[PATCH v2 15/24] x86/xen: Make write_cr2() noinstr

Peter Zijlstra
2021-06-24T09:55:52Z

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@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(-)

--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -140,7 +140,7 @@ static __always_inline unsigned long rea
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);
}
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -243,6 +243,11 @@ static noinstr unsigned long pv_native_r
return native_read_cr2();
}

+static noinstr void pv_native_write_cr2(unsigned long val)
+{
+ native_write_cr2(val);
+}
+
struct paravirt_patch_template pv_ops = {
/* Cpu ops. */
.cpu.io_delay = native_io_delay,
@@ -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,

--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -1204,7 +1204,8 @@ static void __init xen_pagetable_init(vo
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;
}