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

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index a13a9a3..8878065 100644 (file)
--- 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..e351014 100644 (file)
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -218,6 +218,11 @@ void paravirt_end_context_switch(struct task_struct *next)
        if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
                arch_enter_lazy_mmu_mode();
 }
+
+static noinstr unsigned long pv_native_read_cr2(void)
+{
+       return native_read_cr2();
+}
 #endif
 
 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
@@ -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 (file)
--- 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)