Re: [PATCH v6 22/25] x86/asm: annotate indirect jumps

Peter Zijlstra
2020-10-21T09:32:46Z

On Wed, Oct 21, 2020 at 10:56:06AM +0200, Peter Zijlstra wrote:

> I do not see these in particular, although I do see a lot of:
>
> "sibling call from callable instruction with modified stack frame"

defconfig-build/vmlinux.o: warning: objtool: msr_write()+0x10a: sibling call from callable instruction with modified stack frame
defconfig-build/vmlinux.o: warning: objtool: msr_write()+0x99: (branch)
defconfig-build/vmlinux.o: warning: objtool: msr_write()+0x3e: (branch)
defconfig-build/vmlinux.o: warning: objtool: msr_write()+0x0: <=== (sym)

$ nm defconfig-build/vmlinux.o | grep msr_write
0000000000043250 t msr_write
00000000004289c0 T msr_write
0000000000003056 t msr_write.cold

Below 'fixes' it. So this is also caused by duplicate symbols.

---
diff --git a/arch/x86/lib/msr.c b/arch/x86/lib/msr.c
index 3bd905e10ee2..e36331f8f217 100644
--- a/arch/x86/lib/msr.c
+++ b/arch/x86/lib/msr.c
@@ -48,17 +48,6 @@ int msr_read(u32 msr, struct msr *m)
return err;
}

-/**
- * Write an MSR with error handling
- *
- * @msr: MSR to write
- * @m: value to write
- */
-int msr_write(u32 msr, struct msr *m)
-{
- return wrmsrl_safe(msr, m->q);
-}
-
static inline int __flip_bit(u32 msr, u8 bit, bool set)
{
struct msr m, m1;
@@ -80,7 +69,7 @@ static inline int __flip_bit(u32 msr, u8 bit, bool set)
if (m1.q == m.q)
return 0;

- err = msr_write(msr, &m1);
+ err = wrmsr_safe(msr, m1.q);
if (err)
return err;