Merge branch 'x86-iopl-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[platform/kernel/linux-rpi.git] / arch / x86 / entry / entry_32.S

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 09fe560..5832b11 100644 (file)
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -739,6 +739,11 @@ SYM_CODE_START(__switch_to_asm)
        pushl   %ebx
        pushl   %edi
        pushl   %esi
+       /*
+        * Flags are saved to prevent AC leakage. This could go
+        * away if objtool would have 32bit support to verify
+        * the STAC/CLAC correctness.
+        */
        pushfl
 
        /* switch stack */
@@ -761,8 +766,9 @@ SYM_CODE_START(__switch_to_asm)
        FILL_RETURN_BUFFER %ebx, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW
 #endif
 
-       /* restore callee-saved registers */
+       /* Restore flags or the incoming task to restore AC state. */
        popfl
+       /* restore callee-saved registers */
        popl    %esi
        popl    %edi
        popl    %ebx