x86/mce: Annotate mce_rd/wrmsrl() with noinstr

They do get called from the #MC handler which is already marked
"noinstr".

Commit

  e2def7d49d08 ("x86/mce: Make mce_rdmsrl() panic on an inaccessible MSR")

already got rid of the instrumentation in the MSR accessors, fix the
annotation now too, in order to get rid of:

  vmlinux.o: warning: objtool: do_machine_check()+0x4a: call to mce_rdmsrl() leaves .noinstr.text section

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200915194020.28807-1-bp@alien8.de

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 5b1d5f3..11b6697 100644 (file)
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -392,16 +392,25 @@ __visible bool ex_handler_rdmsr_fault(const struct exception_table_entry *fixup,
 }
 
 /* MSR access wrappers used for error injection */
-static u64 mce_rdmsrl(u32 msr)
+static noinstr u64 mce_rdmsrl(u32 msr)
 {
        DECLARE_ARGS(val, low, high);
 
        if (__this_cpu_read(injectm.finished)) {
-               int offset = msr_to_offset(msr);
+               int offset;
+               u64 ret;
 
+               instrumentation_begin();
+
+               offset = msr_to_offset(msr);
                if (offset < 0)
-                       return 0;
-               return *(u64 *)((char *)this_cpu_ptr(&injectm) + offset);
+                       ret = 0;
+               else
+                       ret = *(u64 *)((char *)this_cpu_ptr(&injectm) + offset);
+
+               instrumentation_end();
+
+               return ret;
        }
 
        /*
@@ -437,15 +446,21 @@ __visible bool ex_handler_wrmsr_fault(const struct exception_table_entry *fixup,
        return true;
 }
 
-static void mce_wrmsrl(u32 msr, u64 v)
+static noinstr void mce_wrmsrl(u32 msr, u64 v)
 {
        u32 low, high;
 
        if (__this_cpu_read(injectm.finished)) {
-               int offset = msr_to_offset(msr);
+               int offset;
 
+               instrumentation_begin();
+
+               offset = msr_to_offset(msr);
                if (offset >= 0)
                        *(u64 *)((char *)this_cpu_ptr(&injectm) + offset) = v;
+
+               instrumentation_end();
+
                return;
        }