diff options
| author | David Woodhouse <dwmw@amazon.co.uk> | 2018-02-19 13:50:56 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-03-15 12:54:36 +0300 |
| commit | a66fe0437d85ee3528b79ccaaa5806e0acacb480 (patch) | |
| tree | 1dcde709a9fc45cc0f0cae0aac97ed083c10f5e2 /arch/x86/entry | |
| parent | 8cb4113443393481f753ae50bdb6e898b845e086 (diff) | |
| download | linux-a66fe0437d85ee3528b79ccaaa5806e0acacb480.tar.xz | |
Revert "x86/retpoline: Simplify vmexit_fill_RSB()"
commit d1c99108af3c5992640aa2afa7d2e88c3775c06e upstream.
This reverts commit 1dde7415e99933bb7293d6b2843752cbdb43ec11. By putting
the RSB filling out of line and calling it, we waste one RSB slot for
returning from the function itself, which means one fewer actual function
call we can make if we're doing the Skylake abomination of call-depth
counting.
It also changed the number of RSB stuffings we do on vmexit from 32,
which was correct, to 16. Let's just stop with the bikeshedding; it
didn't actually *fix* anything anyway.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: arjan.van.de.ven@intel.com
Cc: bp@alien8.de
Cc: dave.hansen@intel.com
Cc: jmattson@google.com
Cc: karahmed@amazon.de
Cc: kvm@vger.kernel.org
Cc: pbonzini@redhat.com
Cc: rkrcmar@redhat.com
Link: http://lkml.kernel.org/r/1519037457-7643-4-git-send-email-dwmw@amazon.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/entry')
| -rw-r--r-- | arch/x86/entry/entry_32.S | 3 | ||||
| -rw-r--r-- | arch/x86/entry/entry_64.S | 3 |
2 files changed, 2 insertions, 4 deletions
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 2a35b1e0fb90..60c4c342316c 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -252,8 +252,7 @@ ENTRY(__switch_to_asm) * exist, overwrite the RSB with entries which capture * speculative execution to prevent attack. */ - /* Clobbers %ebx */ - FILL_RETURN_BUFFER RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW + FILL_RETURN_BUFFER %ebx, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW #endif /* restore callee-saved registers */ diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 0c48422085d2..6f3cc15e0c73 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -360,8 +360,7 @@ ENTRY(__switch_to_asm) * exist, overwrite the RSB with entries which capture * speculative execution to prevent attack. */ - /* Clobbers %rbx */ - FILL_RETURN_BUFFER RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW + FILL_RETURN_BUFFER %r12, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_CTXSW #endif /* restore callee-saved registers */ |