[tip: objtool/core] x86/xen: Make read_cr2() noinstr

tip-bot2 for Peter Zijlstra
2021-09-15T15:49:43Z

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

Commit-ID: ee6781aba03fc3040e3dfaa57fe8c2cea751ee35
Gitweb: https://git.kernel.org/tip/ee6781aba03fc3040e3dfaa57fe8c2cea751ee35
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Thu, 24 Jun 2021 11:41:13 +02:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 15 Sep 2021 15:51:48 +02:00

x86/xen: Make read_cr2() noinstr

vmlinux.o: warning: objtool: pv_ops[41]: native_read_cr2
vmlinux.o: warning: objtool: pv_ops[41]: xen_read_cr2
vmlinux.o: warning: objtool: pv_ops[41]: xen_read_cr2_direct
vmlinux.o: warning: objtool: exc_double_fault()+0x15: call to pv_ops[41]() leaves .noinstr.text section

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20210624095148.500331616@infradead.org
---
arch/x86/include/asm/paravirt.h | 2 +-
arch/x86/kernel/paravirt.c | 7 ++++++-
arch/x86/xen/xen-asm.S | 2 ++
3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index a13a9a3..8878065 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -133,7 +133,7 @@ static inline void write_cr0(unsigned long x)
PVOP_VCALL1(cpu.write_cr0, x);
}

-static inline unsigned long read_cr2(void)
+static __always_inline unsigned long read_cr2(void)
{
return PVOP_ALT_CALLEE0(unsigned long, mmu.read_cr2,
"mov %%cr2, %%rax;",
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 04cafc0..ff4ade8 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -238,6 +238,11 @@ struct pv_info pv_info = {
/* 64-bit pagetable entries */
#define PTE_IDENT __PV_IS_CALLEE_SAVE(_paravirt_ident_64)

+static noinstr unsigned long pv_native_read_cr2(void)
+{
+ return native_read_cr2();
+}
+
struct paravirt_patch_template pv_ops = {
/* Cpu ops. */
.cpu.io_delay = native_io_delay,
@@ -298,7 +303,7 @@ struct paravirt_patch_template pv_ops = {
.mmu.exit_mmap = paravirt_nop,

#ifdef CONFIG_PARAVIRT_XXL
- .mmu.read_cr2 = __PV_IS_CALLEE_SAVE(native_read_cr2),
+ .mmu.read_cr2 = __PV_IS_CALLEE_SAVE(pv_native_read_cr2),
.mmu.write_cr2 = native_write_cr2,
.mmu.read_cr3 = __native_read_cr3,
.mmu.write_cr3 = native_write_cr3,
diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S
index 1e62644..aef4a1e 100644
--- a/arch/x86/xen/xen-asm.S
+++ b/arch/x86/xen/xen-asm.S
@@ -102,6 +102,7 @@ SYM_FUNC_START(check_events)
ret
SYM_FUNC_END(check_events)

+.pushsection .noinstr.text, "ax"
SYM_FUNC_START(xen_read_cr2)
FRAME_BEGIN
_ASM_MOV PER_CPU_VAR(xen_vcpu), %_ASM_AX
@@ -116,6 +117,7 @@ SYM_FUNC_START(xen_read_cr2_direct)
FRAME_END
ret
SYM_FUNC_END(xen_read_cr2_direct);
+.popsection

.macro xen_pv_trap name
SYM_CODE_START(xen_\name)