juergen Gross <jgross@...e.com>
Link: https://lore.kernel.org/r/20210624095148.563524913@infradead.org
---
 arch/x86/include/asm/paravirt.h | 2 +-
 arch/x86/kernel/paravirt.c      | 7 ++++++-
 arch/x86/xen/mmu_pv.c           | 3 ++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 8878065..be82b52 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -140,7 +140,7 @@ static __always_inline unsigned long read_cr2(void)
 				ALT_NOT(X86_FEATURE_XENPV));
 }
 
-static inline void write_cr2(unsigned long x)
+static __always_inline void write_cr2(unsigned long x)
 {
 	PVOP_VCALL1(mmu.write_cr2, x);
 }
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index e351014..fc2cf2b 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -223,6 +223,11 @@ static noinstr unsigned long pv_native_read_cr2(void)
 {
 	return native_read_cr2();
 }
+
+static noinstr void pv_native_write_cr2(unsigned long val)
+{
+	native_write_cr2(val);
+}
 #endif
 
 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
@@ -304,7 +309,7 @@ struct paravirt_patch_template pv_ops = {
 
 #ifdef CONFIG_PARAVIRT_XXL
 	.mmu.read_cr2		= __PV_IS_CALLEE_SAVE(pv_native_read_cr2),
-	.mmu.write_cr2		= native_write_cr2,
+	.mmu.write_cr2		= pv_native_write_cr2,
 	.mmu.read_cr3		= __native_read_cr3,
 	.mmu.write_cr3		= native_write_cr3,
 
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index 1df5f01..f3cafe5 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -1204,7 +1204,8 @@ static void __init xen_pagetable_init(void)
 	xen_remap_memory();
 	xen_setup_mfn_list_list();
 }
-static void xen_write_cr2(unsigned long cr2)
+
+static noinstr void xen_write_cr2(unsigned long cr2)
 {
 	this_cpu_read(xen_vcpu)->arch.cr2 = cr2;
 }